Abstract
Purpose :
Orthokeratology is a form of temporary corneal refractive therapy involving the overnight use of contact lenses. During sleep, eyelid occlusion and contact lenses act as barriers to oxygen flow for corneal metabolism and may induce adverse effects and complications such as Corneal Oxygen Deficiency (COD), causing morphological alterations in the endothelium cells. Specular microscopy (SM) has been the main technique to evaluate the corneal endothelium. Recently, reliability indexes have been suggested for SM procedures that decrease in 75% the differences between serial SMs. No studies have assessed the endothelial mosaic according to the suggested reliability indexes for patients undergoing Orthokeratology. The purpose of the study is to evaluate the endothelial mosaic of Paragon CRT® 100 wearers whose sampling error of 5% or less is accepted.
Methods :
Clinical trial performed at Clínica Schaefer Research Center, Brazil, Authorization 1.766.502 CONEP, in myopic patients, age 18-27, between -0.75 and -6,00D, with or without astigmatism up to -1.75D. Patients with diseases that restrict the fitting of CL were excluded from the study. Ortho-K lenses used include Paragon CRT® and Paragon CRT® 100, paflufocon B and D. Specular Microscope (Gamagori, Japan) was used to calculate the endothelial cell density (ECD), cellular area (CA), coefficient of variation (CV), and percentage of hexagonal cells (%H). The Reliability Index was calculated by the Cells Analyzer (CA), Technicall, Brazil, and provided sample accuracy of 95% Reliability Degree and 0.05 Relative Error (RE). Sampling included cells from 3 different endothelial images of the corneal central area, considered representative of the endothelial mosaic: RE<5%. To compare the studied times (T0 control, T1-T3 (monthly) and T4 (5th month)), Student’s t-test was used for paired samples. Values of p<0.05 showed statistical significance. Statistical analysis was conducted with IBM SPSS Statistics v.20.0. Armonk, NY.
Results :
Results for ECD, CA, CV, %H and the differences between T0-T1, T0-T2, T0-T3 and T0-T4 are shown in the Table. Student’s t test for paired samples did not show significant statistical difference for ECD, CA, CV, and %H (p<0.05).
Conclusions :
During the study period, Paragon CRT® 100 lens did not cause detectable morphological alterations in the corneal endothelium measured with SM. A two-year follow-up is planned.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.