Asymmetry in keratoconus and vision-related quality of life.

PURPOSE: To examine the relationship of increased ocular asymmetry over time to vision-related quality of life in keratoconus.

METHODS

The subjects were from the Collaborative Longitudinal Evaluation of Keratoconus Study and had complete data on a least 1 scale of the National Eye Institute Visual Function Questionnaire and examination data at baseline and at least 1 follow-up visit. Three measures of disease asymmetry [visual acuity (VA), corneal curvature, and refractive error] and better eye status were assessed. Multilevel models were fit to the data.

RESULTS

The analyses were completed using the data from 961 subjects. Six scales on the National Eye Institute Visual Function Questionnaire had adequate variability to the model (distance activity, driving, mental health, near activity, ocular pain, and role difficulties). Refractive error changes were not associated with statistically significant quality-of-life differences. Except for ocular pain, statistically significant, but not clinically meaningful, differences were found for VA changes and corneal curvature changes. For a 0.1-unit logarithm of the minimum angle of resolution of VA change, the quality-of-life scales decreased between 0.20 and 0.99 units. For a 1.00-diopter steepening of corneal curvature, these decreases were on the order of 0.20 to 0.59 units. Changes related to asymmetry were small as well; decreases were on the order of 0.20 to 0.38 units.

CONCLUSIONS

Increasing ocular asymmetry and decreases in VA and corneal steepening in the better eye were associated with decreasing vision-related quality of life, although the magnitudes of the changes were not clinically meaningful. Of these 2 disease status indicators, the vision in the better eye had greater effect on the vision-related quality of life.