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1.  Diagnosis and treatment outcome of mycotic keratitis at a tertiary eye care center in eastern india 
BMC Ophthalmology  2011;11:39.
Background
Mycotic keratitis is an important cause of corneal blindness world over including India. Geographical location and climate are known to influence the profile of fungal diseases. While there are several reports on mycotic keratitis from southern India, comprehensive clinico-microbiological reports from eastern India are few. The reported prevalence of mycotic keratitis are 36.7%,36.3%,25.6%,7.3% in southern, western, north- eastern and northern India respectively. This study reports the epidemiological characteristics, microbiological diagnosis and treatment outcome of mycotic keratitis at a tertiary eye care center in eastern India.
Methods
A retrospective review of medical and microbiology records was done for all patients with laboratory proven fungal keratitis.
Results
Between July 2006 and December 2009, 997 patients were clinically diagnosed as microbial keratitis. While no organisms were found in 25.4% (253/997) corneal samples, 23.4% (233/997) were bacterial, 26.4% (264/997) were fungal (45 cases mixed with bacteria), 1.4% (14/997) were Acanthamoeba with or without bacteria and 23.4% (233/997) were microsporidial with or without bacteria. Two hundred fifteen of 264 (81.4%, 215/264) samples grew fungus in culture while 49 corneal scrapings were positive for fungal elements only in direct microscopy. Clinical diagnosis of fungal keratitis was made in 186 of 264 (70.5%) cases. The microscopic detection of fungal elements was achieved by 10% potassium hydroxide with 0.1% calcoflour white stain in 94.8%(238/251) cases. Aspergillus species (27.9%, 60/215) and Fusarium species (23.2%, 50/215) were the major fungal isolates. Concomitant bacterial infection was seen in 45 (17.1%, 45/264) cases of mycotic keratitis. Clinical outcome of healed scar was achieved in 94 (35.6%, 94/264) cases. Fifty two patients (19.7%, 52/264) required therapeutic PK, 9 (3.4%, 9/264) went for evisceration, 18.9% (50/264) received glue application with bandage contact lens (BCL) for impending perforation, 6.1% (16/264) were unchanged and 16.3% (43/264) were lost to follow up. Poor prognosis like PK (40/52, 75.9%, p < 0.001) and BCL (30/50, 60%, p < 0.001) was seen in significantly larger number of patients with late presentation (> 10 days).
Conclusions
The relative prevalence of mycotic keratitis in eastern India is lower than southern, western and north-eastern India but higher than northern India, however, Aspergillus and Fusarium are the predominant genera associated with fungal keratitis across India. The response to medical treatment is poor in patients with late presentation.
doi:10.1186/1471-2415-11-39
PMCID: PMC3286391  PMID: 22188671
Mycotic; fungal; keratitis; microscopy; culture; treatment outcome
2.  Management and treatment of contact lens-related Pseudomonas keratitis 
Pubmed and Medline were searched for articles referring to Pseudomonas keratitis between the years 2007 and 2012 to obtain an overview of the current state of this disease. Keyword searches used the terms “Pseudomonas” + “Keratitis” limit to “2007–2012”, and [“Ulcerative” or “Microbial”] + “Keratitis” + “Contact lenses” limit to “2007–2012”. These articles were then reviewed for information on the percentage of microbial keratitis cases associated with contact lens wear, the frequency of Pseudomonas sp. as a causative agent of microbial keratitis around the world, the most common therapies to treat Pseudomonas keratitis, and the sensitivity of isolates of Pseudomonas to commonly prescribed antibiotics. The percentage of microbial keratitis associated with contact lens wear ranged from 0% in a study from Nepal to 54.5% from Japan. These differences may be due in part to different frequencies of contact lens wear. The frequency of Pseudomonas sp. as a causative agent of keratitis ranged from 1% in Japan to over 50% in studies from India, Malaysia, and Thailand. The most commonly reported agents used to treat Pseudomonas keratitis were either aminoglycoside (usually gentamicin) fortified with a cephalosporin, or monotherapy with a fluoroquinolone (usually ciprofloxacin). In most geographical areas, most strains of Pseudomonas sp. (≥95%) were sensitive to ciprofloxacin, but reports from India, Nigeria, and Thailand reported sensitivity to this antibiotic and similar fluoroquinolones of between 76% and 90%.
doi:10.2147/OPTH.S25168
PMCID: PMC3392919  PMID: 22791973
Pseudomonas; keratitis; contact lens
3.  Epidemiological profile of fungal keratitis in urban population of West Bengal, India 
Oman Journal of Ophthalmology  2009;2(3):114-118.
Background
Corneal diseases are one of the major causes of visual loss and blindness, second only to cataract. Amongst corneal diseases, microbial keratitis is a major blinding disease. In some countries, fungal keratitis accounts for almost 50% of patients with culture-proven microbial keratitis.
Aim
This study was conducted to determine the epidemiological characteristics of fungal keratitis in an urban population of West Bengal and identify the specific pathogenic organisms.
Methods
The charts of patients with microbial keratitis who attended the Cornea Services of Priyamvada Birla Aravind Eye Hospital from January to December 2008 were retrospectively reviewed. Records of patients with 10% KOH mount and culture positive fungal keratitis were analyzed for epidemiological features, laboratory findings and treatment outcomes.
Results
Of the 289 patients of microbial keratitis included in the study, 110 patients (38.06%) were diagnosed with fungal keratitis (10% KOH mount positive). Of the 110 patients, 74 (67.27%) fitted the study inclusion criteria (10% KOH mount and culture positive). Forty five of 74 patients (60.81%) in the study group were in the older age group (>50 years). Ocular trauma in 35 cases (47.29%) was identified as a high risk factor and vegetative injuries in 17 cases (22.97%) were identified as a significant cause for fungal keratitis. Maximum organism source was from corneal scrapings in 41 cases (55%). The predominant fungal species isolated was Aspergillus sp (55.40%) followed by Candida albicans 14 cases (18.91%) and Fusarium sp. in 8 cases (10.81%). Agricultural activity related ocular trauma was the principal cause of mycotic keratitis and males were more commonly affected. Thirty of 74 cases (40.55%) of the culture positive patients healed with corneal scar formation with medical treatment whereas 44 cases (59.45%) required therapeutic keratoplasty.
Conclusion
Fungal keratitis is an important cause of microbial keratitis with injury to the cornea being a leading predisposing factor. Although Aspergillus sp. was implicated in most of the patients in our study population, Candida sp. were found in higher numbers than previously reported. Keratitis caused by filamentous fungi responds adequately to medical management. Therapeutic keratoplasty continues to remain an important treatment modality in infections with Candida sp. Early diagnosis with prompt identification of the pathogenic organism is mandatory to initiate appropriate therapy and thereby reduce morbidity.
