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Kumar Sambhav, Sandeep Grover, K V Chalam; Three dimensional Swept source OCT accurately measures optic disc volume in primary open angle glaucoma and correlates with severity of visual field loss. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):643. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To measure optic nerve cup volume (CV) in primary open angle glaucoma (POAG) using 3-dimensional [3D] swept-source optical coherence tomography (SS-OCT) and correlate with severity of visual field loss.
In this prospective, observational case series, SS-OCT scans of the optic nerve head (ONH) (12X9-mm area; 100000 B-scans; interval 100μ) were obtained in 64 POAG eyes. Bruch’s membrane opening (BMO) and anterior lamina cribrosa boundary were automatically delineated. The point with maximum lamina cribrosa (LC) depth and pre-laminar neural (PLT) thickness were averaged. RPE edge points, which are detected radially from the disc center were outlined with automated software. By default, the "referring surface” was set optionally 120μm above the RPE edge. Cup volume of the area surrounded by the reference surface and ILM line was calculated. 30 - 2 HVF analysis along with SS - OCT optic nerve analysis were done in all patients. Reliability of HVF in all the subjects was good (false positive <20%, false negative <20% and fixation losses <33%). All investigations were done on the same day or within a week of each other.
Mean age of the cohort was 63.5 years (median - 64 yrs). There were 18 females and 14 males included in the study. There were 28 African American and 4 Caucasians. Mean IOP was 14.21 (SD - 3.07) mm Hg, with a range of 9 - 21 mm Hg. On HVF analysis, average mean deviation (MD) was - 4.12 and average pattern standard deviation (PSD) was 4.26. Mean cup volume (CV) in our cohort was 0.45 cu mm and mean cup to disc ratio (CDR) was 0.75. The value of R (Pearson’s correlation coefficient) between CV and MD was -0.63 and that between CV and PSD was 0.64. However, there was a weak correlation between CV and CDR (R - 0.28).
SS - OCT objectively and accurately measured cup volume in POAG and correlated well with the visual field loss. This may be a useful tool in the longitudinal monitoring of primary open angle glaucoma.
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