Evaluation of signs and symptoms in 3- and 9-o'clock staining

This study evaluates the relationship between bulbar hyperemia, conjunctival staining, lens comfort and 3- and 9-o'clock corneal staining in rigid gas permeable (GP) contact lens wear.

The study involved 55 GP contact lens wearers (with and without 3- and 9-o'clock staining) and 26 non-lens wearers. Corneal staining was graded based on a specially designed image grading scale developed at the University of Maastricht. The Efron grading scale was used to grade bulbar hyperemia and conjunctival staining. Ocular comfort and lens comfort were analyzed using a visual analogue scale (VAS) and a questionnaire to differentiate symptomatic from asymptomatic subjects.

Bulbar hyperemia showed a significant but low correlation with corneal staining, and eyes with conjunctival staining showed more corneal staining than eyes without conjunctival staining. No correlation was found between staining in the nasal and temporal regions of the cornea in subjects with substantial 3- and 9-o'clock staining. No correlation was found between VAS comfort scores and corneal staining. In those subjects with substantial 3- and 9-o'clock staining, symptomatic subjects showed more corneal staining than asymptomatic subjects.

Practitioners are advised to evaluate both the nasal and temporal regions of the cornea when assessing 3- and 9-o'clock staining, and they should be hesitant to rely on the amount of bulbar hyperemia for the prediction of the severity of 3- and 9-o'clock staining. Assessment of conjunctival staining could potentially be a useful tool in clinical practice to identify patients at risk of developing 3- and 9-o'clock staining. The lack of correlation between corneal staining and lens comfort stresses the need for regular contact lens check-ups in GP lens wearers. It appears that the simple registration of the presence or absence of ocular symptoms is a better predictor of 3- and 9-o'clock staining than using VAS comfort scores.