Association between radiation, glaucoma subtype, and retinal vessel diameter in atomic bomb survivors

Abstract

We examined the relationship between glaucoma subtype and retinal vascular caliber as markers of ocular circulation. Subjects were Japanese atomic bomb survivors in Hiroshima and Nagasaki. After a screening examination, potential cases were subjected to further definitive examination. The diameters of central retinal artery and vein equivalents (CRAE and CRVE) on digitized retinal photographs were measured using an established method. Generalized linear regression analyses were used to examine the associations among vessel diameters, radiation exposure, and prevalence of glaucoma subtypes among the study subjects. We identified 196 cases of glaucoma (12%) based on optic disc appearance, perimetry results, and other ocular findings. The main subtypes were primary angle-closure glaucoma, primary open-angle glaucoma and normal-tension glaucoma (NTG). NTG was the dominant subtype (78%). NTG was negatively associated with CRAE and CRVE, and positively associated with radiation dose. CRVE was negatively associated with radiation dose and the association was unclear for CRAE. The smaller retinal vessel caliber in NTG patients than in subjects without glaucoma may indicate an association between ocular blood flow and the pathogenesis of NTG. However, significant relationships among vessel calibers, NTG and radiation exposure were not clear.

Figure 1

Estimated probabilities for each glaucoma type as a function of retinal vessel diameters among Adult Health Study subjects (N = 1,640), 2006–2008. The predicted probability of normal tension glaucoma tended to sharply decline with increasing central retinal artery equivalents and central retinal vein equivalents. Abbreviations: NTG, normal-tension glaucoma; POAG, primary open-angle glaucoma; PACG, primary angle-closure glaucoma.

Figure 2

Data sample exclusion. Abbreviations: AHS, Adult Health Study of the Japanese atomic bomb survivors.