Corneal Epithelial Remodeling After Standard Epithelium-off Corneal Cross-linking in Keratoconic Eyes.

PURPOSE: To evaluate remodeling of the corneal epithelium after epithelium-off corneal cross-linking (CXL). METHODS: In this prospective single-center study, 93 eyes of 93 patients with progressive keratoconus underwent standard CXL. The maximum keratometry was assessed before and after CXL with Scheimpflug imaging, and the epithelial thickness profile across the central 5 mm of the cornea was assessed with spectral-domain optical coherence tomography anterior segment imaging. RESULTS: The mean patient age was 27 ± 11 years; 76 patients (81%) were male and 17 (19%) were female. Between baseline and 6 months after CXL, the mean corneal maximum keratometry flattened from 58.90 to 57.80 diopters (P < .0001). The mean minimum epithelial thickness increased slightly (from 41 ± 6 to 42 ± 7 µm, P = .12), whereas the mean maximum epithelial thickness decreased slightly (from 65 ± 6 to 64 ± 7 µm, P = .067), reducing the net difference between the minimum and maximum epithelial thickness (from 24 ± 9 to 22 ± 9 µm, P = .0023). The difference between the minimum and maximum epithelial thickness was strongly positively correlated with the maximum keratometry reading at baseline (R2 = 0.38) and at 6 months after CXL (R2 = 0.59). CONCLUSIONS: Epithelium-off CXL resulted in modest regularization of the epithelial thickness profile across the central 5 mm of the cornea at 6 months. This could slightly mask flattening of the underlying stroma. [J Refract Surg. 2018;34(6):408-412.].

Intraoperative hyphema in Descemet membrane endothelial keratoplasty alone or combined with phacoemulsification.

PURPOSE: To identify whether intraoperative hyphema from the peripheral iridotomy during Descemet membrane endothelial keratoplasty (DMEK) is associated with anticoagulant or antiplatelet use, age, combined phacoemulsification, or adverse outcomes. SETTING: Price Vision Group, Indianapolis, Indiana, USA. DESIGN: Retrospective case series. METHODS: Data were obtained from consecutive DMEK cases with an intraoperative iridotomy from July 2015 through July 2016. Hyphema was classified as negative or positive (small or large). Associations with possible risk factors and with transplant outcomes were assessed. RESULTS: Of 445 cases, 262 (59%) were negative for hyphema and 183 (41%) were positive. The proportion of patients who used preoperative anticoagulant or antiplatelet medication did not differ significantly with the hyphema classification (negative hyphema 42%, small hyphema 34%, large hyphema 46%) (P = .31). Likewise, recipient age was not a risk factor for hyphema (P = .085). Hyphema was more likely in cases combined with phacoemulsification than in single DMEK procedures (relative risk, 1.5 [95% confidence interval, 1.2-1.9]). Hyphema was not associated with postoperative rebubbling rates (negative hyphema 10.5%, small hyphema 10.3%, large hyphema 8.0%) (P = .33), 6-month endothelial cell loss (mean = 29%, P = .19), or 6-month visual acuity (mean = 20/25 Snellen in all hyphema groups, P = .98). CONCLUSIONS: Preoperative anticoagulant or antiplatelet use was not a significant risk factor for hyphema. The risk for hyphema was increased somewhat when DMEK was combined with cataract surgery. Intraoperative hyphema did not significantly affect the rebubbling rate, endothelial cell loss, or visual acuity outcomes.

Hypoxia and the Prolyl Hydroxylase Inhibitor FG-4592 Protect Corneal Endothelial Cells From Mechanical and Perioperative Surgical Stress.

PURPOSE: To determine whether hypoxia preconditioning can protect corneal endothelial cells from mechanical stress and perioperative procedures mimicking Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Preconditioning was delivered by 2 hours of 0.5% oxygen incubation in a hypoxia chamber or by exposure to the prolyl hydroxylase inhibitor FG-4592, which prevents hypoxia-inducible factor-1 alpha degradation. Damage to whole corneas was produced by brief sonication. To mimic use with DSAEK, FG-4592-preconditioned and control donor corneas were dissected with a microkeratome, and the posterior donor button was pulled through a transplant insertion device (Busin glide). The area of endothelial damage was determined by trypan blue staining. RESULTS: In all cases, hypoxia preconditioning or incubation with FG-4592 protected corneal endothelial cells from death by mechanical stress. Hypoxia-preconditioned human and rabbit corneas showed 19% and 29% less cell loss, respectively, relative to controls, which were both significant at P < 0.05. FG-4592 preconditioning reduced endothelial cell loss associated with preparation and insertion of DSAEK grafts by 23% relative to the control (P < 0.01). CONCLUSIONS: These results support the hypothesis that preconditioning by hypoxia or exposure to FG-4592 improves corneal endothelial cell survival and may also provide protection during surgical trauma.