Comparison of Clinical Characteristics Between Korean and Western Normal-Tension Glaucoma Patients

Abstract

To detect potential differences in the phenotypes between Western normal-tension glaucoma (NTG) and Korean NTG. A retrospective, cross-sectional study. One hundred eighty-four NTG eyes of 71 patients of the Jules Stein Eye Institute, University of California, Los Angeles, and 113 patients of the Seoul National University Hospital, Seoul, Korea, were studied after reviewing medical charts retrospectively. All eligible patients from both institutions who were evaluated between July 2007 and June 2008 were included. The groups were matched for stage of glaucoma severity based on the visual field mean deviation value. All patients underwent a complete ophthalmic examination, Humphrey perimetry, Heidelberg Retina Tomography, Stratus optical coherence tomography, and pachymetry. Structural and functional parameters between the 2 groups were compared. There were no statistically significant differences in the baseline intraocular pressure, disc area, frequency of disc hemorrhage, or peripapillary atrophy (P > .05). Cup-shape measure (by Heidelberg Retina Tomography), average RNFL thickness (by Stratus optical coherence tomography), and central corneal thickness were significantly different (P < .002). The eyes of Korean NTG patients showed higher values for cup-shape measure, higher average RNFL thicknesses, and thinner central corneal thicknesses than Western NTG patients. The difference was significant (P < .001) while controlling for age, sex, disc area, mean deviation, pattern standard deviation, and spherical equivalent with multivariate analysis. Korean NTG patients showed steeper cup shapes, thicker RNFL thickness, and thinner central corneal thickness compared with Western NTG patients with similar amounts of visual field loss. This result may help clinicians understand the clinical characteristics of NTG patients and points to the heterogeneous character of the glaucomas.