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1.  Effect of change in drusen evolution on photoreceptor inner segment/outer segment junction 
Retina (Philadelphia, Pa.)  2012;32(8):1492-1499.
To evaluate the integrity of photoreceptor inner segment/outer segment (IS/OS) junction after change of drusen size in age-related macular degeneration (AMD) using spectral domain optical coherence tomography (SD-OCT).
Drusen volume raster scans were performed with the Spectralis SD-OCT (Heidelberg Engineering) through 2624 drusen in 14 eyes with clinically dry AMD who had been longitudinally followed between 23–28 months without intervention (mean 26.3 months). All eyes had ETDRS visual acuity. A total of 416 out of 2624 drusen were analyzed.
Of 416 drusen, 83 (20%) were found to have regressed spontaneously (group A), 212 (51%) showed no change in size (group B) and 121 (29%) progressed (group C), Mean drusen size of all drusen was 63.7 ± 25.7 microns. Cross-sectional analysis of drusen morphology showed a correlation between drusen size and disrupted IS/OS junction/photoreceptor integrity (r=−0.48, p<0.001). Of the drusen that regressed over time there was intact IS/OS junction integrity. Even drusen that caused a major disruption showed IS/OS restoration in 74% of the drusen (p<0.001).
Progression of drusen shows structural disruption of the IS/OS-junction. After drusen regression the IS/OS-junction is either able to restore as drusen regress or was artifactitiously compressed and not initially visible due to the initial drusen compression of the IS/OS junctional line. Therefore drusen evolution may play an important role in affecting the photoreceptor IS/OS-junction integrity.
PMCID: PMC3792858  PMID: 22481478
2.  Genetic analysis of simultaneous geographic atrophy and choroidal neovascularization 
Eye  2012;26(8):1106-1113.
To investigate clinical presentation and genotypes in patients with simultaneous geographic atrophy (GA) and choroidal neovascularization (CNV) and to compare with patients with GA or CNV only.
Patients and methods
Twenty patients with combined CNV–GA and 154 CNV only and 154 GA only were chosen based on clinical exam and imaging. Six single-nucleotide polymorphisms (SNPs)—rs2274700 and rs1061170 (complement factor H), rs10490924 and rs11200638 (HTRA1/LOC387715), rs2230199 (C3), rs9332739 (C2)—were genotyped using the SNaPshot method. Chi-squared tests were used for genetic analysis.
In patients with CNV–GA, GA progressed slowly and often preceded CNV. CNV presented as subretinal haemorrhage or fluid, with a sudden drop in visual acuity (VA). Comparing combined CNV–GA to GA and CNV only, patients with both had a higher frequency of at-risk alleles at both SNPs within the HTRA1 gene—rs10490924 (52.5%), rs11200638 (52.6%). Statistical significance was not achieved. CNV–GA patients had no protective alleles at SNP rs9332739 (C2), compared with GA (27%) and CNV only (10%).
There is a paucity of reports describing simultaneous CNV–GA. Clinical and genetic results may support the fact that GA and CNV fit on an age-related macular degeneration (AMD)-disease continuum and may clarify the disease processes in AMD.
PMCID: PMC3420042  PMID: 22699975
age-related macular degeneration; geographic atrophy; choroidal neovascularization; genetics
3.  Real-time Monitoring of Sustained Drug Release using the Optical Properties of Porous Silicon Photonic Crystal Particles 
Biomaterials  2010;32(7):1957-1966.
A controlled and observable drug delivery system that enables long-term local drug administration is reported. Biodegradable and biocompatible drug-loaded porous Si microparticles were prepared from silicon wafers, resulting in a porous 1-dimensional photonic crystal (rugate filter) approx. 12 micrometers thick and 35 micrometers across. An organic linker, 1-undecylenic acid, was attached to the Si-H terminated inner surface of the particles by hydrosilylation and the anthracycline drug daunorubicin was bound to the carboxy terminus of the linker. Degradation of the porous Si matrix in vitro was found to release the drug in a linear and sustained fashion for 30 d. The bioactivity of the released daunorubicin was verified on retinal pigment epithelial (RPE) cells. The degradation/drug delivery process was monitored in situ by digital imaging or spectroscopic measurement of the photonic resonance reflected from the nanostructured particles, and a simple linear correlation between observed wavelength and drug release was observed. Changes in the optical reflectance spectrum were sufficiently large to be visible as a distinctive red to green color change.
