Study on ocular surface condition and discomfort due to dryness under low humidity

Comparison between contact lens wearers and non-wearers

Abstract

To reveal how dryness sensation at eye occurs, we investigated the physiological and subjective responses of the human eye under low humidity. Twenty-five subjects were exposed to indoor air set at 10%RH (26°C) for 160 minutes in a climate chamber; after 40 minutes’ exposure, head skin temperature, ocular surface temperature (OST), maximum blink interval (MBI), brink rate and subjective votes of dryness and comfort sensation were measured every 5 minutes. The soft contact lens (SCL) wearers showed 1.6°C lower OST on average than the non-wearers with larger variation between subjects. This results seem to be mainly due to higher evaporation rate on the SCL. Moreover, as for the SCL wearers, higher discomfort and dryness sensation were associated with lower OST, while they weren’t associated with either brink rate or MBI. On the other hand, as for the non-wearers, higher discomfort and dryness sensation were associated with shorter MBI. The findings suggest that OST for SCL wearers and MBI for non-wearers are associated with discomfort due to dryness and could be an indicator of it.