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B. Golebiowski, E.B. Papas, F. Stapleton; Ocular Surface Sensitivity Following Discontinuation of Low DK Extended Contact Lens Wear and Refitting with High DK Extended Wear . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3705.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Deprivation of oxygen to the ocular surface during contact lens wear disturbs normal corneal metabolism which is thought to alter nerve function and result in diminished sensation. To determine whether increasing oxygen availability through the suspension of contact lens wear or transfer into highly oxygen transmissible (high Dk/t) lenses leads to a change in corneal or conjunctival sensitivity Methods: 27 (M=13, F=14, mean age 40.1±6.9 years) long term (mean wearing time 13.5±4.7 years) extended wearers of low oxygen transmissibility (low Dk/t) soft contact lenses were asked to cease lens wear for 1 week prior to being refitted with high Dk/t silicone hydrogel contact lenses. Corneal and conjunctival sensitivity threshold measurements were obtained using the CRCERT-Belmonte Aesthesiometer. 1 second pulses of air (flow rates 0-400 ml/min, temperature 34°C at ocular surface) were applied 30s apart to the central cornea and inferior bulbar conjunctiva (2mm from the limbus), of one randomly selected eye of each subject. Threshold was determined using a staircase technique. Measurements were taken during low Dk/t wear (B1), following one week of no lens wear (B2) and after 1, 3 and 6 months of high Dk/t lens wear (1M, 3M, 6M) Results: Group mean corneal thresholds were 85.2±31.9 ml/min at B1, 97.3±35.8 ml/min at B2, 95.8±38.0 ml/min at 1M, 100.2±37.1 ml/min at 3M and 91.9±25.4 ml/min at 6M. Mean conjunctival thresholds were 130.3±37.5 ml/min at B1, 130.1±49.7 ml/min at B2, 133.3±54.5 ml/min at 1M, 141.1±44.6 ml/min at 3M and 132.5±56.0 ml/min at 6M. Repeated Measures Analysis of Variance indicated a significant linear trend towards a reduction of sensitivity over the period of observation (p=0.02). No effect was found on conjunctival sensitivity at any timepoint Conclusions: The decrease in central corneal sensitivity observed in this group of successful long term extended wearers following suspension of low Dk/t contact lens wear and transfer into high Dk/t wear may indicate that factors other than oxygen availability alone are involved in determining the sensitivity of the ocular surface.
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