doi:10.4103/0974-620X.57310
PMCID: PMC2903915  PMID: 20927207
Candida sp.; fungal keratitis; therapeutic keratoplasty
4.  The treatment of herpes simplex virus epithelial keratitis. 
PURPOSE: Epithelial keratitis is the most common presentation of ocular infection by herpes simplex virus (HSV). Quantitative assessment of available therapy is needed to guide evidence-based ophthalmology. This study aimed to compare the efficacy of various treatments for dendritic or geographic HSV epithelial keratitis and to evaluate the role of various clinical characteristics on epithelial healing. METHODS: Following a systematic review of the literature, information from clinical trials of HSV dendritic or geographic epithelial keratitis was extracted, and the methodological quality of each study was scored. Methods of epithelial cauterization and curettage were grouped as relatively equivalent physicochemical therapy, and solution and ointment formulations of a given topical antiviral agent were combined. The proportion healed with 1 week of therapy, a scheduled follow-up day that approximated the average time of resolution with antiviral therapy, was selected as the primary outcome based on a masked evaluation of maximum treatment differences in published healing curves. The proportion healed at 14 days was recorded as supplemental information. Fixed-effects and random-effects meta-analysis models were used to obtain summary estimates by pooling results from comparative treatment trials. Hypotheses about which prognostic factors might affect epithelial healing during antiviral therapy were developed by multivariate analysis of the Herpetic Eye Disease Study dataset. RESULTS: After excluding 48 duplicate reports, 14 nonrandomized studies, 15 studies with outdated or similar treatments, and 29 trials lacking sufficient data on healing or accessibility, 76 primary reports were identified. These reports involved 4,251 patients allocated to 93 treatment comparisons of dendritic epithelial keratitis in 28 categories and 9 comparisons of geographic epithelial keratitis in 6 categories. For dendritic keratitis, idoxuridine was better than placebo at 7 days (combined odds ratio [OR], 3.59; 95% confidence interval [CI], 1.92-6.70), and at 14 days (OR, 4.17; 95% CI, 1.33-13.04), but pooling was limited by lack of homogeneity and low study quality. Direct comparisons at 1 week of treatment showed that trifluridine or acyclovir was significantly better than idoxuridine (OR, 3.12 and 4.56; 95% CI, 1.55-6.29 and 2.76-7.52, respectively), and indirect comparisons were also consistent with a clinically significant benefit. Vidarabine was not significantly better than idoxuridine in pooled treatment comparisons at 1 week (OR, 1.20; 95% CI, 0.72-2.00) but was better in 2 indirect comparisons (OR, 4.22 and 4.78; 95% CI, 1.69-10.54 and 2.15-10.65, respectively). At 14 days, trifluridine (OR, 6.05; 95% CI, 2.50-14.66), acyclovir (OR, 2.88; 95% CI, 1.39-4.78), and vidarabine (OR, 1.24; 95% CI, 0.65-2.37) were each better than idoxuridine. Trials of geographic epithelial keratitis also suggested that trifluridine, acyclovir, and vidarabine were more effective that idoxuridine. Other topical antiviral agents, such as bromovinyldeoxuridine, ganciclovir, and foscarnet, appeared equivalent to trifluridine or acyclovir. Oral acyclovir was equivalent to topical antiviral therapy and did not hasten healing when used in combination with topical treatment. Antiviral agents did not increase the speed of healing when compared to debridement but reduced the risk of recrudescent epithelial keratitis. The combination of physicochemical treatment with an antiviral agent seemed to be better than either physicochemical or antiviral treatment alone, but the heterogeneous cauterization and curettage techniques and the various treatment combinations limited valid quantitative summary effect measures. The combination of topical interferon with an antiviral agent was significantly better than antiviral therapy at 7 days (OR, 13.49; 95% CI, 7.39-24.61) but not at 14 days (OR, 2.36; 95% CI, 0.82-6.79). Finding apparent heterogeneity for some pooled estimates suggested that dissimilarities in patients, interventions, outcomes, or other logistical aspects of clinical trials occur across studies. CONCLUSIONS: The available evidence on the acute treatment of presumed HSV epithelial keratitis demonstrates the effectiveness of antiviral treatment and shows the log-logistic healing curve of treated dendritic epithelial keratitis. Topical trifluridine, acyclovir, and vidarabine were significantly more effective than idoxuridine but similar in relative effectiveness for dendritic epithelial keratitis. Physicochemical methods of removing infected corneal epithelium are effective, but adjunctive virucidal agents are needed to avert recrudescent epithelial keratitis. Whether debridement in combination with antiviral therapy is more beneficial than antiviral chemotherapy alone appears likely but remains inconclusive. The combination of topical interferon with an antiviral agent significantly speeds epithelial healing. Future trials of the acute treatment of HSV epithelial keratitis must aim to achieve adequate statistical power for assessing the primary outcome and should consider the effect of lesion size and other characteristics on treatment response.
PMCID: PMC1298240  PMID: 11190039
5.  Epidemiological and microbiological profile of infective keratitis in Ahmedabad 
Indian Journal of Ophthalmology  2012;60(4):267-272.
Context:
Study of patients attending tertiary care ophthalmology institute at Ahmedabad.
Aims:
To study the microbiological etiology and epidemiological factors associated with suppurative keratitis.
Settings and Design:
A total of 150 corneal scrapings were evaluated from patients presenting with corneal ulcers at a tertiary ophthalmology center, Ahmedabad from July 2007 to June 2008.
Materials and Methods:
Scrapings were subjected to Gram stain, potassium hydroxide preparation and culture for bacterial and fungal pathogens. Socio-demographic data and risk factors were recorded.
Results:
Ninety percent (135/150) people with corneal ulcers had trauma as predisposing factor for keratitis. Trauma due to wooden objects was the leading cause (46/135) followed by vegetable matter and stone injury (23/135). Microbial etiology was established in 59.3% (89/150) of scrapings. Out of 89 positive isolates, 65.1% (58/89) were bacterial while 34.9% (31/89) were fungal. Among the bacterial isolates, 60.3% (35/58) were Gram-positive cocci while 39.7% (23/58) were Gram-negative bacilli. The most common bacterial isolate was Staphylococus aureus (32.7%, 19/58) followed by coagulase-negative Staphylococci (25.8%, 15/58) and Pseudomonas (18.9%, 11/58). Among the 31 fungal pathogens, Aspergillus species was the most common (35.4%11/31), followed by Fusarium species (22.5%, 7/31).
Conclusion:
Trauma with wooden material is the most common predisposing factor for suppurative keratitis. Males were more affected than females. Bacterial ulcers were more common than fungal in areas in and around Ahmedabad. Staphylococcus aureus and Aspergillus were the commonest bacterial and fungal isolates respectively. Geographical variation persists in microbial etiology of suppurative keratitis.
doi:10.4103/0301-4738.98702
PMCID: PMC3442460  PMID: 22824594
Microbial etiology; mucopurulent keratitis; suppurative keratitis
6.  Incidence and microbiological profile of mycotic keratitis in a tertiary care eye hospital: A retrospective analysis 
Saudi Journal of Ophthalmology  2011;26(2):217-221.
Purpose
To determine the incidence and microbiological profile of mycotic keratitis seen at a tertiary care eye hospital.
Materials and methods
A retrospective review of microbiology records of patients presenting with suspected microbial keratitis seen between January 2006 and December 2009 was performed. Patients with positive fungal cultures were further analyzed for the type of fungus isolated and associated bacterial pathogens.
Results
Microbiology records of 2300 patients with suspected microbial keratitis were reviewed. A microbiological diagnosis of mycotic keratitis was established in 87 (3.8%) patients over a four year period based on positive fungal cultures. The yearly incidence of mycotic keratitis was 3.2% (2006), 4.9% (2007), 3.3% (2008) and 3.6% (2009). Filamentous fungi were isolated more often than yeasts. Aspergillus species followed by Fusarium species and Trichophyton species were the commonest filamentous fungi isolated while Candida albicans was the most frequently encountered yeast. Mixed infections due to fungal and bacterial pathogens were seen in 25/87 (28.7%) patients.
Conclusion
Cumulative incidence of mycotic keratitis was 3.8% over a four year period. Aspergillus species and Candida albicans were the most frequent pathogenic organisms causing mycotic keratitis in this part of the world. Mixed infections were seen in 28.7% of the patients. Knowledge of the “local” etiology within a region may be valuable in the management of mycotic keratitis in instituting an empirical therapy, especially when facilities for microscopy, cultures and antifungal susceptibility are not readily available. The baseline information presented will also be helpful in the planning of a corneal ulcer management strategy and for future studies on mycotic keratitis.
doi:10.1016/j.sjopt.2011.11.005
PMCID: PMC3729643  PMID: 23960995
Mycotic keratitis; Incidence; Microbiological profile
7.  Topical corticosteroids as adjunctive therapy for bacterial keratitis 
Background
Bacterial keratitis is a serious ocular infectious disease that can lead to severe visual disability. Risk factors for bacterial corneal infection include contact lens wear, ocular surface disease, corneal trauma, and previous ocular or eyelid surgery. Topical antibiotics constitute the mainstay of treatment in cases of bacterial keratitis, whereas the use of topical corticosteroids as an adjunctive therapy to antibiotics remains controversial. Topical corticosteroids are usually used to control inflammation using the smallest amount of the drug. Their use requires optimal timing, concomitant antibiotics, and careful follow-up.
Objectives
The objective of the review was to assess the effectiveness and safety of corticosteroids as adjunctive therapy for bacterial keratitis. Secondary objectives included evaluation of health economic outcomes and quality of life outcomes.
Search methods
We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2014), EMBASE (January 1980 to July 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to July 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 14 July 2014. We also searched the Science Citation Index to identify additional studies that had cited the only trial included in the original version of this review, reference lists of included trials, earlier reviews, and the American Academy of Ophthalmology guidelines. We also contacted experts to identify any unpublished and ongoing randomized trials.
Selection criteria
We included randomized controlled trials (RCTs) that had evaluated adjunctive therapy with topical corticosteroids in people with bacterial keratitis who were being treated with antibiotics.
