Effect of corneal cross-linking on endothelial cell density and morphology in the peripheral cornea.

BACKGROUND: To compare the endothelial cell density and morphology in the peripheral cornea before and after corneal cross-linking (CXL). METHODS: This study evaluated thirty-one eyes of 31 patients who were treated with standard CXL for progressive keratoconus. Preoperatively and 6 months postoperatively, we compared the corneal endothelial cell density (ECD), the coefficient of variation in cell size (CV), and the percentage of hexagonal cells (HEX), in the peripheral regions of the cornea, using a non-contact specular microscope (EM-3000, Tomey). RESULTS: All keratoconic eyes in this series were measurable in the peripheral regions. No significant differences were found in the peripheral ECD preoperatively and 6 months postoperatively at each point (Wilcoxon signed-rank test, superior, p = 0.16, nasal superior, p = 0.12, temporal superior, p = 0.17, inferior, p = 0.37, nasal inferior, p = 0.28, temporal inferior, p = 0.17). The mean percentage of the ECD loss was 1.3, 1.3, 1.0, 1.4, 0.7, and 1.4%, respectively. No significant differences in the peripheral CV or HEX were found preoperatively and 6 months postoperatively at each point. CONCLUSIONS: Standard CXL does not cause significant changes in endothelial cell density, polymegethism, or polymorphism, in the peripheral regions of the cornea. It is suggested that CXL is a minimally invasive surgical approach for progressive keratoconus, even in terms of peripheral endothelial cells. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trial Registry (000031162).

Comparison of Humphrey Field Analyzer and imo visual field test results in patients with glaucoma and pseudo-fixation loss.

The aim of this cross-sectional study was to evaluate the results of a visual field (VF) test for patients with glaucoma and pseudo-fixation loss. These patients exhibit fixation loss (FL) rates >20% with the Humphrey Field Analyzer (HFA); however, actual fixation stabilizes when a head-mounted perimeter (imo) is used. This device is able to adjust the stimulus presentation point by tracking eye movements. We subjected 54 eyes of 54 patients with glaucoma and pseudo-FL to the HFA 30-2 or 24-2 Swedish Interactive Threshold Algorithm -Standard protocol. All patients also underwent the imo 30-2 or 24-2 Ambient Interactive Zipper Estimated Sequential Testing protocol after HFA measurement. We compared HFA and imo reliability indices [including false-positive (FP) responses, false-negative (FN) responses, and FL rate], global indices [including mean deviation (MD), visual field index (VFI), and pattern standard deviation (PSD)], and retinal sensitivity for each test point. There were no significant differences in MD, VFI, and PSD between HFA and imo, and these measures were strongly correlated (r > 0.96, p < 0.01). There were no significant differences in FP and FN between both devices, while FL measured with HFA (27.5%) was significantly reduced when measured with imo (13.2%) (p < 0.01). There was no correlation in FL and FN between both devices, and a weak correlation for FP (r = 0.29, p = 0.04). At each test point, retinal sensitivity averaged 1.7 dB higher with HFA, compared with imo (p < 0.01). There was no significant variability in global indices in patients with pseudo-FL. The FP response rate might have influenced measures of FL in patients with glaucoma and pseudo-FL.

Comparison of corneal endothelial cell density and morphology after posterior chamber phakic intraocular lens implantation with and without a central hole.

AIM: To compare the corneal endothelial cells after posterior chamber phakic intraocular lens with and without a central hole (hole implantable collamer lens (ICL) and conventional ICL) implantation for the correction of moderate to high myopia. METHODS: This retrospective study evaluated 34 eyes of 34 patients who underwent hole ICL implantation and 25 eyes of 25 patients who underwent conventional ICL implantation. Preoperatively and 3 months, and 1 and 2 years postoperatively, we compared the central corneal endothelial cell density (ECD), coefficient of variation in cell size (CV) and the percentage of hexagonal cells (HEX) between the two groups using a non-contact specular microscope (EM-3000, Tomey). Preoperatively and 2 years postoperatively, we also compared them in the peripheral regions. RESULTS: The mean central ECD loss was 0.3% and 1.1%, 2 years after hole ICL and conventional ICL implantation, respectively (Mann-Whitney U test, p=0.72). There were no significant changes in central ECD, CV or HEX at any time points either after hole ICL or conventional ICL implantation, and a significant decrease only in terms of ECD in the superior regions after conventional ICL implantation. CONCLUSIONS: Both ICLs do not induce a significant change in the density, polymegethism or polymorphism of corneal endothelial cells even 2 years postoperatively, except for the density in the superior regions after conventional ICL implantation. However, hole ICL implantation may have advantages over conventional ICL implantation only in terms of the density in the superior regions, possibly because preoperative laser iridotomies are unnecessary.