| Abstract: | Background: The symptom of dryness in hydrogel lens wear is common but its origins remain poorly understood. To assess the theory that anterior lens surface interactions are responsible for the sensation of dryness during lens wear, 50 contact lens wearers were evaluated. Method: The Efron comfort scale was used to divide the group into subjects with comfortable lenses (26 control subjects) and those who were symptomatic (24 study subjects). The two groups were matched for gender, age, lens age, lens water content, lens wear experience and wearing environment. The only difference between the groups was that the non-symptomatic wearers had a greater wearing time (ANOVA, p = 0.005). Lens deposits and pre-lens tear thinning time (PLTTT) were assessed for each group. Results: The median PLTTT for the control group was three seconds (25th percentile, two seconds; 75th percentile five seconds); the study group had a median PLTTT of 3.5 seconds (25th percentile, 1.5 seconds; 75th percentile, four seconds). There was no significant difference in lens deposits and PLTTT between the comfortable and uncomfortable lens wearing groups, in particular, subjects with a short PLTTT (for example, less than four seconds) could still be comfortable. However, there was a significant inverse correlation between the grade of lens deposits and PLTTT (Spearman rank correlation, p = 0.01); a positive correlation between the grade of lens deposits and lens age (Spearman rank correlation, p = 0.001). Conclusions: The findings suggest that pre-lens tear stability is not necessarily an influence on comfort. It may be that the source of soft lens discomfort arises more from the exposed bulbar conjunctiva than the interaction between anterior lens surface and the tarsal conjunctiva. (Clin Exp Optom 1995; 78: 5: 168–175) |