Data collection and analysis
We used the standard methodological procedures expected by The Cochrane Collaboration.
Main results
We found four RCTs that met the inclusion criteria of this review. The total number of included participants was 611 (612 eyes), ranging from 30 to 500 participants per trial. One trial was included in the previous version of the review, and we identified three additional trials through the updated searches in July 2014. One of the three smaller trials was a pilot study of the largest study: the Steroids for Corneal Ulcers Trial (SCUT). All trials compared the treatment of bacterial keratitis with topical corticosteroid and without topical corticosteroid and had follow-up periods ranging from two months to one year. These trials were conducted in the USA, Canada, India, and South Africa.
All trials reported data on visual acuity ranging from three weeks to one year, and none of them found any important difference between the corticosteroid group and the control group. The pilot study of the SCUT reported that time to re-epithelialization in the steroid group was 53% slower than the placebo group after adjusting for baseline epithelial defect size (hazard ratio (HR) 0.47; 95% confidence interval (CI) 0.23 to 0.94). However, the SCUT did not find any important difference in time to re-epithelialization (HR 0.92; 95% CI 0.76 to 1.11). For adverse events, none of the three small trials found any important difference between the two treatment groups. The investigators of the largest trial reported that more patients in the control group developed intraocular pressure (IOP) elevation (risk ratio (RR) 0.20; 95% CI 0.04 to 0.90). One trial reported quality of life and concluded that there was no difference between the two groups (data not available). We did not find any reports regarding economic outcomes.
Although the four trials were generally of good methodological design, all trials had considerable losses to follow-up (10% or more) in the final analyses. Further, three of the four trials were underpowered to detect treatment effect differences between groups and inconsistency in outcome measurements precluded meta-analyses for most outcomes relevant to this review.
Authors’ conclusions
There is inadequate evidence as to the effectiveness and safety of adjunctive topical corticosteroids compared with no topical corticosteroids in improving visual acuity, infiltrate/scar size, or adverse events among participants with bacterial keratitis. Current evidence does not support a strong effect of corticosteroid, but may be due to insufficient power to detect a treatment effect.
doi:10.1002/14651858.CD005430.pub3
PMCID: PMC4269217  PMID: 25321340
Adrenal Cortex Hormones [*therapeutic use]; Chemotherapy, Adjuvant [methods]; Eye Infections, Bacterial [*drug therapy]; Keratitis [*drug therapy; microbiology]; Humans
8.  Limbal Stem Cell Transplantation 
Executive Summary
Objective
The objective of this analysis is to systematically review limbal stem cell transplantation (LSCT) for the treatment of patients with limbal stem cell deficiency (LSCD). This evidence-based analysis reviews LSCT as a primary treatment for nonpterygium LSCD conditions, and LSCT as an adjuvant therapy to excision for the treatment of pterygium.
Background
Clinical Need: Condition and Target Population
The outer surface of the eye is covered by 2 distinct cell layers: the corneal epithelial layer that overlies the cornea, and the conjunctival epithelial layer that overlies the sclera. These cell types are separated by a transitional zone known as the limbus. The corneal epithelial cells are renewed every 3 to 10 days by a population of stem cells located in the limbus.
Nonpterygium Limbal Stem Cell Deficiency
When the limbal stem cells are depleted or destroyed, LSCD develops. In LSCD, the conjunctival epithelium migrates onto the cornea (a process called conjunctivalization), resulting in a thickened, irregular, unstable corneal surface that is prone to defects, ulceration, corneal scarring, vascularization, and opacity. Patients experience symptoms including severe irritation, discomfort, photophobia, tearing, blepharospasm, chronic inflammation and redness, and severely decreased vision.
Depending on the degree of limbal stem cell loss, LSCD may be total (diffuse) or partial (local). In total LSCD, the limbal stem cell population is completed destroyed and conjunctival epithelium covers the entire cornea. In partial LSCD, some areas of the limbus are unharmed, and the corresponding areas on the cornea maintain phenotypically normal corneal epithelium.
Confirmation of the presence of conjunctivalization is necessary for LSCD diagnosis as the other characteristics and symptoms are nonspecific and indicate a variety of diseases. The definitive test for LSCD is impression cytology, which detects the presence of conjunctival epithelium and its goblet cells on the cornea. However, in the opinion of a corneal expert, diagnosis is often based on clinical assessment, and in the expert’s opinion, it is unclear whether impression cytology is more accurate and reliable than clinical assessment, especially for patients with severe LSCD.
The incidence of LSCD is not well understood. A variety of underlying disorders are associated with LSCD including chemical or thermal injuries, ultraviolet and ionizing radiation, Stevens-Johnson syndrome, multiple surgeries or cryotherapies, contact lens wear, extensive microbial infection, advanced ocular cicatricial pemphigoid, and aniridia. In addition, some LSCD cases are idiopathic. These conditions are uncommon (e.g., the prevalence of aniridia ranges from 1 in 40,000 to 1 in 100,000 people).
Pterygium
Pterygium is a wing-shaped fibrovascular tissue growth from the conjunctiva onto the cornea. Pterygium is the result of partial LSCD caused by localized ultraviolet damage to limbal stem cells. As the pterygium invades the cornea, it may cause irregular astigmatism, loss of visual acuity, chronic irritation, recurrent inflammation, double vision, and impaired ocular motility.
Pterygium occurs worldwide. Incidence and prevalence rates are highest in the “pterygium belt,” which ranges from 30 degrees north to 30 degrees south of the equator, and lower prevalence rates are found at latitudes greater than 40 degrees. The prevalence of pterygium for Caucasians residing in urban, temperate climates is estimated at 1.2%.
Existing Treatments Other Than Technology Being Reviewed
Nonpterygium Limbal Stem Cell Deficiency
In total LSCD, a patient’s limbal stem cells are completely depleted, so any successful treatment must include new stem cells. Autologous oral mucosal epithelium transplantation has been proposed as an alternative to LSCT. However, this procedure is investigational, and there is very limited level 4c evidence1 to support this technique (fewer than 20 eyes examined in 4 case series and 1 case report).
For patients with partial LSCD, treatment may not be necessary if their visual axis is not affected. However, if the visual axis is conjunctivalized, several disease management options exist including repeated mechanical debridement of the abnormal epithelium; intensive, nonpreserved lubrication; bandage contact lenses; autologous serum eye drops; other investigational medical treatments; and transplantation of an amniotic membrane inlay. However, these are all disease management treatments; LSCT is the only curative option.
Pterygium
The primary treatment for pterygium is surgical excision. However, recurrence is a common problem after excision using the bare sclera technique: reported recurrence rates range from 24% to 89%. Thus, a variety of adjuvant therapies have been used to reduce the risk of pterygium recurrence including LSCT, amniotic membrane transplantation (AMT), conjunctival autologous (CAU) transplantation, and mitomycin C (MMC, an antimetabolite drug).
New Technology Being Reviewed
To successfully treat LSCD, the limbal stem cell population must be repopulated. To achieve this, 4 LSCT procedures have been developed: conjunctival-limbal autologous (CLAU) transplantation; living-related conjunctival-limbal allogeneic (lr-CLAL) transplantation; keratolimbal allogeneic (KLAL) transplantation; and ex vivo expansion of limbal stem cells transplantation. Since the ex vivo expansion of limbal stem cells transplantation procedure is considered experimental, it has been excluded from the systematic review. These procedures vary by the source of donor cells and the amount of limbal tissue used. For CLAU transplants, limbal stem cells are obtained from the patient’s healthy eye. For lr-CLAL and KLAL transplants, stem cells are obtained from living-related and cadaveric donor eyes, respectively.
In CLAU and lr-CLAL transplants, 2 to 4 limbal grafts are removed from the superior and inferior limbus of the donor eye. In KLAL transplants, the entire limbus from the donor eye is used.
The recipient eye is prepared by removing the abnormal conjunctival and scar tissue. An incision is made into the conjunctival tissue into which the graft is placed, and the graft is then secured to the neighbouring limbal and scleral tissue with sutures. Some LSCT protocols include concurrent transplantation of an amniotic membrane onto the cornea.
Regulatory Status
Health Canada does not require premarket licensure for stem cells. However, they are subject to Health Canada’s clinical trial regulations until the procedure is considered accepted transplantation practice, at which time it will be covered by the Safety of Human Cells, Tissues and Organs for Transplantation Regulations (CTO Regulations).