PMCID: PMC3025697  PMID: 21122914
Porous silicon; photonic crystal; ophthalmic drug delivery; daunorubicin; sustained drug release
4.  Comparison of 4 mg versus 20 mg intravitreal triamcinolone acetonide injections 
To compare the non-decanted (standard) 4 mg versus the decanted 20 mg intravitreal triamcinolone acetonide (IVTA) injections and to assess their effect on intraocular pressure (IOP).
We retrospectively reviewed the records of 92 consecutive eyes, which received an intravitreal injection of either dose of triamcinolone acetonide, at a single retina centre. The change in IOP (elevation of at least 5 mm Hg from baseline or above 21 mm Hg) was analysed with a multivariate logistic analysis. The mean follow-up period in both groups was 27 weeks. A subgroup analysis comparing vitrectomised to non-vitrectomised eyes in both groups was also performed.
Of the 92 eyes, 46% (23 of 51) in the 4 mg group versus 30% (12 of 41) in the 20 mg group had an IOP >21 mm of Hg (p = 0.14) after a mean follow-up period of 27 weeks. The vitrectomised eyes (3 of 24) in the 20 mg group had a significantly lower rate of IVTA induced IOP elevation than the non-vitrectomised eyes (9 of 17) (p = 0.013). The IOP elevation occurred significantly earlier in the 4 mg group (vitrectomised eyes 27 (SD 43) days and non-vitrectomised eyes 61 (52) days) than in the 20 mg group (vitrectomised eyes 104 (56) days and non-vitrectomised eyes 119 (82) days), independent of the vitreous status (vitrectomised p = 0.05 and non-vitrectomised p = 0.04). The mean value of initial high IOP in the non-vitrectomised eyes was higher in the 4 mg group than in the corresponding 20 mg group (p = 0.048).
Decanted 20 mg IVTA may not pose a significantly greater risk of IOP elevation than the 4 mg non-decanted IVTA.
PMCID: PMC2776725  PMID: 18420748
5.  Phase I clinical trial results of verteporfin enhanced feeder vessel therapy in subfoveal choroidal neovascularisation in age related macular degeneration 
The British Journal of Ophthalmology  2006;90(9):1152-1156.
To investigate the safety and effectiveness of extrafoveal photodynamic therapy (PDT) occlusion of feeder vessels (FVs) in patients with subfoveal choroidal neovascularisation (CNV) as a result of age related macular degeneration.
FVs were identified using dynamic fluorescein and indocyanine green angiography with scanning laser ophthalmoscope. The standard doses of verteporfin and laser wavelength were used. The light dose was escalated by increasing the duration of the light dose so the light regimen was 50 J/cm2 for patients 1 and 2; 100 J/cm2 for patients 3, 4, 5; 125 J/cm2 for patients 6 and 7; and 150 J/cm2 for patients 8 and 9. Patients were examined at weeks 1, 4, and 12.
The mean improvement on EDTRS chart 3 months after treatment was an increase of 2.1 lines (p = 0.07). Closure of the FV was achieved angiographically in three eyes at various light doses, in three eyes the FV was hypoperfused, and in three eyes the vessels were were neither closed nor hypoperfused. At the last follow up all FVs were reperfused. There was no evidence of retinal damage.
Verteporfin enhanced FV therapy does not cause subfoveal retinal damage and may have potential to improve central vision in subfoveal CNV caused by exudative macular degeneration. It is not recommended as a monotherapy for CNV.
PMCID: PMC1857394  PMID: 16774958
macular degeneration; photodynamic therapy; choroidal neovascular membrane; feeder vessel
6.  Photographic estimation of the duration of high dose intravitreal triamcinolone in the vitrectomised eye 
To determine the duration of residence of triamcinolone in the vitrectomised eye.
23 eyes of 23 patients underwent intravitreal injection of high dose (20 mg) decanted triamcinolone acetonide (Kenalog) at the conclusion of vitrectomy surgery or in previously vitrectomised eyes with macular oedema from diabetes, uveitis, cataract surgery, or other surgery.
The median time to disappearance of triamcinolone in the vitrectomised eye was 113 days (95% confidence interval (CI) 85 to 191). In the phakic eyes the median time to disappearance was 191 days (95% CI 148 to 191). In the pseudophakic eyes the median time to disappearance was 102 days (95% CI 85 to 113). This difference was not significant (p = 0.12). There were no cases of endophthalmitis or severe inflammatory reaction. Five eyes (22%) experienced intraocular pressure rise ⩾10 mm Hg.
High dose decanted intravitreal triamcinolone has a median residence time of 113 days in the vitrectomised eye. Although this appears to be shorter than in the non‐vitrectomised eye, this study suggests that a sufficient duration of action will be present to be clinically useful.
