Effects of different contact lens materials and contact lens-wearing periods on conjunctival cytology in asymptomatic contact lens wearers.

Purpose: To investigate the conjunctival cytologic changes induced by different contact lens materials and contact lens-wearing periods in asymptomatic contact lens wearers.

Methods: Seventy-five patients (150 eyes) who were to wear contact lenses for the first time were evaluated in this study. Forty eyes of 20 soft hydroxyethylmethacrylate (vinyl pyrrolidone copolymer) contact lens wearers, 70 eyes of 35 soft Polymacon contact lens wearers, and 40 eyes of 20 hard gas-permeable contact lens wearers used the lenses on a daily-wear basis. Conjunctival cytologic changes were investigated by using impression cytology. Impression cytologic samples were obtained before contact lens fitting and after contact lens wear (mean evaluation time, 6.9 +/- 2.6 months; range, 4-12 months). The samples were appropriately stained and were assessed by using the Nelson grading system and for the presence of snakelike chromatin. The Kruskal-Wallis test, the Wilcoxon test, and logistic regression were used for statistical analysis.

Results: There were statistically significant differences in impression cytologic findings for all three materials before versus after contact lens wear (P=0.00, P=0.00, P=0.00, Wilcoxon test). The contact lens-wearing period produced a statistically significant effect on conjunctival cytologic changes and snakelike chromatin formation (P=0.00, P=0.00, logistic regression analysis), but the effects of different contact lens materials were insignificant (P=0.88, P=0.62).

Conclusions: Conjunctival cytologic changes occurred in asymptomatic contact lens wearers and were related to the duration of lens wear. For this reason, asymptomatic contact lens wearers may be followed up because of conjunctival cytologic changes.