The role of optical coherence tomography angiography in early detection of primary open-angle glaucoma

Abstract

Introduction Glaucoma is a slowly progressive disease with characteristic optic nerve abnormalities caused by accelerated ganglion cell complex (GCC) loss and concomitant retinal nerve fiber layer (RNFL) thinning. Glaucoma suspects are the key group to identify and treat with intraocular pressure lowering therapy in an effort to prevent blindness. Aim Determination and correlation of the role of the whole image, peripapillary, and inside disk vascular density (%) (wiVD%, ppVD%, and idVD%) in the RNFL of optic nerve head by optical coherence tomography angiography (OCT-A) and their correlation to GCC and RNFL thickness by OCT in early detection of preperimetric primary open-angle glaucoma. Patients and methods This prospective, nonrandomized, noninvasive, and observational case–control study was performed at the Ophthalmology Department and clinics of Al-Zahraa University Hospital, Al-Azhar University. It included 46 eyes of 23 participants who were divided into two groups: group I (control) consisted of 20 eyes of 10 healthy eyes. Group II (glaucoma suspects) consisted of 26 eyes of 13 preperimetric glaucoma suspects of the same age group. The peripapillary and inside disk optic nerve head vessel density were measured. Clinical data, visual field (VF) parameters, and spectral-domain OCT evaluation (RNFL thickness, GCC thickness, and rim area) were recorded. Results Significant decreases were found in whole image, peripapillary, and inside disk vascular density (%) and RNFL thickness especially in the temporal side, GCC, VF mean deviation, and VF index in suspected eyes than the normal eyes indicating the presence of early vascular changes in glaucoma. Conclusion OCT-A is a novel, noninvasive imaging technology that detects vascular changes as early signs in glaucoma disease progression; reduced vessel density also was associated with thinning of RNFL, and decrease in GCC count in a majority of cases. So, the diagnostic ability of OCT-A is a promising tool for early diagnosis of glaucoma.