Eyeblink frequency and type in relation to 3- and 9-o'clock staining and gas permeable contact lens variables

The primary goal of this study was to evaluate if there is a difference in frequency and in completeness of eyeblinks (type of eyeblink) in rigid gas permeable (GP) lens wearers experiencing 3- and 9-o'clock staining compared with GP lens wearers without substantial staining and nonlens wearers.

The study involved 26 nonlens wearers and 55 GP contact lens wearers, with and without 3- and 9-o'clock staining. Every eyeblink over a 5-min period was categorized as a complete eyeblink, incomplete eyeblink, or an eyeblink attempt. In addition, type of lens fit (interpalpebral vs. lid attachment), lens-to-cornea fit (flat vs. steep), spherical equivalent of the refraction, and corneal coverage (on-eye lens diameter) were analyzed.

No difference in overall eyeblink frequency was found between nonlens wearers (group I, n = 26), GP lens wearers with less than grade 1 corneal staining (group II, n = 25) and GP lens wearers with grade 1 or more corneal staining (group III, n = 30). Fewer complete eyeblinks, more incomplete eyeblinks and more eyeblink attempts were seen in group III than in group I or II (p < 0.01, p = 0.03, p < 0.01, respectively). Fewer complete eyeblinks and more eyeblink attempts (p < 0.01 for both) were found in interpalpebral lens fits than in lid attachment fits. Fewer complete eyeblinks (p = 0.02) and more incomplete eyeblinks (p = 0.03) were found with lenses rated as large or optimal in size than with lenses rated as small.

GP lens wearers experiencing 3- and 9-o'clock staining showed a different eyeblink frequency for individual types of eyeblinks, but not for overall eyeblinks. Fewer complete eyeblinks, more incomplete eyeblinks, and more eyeblink attempts were observed in GP wearers with 3- and 9-o'clock staining compared with wearers with minimal staining and nonwearers. In addition, some individual contact lens variables were associated with more incomplete eyeblinks.