Central Corneal Thickness and IOP Response to Topical Ocular Hypotensive Medication in the Low-pressure Glaucoma Treatment Study

Abstract

Purpose: The Ocular Hypertension Treatment Study (OHTS) showed that IOP response to medical therapy was associated with central corneal thickness (CCT) and that eyes with thinner corneas have a more substantial IOP lowering than those with thick corneas. We aimed to investigate whether CCT correlated with IOP response to topical ocular hypotensive medication in the Low-pressure Glaucoma Treatment Study (LoGTS).

Methods: 253 LoGTS participants were analyzed. The groups were divided into tertiles based on CCT, and the 85 patients with the thickest corneas (Group A) and 85 patients with the thinnest corneas (Group B) were compared. Various parameters were analyzed, including mean IOP during the diurnal curve prior to treatment, follow up IOP peak, trough, mean and fluctuation, absolute and percent IOP reduction, and mean deviation (MD) rate of progression (dB/yr).

Results: As expected, Group A had a thicker CCT than Group B (580.2±23.4 vs. 508.6±20.6 microns, p<0.001). During the diurnal curve, Group A had a higher mean IOP than Group B (16.1±2.3 vs. 15.3±2.6, p=0.05). Follow up mean IOP was lower in Group B than Group A (13.4±2.4 vs. 14.4±2.1 mmHg, p=0.005) as was IOP trough during follow up (10.9±2.4 vs. 11.7±2.5, p=0.037). There was no difference in IOP peak during follow up (p=0.179), IOP fluctuation (p=0.277), absolute IOP reduction (p=0.41) or percent IOP reduction (p=0.20). There was no difference in the mean deviation slopes between Group A and B (-0.14±0.82 vs. -0.26±1.01, p=0.38).

Conclusions: Unlike the OHTS findings, there was no correlation between IOP response to medical therapy and CCT in eyes with low pressure glaucoma.

Keywords: 568 intraocular pressure • 615 neuroprotection