Refractive surprise after routine cataract surgery with multifocal IOLs attributable to corneal epithelial basement membrane dystrophy.

We describe two patients in whom postsurgical refractive error occurred after routine refractive lens exchange cataract surgery with multifocal intraocular lens insertion most likely attributable to the presence of underlying corneal epithelial basement membrane dystrophy (EBMD). In Case 1, there was an unexpected hyperopic postoperative spherical equivalent refractive error of +1.50 diopters and in Case 2, a cylindrical refractive error of 2.75 diopter cylinder. We examine the possible causes of error and discuss potential management strategies to prevent and address these unpredictable postoperative outcomes. The importance of comprehensive and careful ocular surface assessment before cataract or refractive surgery as part of the presurgical workup is reemphasized. EBMD can be subtle and if overlooked, can affect the validity of biometric keratometric measurements preoperatively, resulting in an inaccurate biometry measurement, incorrect IOL selection, and reduced visual performance and patient satisfaction.

An Investigation of the Effects of Riboflavin Concentration on the Efficacy of Corneal Cross-Linking Using an Enzymatic Resistance Model in Porcine Corneas.

Purpose: To investigate riboflavin concentration on enzymatic resistance following corneal cross-linking (CXL). Methods: Ninety-six porcine eyes were divided into five groups in two treatment runs. Group 1 remained untreated. Group 2 received riboflavin 0.05%, group 3 riboflavin 0.1%, group 4 riboflavin 0.2%, and group 5 riboflavin 0.3%. Treated eyes underwent CXL with ultraviolet A at 9 mW/cm2 for 10 minutes. Eight-millimeter discs from each cornea were submerged in pepsin digest solution. In the first run, disc diameters were measured daily. After 10 days, dry weights were recorded from five samples in each group. In the second run, dry weights were recorded in five samples in each group at 10 and 20 days. Results: CXL-treated corneas took longer to digest than untreated (P < 0.001). Although eyes treated with higher riboflavin concentrations generally took longer to digest, there were no significant differences between groups (P = 0.3). Dry weights at 10 days demonstrated, with each increase in concentration, an increase in weight of residual undigested tissue (P < 0.001). In the second run, with each increase in riboflavin concentration there was an increase in weight of residual tissue (P < 0.001) at 10 days. At 20 days, the dry weight was lower with 0.05% riboflavin compared to 0.3% (P < 0.001) and 0.2% and 0.1% solutions (P < 0.05), with no other difference between groups. Conclusions: There is a consistent dose-response curve with higher concentrations of riboflavin achieving greater CXL efficacy, suggesting that manipulation of riboflavin dosage as well as the UVA protocol can be used to optimize CXL.

Evaluation of transepithelial stromal riboflavin absorption with enhanced riboflavin solution using spectrophotometry.

PURPOSE: To assess transepithelial stromal riboflavin absorption with an enhanced riboflavin solution (riboflavin 0.1%, 15% dextran T500 with trometamol (Tris-[hydroxymethyl]aminomethane) and sodium ethylenediaminetetraacetic acid by analyzing light-transmission properties of ex vivo rabbit corneas. SETTING: School of Optometry and Vision Sciences, Cardiff, Wales. DESIGN: Experimental study. METHODS: The enhanced riboflavin drops (Ricrolin TE) were applied every 3 minutes for 1 hour to 12 corneas (4 with intact epithelium, 4 with superficial scratches, 4 with 8.0 mm epithelial debridement). As a comparison, riboflavin drops without the enhancers (riboflavin 0.1%, 20% dextran T500) (normal riboflavin group) were applied to 12 corneas (4 with intact epithelium, 4 with superficial scratches, 4 with central epithelial debridement). A control group of 4 corneas with intact epithelium received balanced saline 0.9%. To assess enhanced riboflavin absorption, light-transmission spectra of the corneas were analyzed with a spectrophotometer. RESULTS: The spectra in corneas with intact epithelium in both riboflavin groups and in eyes with superficial scratches treated with normal riboflavin were similar to controls. Those with enhanced riboflavin and superficial scratches showed a homogeneous yellow discoloration of the cornea with a dip in light transmission between 400 and 490 nm, similar to that of the enhanced riboflavin solution. This was also seen, albeit of a greater magnitude, with complete epithelial removal, with eyes receiving enhanced riboflavin having a greater dip in transmission than eyes receiving normal riboflavin. CONCLUSIONS: Administration of enhanced riboflavin and superficial epithelial scratches allowed sufficient riboflavin stromal absorption to homogeneously alter the transmission spectra of rabbit corneas. This did not occur to the same extent with an intact epithelium or normal riboflavin with superficial scratches. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.