Review Strategy
The Medical Advisory Secretariat systematically reviewed the literature to assess the effectiveness and safety of LSCT for the treatment of patients with nonpterygium LSCD and pterygium. A comprehensive search method was used to retrieve English-language journal articles from selected databases.
The GRADE approach was used to systematically and explicitly evaluate the quality of evidence and strength of recommendations.
Summary of Findings
Nonpterygium Limbal Stem Cell Deficiency
The search identified 873 citations published between January 1, 2000, and March 31, 2008. Nine studies met the inclusion criteria, and 1 additional citation was identified through a bibliography review. The review included 10 case series (3 prospective and 7 retrospective).
Patients who received autologous transplants (i.e., CLAU) achieved significantly better long-term corneal surface results compared with patients who received allogeneic transplants (lr-CLAL, P< .001; KLAL, P< .001). There was no significant difference in corneal surface outcomes between the allogeneic transplant options, lr-CLAL and KLAL (P = .328). However, human leukocyte antigen matching and systemic immunosuppression may improve the outcome of lr-CLAL compared with KLAL. Regardless of graft type, patients with Stevens-Johnson syndrome had poorer long-term corneal surface outcomes.
Concurrent AMT was associated with poorer long-term corneal surface improvements. When the effect of the AMT was removed, the difference between autologous and allogeneic transplants was much smaller.
Patients who received CLAU transplants had a significantly higher rate of visual acuity improvements compared with those who received lr-CLAL transplants (P = .002). However, to achieve adequate improvements in vision, patients with deep corneal scarring will require a corneal transplant several months after the LSCT.
No donor eye complications were observed.
Epithelial rejection and microbial keratitis were the most common long-term complications associated with LSCT (complications occurred in 6%–15% of transplantations). These complications can result in graft failure, so patients should be monitored regularly following LSCT.
Pterygium
The search yielded 152 citations published between January 1, 2000 and May 16, 2008. Six randomized controlled trials (RCTs) that evaluated LSCT as an adjuvant therapy for the treatment of pterygium met the inclusion criteria and were included in the review.
Limbal stem cell transplantation was compared with CAU, AMT, and MMC. The results showed that CLAU significantly reduced the risk of pterygium recurrence compared with CAU (relative risk [RR], 0.09; 95% confidence interval [CI], 0.01–0.69; P = .02). CLAU reduced the risk of pterygium recurrence for primary pterygium compared with MMC, but this comparison did not reach statistical significance (RR, 0.48; 95% CI, 0.21–1.10; P = .08). Both AMT and CLAU had similar low rates of recurrence (2 recurrences in 43 patients and 4 in 46, respectively), and the RR was not significant (RR, 1.88; 95% CI, 0.37–9.5; P = .45). Since sample sizes in the included studies were small, failure to detect a significant difference between LSCT and AMT or MMC could be the result of type II error. Limbal stem cell transplantation as an adjuvant to excision is a relatively safe procedure as long-term complications were rare (< 2%).
GRADE Quality of Evidence
Nonpterygium Limbal Stem Cell Deficiency
The evidence for the analyses related to nonpterygium LSCD was based on 3 prospective and 7 retrospective case series. Thus, the GRADE quality of evidence is very low, and any estimate of effect is very uncertain.
Pterygium
The analyses examining LSCT as an adjuvant treatment option for pterygium were based on 6 RCTs. The quality of evidence for the overall body of evidence for each treatment option comparison was assessed using the GRADE approach. In each of the comparisons, the quality of evidence was downgraded due to serious or very serious limitations in study quality (individual study quality was assessed using the Jadad scale, and an assessment of allocation concealment and the degree of loss to follow-up), which resulted in low- to moderate-quality GRADE evidence ratings (low-quality evidence for the CLAU and AMT and CLAU and MMC comparisons, and moderate-quality evidence for the CLAU and CAU comparison).
Ontario Health System Impact Analysis
Nonpterygium Limbal Stem Cell Deficiency
Since 1999, Ontario’s out-of-country (OOC) program has approved and reimbursed 8 patients for LSCTs and 1 patient for LSCT consultations. Similarly, most Canadian provinces have covered OOC or out-of-province LSCTs. Several corneal experts in Ontario have the expertise to perform LSCTs.
As there are no standard guidelines for LSCT, patients who receive transplants OOC may not receive care aligned with the best evidence. To date, many of the patients from Ontario who received OOC LSCTs received concurrent AMTs, and the evidence from this analysis questions the use of this procedure. In addition, 1 patient received a cultured LSCT, a procedure that is considered investigational. Many patients with LSCD have bilateral disease and therefore require allogeneic transplants. These patients will require systemic and topical immunosuppression for several years after the transplant, perhaps indefinitely. Thus, systemic side effects associated with immunosuppression are a potential concern, and patients must be monitored regularly.
Amniotic membrane transplantation is a common addition to many ocular surface reconstruction procedures, including LSCT. Amniotic membranes are recovered from human placentas from planned, uneventful caesarean sections. Before use, serological screening of the donor’s blood should be conducted. However, there is still a theoretical risk of disease transmission associated with this procedure.
Financial Impact
For the patients who were reimbursed for OOC LSCTs, the average cost of LSCT per eye was $18,735.20 Cdn (range, $8,219.54–$33,933.32). However, the actual cost per patient is much higher as these costs do not include consultations and follow-up visits, multiple LSCTs, and any additional procedures (e.g., corneal transplants) received during the course of treatment OOC. When these additional costs were considered, the average cost per patient was $57,583 Cdn (range, $8,219.54–$130,628.20).
The estimated average total cost per patient for performing LSCT in Ontario is $2,291.48 Cdn (range, $951.48–$4,538.48) including hospital and physician fees. This cost is based on the assumption that LSCT is technically similar to a corneal transplant, an assumption which needs to be verified. The cost does not include corneal transplantations, which some proportion of patients receiving a LSCT will require within several months of the limbal transplant.
Pterygium
Pterygium recurrence rates after surgical excision are high, ranging from 24% to 89%. However, according to clinical experts, the rate of recurrence is low in Ontario. While there is evidence that the prevalence of pterygium is higher in the “pterygium belt,” there was no evidence to suggest different recurrence rates or disease severity by location or climate.
Conclusions
Nonpterygium Limbal Stem Cell Deficiency
Successful LSCTs result in corneal re-epithelialization and improved vision in patients with LSCD. However, patients who received concurrent AMT had poorer long-term corneal surface improvements. Conjunctival-limbal autologous transplantation is the treatment option of choice, but if it is not possible, living-related or cadaveric allogeneic transplants can be used. The benefits of LSCT outweigh the risks and burdens, as shown in Executive Summary Table 1. According to GRADE, these recommendations are strong with low- to very low-quality evidence.
Benefits, Risks, and Burdens – Nonpterygium Limbal Stem Cell Deficiency
Short- and long-term improvement in corneal surface (stable, normal corneal epithelium and decreased vascularization and opacity)
Improvement in vision (visual acuity and functional vision)
Long-term complications are experienced by 8% to 16% of patients
Risks associated with long-term immunosuppression for recipients of allogeneic grafts
Potential risk of induced LSCD in donor eyes
High cost of treatment (average cost per patient via OOC program is $57,583; estimated cost of procedure in Ontario is $2,291.48)
Costs are expressed in Canadian dollars.
GRADE of recommendation: Strong recommendation, low-quality or very low-quality evidence
benefits clearly outweigh risks and burdens
case series studies
strong, but may change if higher-quality evidence becomes available
Pterygium
Conjunctival-limbal autologous transplantations significantly reduced the risk of pterygium recurrence compared with CAU. No other comparison yielded statistically significant results, but CLAU reduced the risk of recurrence compared with MMC. However, the benefit of LSCT in Ontario is uncertain as the severity and recurrence of pterygium in Ontario is unknown. The complication rates suggest that CLAU is a safe treatment option to prevent the recurrence of pterygium. According to GRADE, given the balance of the benefits, risks, and burdens, the recommendations are very weak with moderate quality evidence, as shown in Executive Summary Table 2.
Benefits, Risks, and Burdens – Pterygium
Reduced recurrence; however, if recurrence is low in Ontario, this benefit might be minimal
Long-term complications rare
Increased cost
GRADE of recommendation: Very weak recommendations, moderate quality evidence.
uncertainty in the estimates of benefits, risks, and burden; benefits, risks, and burden may be closely balanced
RCTs
very weak, other alternatives may be equally reasonable
PMCID: PMC3377549  PMID: 23074512
9.  Clinical and Microbiological Characteristics of Fungal Keratitis in the United States, 2001–2007: A Multicenter Study 
Ophthalmology  2011;118(5):920-926.
