Steven A. Koopmans

To moderate the capsular opacification (CO) response after lens surgery, an experimental study was performed in which nanofibre-based hydrogels (nanogels) with different ratios of attached peptides were applied to provide extracellular matrix-related cues for lens epithelial cells (LECs) in a porcine eye model. The lens content was removed, and the capsules were refilled with nanogel. Lenses were divided into two groups, the first group (n = 34) was refilled with nanogels containing different ratios of two laminin-derived peptides (IKVAV + YIGSR), and the latter group (n = 26) was refilled with nanogel combinations of a fibronectin-derived and a type IV collagen-derived peptide (RGDS + DGEA). Two lenses were refilled with culture medium to investigate the effect of the medium on LECs. After refilling, lenses were extracted and cultured for 3 weeks. Lens epithelial cells (LECs) were assessed for morphology and alpha-smooth muscle actin (αSMA) expression using confocal laser scanning microscopy. Differences were seen in cell morphology between lenses refilled with nanogels with IKVAV + YIGSR and RGDS + DGEA peptides. In nanogels with IKVAV + YIGSR peptides, differences in LEC morphology were largest when ratios between the peptides were unequal, whereas LEC responses from the RGDS + DGEA refilled groups showed variation in LEC morphology dependent on the total quantity of mixed-in peptides. The culture medium did not induce proliferation or transformation of LECs. Ratios and concentrations of cell adhesion-mediating peptides both can direct the LEC response, depending on the adhesion molecules of origin, by influencing LEC proliferation and transformation. Nanogels with incorporated peptides may be tuned towards CO prevention.

To determine the extent to which stereoscopic depth perception influences the performance of tasks executed under an operating microscope. Laboratory of Experimental Ophthalmology, University Medical Center Groningen, the Netherlands. Experimental study. Medical students were assigned (on the basis of their stereoacuity) to a stereo-sufficient group (depth perception ≤240 seconds of arc [arcsec]) or stereo-deficient group (≥480 arcsec). They performed a bead-stringing task (a mockup surgical test) under an operating microscope or a task on a cataract surgery simulator. The stereo-sufficient subjects also performed the bead-stringing task under artificial stereo-deficient conditions (binocular and monocular viewing). The study comprised 77 medical students. The stereo-sufficient subjects performed both tasks faster than the stereo-deficient subjects and artificially stereo-deficient subjects (P ≤ .024). In addition, a within-group analysis established that the stereo-sufficient subjects were faster at the bead-stringing task with stereoscopic viewing than under artificial stereo-deficient conditions with binocular viewing (P ≤ .011). Having stereovision resulted in better initial performance on certain tasks involving the use of an operating microscope or cataract surgery simulator. However, this study did not show that stereo deficiency necessarily results in an inability to perform such tasks properly. Hence, it was not evident that for admission to an ophthalmology residency program, stereovision should be judged more stringently than other traits. No author has a financial or proprietary interest in any material or method mentioned.

Purpose: To develop a procedure for describing wavefront‐optimized photorefractive keratectomy (PRK) corneas and to characterize PRK‐induced changes in shape. Methods: We analyzed preoperative and postoperative corneal elevation data of 41 eyes of 41 patients (mean [±SD] age, 38 [±11] years) who underwent a myopia‐correcting (preoperative spherical equivalent refraction −3.9 [±1.5] diopters) wavefront‐optimized PRK, assessed with Scheimpflug imaging. Zernike polynomials were fitted to the elevation data. The diameter of the greatest corneal zone that could be analyzed and the number of Zernike orders needed to make a reliable fit were determined, based on the fitting error. The PRK‐induced changes in corneal shape were studied. Results: All subjects could be included for analysis of zones up to 6 mm in diameter. This was 90, 83, and 44% for 7, 8, and 9 mm, respectively. The number of Zernike orders (terms) needed for an accurate fit ranged from four (15) for a 4‐mm analyzed zone diameter to eight (45) for 8 mm. For the anterior surface, the spherical aberration term decreased significantly (p < 0.01) after PRK for the 4‐mm analyzed zone diameter (−0.09 μm), remained unchanged for 5 mm (+0.01 μm; p = 0.56), and increased significantly for 6 mm (+0.40 μm) and above (p < 0.01). There was no significant change in any other higher‐order Zernike term, but the square root of the sum of the squares of all higher‐order terms increased significantly for all analyzed zone diameters. Photorefractive keratectomy did not influence the posterior corneal shape. Conclusions: The cornea after wavefront‐optimized PRK can be described as accurately as a healthy cornea and with a similar number of Zernike polynomials. The anterior corneal shape changes significantly after treatment, whereas the posterior corneal shape remains unchanged. The observed effect of wavefront‐optimized ablation on the spherical aberration term depends on the diameter of the analyzed zone.

Purpose To test 2 strategies to prevent capsule opacification after accommodating lens refilling in a rhesus monkey model. Setting Animal laboratory and laboratory of European university medical centers. Design Experimental study. Methods Six rhesus monkeys had refilling of the lens capsular bag. In the first strategy, before it was filled with a silicone polymer, the capsular bag was treated with noncommercial sodium hyaluronate 1.0% containing cytotoxic substances. In the second strategy, the capsular bag was filled with clinically used sodium hyaluronate 1.0% (Healon) after treatment with actinomycin-D. Slitlamp inspection was performed during a follow-up of 40 to 50 weeks. After enucleation, magnetic resonance images were obtained and confocal fluorescence imaging was performed. Results Using the first strategy, capsule opacification developed in all eyes. Using the second strategy, 1 monkey did not develop capsule opacification after a 9-month follow-up. In a second monkey, the lens capsule remained clear for 3 months, after which the hyaluronate refill material was exchanged with a silicone polymer and capsule opacification developed. Combining these results with those in a previous study, the difference in opacification between silicone and sodium hyaluronate as refilling materials was statistically significant (P<.01). Conclusions That no capsular bag fibrosis occurred in the presence of hyaluronate suggests that the properties of hyaluronate are the reason that remaining lens epithelial cells do not develop into fibrotic cells. The choice of a suitable lens-refilling material prevents the development of capsule opacification. Financial Disclosure Mr. Terwee was an employee of Abbott Medical Optics B.V. during the study period. No other author has a financial or proprietary interest in any material or method mentioned.

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PURPOSE: To design a method to preserve enucleated porcine eyes for use in a wet laboratory. SETTING: Laboratory of Experimental Ophthalmology, University Medical Center Groningen, the Netherlands. DESIGN: Experimental study. METHODS: Porcine eyes were preserved using 15 methods including salt solutions, anterior chamber infusion fluids, tap water, mineral water, air, and topical glycerol on the cornea. The central corneal thickness (CCT) was measured by A-scan ultrasound over 3 days. Differences between increases in CCT were compared using repeated-measures multivariate analyses of variance. Also, lenses from eyes preserved in tap water were extracted and the lens epithelial cell morphology was studied. RESULTS: There was a significant interaction between the preservation method and CCT over 3 days (P CONCLUSIONS: Of the 15 tested methods to preserve porcine eyes, tap water (mineral content 1.79 mmol/L) resulted in the least corneal swelling. It is not necessary to use more expensive anterior chamber infusion fluids or other salt solutions. (C) 2014 ASCRS and ESCR