PMCID: PMC1860213  PMID: 16531422
diabetes; macular degeneration; macular oedema; triamcilone; vitreous injection
8.  Scanning laser entoptic perimetry for the detection of visual defects associated with diabetic retinopathy 
To determine the sensitivity and specificity of entoptic perimetry for diagnosing diabetic retinopathy at all levels of severity.
A prospective clinical study at the Shiley Eye Center, University of California, and San Diego. 30 patients with photographically documented diabetic retinopathy and 24 controls with a similar age distribution. Sensitivity and specificity of entoptic perimetry were computed for detecting clinically significant macular oedema within the central 120 degree radius of the fovea compared to fundus photographs.
Entoptic perimetry can detect clinically significant diabetic retinopathy with a sensitivity of 0.88 and specificity of 1.00. Entoptic perimetry can detect the earliest stages of diabetic retinopathy with a sensitivity of 0.86.
Scanning laser entoptic perimetry is an effective tool for detecting visual function loss caused by diabetic retinopathy.
PMCID: PMC1856910  PMID: 16361659
diabetic retinopathy; visual field; vision; retina; perimetry
9.  Intravitreal properties of porous silicon photonic crystals 
To determine the suitability of porous silicon photonic crystals for intraocular drug-delivery.
A rugate structure was electrochemically etched into a highly doped p-type silicon substrate to create a porous silicon film that was subsequently removed and ultrasonically fractured into particles. To stabilise the particles in aqueous media, the silicon particles were modified by surface alkylation (using thermal hydrosilylation) or by thermal oxidation. Unmodified particles, hydrosilylated particles and oxidised particles were injected into rabbit vitreous. The stability and toxicity of each type of particle were studied by indirect ophthalmoscopy, biomicroscopy, tonometry, electroretinography (ERG) and histology.
No toxicity was observed with any type of the particles during a period of >4 months. Surface alkylation led to dramatically increased intravitreal stability and slow degradation. The estimated vitreous half-life increased from 1 week (fresh particles) to 5 weeks (oxidised particles) and to 16 weeks (hydrosilylated particles).
The porous silicon photonic crystals showed good biocompatibility and may be used as an intraocular drug-delivery system. The intravitreal injectable porous silicon photonic crystals may be engineered to host a variety of therapeutics and achieve controlled drug release over long periods of time to treat chronic vitreoretinal diseases.
PMCID: PMC2666262  PMID: 18441177
10.  Improved visualisation of choroidal neovascularisation by scanning laser ophthalmoscope using image averaging 
The British Journal of Ophthalmology  2005;89(8):1026-1030.
Aims: To improve visualisation of angiographic features in patients with age related macular degeneration associated with choroidal neovascularisation (CNV) and related complications. To evaluate if image averaging can achieve this goal.
Methods: 27 eyes of 20 sequential patients with age related macular degeneration over a 3 month period were studied. Indocyanine green angiograms (ICGA), fluorescein angiograms (FA), and oral fluorescein angiograms were recorded with a confocal scanning laser ophthalmoscope. Software was used to average multiple images from a 10–20 image series (over 0.5–1.0 seconds). Image quality was assessed by two masked observers and graded on a scale of 0–3. A more quantifiable grading method was devised by adding a variable amount of Gaussian noise to the improved image until the original and image averaged image appeared equal.
Results: Masked review showed mild to strong improvement of visualisation of structures including borders of CNV. Improvement varied depending on the type and phase of the angiogram. Improvement was highest in late phase FA, mid and late phase ICGA, and all phases of oral FA.
Conclusion: Image averaging using software based algorithms improves the quality of angiographic images, particularly late ICGA images and oral FAs. This method may assist in the visualisation of choroidal neovascularisation in age related macular degeneration.
PMCID: PMC1772758  PMID: 16024859
scanning laser ophthalmoscope; image averaging; image processing; age related macular degeneration; choroidal neovascularisation
11.  Long term visual outcome of patients with cytomegalovirus retinitis treated with highly active antiretroviral therapy 
Background: Healed cytomegalovirus (CMV) retinitis in the setting of highly active antiretroviral therapy (HAART) is complicated by inflammatory sequelae and vision loss.
Aim: To determine the long term visual outcome of AIDS patients with CMV retinitis who received HAART.
Methods: 90 eyes of 63 consecutive AIDS patients with extramacular CMV retinitis were studied prospectively.
Results: Immune recovery status was related to time to onset of epiretinal membrane (p=0.05) and cystoid macular oedema (p=0.06) as well as to the incidence of cataract (p=0.001) and moderate vision loss (p<0.0001). Severe vision loss was associated with retinal detachment (p<0.001).
