An otherwise healthy 23-year-old Caucasian man was referred to our institute as a potential candidate for CXL. According to his referral documents, the patient had an uneventful medical history, and despite progressive bilateral keratoconus he had no other ophthalmological problems. However, during the past year, he had developed contact lens intolerance.
At presentation, his uncorrected visual acuities were 0.4 logMar and 0.5 logMar in his right and left eyes, respectively. His best corrected visual acuities (BCVA) were 0.1 logMar (-0.25 spherical (SPH), -2.50 cylindrical (CYL) × 20) in his right eye and 0.3 logMar (-0.50 SPH, -3.00 CYL × 155) in his left eye. Central corneal pachymetry measured with a Scheimpflug camera (Pentacam Oculyzer; Oculus Optikgerate GmbH, Heidelberg, Germany) was 462 μm and 455 μm in his right and left eyes, respectively. The thickness of the thinnest corneal point (TCT) in the left eye was 443 μm (Figure ), while the keratometric readings derived from the Pentacam test were K1-43.1, K2-46.4 in the right eye and K1-43.2, K2-46.6 in the left eye, respectively. In comparison to the patient's referral documents, within the past year the patient had demonstrated deterioration in his BCVA (former BCVA 0.2 logMar (-0.50 SPH, -2.25 CYL × 155) and in the TCT (former TCT was 449 μm). According to the topographical keratometric data, he was diagnosed with KC stage 1 or 2 and scheduled for CXL therapy.
Preoperative Pentacam Oculyzer image of the patient's left eye.
Standard CXL treatment was performed in the patient's left eye according to the following procedure: Alcaine drops were used for topical anesthesia, followed by application of a sponge saturated with 20% alcohol to the central cornea for 15 seconds. De-epithelialization was performed by means of a hockey knife. The residual corneal thickness after debridement was 407 μm as measured by ultrasound contact pachymetry (Pacline; Optikon 2000 SpA, Rome, Italy). After de-epithelialization, a mixture of 0.1% riboflavin in 20% dextran solution was instilled into the cornea for 30 minutes (two drops every two minutes) until the stroma was completely penetrated and the aqueous humor was stained yellow. Regarding the UVA radiation source, the UV-X system (Peschke Meditrade GmbH, Cham, Switzerland) was employed. An 8.0 mm diameter of the central cornea was irradiated for 30 minutes by UVA light with a wavelength of 370 nm and at surface radiance of 3 mW/cm2, which corresponds to a surface dose of 5.4 J/cm2. It should be mentioned that the use of riboflavin was continued during irradiation to maintain the necessary concentration. Moreover, balanced salt solution was applied every six minutes to moisten the cornea. When the irradiation was complete, a soft contact lens (Day & Night; CIBA Vision, Duluth, GA, USA) was applied until full re-epithelialization was completed.
The patient was administered the following postoperative medications: (1) gentamicin sulfate and dexamethasone dihydrogenophosphate drops (Dexamytrex Ophtiole; Bausch & Lomb, Berlin, Germany) four times daily and (2) a monodose combination of sodium hyaluronate 0.15% and dexpanthenol 2% (HyloPan; ZwitterPharmaceuticals, Halandri, Greece) every hour.
Despite an uneventful CXL treatment, during the first postoperative day the patient developed intense photophobia, watering and a non-specific ocular discomfort. Slit lamp biomicroscopy revealed redness, especially at the limbal region, severe corneal haze accompanied by non-specific endothelial precipitates and a few inflammatory cells in the anterior chamber (Tyndall effect +1) (Figure ). The aforementioned findings resembled an acute inflammatory response to the CXL procedure and/or possibly to the postoperative medication. Moreover, no evidence of re-epithelialization was observed, and the patient's visual acuity was limited to counting fingers.
Slit lamp biomicroscopic image showing severe corneal haze and endothelial precipitates due to the acute inflammatory response.
The patient's postoperative medication was modified to ofloxacin drops four times per day quid (Exocin; Allergan, Castlebar Road, Westport, CoMayo, Ireland), dexamethasone drops every two hours (Maxidex; Alcon Cusi, SA, Spain), frequent use of carboxymethylcellulose 0.5% drops (Optive; Allergan, Irvine, Ca) and oral acyclovir 400 mg four times daily (Zovirax; GlaxoSmithkline, Aranda, Spain). Further to the postoperative regimen change, the patient underwent a complete laboratory examination for autoimmune and infectious diseases, including markers for rheumatoid factor, immune complexes, C-reactive protein, antineutrophilic cytoplasmic antibodies and erythrocyte sedimentation rate, as well as polymerase chain reaction for herpes simplex virus DNA detection, which were all negative or within normal limits. Moreover, repeated cultures from cornea samples and the contact lens were all negative. However, the patient was evaluated for hypersensitivity to riboflavin (vitamin B2) and other components of the B vitamin complex as well as a series of common allergens. According to the results presented in Table , no evidence of a hypersensitivity reaction could be detected.
Patient's serum allergen valuesa
The treatment change resulted in subjective improvement of ocular discomfort and disappearance of the inflammatory cells in the anterior chamber. However, the cornea presented extremely slow re-epithelialization and progressive thinning, which resulted in descemetocele and finally perforation in the second postoperative month. The patient underwent uncomplicated penetrating keratoplasty with an uneventful postoperative period.