Abstract
Purpose: :
To determine the factors that influence CCT and to test the hypothesis that CCT is stable over a period of several years in patients with high-risk Ocular Hypertension or Early Glaucoma.
Methods: :
We analyzed the most recent ultrasonic CCT measurement for both eyes of 176 participants enrolled in a longitudinal study of ocular hypertension and early glaucoma. This cross-sectional analysis examined the effect of age, sex, history of medical IOP lowering treatment and IOP on CCT. We also performed a longitudinal analysis of the 121 subjects who had at least 4 measures of CCT over a 3 to 4 year period. We used linear regression to determine the rate of change of CCT over time and calculated the effect of age, sex, and history of medication on the rate of change. All analyses were performed using generalized estimating equations with subject nested in the model to control for the correlation between eyes.
Results: :
The cross sectional analysis included 73 men and 103 women (Age 65 +/- 11; range 41 - 90). 85 participants (48%) had received ocular hypotensive medication at some point up to the time of the CCT measurement or were currently on medication. Average CCT was 555 +/- 37 µm (451 - 667). In a multivariate analysis, being female resulted in a significantly greater CCT by 11 µm (p = 0.045) whereas a history of medication resulted in a lower CCT by 17 µm (p = 0.002). The longitudinal analysis included 56 men and 65 women. Average age midway between the most and least recent CCT measurements was 63 +/- 10 years (42 - 86). 64 participants (53%) had or were receiving medication. The average rate of CCT change for the 121 subjects was -1.45 µm/year (p < 0.001). In a multivariate analysis including age, sex and medication history, only medication history was found to significantly affect the rate of CCT change (p = 0.008). The CCT of untreated eyes thinned by 0.66 µm/year (p = 0.049 compared to no change) whereas the CCT of treated eyes thinned by 2.15 µm/year (p < 0.001 compared to no change, p = 0.003 compared to untreated).
Conclusions: :
There are significant gender and medication effects on CCT. Eyes with a history of ocular hypotensive medication show a significantly greater rate of corneal thinning.
Keywords: cornea: clinical science • drug toxicity/drug effects