Relationship Between Central Corneal Thickness and Topographical Change of the Optic Nerve Head After Treatment With Topical Travoprost

Abstract

Purpose: : To evaluate the effect of topical travoprost 0.004% on optic nerve head topography in relationship to central corneal thickness.

Methods: : 28 open angle glaucoma and ocular hypertensive patients were prospectively recruited and underwent Heidelberg retina tomography in one eye before and four weeks after daily treatment with topical travoprost 0.004%. Patients were divided two groups (with thick or thin corneas) based on the entire group’s median central corneal thickness. Optic nerve neuroretinal rim blood flow was also assessed using SLDF.

Results: : The mean reduction in IOP was 7.1 ± 4.5 mmHg (p<0.001). The cup disc ratio decreased significantly from 0.418 ± 0.185 to 0.397 ± 0.183 in the entire study population (p=0.03). A significant mean cup depth decrease from 0.291 ± 0.109 to 0.283 ± 0.111 was also observed (p=0.04). For all topographical parameters, the decrease was not significantly different between OHT and OAG groups (p>0.05).Considering only patients with IOP reduction more than 20% (n=21), the cup disc ratio decreased significantly from 0.456 ± 0.249 to 0.411 ± 0.253 (p<0.01) in the thinner cornea group (mean CCT 506 µm) compared to an increase from 0.376 ± 0.113 to 0.387 ± 0.126 in the thicker cornea group (mean CCT 574 µm ) (p=0.48). The change in cup disc ratio differed significantly between the thin and thick cornea groups (p=0.01). Mean cup depth decreased from 0.335 ± 0.129 to 0.322 ± 0.137 in the thinner CCT group compared to a decrease from 0.282 ± 0.080 to 0.279 ± 0.082 in the thicker CCT group. The mean cup depth decrease was of borderline significance considering both groups (p=0.056) but did not differ between groups (p=0.2). The neuroretinal rim blood flow increased in the entire population (p=0.04). Mean change was greater in patients with thicker cornea (28AU ±28) than in those with thinner cornea (18AU±36) but the difference between groups was not significant (p=0.502).

Conclusions: : Treatment with topical travoprost was associated with a significant improvement of optic nerve head topographical parameters (particularly cup disc ratio). Among patients having a minimum 20% reduction of IOP, greater topographical changes were found in the patients with thinner corneas. A small significant mean increase in neuroretinal rim blood flow was also observed in the entire study group.

Keywords: blood supply • clinical (human) or epidemiologic studies: risk factor assessment • optic nerve