Quantifying the Effect of Spectacle Frame Dimensions on Wind-Induced Ocular Plane Evaporation Using an in Vitro Model.

Abstract

To quantify the effect of spectacle frame dimensions on wind-induced ocular plane evaporation. A drop of 0.5 μL water was pipetted onto an eye of a mannequin head. The face was fitted with a spectacle frame. A fan positioned 10 cm away directed air (185 CFM) toward the face and the time required for the drop to evaporate was recorded. This procedure was repeated with 31 different frames to obtain evaporation times for various eye sizes, vertical heights, vertex distances, temperature, and humidity. This was also repeated 30 times without spectacle wear to obtain evaporation times for various temperature and humidity conditions. Spectacle wear increased evaporation times compared with nonspectacle wear, in both high (>35%) and low humidity (<30%) conditions (both P<0.01). Humidity was correlated with evaporation time, regardless of spectacle and nonspectacle wear (both P<0.01). Evaporation time did not correlate with spectacle eye size, vertical height, or vertex distance (all P≥0.21). This study showed that spectacle wear guarded against wind-induced evaporation at the ocular plane compared with nonspectacle wear. However, once spectacles were worn, eye size, vertical height, and vertex distance were not correlated with evaporation times. Humidity drove evaporation independent of spectacle wear.