Effect of controlled adverse chamber environment exposure on tear functions in silicon hydrogel and hydrogel soft contact lens wearers

To prospectively evaluate the effect of controlled adverse chamber environment (CACE) exposure on tear function, including tear osmolarity, in subjects wearing narafilcon A versus those wearing etafilcon A soft contact lens (SCL). Thirty-one healthy subjects with no history of contact lens wear (13 women, 18 men; average age, 30.5 ± 6.5 years) were randomly divided into age- and sex-matched groups (15 subjects wearing narafilcon A SCL; 16 subjects wearing etafilcon A SCL) and entered a CACE for 20 minutes. All subjects underwent tear osmolarity, tear evaporation rate, strip meniscometry, tear film breakup time, fluorescein vital staining, and functional visual acuity measurement before and after exposure to the controlled adverse chamber. The mean blink rate increased with significant deteriorations in the mean symptom VAS scores, mean tear osmolarity, tear evaporation rate, strip meniscometry score, and tear stability with CACE exposure along with a decrease in visual maintenance ratio in functional visual acuity testing in etafilcon A wearers. The mean symptom VAS scores, mean tear evaporation rate, tear stability, blink rates, and visual maintenance ratios did not change significantly in narafilcon A wearers after CACE exposure. This study suggested marked tear instability, higher tear osmolarity, and increased tear evaporation with marked dry eye and visual symptomatology in nonadapted hydrogel SCL wearers, suggesting that silicone hydrogel SCLs may be suitable for persons who live and work in cool, low-humidity, and windy environments, as tested in this study.