Short-Term Effects of Overnight Orthokeratology on Corneal Sub-basal Nerve Plexus Morphology and Corneal Sensitivity

Objective: To assess the effects of a short period of orthokeratology (OK) on corneal sub-basal nerve plexus (SBNP) morphology and corneal sensitivity. Methods: Measurements were made in 56 right eyes of 56 subjects with low-to-moderate myopia who wore 2 OK lens designs (Group CRT: HDS 100 Paragon CRT, n=35; Group SF: Seefree; n=21) for a period of 1 month and in 15 right eyes of noncontact lens wearers as controls. The variables determined in each participant were corneal sensitivity using a Cochet-Bonnet esthesiometer and 12 SBNP variables determined on laser scanning confocal microscopy images using 3 different software packages. Correlation between SBNP architecture and corneal sensitivity was also examined. Results: Few changes were observed over the 1-month period in the variables examined in the OK treatment and control groups. However, significant reductions were detected over time in the number of nerves in the central cornea in the groups CRT ( P =0.029) and SF ( P =0.043) and in central corneal sensitivity in CRT ( P =0.047) along with significant increases in central and midperipheral corneal Langerhans cell counts in SF ( P =0.001 and 0.048, respectively). Conclusions: This study provides useful data to better understand the anatomical changes induced by OK in corneal SBNP. The different response observed to the 2 OK lens designs requires further investigation.