Abstract
Purpose: :
To determine whether central corneal thickness (CCT) changes over time and whether long term use of topical antiglaucoma medications influences this change .We also aim to determine whether CCT or change in CCT correlates with subsequent visual field progression.
Methods: :
This study included 209 glaucoma patients treated with topical antiglaucoma medications for at least 3 years and followed up for a mean period of 6.8 ±1.8 years. Patients with laser or surgery were excluded. The CCT, intraocular pressure, visual fields and confocal scanning laser tomography were performed both at initial diagnosis and at present visit. They were compared with 100 age matched controls who were glaucoma suspects not on any treatment.
Results: :
There was a significant reduction in CCT (p < 0.0001) in treated eyes (12.03 ± 12.72 µm) wheras no significant change (p > 0.05) was detected in control eyes (1.20 ± 9.18 µm). Amongst treated eyes, significant reduction in CCT (p< 0.0001) occurred in those treated with either Prostaglandins or a combination of Prostaglandins and Betablockers, while no significant reduction occured in eyes treated only with Betablockers (p > 0.05) as compared to control eyes.Baseline CCT correlated positively with both mean deviation (MD) (p= 0.001) and neuroretinal rim area( p = 0.012) such that thinner corneas were associated with more advanced presentation. Visual field progression was detected in 16% eyes wheras 84% revealed no progression. Progressive eyes had significantly thinner baseline CCT (p = 0.001) and significantly worse MD (p< 0.001) compared to non progressive eyes. Kaplan Meier analysis revealed higher survival (p=0.001) in eyes with a baseline CCT greater than 540 um as compared to eyes with CCT lesser than 540 um. There was no difference in the amount of change in CCT between progressive and non progressive eyes and the amount of change in CCT did not correlate with the change in MD and rim area.
Conclusions: :
Prostaglandins appear to cause a small but significant reduction in CCT over time. CCT correlates significantly with the amount of baseline glaucomatous damage and thinner corneas may be associated with increased risk of visual field progression. CCT reduced slightly over time in eyes with glaucoma however this was not related to visual field progression.
Keywords: cornea: clinical science • drug toxicity/drug effects • visual fields