TUNEL-Positive Ganglion Cells in Human Primary Open-angle Glaucoma

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Abstract
Objective: To determine whether retinal ganglion cell death in primary open-angle glaucoma occurs by apoptosis. Methods: Eighteen eyes of 17 subjects with documented primary open-angle glaucoma were compared with 21 control eyes that were group matched for age, race, and sex. Staging of glaucoma severity was performed by histologic optic nerve evaluation. Fixed, paraffin-embedded retinal sections were assayed by the TUNEL (terminal deoxynucleotidyl transferase—mediated deoxyuridine triphosphate (UTP)-biotin nick end-labeling) method to detect the internucleosomal DNA fragmentation that is characteristic of apoptosis. Results: A positive TUNEL reaction was observed among ganglion layer cells in 10 of 18 cases with glaucoma, compared with 1 of 11 control cases without confounding systemic disease (5 control eyes were excluded owing to artifactual staining and 4 eyes had confounding systemic disease). Sections containing more than 250 000 cells in the ganglion cell layer were examined in cases and controls. The frequency of TUNEL-positive cells in the ganglion cell layer in cases with glaucoma was 1.76 per 10 000, or 15.2 times greater than the control frequency from individuals without confounding disease (P<.001; 95% CI, 2.46-623). Eyes without glaucoma from subjects with diabetes and amyotrophic lateral sclerosis showed more positive cells than other controls. Conclusion: Apoptosis seems to be a mechanism of cell death in human eyes with primary open-angle glaucoma.