Conclusion: AIDS patients with extramacular CMV retinitis lose vision while on HAART. HAART related immune recovery is associated with increased frequencies of epiretinal membrane, cystoid macular oedema, cataract, and retinal detachment with resultant vision loss in AIDS patients with healed CMV retinitis.
PMCID: PMC1771778  PMID: 12812884
cytomegalovirus retinitis; highly active antiretroviral therapy
12.  Interobserver and intraobserver variability of measurements of uveal melanomas using standardised echography 
The British Journal of Ophthalmology  2002;86(12):1390-1394.
Aim: To report on the intraindividual and interindividual variability of tumour size (height and base diameter) measurements using standardised echography in a masked prospective study.
Methods: 20 consecutive eyes of 20 patients were examined on four different visits by three experienced examiners using standardised echography. As common in standardised echography, tumour height was evaluated with A-scan technique, while transverse and longitudinal base diameter were calculated with B-scan.
Results: Tumour height measurements using A-scan were more accurate than base diameter measurements using B-scan. The standard deviation for tumour height over all visits/measurements was 0.18 mm (A-scan), 0.79 mm for transverse, and 0.69 mm for longitudinal base diameters (B-scan). The interclass correlation coefficient (ICC) was much higher for tumour height measurements with A-scan (0.7735 for three examiners on one visit) than for transverse (0.6563) or longitudinal (0.4522) base diameter measurements with B-scan techniques.
Conclusions: A-scan techniques for tumour height measurements provide very reproducible results with little intraindividual and interobserver variability. As B-scan techniques for tumour base evaluation are less accurate they should be used for topographic and morphological examinations.
PMCID: PMC1771401  PMID: 12446372
uveal melanomas; echography; observer variability
13.  Antiviral effect in human cytomegalovirus-infected cells, pharmacokinetics, and intravitreal toxicology in rabbits of acyclovir diphosphate dimyristoylglycerol. 
Acyclovir diphosphate dimyristoylglycerol (ACVDP-DG) is a lipid prodrug which is active against ACV-resistant strains of herpes simplex virus because of its intracellular metabolism to ACV monophosphate. In human cytomegalovirus (HCMV)-infected MRC-5 cells, ACVDP-DG was ninefold more active than ACV. When liposomal [8-3H]ACVDP-DG was injected intravitreally at the maximum nontoxic dose of 1 mumol in rabbits, the drug remained above its estimated 90% HCMV-inhibitory concentration for 18 days. Intravitreal ganciclovir persists above its 90% inhibitory concentration for only 1 to 2 days. ACVDP-DG may be useful as a local treatment for HCMV retinitis.
PMCID: PMC162748  PMID: 7574537
14.  Useful adjuncts for vitreoretinal surgery. 
Many vitreoretinal procedures are performed in offices and hospitals where cost control is important. We describe three useful devices and techniques that facilitate these procedures at minimal expense and often greater convenience. These include an accurate method for localising the pars plana without the use of callipers, an inexpensive, reliable, pressure regulated air pump for fluid-air exchange, and an easy method for intraocular injection of silicone oil through 20 gauge instrumentation without the need for expensive pumps. These procedures and techniques should prove to be useful in the treatment of vitreoretinal disease.
PMCID: PMC1041764  PMID: 2751976
15.  Evaluation of outpatient experience with vitreoretinal surgery. 
The experience of 55 consecutive individuals undergoing outpatient vitreoretinal surgery was evaluated. Objective variables, including preoperative and intraoperative information, subjective postoperative pain, and discomfort were measured with a previously validated 100 mm visual analogue scale. Patients also ranked the overall experience. Average pain and discomfort scores in the recovery room were 21.8 and 22.6 and overnight were 26.7 and 30.4 (scale 0 to 100), respectively. Eighty eight per cent of subjects were satisfied with the experience. Elevated pain and discomfort scores were statistically correlated with scleral buckling, prolonged surgical or recovery room time, requirement for parenteral pain medications, and high intraocular pressure on the first postoperative visit. None of the patients needed further hospital treatment. This study suggests that vitreoretinal surgery in an appropriately selected population does not require routine inpatient care.
PMCID: PMC504163  PMID: 1739718
17.  Immune predispositions for cytomegalovirus retinitis in AIDS. The HNRC Group. 
Journal of Clinical Investigation  1995;95(4):1741-1746.
