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Fiona Soong, Jalaiah Varikooty, Nancy Keir, Lyndon Jones, Piyush Patel; In-Vivo Wettability of Contact Lenses Worn in a Low Humidity Environmental Exposure Chamber (LH-EEC) Show Comparable Changes to Traditional Field Trials. Invest. Ophthalmol. Vis. Sci. 2013;54(15):499.
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© ARVO (1962-2015); The Authors (2016-present)
The LH-EEC is a natural provocation research model, which tightly controls environmental variables (humidity; temperature; air flow) and is a valuable tool to study dry eye, with little information on its utility to evaluate contact lens (CL) wear. The purpose of this study was to use the LH-EEC model to observe in-vivo CL wettability changes and to compare these results with those reported in typical CL field studies.
Ten symptomatic CL wearers were randomized and fit with 1-day Acuvue® Moist® (etafilcon A): CLA in one eye and 1-Day Acuvue® TruEye™ (narafilcon A): CLB in the contralateral eye. They were exposed to LH-EEC for 180 mins with instruction to watch a movie screen. Following CL insertion, 3 consecutive measures of tear osmolarity were taken with TearLab® prior to LH-EEC entry and exit. Dryness symptoms were rated from 0 (no discomfort) to 4 (constant discomfort), and were collected at specified intervals throughout the chamber visit as were observations of blink rate (#blinks/min). In-vivo wettability was graded using a 0 (excellent) to 4 (extremely poor) scale with 0.25 steps.
After only 180 mins in the LH-EEC, there was trend of increasing tear osmolarity for both CLA (7.4±3.6mOsmol) and CLB (4.80±3.23mOsmol), but this was not significant (p>0.05). Dryness symptom scores showed non-significant increase from pre to post chamber for CLA (+1.10±0.53) but a significant (p=0.001) increase for CLB (+1.40±0.31). Blink rate significantly increased (p<0.003) from pre-EEC rates of 42.0±4.8 blinks/min to average maximum of 61.2±4.3 blinks/min. Lens wettability worsened significantly over time for both CLA and CLB 0.58±0.18 (p=0.01) and 0.65±0.25 (p=0.03) respectively. These values are comparable to changes in wettability seen after 8 hrs of wear with both study materials (Luensmann et al; Keir et al.)
The LH-EEC exacerbates ocular symptoms and signs after 180 mins with CL wear. Significant changes in lens wettability were seen during the exposure and yielded values comparable to results shown in traditional trials with 8 hrs of lens wear. The LH-EEC provides a way to accelerate extended day CL wear and provides noteworthy research options for a controlled provocation study of CL and dry eye signs and symptoms in a shorter time course.
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