Objective
To study the epidemiology, clinical observations, and microbiologic characteristics of fungal keratitis at tertiary eye care centers in the United States.
Design
Retrospective multicenter case series.
Participants
Fungal keratitis cases presenting to participating tertiary eye care centers.
Methods
Charts were reviewed for all fungal keratitis cases confirmed by culture, histology, or confocal microscopy between January 1, 2001, and December 31, 2007, at 11 tertiary clinical sites in the United States.
Main Outcome Measures
Frequency of potential predisposing factors and associations between these factors and fungal species.
Results
A total of 733 cases of fungal keratitis were identified. Most cases were confirmed by culture from corneal scraping (n = 693) or biopsies (n = 19); 16 cases were diagnosed by microscopic examination of corneal scraping alone; and 5 cases were diagnosed by confocal microscopy alone. Some 268 of 733 cases (37%) were associated with refractive contact lens wear, 180 of 733 cases (25%) were associated with ocular trauma, and 209 of 733 cases (29%) were associated with ocular surface disease. No predisposing factor was identified in 76 cases (10%). Filamentous fungi were identified in 141 of 180 ocular trauma cases (78%) and in 231 of 268 refractive contact lens-associated cases (86%). Yeast was the causative organism in 111 of 209 cases (53%) associated with ocular surface disease. Yeast accounted for few cases of fungal keratitis associated with refractive contact-lens wear (20 cases), therapeutic contact-lens wear (11 cases), or ocular trauma (21 cases). Surgical intervention was undertaken in 26% of cases and was most frequently performed for fungal keratitis associated with ocular surface disease (44%). Surgical intervention was more likely in cases associated with filamentous fungi (P = 0.03). Among contact lens wearers, delay in diagnosis of 2 or more weeks increased the likelihood of surgery (age-adjusted odds ratio = 2.2; 95% confidence interval, 1.2–4.2).
Conclusions
Trauma, contact lens wear, and ocular surface disease predispose patients to developing fungal keratitis. Filamentous fungi are most frequently the causative organism for fungal keratitis associated with trauma or contact lens wear, whereas yeast is most frequently the causative organism in patients with ocular surface disease. Delay in diagnosis increases the likelihood of surgical intervention for contact lens-associated fungal keratitis.
Financial Disclosure(s)
Proprietary or commercial disclosure may be found after the references.
doi:10.1016/j.ophtha.2010.09.011
PMCID: PMC3673009  PMID: 21295857
10.  Simplifying Collection of Corneal Specimens in Cases of Suspected Bacterial Keratitis 
Journal of Clinical Microbiology  2003;41(7):3192-3197.
Identification of the causative organisms in suspected bacterial keratitis traditionally involves collecting multiple corneal scrapes, which are plated directly onto different solid agar culture media. Difficulties have been reported with this practice, so the development of a simpler diagnostic method in suspected bacterial keratitis would be useful. It is unclear whether a single corneal scrape sent to the microbiology laboratory in a liquid transport culture medium (indirect method) is as reliable for the diagnosis of bacterial keratitis as inoculation of multiple scrapes directly onto agar plates (direct method). To investigate this, bacterial recovery was assessed following transfer and transport of different concentrations and types of bacteria from an artificially contaminated surgical blade into brain heart infusion (BHI). Bacterial recovery rates between the proposed (indirect) and standard (direct) method were then compared after the in vitro inoculation of pig corneas and following specimen collection in patients with presumed bacterial ulcerative keratitis. Recovery of bacteria from contaminated surgical blades was found to be the same from both solid and liquid culture media. There was no significant difference in the numbers of positive cultures from solid (direct) and liquid (indirect) culture media, both in the experimental pig cornea inoculation study (P = 0.34) and in experiments with patients with clinical infections (P = 0.4), with an 85.2% agreement between methods (kappa = 0.61, P < 0.0001). In conclusion, therefore, the collection of two corneal scrapes, one used for Gram staining and the other transported in BHI followed by plating and subculturing in an enrichment medium, provides a simple method for the investigation of presumed bacterial keratitis.
doi:10.1128/JCM.41.7.3192-3197.2003
PMCID: PMC165349  PMID: 12843063
11.  Corneal ulceration in the elderly in Hyderabad, south India 
AIMS—To report demographic, microbiological, therapeutic, anatomical, and visual results of corneal ulceration in the elderly patients seen at a tertiary eye care centre in south India.
METHODS—102 consecutive cases of microbial keratitis in patients 65 years and older were studied. Inclusion criteria were: (i) presence of corneal stromal infiltrate upon slit lamp examination; and (ii) microbiological evaluation of corneal scrapings for suspected microbial keratitis.
RESULTS—The principal predisposing factors identified in this study were ocular disease (38.2%), previous ocular surgery in the same eye (29.4%), trauma (17.6%), and severe systemic disease (16.7%). Contact lens wear was associated with only two cases (2.0%). 99 organisms were isolated in cultures of corneal scrapings from 74 (72.5%) of the 102 cases. Staphylococcus epidermidis (31.1%), filamentous fungi (25.7%), and Streptococcus pneumoniae (13.5%) were the most common isolates. 12 eyes (11.8%) required surgery, 15 (14.7%) eventually required evisceration, and nine (9.6%) of the 94 followed patients achieved an unaided vision of 20/60 or better at last follow up.
CONCLUSIONS—This work represents the largest recent single centre study on (non-viral) microbial keratitis in the elderly, its management, and outcomes of therapy. While the predisposing factors differ from those of general population, the spectrum of microbes responsible for keratitis in the elderly appears to reflect the local microbial flora rather than a predilection for elderly patients. Delay in diagnosis and systemic conditions associated with advancing age probably contribute to poorer outcome from therapeutic measures.


doi:10.1136/bjo.84.1.54
PMCID: PMC1723216  PMID: 10611100
12.  Diagnosis of Fusarium keratitis in an animal model using the polymerase chain reaction 
AIMS/BACKGROUND—The purpose of this study was apply the polymerase chain reaction (PCR) to develop a sensitive, specific, and rapid test to diagnose Fusarium keratitis. Fusarium is the most common cause of fungal corneal infection in some parts of the world. It is often difficult to establish that a keratitis is due to fungal infection.
METHODS—Fusarium solani keratitis was induced in three eyes of three rabbits by injection of a suspension of the fungus into the anterior corneal stroma. In one rabbit the contralateral eye served as a control. From four to 28 days after inoculation, the corneas were scraped for culture, then scraped and swabbed for PCR analysis. The PCR was performed with primers directed against a portion of the Fusarium cutinase gene, and the presence or absence of this amplified target sequence was determined by agarose gel.
RESULTS—The amplified DNA sequence was detected in 25 of 28 samples from the corneas infected with Fusarium, for a sensitivity of 89%. Only three of the 14 samples from these eyes with Fusarium keratitis were positive by culture, for a sensitivity of 21%. Seven of eight control samples were negative by the PCR based test, for a specificity of 88%.
CONCLUSION—This PCR based test holds promise of being an effective method of diagnosing Fusarium keratitis as well as Fusarium infections at other sites.

 Keywords: keratitis; Fusarium; ulcer; cornea; polymerase chain reaction
PMCID: PMC1722506  PMID: 9602631
13.  Antimicrobial management of presumed microbial keratitis: guidelines for treatment of central and peripheral ulcers 
AIMS—To determine the quantitative relation between the major risk factors for microbial keratitis of previous ocular surface disease and contact lens wear and central and peripheral infiltration, often associated with ulceration, in order to establish a rational chemotherapeutic management algorithm.
METHODS—Data from 55 patients were collected over a 10 month period. All cases of presumed microbial keratitis where corneal scrapes had been subjected to microbiological examination were included. Risk factor data and laboratory outcome were recorded. Antimicrobial regimens used to treat each patient were documented.
RESULTS—57 episodes of presumed microbial keratitis were identified from 55 patients, 24 male and 31 female. There were 30 central infiltrates and 27 peripheral infiltrates of which 28 were culture positive (73% of central infiltrates, 22% of peripheral infiltrates). 26 patients had worn contact lenses of whom 12 had culture positive scrapes (9/14 for central infiltrates, 3/12 for peripheral infiltrates). 31 patients had an ocular surface disease of whom five previous herpes simplex virus keratitis patients developed secondary bacterial infection. Anterior chamber activity and an infiltrate size ⩾ 4 mm2 were more common with culture positive central infiltrates than peripheral infiltrates (χ2 test = 11.98, p<0.001).
