Shape of the anterior surface of the cornea after extended wear of silicone hydrogel soft contact lenses.

PURPOSE: To measure geometrical changes in the anterior surface of the cornea after wearing silicon hydrogel (SiH) soft contact lenses continuously for 1 week. METHODS: Forty-three eyes with 3.0D of myopia and 22 eyes with 3.0D of hyperopia were enrolled in the prospective, interventional study. All subjects underwent a general eye examination, corneal tomography with wavefront aberration analysis, corneal thickness measurements and epithelial thickness mapping before and after wearing SiH lenses (Acuvue Oasys) for 7 days. RESULTS: No significant changes in average keratometry were observed in either refractive group. In the myopic group, keratometry findings for the flat meridian (K1) and central corneal thickness decreased significantly. After +3.0 D lens wear in the hyperopic group, a significant decrease in epithelial thickness up to 3.19 µm was observed in the central and paracentral cornea, (p < 0.001). In both refractive groups, the largest epithelial thickness increase was seen in the periphery. A decrease in spherical aberration was noted in myopic eyes, while an increase of both higher order corneal aberrations and coma was found in hyperopic subjects. CONCLUSION: Extended wear of SiH lenses results in a significant change in epithelial thickness leading to alteration in the geometry of the anterior surface of the cornea, particularly in hyperopic patients. These epithelial thickness variations lead to changes in the higher order aberrations of the cornea.

Scheimpflug Camera Measurement of Optical Density of the Corneal Epithelium, Stroma, and Endothelium in Patients with Pseudoexfoliation Syndrome.

BACKGROUND The present study evaluated the optical density of particular layers of the cornea and anterior lens capsule in patients with pseudoexfoliation syndrome (PEX). MATERIAL AND METHODS Sixty patients with cataract and PEX (mean age 76.6±5.6 years, range 62-88 years) were compared to 55 controls with cataract without PEX syndrome (mean age 76.3±6.09 years, range 62-90 years; P>0.05). The anterior segment of one eye was examined in each patient using Pentacam HR by Oculus before the planned cataract surgery. RESULTS The average optical density of the corneal epithelium, stroma, and endothelium was 25.3±6.09% and 19.9±3.41% (P<0.001), 23.1±5.5% and 19.2±3.6% (P<0.0001), and 14.6±3.4% and 12.3±2.1% (P<0.0001) in the PEX and control groups, respectively. The optical density of the anterior lens capsule was 13.6±4.2% in the PEX group and 9.74± 2.23% in the control group (P<0.0001). The average thickness of the cornea was 555 µm and 556 µm and the average optical density of endothelial cells 2240/mm² and 2323/mm² in the PEX and control groups, respectively (P<0.05). CONCLUSIONS In patients with PEX, increased optical density was observed not only in the structures with pseudoexfoliative material detectable by a slit-lamp), but also in the corneal epithelium and stroma. The increased optical density was not associated with reduced endothelial cell density or increased central cornea thickness.