Tear film instability induced by rigid contact lenses

Purpose. To evaluate rigid contact lens-associated epithelial damage, the relationship between the tear film and the ocular surface epithelium was evaluated at the perilimbal area around rigid contact lenses (RCLs). Methods. Twenty RCL [six poly methylmethacrylate (PMMA) and 14 rigid gas-permeable lens (RGPL)] wearers and 20 non-CL wearers were enrolled in this study. By using a newly developed tear interferometer, the noninvasive tear film break-up time (NIBUT) on the conjunctiva at the 3- and 9-o'clock portions was measured, and its stability evaluated. Fluorescein and sulforhodamine B staining was used to observe ocular-surface epithelial damage, and rose bengal staining was used to evaluate the mucin layer distribution. Results. The conjunctival NIBUT at the 3- or 9-o'clock portions or both was abnormally shortened in 15 (75%) of 20 RCL-wearer eyes. Conjunctival epithelial staining at the 3- or 9-o'clock portion was seen in six (30%) of 20 eyes by using sulforhodamine B. and in four (20%) of 20 eyes by rose bengal; all of these eves also demonstrated an abnormal tear film break up. Corneal epithelial damage was seen in two (10%) of 20 RCL-wearer eyes at the 3- or 9-o'clock portions or both, and in both of these cases, conjunctival epithelial damage also was noted. Neither tear-film instability nor epithelial staining was seen in the normal controls. Conclusions, This study indicates that RCL-induced tear-film instability is associated with damage to the ocular-surface epithelium and mucin layer.