CONCLUSIONS—Predisposing factors for "presumed" microbial keratitis, either central or peripheral, were: ocular surface disease (26/57 = 45.6%), contact lens wear (26/57 = 45.6%), and previous trauma (5/57 = 8.8%). Larger ulceration (⩾4 mm2) with inflammation was more often associated with positive culture results for central infiltration. None of these four variables (contact lens wear, ocular surface disease, ulcer size, anterior chamber activity) were of intrinsic value in predicting if a peripheral infiltrate would yield identifiable micro-organisms. Successful management of presumed microbial keratitis is aided by a logical approach to therapy, with the use of a defined algorithm of first and second line broad spectrum antimicrobials, for application at each stage of the investigative and treatment process considering central and peripheral infiltration separately.

 Keywords: ulcerative keratitis; antimicrobials; ulcers
PMCID: PMC1722498  PMID: 9613378
14.  Risk factors for treatment outcome of suspected microbial keratitis 
The British Journal of Ophthalmology  1999;83(9):1027-1031.
BACKGROUND—Primary treatment for suspected microbial keratitis is generally successful. Although risks such as contact lens use are well recognised as causative factors for microbial keratitis, little is known about the risk factors that influence treatment outcome. The present study evaluates the risk factors assessed at diagnosis as prognostic indicators of primary treatment failure.
METHODS—Patients were prospectively enrolled in the ofloxacin treatment trial and data concerning symptoms, treatments, past and concurrent eye disease were collected along with the measurement of corneal ulcer size at the slit lamp. All patients were scraped for microbiological investigation, and treated with either ofloxacin (0.3%) or standard therapy of fortified cefuroxime and gentamicin drops. Treatment success was complete healing of the ulcer with zero dimensions of the epithelial defect within 2 weeks of start of treatment. The important prognostic indicators were selected by comparison among those who failed treatment, had delayed healing, or were culture positive with other patients using univariate and stratified analysis. These were then used in a Poisson model for multiple regression analysis to estimate the relative risk of the main prognostic variables.
RESULTS—Of the 118 patients enrolled in the study, 14 were identified as primary treatment failures, 17 had slow healing, and 15 indolent ulcers. There were 49 culture positive patients. The multivariate analysis identified that large culture positive ulcers in patients 60 years or older had 5.5 times the risk of primary treatment failure (p<0.001). Significant predictors of slow healing were previous ocular disease and a positive culture; significant predictors of indolent ulceration were previous ocular disease and steroid use at diagnosis; the main predictor of a culture positive result was ulcer size.
CONCLUSIONS—Elderly patients with large ulcers were more likely to be culture positive, fail primary therapy, and require surgical intervention. A positive microbial culture provided prognostic information regardless of the organism isolated. However, this information was of less value for those with small ulcers and for younger patients.


PMCID: PMC1723169  PMID: 10460769
15.  Review of epidemiological features, microbiological diagnosis and treatment outcome of microbial keratitis: Experience of over a decade 
Indian Journal of Ophthalmology  2009;57(4):273-279.
Purpose:
To review the epidemiological characteristics, microbiological profile, and treatment outcome of patients with suspected microbial keratitis.
Materials and Methods:
Retrospective analysis of a non-comparative series from the database was done. All the patients presenting with corneal stromal infiltrate underwent standard microbiologic evaluation of their corneal scrapings, and smear and culture-guided antimicrobial therapy.
Results:
Out of 5897 suspected cases of microbial keratitis 3563 (60.4%) were culture-proven (bacterial – 1849, 51.9%; fungal – 1360, 38.2%; Acanthamoeba – 86, 2.4%; mixed – 268, 7.5%). Patients with agriculture-based activities were at 1.33 times (CI 1.16–1.51) greater risk of developing microbial keratitis and patients with ocular trauma were 5.33 times (CI 6.41–6.44) more likely to develop microbial keratitis. Potassium hydroxide with calcofluor white was most sensitive for detecting fungi (90.6%) and Acanthamoeba (84.0%) in corneal scrapings, however, Gram stain had a low sensitivity of 56.6% in detection of bacteria. Majority of the bacterial infections were caused by Staphylococcus epidermidis (42.3%) and Fusarium species (36.6%) was the leading cause of fungal infections. A significantly larger number of patients (691/1360, 50.8%) with fungal keratitis required surgical intervention compared to bacterial (799/1849, 43.2%) and Acanthamoeba (15/86, 17.4%) keratitis. Corneal healed scar was achieved in 75.5%, 64.8%, and 90.0% of patients with bacterial, fungal, and Acanthamoeba keratitis respectively.
Conclusions:
While diagnostic and treatment modalities are well in place the final outcome is suboptimal in fungal keratitis. With more effective treatment available for bacterial and Acanthamoeba keratitis, the treatment of fungal keratitis is truly a challenge.
doi:10.4103/0301-4738.53051
PMCID: PMC2712695  PMID: 19574694
Diagnosis; epidemiology; infective keratitis; outcome; treatment
16.  Use of 18S rRNA Gene-Based PCR Assay for Diagnosis of Acanthamoeba Keratitis in Non-Contact Lens Wearers in India 
Journal of Clinical Microbiology  2003;41(7):3206-3211.
Identification of Acanthamoeba cysts and trophozoites in ocular tissues requires considerable expertise and is often time-consuming. An 18S rRNA gene-based PCR test, highly specific for the genus Acanthamoeba, has recently been reported in the molecular diagnosis of Acanthamoeba keratitis. This PCR assay was compared with conventional microbiological tests for the diagnosis of Acanthamoeba keratitis. In a pilot study, the PCR conditions with modifications were first tested on corneal scrapings from patients with culture-proven non-contact lens-related Acanthamoeba, bacterial, and fungal keratitis. This was followed by testing of corneal scrapings from 53 consecutive cases of microbial keratitis to determine sensitivity, specificity, and predictive values of the assay. All corneal scrapings from patients with proven Acanthamoeba keratitis showed a 463-bp amplicon, while no amplicon was obtained from patients with bacterial or fungal keratitis. Some of these amplified products were sequenced and compared with EMBL database reference sequences to validate these to be of Acanthamoeba origin. Out of 53 consecutive cases of microbial keratitis included for evaluating the PCR, 10 (18.9%) cases were diagnosed as Acanthamoeba keratitis on the basis of combined results of culture, smear, and PCR of corneal scrapings. Based on culture results as the “gold standard,” the sensitivity of PCR was the same as that of the smear (87.5%); however, the specificity and the positive and negative predictive values of PCR were marginally higher than the smear examination (97.8 versus 95.6%, 87.5 versus 77.8%, and 97.8 versus 97.7%) although the difference was not significant. This study confirms the efficacy of the PCR assay and is the first study to evaluate a PCR-based assay against conventional methods of diagnosis in a clinical setting.
doi:10.1128/JCM.41.7.3206-3211.2003
PMCID: PMC165372  PMID: 12843065
17.  The Clinical Diagnosis of Microbial Keratitis 
American journal of ophthalmology  2007;143(6):940-944.
Purpose
To evaluate the ability of ophthalmologists to predict the laboratory results of presumed microbial keratitis and to explore which findings might influence diagnostic prognostication.
Design
Prospective cross-sectional study.
Methods
Fifteen ophthalmologists completed study forms at the initial presentation of patients with presumed microbial keratitis. After predicting the category of microbial recovery, clinicians submitted corneal scrapings for masked laboratory processing. The relative effects of ocular inflammatory signs on correct microbial diagnosis were explored with Poisson regression.
Results
Clinical examiners correctly predicted the presence or absence of microbial recovery in 79 (76%) of 104 ulcerative keratitis and successfully distinguished among bacterial, fungal, and amoebic keratitis for 54 (73%) of 74 culture-positive infections, although only 31 (42%) were properly subcategorized. The positive predictive value of clinical diagnosis was 65% (95% confidence interval (CI), 43%–84%) for 20 eyes with Pseudomonas keratitis, 48% (95% CI, 32%–63%) for 38 other bacterial keratitis, 45% (95% CI, 17%–77%) for 13 fungal keratitis, and 89% (95% CI, 52%–100%) for nine Acanthamoeba keratitis. The recognition of Pseudomonas keratitis was significantly improved by the occurrence of a larger infiltrate (P = .02), and correctly predicting Acanthamoeba keratitis was enhanced by observing a ring infiltrate (P < .001). Antimicrobial use before referral significantly attenuated clinical diagnosis (P = 0.03) and hampered microbial recovery (P = 0.004).
