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Marguerite Devereux, Rong Liu, MiYoung Kwon; The role of binocularly asymmetric peripheral field loss in abnormal binocular function in glaucoma. Journal of Vision 2018;18(10):997. doi: https://doi.org/10.1167/18.10.997.
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Glaucoma is characterized by progressive loss of retinal ganglion cells and resulting visual field defects. Studies have shown that, even in early stages of glaucoma, binocular function such as stereopsis is significantly impaired (Essock et al., 1996). However, the mechanism underlying abnormal binocular function in glaucoma still remains unclear. Here we examined the factors that may undermine binocular function in glaucoma, particularly whether binocularly asymmetric peripheral field loss plays a significant role. The study included 17 glaucoma patients (mean age=65.76) and 17 age-similar normally-sighted individuals (mean age=60.12). Binocular function was assessed with a stereopsis test (Titmus Fly SO-001 StereoTest) in combination with a binocular fusion test (a Worth 4-dot test). For each subject, visual field loss (24-2 Humphrey Field Analyzer), visual acuity (ETDRS charts), and contrast sensitivity (Pelli-Robson charts) were also measured for each eye separately. Interocular differences of each functional measurement were computed to quantify the binocular asymmetry of vision loss. The interocular difference of visual field loss was further analyzed into four sub-regions: the foveal, parafoveal, perifoveal, and peripheral regions. Our data showed that compared to normal controls, glaucoma patients exhibited significantly poorer stereopsis (122 vs. 44 arcsec, t(31)=-2.70, p=0.01) and a larger interocular difference in visual field loss and contrast sensitivity (both p< 0.05), indicating binocularly asymmetric visual impairment in glaucoma. Furthermore, stereopsis results were significantly correlated with interocular differences of field loss in all the sub-regions beyond the fovea (all p< .01), but not with any of foveal interocular differences (all p>.05). Our results showed that stereopsis deficits in glaucoma can be largely attributed to binocularly asymmetric peripheral field loss. Our findings further suggest a significant role of peripheral vision in binocular function.
Meeting abstract presented at VSS 2018
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