Abstract
Purpose :
The prevalence of normal tension glaucoma (NTG) increased with radiation dose among Japanese atomic bomb survivors (Radiat Res.2013;180:422-30), but the pathophysiology has been unclear. Glaucoma is thought to be a multifactorial disease, and it is hypothesized that abnormal ocular blood flow is involved in the pathogenesis of glaucoma, and in particular NTG. We conducted an observational cross-sectional study to examine the relationship between glaucoma and retinal vascular caliber as markers of ocular circulation, in relation to radiation dosage.
Methods :
In the Adult Health Study of Japanese atomic bomb survivors, 1,664 subjects were diagnosed with prevalent glaucoma and their retinal photographs from 2006 to 2008 were included. Glaucoma was diagnosed from disc cup ratio and visual field tests, and was classified into primary open angle glaucoma (POAG), NTG, and primary angle closure glaucoma (PACG) based on gonioscopic findings and intraocular pressure. Central retinal artery and vein equivalents (CRAE and CRVE) were calculated using a semi-automated software program. Multiple linear regression analyses were used to identify the associations between radiation exposure, glaucoma subtype, and CRAE and CRVE.
Results :
Baseline characteristics including age at examination (ATE), sex, blood pressure, and radiation dose were heterogeneously distributed across the glaucoma subtypes. Notably, patients with NTG had higher mean radiation doses (731 mGy) than those with other glaucoma subtypes (POAG, 341.8 and PACG, 203 mGy). Multiple regression analyses showed that CRAE and CRVE had statistically significant associations with ATE (P<0.001), smoking status (P=0.03), and glaucoma subtypes (P<0.001). Decreases in CRAE and CRVE in the NTG group were statistically significant compared to contol, while no relationships were found between radiation doses and CRAE and CRVE.
Conclusions :
Among the atomic bomb survivors, the smaller CRAE and CRVE in NTG patients than in normal subjects may indicate an association between ocular blood flow and the pathogenesis of NTG. However, significant relationships between vessel calibers and radiation exposure were not shown.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.