Conclusions
Established Pseudomonas keratitis and Acanthamoeba keratitis can be suspected before laboratory confirmation, but overlapping inflammatory features and recent empiric antimicrobial treatment limits etiologic recognition of most microbial corneal infections.
doi:10.1016/j.ajo.2007.02.030
PMCID: PMC1973090  PMID: 17408586
18.  Aetiology of suppurative corneal ulcers in Ghana and south India, and epidemiology of fungal keratitis 
The British Journal of Ophthalmology  2002;86(11):1211-1215.
Background: A multicentre study was carried out in Ghana and southern India to determine the aetiology of suppurative keratitis in two regions located at similar tropical latitudes. Studies of fungal keratitis from the literature were reviewed.
Methods: Patients presenting at rural and urban eye units with suspected microbial keratitis were recruited to the study. Corneal ulceration was defined as loss of corneal epithelium with clinical evidence of infection with or without hypopyon. Microscopy and culture were performed on all corneal specimens obtained.
Results: 1090 patients were recruited with suspected microbial keratitis between June 1999 and May 2001. Overall the principal causative micro-organisms in both regions were filamentous fungi (42%): Fusarium species and Aspergillus species were the commonest fungal isolates. Pseudomonas species were most frequently isolated from cases of bacterial keratitis in Ghana but in India the commonest bacterial isolates were streptococci.
Conclusion: Infections of the cornea due to filamentous fungi are a frequent cause of corneal damage in developing countries in the tropics and are difficult to treat. Microscopy is an essential tool in the diagnosis of these infections. A knowledge of the “local” aetiology within a region is of value in the management of suppurative keratitis in the event that microscopy cannot be performed.
PMCID: PMC1771352  PMID: 12386069
keratitis; Fusarium; Aspergillus
19.  Childhood microbial keratitis 
Oman Journal of Ophthalmology  2012;5(1):28-31.
Purpose:
To evaluate risk factors for pediatric microbial keratitis and to describe the clinical picture, microbial spectrum, treatment modalities, posttreatment sequelae, and visual outcome in cases with pediatric microbial keratitis.
Materials and Methods:
All cases of microbial keratitis that occurred in children 16 years or younger who had an initial examination between January 2000 and December 2010 at a tertiary referral eye hospital in Riyadh, Saudi Arabia, were identified. A retrospective review of medical records was conducted using a computer-based diagnosis code. Demographic data, predisposing factors, clinical course, microbial culture results, and visual outcomes were recorded.
Results:
Sixty-eight eyes were included in this study. Predisposing factors were identified in 63 eyes (92.6%). All patients had unilateral microbial keratitis. The mean±SD age was 4.5 ± 4.8 years and 57.4% were male. Trauma was the leading cause [27 eyes (39.7%)], followed by systemic diseases [14 eyes (20.6%)], contact lens wear [11 eyes (16.1%)], and ocular diseases [11 eyes (16.1%)]. Corneal scraping was performed in all cases. Five patients needed general anesthesia to carry out the corneal scraping. Thirty-four (50.0%) eyes showed positive cultures. Gram-positive bacteria accounted for 67.8% and gram-negative bacteria for 38.2% of isolates. Streptococcus pneumoniae was the most commonly isolated organism [8 eyes (25.8%)], followed by Staphylococcus epidermidis [7 eyes (22.7%)]. Pseudomonas aeruginosa was the most commonly isolated gram-negative [6 eyes (17.6%)] organism. One eye had corneal perforation and required surgical intervention. Forty-five of 68 eyes (66.2%) had a best-corrected visual acuity evaluation at the last follow-up and 28 eyes (62.2%) of them had a best-corrected visual acuity of 20/40 or better.
Conclusion:
Children with suspected microbial keratitis require comprehensive evaluation and management. Early recognition, identifying the predisposing factors and etiological microbial organisms, and instituting appropriate treatment measures have a crucial role in outcome. Ocular trauma was the leading cause of childhood microbial keratitis in our study.
doi:10.4103/0974-620X.94763
PMCID: PMC3339670  PMID: 22557873
Bacteria; children; keratitis; trauma
20.  Severe infective keratitis leading to hospital admission in New Zealand 
The British Journal of Ophthalmology  2003;87(9):1103-1108.
Aim: To identify key risk factors and the management and outcome of severe infective keratitis leading to public hospital admission in New Zealand.
Methods: Over a 2 year period, all admissions of presumed infective keratitis to Auckland Hospital were identified. The clinical records of all 103 cases were retrospectively reviewed with respect to clinical features, risk factors, management, and outcomes.
Results: The mean time from first symptoms or signs and presentation to hospital was 8.9 (SD 15.5) days. The majority of subjects, 88%, had at least one of the risk factors commonly associated with infective keratitis including previous ocular surgery (30%), contact lens wear (26%), topical corticosteroid use (25%), and ocular trauma (24%). Corneal scraping was performed in 92% and of a total of 105 scrapes, 71% were positive. Bacteria were isolated in all these cases, the majority being Gram positive organisms (72%). The most common isolates identified were coagulase negative Staphylococcus (16%), Propionibacterium acnes (14%), Staphylococcus epidermidis (11%), and Streptococcus pneumoniae (9%). In addition, yeasts were isolated in 5%, fungi in 4%, virus in 2%, and chlamydia in 1%. Importantly, polymicrobial infection accounted for 33% of culture positive cases. Antimicrobial treatment was changed on the basis of culture results in 17 cases (16.5%). Median initial visual and final best corrected visual acuity was 6/36–6/48 (logMAR 0.86) (IQR 0.39–2.00) and 6/12–6/15 (logMAR 0.360) (IQR 0.15–1.70), respectively. Previous ocular surgery and topical corticosteroid use were significantly associated with poorer visual acuity. The mean hospital stay was 5.8 days and the median 4.0 (IQR 2.0–8.0) days. Longer duration of stay was associated with the presence of hypopyon, larger ulcers, previous ocular surgery, and poor visual acuity.
Conclusions: Infectious keratitis is an important cause of ocular morbidity. A significant proportion of cases have potentially modifiable risk factors. Previous ocular surgery and topical corticosteroid use, in particular, were associated with poorer visual outcomes. Many cases of severe keratitis might be avoided, or their severity reduced, by appropriate education of patients and ophthalmologists.
PMCID: PMC1771869  PMID: 12928276
keratitis; hospital admission; New Zealand
21.  Microbial Keratitis in Kingdom of Bahrain: Clinical and Microbiology Study 
Background:
Microbial keratitis is a potentially vision threatening condition worldwide. Knowing the predisposing factors and etiologic microorganism can help control and prevent this problem. This is the first study of its kind in Kingdom of Bahrain.
Objective:
To study the profile of microbial keratitis in Bahrain with special focus on risk factors, clinical outcome and microbilogical results.
Methods:
A retrospective analysis of all patients admitted in Salmaniya Medical Complex over a period of three years from January 2005 to January 2007 was performed. A total of 285 patients with keratitis were analysed. Non infectious corneal ulceration were excluded. Data collected from medical records were demographic features, predisposing factors, history of corneal trauma, associated ocular conditions, visual acuity at the time of presentation and the clinical course. Predisposing risk factors measured were contact lens use, presence of blepharitis, diabetes, lid abnormalities, dry eyes, keratoplasty and refractive surgery. For contact lens wearers any contact lens related risk factors that can lead to keratitis were measured. Pearson's chi-square test was used to carry out statistical analysis wherever required.
Results:
Contact lens wear, as a risk factor for microbial keratitis, formed 40% of the total study population. Other risk factors identified were dry eyes 24 cases (8%), 10 blepharitis (3%), 22 trauma (8%), abnormal lid position 14 cases (5%). 6 patients keratitis in a graft (2%), 3 had refractive surgery (1%). The most common causative organism isolated was pseudomonas aeroginosa (54%) followed by streptococcus 12%, staph 10%, other organisms 6%. 95% of contact lens wearers had pseudomonas Aeroginosa. This was statistically significant (p< 0.0001). The vast majority, 92% healed with scarring. 1% needed therapeutic keratoplasty and 7% lost to follow up. Risk factors in contact lens wearers were; 41 patients (36%) slept with the contact lenses. 12 (8%) had contact lens related trauma and 8 (7%) had poor hygiene. Sleeping with the contact lenses was statistically significant (p< 0.0001).