CMV retinitis develops in approximately 28-35% of all AIDS patients at later stages of disease, often leading to blindness. To determine whether the subset of AIDS patients who developed CMV retinitis (CMV-R) were immunologically predisposed, T cell proliferation responses to CMV were examined prospectively in an HIV infected, HLA typed, longitudinal study population. Individuals who developed CMV-R had significantly lower T cell proliferation responses to CMV, both early and late in disease, compared to CD4 matched controls who have not developed CMV-R. Since HLA proteins influence T-cell recognition, phenotypes of 21 CMV-R patients were examined to determine whether certain HLA alleles were associated with low immune response and predisposed AIDS patients to CMV-R. HLA DR7 and B44 were at increased (nearly twice the expected) frequency in those with CMV-R. The combined association of either B44, 51 or DR7 with CMV-R was highly significant (P = .008, relative risk of CMV-R = 15) with correction for multiple comparisons. Low immune responses were twice as frequent in those with (61%) compared to those without (30%) predisposing alleles. Thus, AIDS patients with immunogenetically related hyporesponsiveness to CMV antigens may be at increased risk of retinitis.
PMCID: PMC295694  PMID: 7706482
18.  Mutations in human cytomegalovirus UL97 gene confer clinical resistance to ganciclovir and can be detected directly in patient plasma. 
Journal of Clinical Investigation  1995;95(1):257-263.
Specific mutations in the UL97 region of human cytomegalovirus (HCMV) have been found to confer resistance to laboratory-adapted strains subjected to ganciclovir selection. In this study, mutations in the UL97 region of HCMV isolates obtained from patients receiving ganciclovir therapy were examined to determine whether they would confer ganciclovir resistance, and if these mutations could be detected directly in the plasma of AIDS patients with progressive HCMV disease despite ganciclovir treatment. A single nucleotide change within a conserved region of UL97 was found in five resistant isolates, resulting in an amino acid substitution in residue 595: from leucine to phenylalanine in one, and from leucine to serine in four resistant isolates. A sixth resistant isolate demonstrated a single nucleotide change, leading to a threonine to isoleucine substitution in residue 659. The role of the 595 amino acid substitution in conferring ganciclovir resistance was confirmed by marker transfer experiments. In further studies, direct sequencing of HCMV DNA present in plasma obtained from persons with resistant viruses revealed the identical amino acid substitutions in plasma as those present in the cultured viruses. These findings indicate that clinical resistance to ganciclovir can result from specific point mutations in the UL97 gene, and that the emergence of the resistant genotype can be detected directly in patient plasma.
PMCID: PMC295420  PMID: 7814623
19.  Ocular examination and diagnosis in patients with the acquired immunodeficiency syndrome. 
Western Journal of Medicine  1993;158(3):254-262.
Ocular involvement is seen frequently and is an important source of morbidity in patients with the acquired immunodeficiency syndrome. We outline here the general skills of physical diagnosis valuable to primary care physicians or infectious diseases specialists in recognizing and evaluating ocular complaints in patients infected with the human immunodeficiency virus. We provide an overview of common ocular diseases in these patients, with an emphasis on signs and symptoms that aid in the differential diagnosis.
PMCID: PMC1311750  PMID: 8384763
20.  A graphical analysis of the interrelationships among waterborne asbestos, digestive system cancer and population density. 
Five statistical procedures were used to partial the correlation between waterborne asbestos and digestive site cancer for the putative effects of population density. These include: analysis based on a data subset with roughly homogeneous population density; standard residual analysis (partial correlation); conditional probability integral transformation; analysis based upon ranked data, and use of logarithmic transformation. Nonparametric regression graphical techniques are applied to examine the nature or shape of the asbestos-cancer dose-response curve. Evidence is presented that suggests that there is considerable difference between analyses involving nonhigh-density tracts and non-San Francisco tracts. Evidence is also presented that the modal-type nonparametric regression curve forks or bifurcates when adjustment is made for population density.
PMCID: PMC1569086  PMID: 6662097
21.  Cytomegalovirus retinitis: a manifestation of the acquired immune deficiency syndrome (AIDS). 
Two homosexual males with the "gay bowel syndrome' experienced an acute unilateral loss of vision. Both patients had white intraretinal lesions, which became confluent. One of the cases had a depressed cell-mediated immunity; both patients ultimately died after a prolonged illness. In one patient cytomegalovirus was cultured from a vitreous biopsy. Autopsy revealed disseminated cytomegalovirus in both patients. Widespread retinal necrosis was evident, with typical nuclear and cytoplasmic inclusions of cytomegalovirus. Electron microscopy showed herpes virus, while immunoperoxidase techniques showed cytomegalovirus. The altered cell-mediated response present in homosexual patients may be responsible for the clinical syndromes of Kaposi's sarcoma and opportunistic infection by Pneumocystis carinii, herpes simplex, or cytomegalovirus.
PMCID: PMC1040068  PMID: 6303386

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