Normal‐Tension Glaucoma and Central Corneal Thickness

ABSTRACT: Purpose. To determine whether a decreased corneal thickness is a primary factor in the lower intraocular pressure readings found in normal‐tension glaucoma patients. Methods. Fourteen patients with normal‐tension glaucoma were compared with 14 age‐ and sex‐matched glaucoma patients. Corneal thickness was measured by ultrasonic pachymetry on each eye. Results. The corneal thickness (mean ± SD) in patients with normal‐tension glaucoma was 0.536 ± 0.035 mm. The corneal thickness in patients with glaucoma was 0.537 ± 0.035 mm. The 95% confidence interval for the difference between the two groups was —0.027 to +0.027 mm. Conclusion. It has been documented that increased corneal thickness leads to high readings of intraocular pressure. Therefore, decreased corneal thickness may lead to a lower intraocular pressure reading. This study suggests that for most normal‐tension glaucoma patients corneal thickness is not a major factor in accounting for the lower intraocular pressure measurements when compared with primary open angle glaucoma patients. (Optom Vis Sci 1999;76:596‐598)