Mean intraocular pressure and progression based on corneal thickness in primary open-angle glaucoma

The aim of this study was to evaluate the association of corneal thickness on the incidence of glaucomatous progression at individual levels of intraocular pressure.

A retrospective, noninterventional evaluation of patients with primary open-angle glaucoma who were either stable over 5 years or had glaucomatous progression before 5 years of follow-up was performed. Each patient had central thickness corneal measurements documented.

We included 310 patients in this study. Patients with thicker (at least 0.571 mm, n = 77) and mid-range corneas (0.511-0.570 mm, n = 177) progressed in 14% (n = 11) and 18% (n = 31) of cases, respectively. The progression rate for patients with a mean pressure of less than 17 mmHg in both groups was 12%-13%. In contrast, the progression rate in patients with 18 mmHg or higher was 23% and 16% in the mid-range and thick corneal groups, respectively. In patients with thinner corneas (equal to or less than 0.510 mm, n = 56), the progression rate was 32% (n = 18). The progression rate was 60% (12 of 20) with mean pressures of at least 18 mmHg or higher, but 18% with mean pressures equal to or less than 17 mmHg. Univariant (P = 0.05), but not multivariant, analysis showed that corneal thickness was a risk factor for progression.

This study suggests that the reduction of intraocular pressure helps to prevent progression in patients with primary open-angle glaucoma. However, for patients with thinner corneas, pressure reduction may potentially be of even greater importance to help avoid glaucomatous progression. Future study should clarify potential variables associated with thin corneas and glaucomatous progression.