Conclusion & Recommendation:
Contact lens wear is the major risk factor for microbial keratitis in Bahrain. Pseudomonas aeroginosa was the commonest bacteria isolated. Sleeping with the contact lenses is the major risk factor among contact lens wearers. Majority of keratitis patients resulted in permanent scarring on the cornea. Educating the public, especially on contact lens care and precaution, can help reduce this visual morbidity.
doi:10.4103/0974-9233.48855
PMCID: PMC2813578  PMID: 20142952
Keratitis; Corneal Ulcer; Pseudomonas Aeroginosa; Contact Lenses
22.  Collection of corneal impression cytology directly on a sterile glass slide for the detection of viral antigen: An inexpensive and simple technique for the diagnosis of HSV epithelial keratitis – A pilot study 
BMC Ophthalmology  2001;1:3.
Background
Herpes simplex keratitis (HSK) is a sight threatening ocular infection and occurs worldwide. A prompt laboratory diagnosis is often very useful. Conventional virology techniques are often expensive and time consuming. We describe here a highly economical, simple, rapid and sensitive technique for the collection of impression cytology, for the laboratory diagnosis of HSK.
Methods
Fifteen patients with a clinical diagnosis of HSK (either dendritic or geographic ulcers) and five patients with other corneal infections (Mycotic keratitis, n = 3, Bacterial keratitis, n = 2) were included in the study. Corneal impression cytology specimens were collected using a sterile glass slide with polished edges instead of a membrane, by pressing the surface of one end of the slide firmly, but gently on the corneal lesion. Additionally, corneal scrapings were collected following the impression cytology procedure. Impression cytology and corneal scrapings were stained by an immunoperoxidase or immunofluorescence assay for the detection of HSV-1 antigen using a polyclonal antibody to HSV-1. Corneal scrapings were processed for viral cultures by employing a shell vial assay.
Results
This simple technique allowed the collection of adequate corneal epithelial cells for the detection of HSV-1 antigen in a majority of the patients. HSV-1 antigen was detected in 12/15 (80%) cases while virus was isolated from 5/15 (33.3%) patients with HSK. All the patients with a clinical diagnosis of HSK (n = 15) were confirmed by virological investigations (viral antigen detection and/or viral cultures). HSV-1 antigen was detected in the impression cytology smears and corneal scrapings in 11/15 (73.3%) and 12/15 (80%) of the patients, respectively (P = 1.00). None of the patients in the control group were positive for viral antigen or virus isolation. Minimal background staining was seen in impression cytology smears, while there was some background staining in corneal scrapings stained by the immunoassays.
Conclusions
Collection of impression cytology on a sterile glass slide is a simple, rapid and inexpensive technique for the diagnosis of HSK. Immunological techniques applied on such smears provide virological results within 2-5 hours. This technique could be modified for use in the diagnosis of other external eye diseases, which needs further evaluation.
doi:10.1186/1471-2415-1-3
PMCID: PMC57753  PMID: 11592921
23.  Microbial keratitis in Gujarat, Western India: findings from 200 cases 
Introduction
The objective of this study was to study the epidemiological characteristics and the microbiological profile of patients suspected with microbial keratitis in Gujarat.
Methods
Corneal scraping was collected from 200 consecutive cases of suspected microbial keratitis and was subjected to direct examination and culture.
Results
Of the 200 ulcers 55% were culture positive, 26.5% were bacterial ulcers of which 47% were due to Staphylococcus spp. Pure fungal growth was seen in 22% while 6% were mixed ulcers. Fusarium spp. (30%) was the most common fungus followed by Aspergillus spp. (21%). Only one case of Acanthamoeba keratitis was encountered. Patients were mainly from rural areas (61.5%) with male preponderance (61.5%). Corneal injury was seen in 78.5% cases of which 53% had injury with vegetative matter. Prior treatment was seen in 58% of which 5% had been treated by village healers. Nineteen patients (9.5%) also used some kind of traditional topical treatment. Increased incidence was seen from August to December. Five case of fugal ulcers lead to perforation of which three were due to Fusarium spp. whereas perforation was seen in only two cases of bacterial ulcers due to Pseudomonas aeruginosa.
Conclusion
Staphylococcus and Fusarium spp. were the most common etiological agents in our region. Predominant outdoor agricultural activity is the principal causative factor for corneal injury. Corneal ulcers complicated due to treatment by village healers are another important concern. The information regarding regional etiology will help empirical management as many eye clinics do not have microbiological facilities.
PMCID: PMC3290878  PMID: 22384294
Microbial; keratitis; village healer; eyes; epidemiology; India
24.  Contact Lens Induced Corneal Ulcer Management in a Tertiary Eye Unit in Oman - A descriptive study 
Objectives:
The corneal disease is a priority problem in Oman. We present patients with contact lens (CL) induced severe keratitis, admitted in the corneal unit of Al Nahdha Hospital in Oman.
Methods:
The study was conducted in 2005–2006. Ophthalmologists examined the eyes using slit lamp bio-microscope. Visual acuity was noted using Snellen’s distance vision chart. Specimens of corneal scraping and CLs were sent for culture and sensitivity tests. Patients with severe keratitis were admitted and treated with medicines. Corneal and visual statuses were noted at the time of discharge from hospital and after six weeks. Numbers, percentages and their 95% confidence intervals were calculated. Pre- and post-treatment vision were compared using a scattergram.
Results:
The 52 eyes of 15 males and 37 female patients with corneal ulcers were examined. Thirty-two patients were between 20 to 30 years of age. Only 13 (25%) patients had visited an ophthalmologist within 24 hours of developing severe keratitis. Seventeen (33%) had central ulcers and six (11.5%) had ulcer ≥5 mm in size. Pseudomonas was found in 29 (55.8%) of CL and corneal material scraped from the eyes of 15 (28.8%) patients. Vision was <6/60 (legally blind) in 12 (23.1%) eyes before and in five (9.6%) eyes after treatment. Twenty-six (50%) patients were lost to follow up.
Conclusion:
CL related severe keratitis causes visual disabilities. Prevention and proper records are essential. Treatment improves vision and hence facilities for management should be strengthened.
PMCID: PMC3074844  PMID: 21748073
Contact lens; Corneal blindness, Keratitis; Prevention of blindness; Refractive error
25.  Randomised trial of 0.2% chlorhexidine gluconate and 2.5% natamycin for fungal keratitis in Bangladesh 
AIM—The management of suppurative keratitis due to filamentous fungi presents severe problems in tropical countries. The aim was to demonstrate the efficacy of chlorhexidine 0.2% drops as an inexpensive antimicrobial agent, which could be widely distributed for fungal keratitis.
METHODS—Successive patients presenting to the Chittagong Eye Institute and Training Complex with corneal ulcers were admitted to the trial when fungal hyphae had been seen on microscopy. They were randomised to drop treatment with chlorhexidine gluconate 0.2% or the standard local treatment natamycin 2.5%. The diameters, depths, and other features of the ulcers were measured and photographed at regular intervals. The outcome measures were healing at 21 days and presence or absence of toxicity. If there was not a favourable response at 5 days, "treatment failure" was recorded and the treatment was changed to one or more of three options, which included econazole 1% in the latter part of the trial.
RESULTS—71 patients were recruited to the trial, of which 35 were randomised to chlorhexidine and 36 to natamycin. One allocated to natamycin grew bacteria and therefore was excluded from the analysis. None of the severe ulcers was fully healed at 21 days of treatment, but three of those allocated to chlorhexidine eventually healed in times up to 60 days. Of the non-severe ulcers, 66.7% were healed at 21 days with chlorhexidine and 36.0% with natamycin, a relative efficacy (RE) of 1.85 (CL 1.01-3.39, p = 0.04). If those ulcers were excluded where fungi were seen in the scraping but did not grow on culture, the estimated efficacy ratio does not change but becomes less precise because of smaller numbers. Equal numbers of Aspergillus (22) and Fusarium (22) were grown. The Aspergillus were the most resistant to either primary treatment.
CONCLUSIONS—Chlorhexidine may have potential as an inexpensive topical agent for fungal keratitis and warrants further assessment as a first line treatment in situations where microbiological facilities and a range of antifungal agents are not available.

 Keywords: fungal keratitis; corneal ulcers; chlorhexidine; Bangladesh
PMCID: PMC1722716  PMID: 9828778

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