Lyndon Jones, PhD, FCOptom, DipCLP, DipOrth is a professor at the School of Optometry and Vision Science and Director of the Centre for Contact Lens Research at the University of Waterloo.
Download the poster (.pdf), which was shared at the Annual Meeting of The Association for Research in Vision and Ophthalmology (ARVO), 2013
Lyndon Jones1, Jalaiah Varikooty1, Nancy Keir1, Fiona Soong2, Piyush Patel2
1Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Canada; 2Inflamax Research, Mississauga, Canada
Purpose: To measure the clinical grades of lid wiper epitheliopathy (LWE) in contact lens (CL) wearers before and after exposure to conditions of temperature, low humidity and air flow in a controlled low humidity environmental exposure chamber (LH-EEC).
Methods: In this double-masked, feasibility study, 10 symptomatic CL wearers were randomized to contralateral lens wear with narafilcon A and etafilcon A lenses. CL wear was discontinued 48 h prior to
assessments and Refresh Plus® artificial tears (ATs) were instilled t.i.d. in both eyes. For LWE measures, the upper (UL) and lower lid (LL) margins were stained with sodium fluorescein and lissamine green dyes using an optimized technique to detect LWE. LWE was graded on a 0-3 scale (Korb et al. Eye Contact Lens, 2005) at Baseline, prior to CL insertion and entry into the LH-EEC. In the LH-EEC, subjects were exposed to controlled temperature of 22±3°C, relative humidity of 10±3% and an air velocity of approx. 5ft/sec for 180 min. Upon exit, CLs were removed and ATs were instilled every 15 min for 120 min. LWE was evaluated after post-chamber exposure (PC), PC+30min, PC+90min and PC+120min. Analyses were undertaken using Statistica.
Results: After 180 min in the LH-EEC, mean LWE grades in the upper lid increased from Baseline to PC and were 1.25 to 2.23 for narafilcon A and 1.18 to 1.93 for etafilcon A. In the lower lid, it changed from 1.00 to 2.48 for narafilcon A and 0.90 to 2.03 for etafilcon A (Wilcoxon matched pairs, all p<0.05). The mean LWE grades did not return to Baseline levels at PC+120mins and were 2.47 and 2.11 for narafilcon A, and 2.42 and 1.89 for etafilcon A in the UL and LL respectively. These LWE responses were similar for the two lenses, despite their markedly different material properties.
Conclusions: LWE grades increased significantly with CL wear in both the UL and LL after 3 hours of exposure to adverse environmental conditions with low humidity and moderate air velocity. The use of lubricant eye drops did not have an effect in LWE reduction during the two hours following exit from the adverse environment. The LH-EEC model may prove a valuable tool to study conditions that result in alterations in LWE.