Discriminant Function of Optical Coherence Tomography Angiography to Determine Disease Severity in Glaucoma.
OBJECTIVE
To determine the discriminant function of optical coherence tomography angiography (OCTA) by disease severity in glaucoma.


METHODS
In this prospective, observational cross-sectional study, all subjects underwent visual fields, retinal nerve fiber layer (RNFL) measurements, and OCTA imaging. Local fractal analysis was applied to OCTA images (radial peripapillary capillaries [RPC] layer). Vessel density en face and inside the disc and spacing between large and small vessels were quantified. Stepwise logistic regression was performed and a glaucoma severity score (range, 0-1: 0, normal; 1, severe glaucoma) was developed by using global and regional (superotemporal [ST], inferotemporal [IT], temporal, superonasal [SN], inferonasal, and nasal) vascular parameters. Glaucoma severity score was compared with visual field and RNFL indices.


RESULTS
One hundred ninety-nine eyes (112 subjects) with glaucoma (28 eyes preperimetric; 83 early, 43 moderate, and 45 severe glaucoma) and 74 normal (54 subjects) eyes were enrolled. Preperimetric and glaucomatous eyes had significantly altered (P < 0.001) global vascular parameters as compared to normal; regionally, ST, then SN and IT sectors (in that order) showed more change in glaucomatous eyes. Vascular parameters showed better discriminant ability (area under the curve [AUC], sensitivity, and specificity of 0.70, 69.2%, and 72.9%, respectively) than structural parameters between normal and preperimetric glaucomatous eyes. Vascular parameters had comparable AUC (P > 0.05) to visual fields for perimetric glaucoma. Glaucoma severity score identified preperimetric glaucoma and early glaucoma better than did visual fields.


CONCLUSIONS
Vascular parameters could be a useful adjunct tool to evaluate/diagnose glaucoma. Longitudinal studies are needed to determine their use in early detection and prognostication.
Narayana Nethralaya Eye Hospital, Bangalore, India.
Rajesh S
RS
Kumar
Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
Neha
N
Anegondi
Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
Rachana S
RS
Chandapura
Narayana Nethralaya Eye Hospital, Bangalore, India.
Suria
S
Sudhakaran
Narayana Nethralaya Eye Hospital, Bangalore, India.
Sujatha V
SV
Kadambi
Narayana Nethralaya Eye Hospital, Bangalore, India.
Harsha L
HL
Rao
Singapore Eye Research Institute and Singapore National Eye Center, Singapore 4Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Tin
T
Aung
Imaging, Biomechanics and Mathematical Modeling Solutions, Narayana Nethralaya Foundation, Bangalore, India.
Abhijit
A
Sinha Roy
D003430:Cross-Sectional Studies; D016002:Discriminant Analysis; D042241:Early Diagnosis; D005260:Female; D005451:Fluorescein Angiography; D005500:Follow-Up Studies; D005654:Fundus Oculi; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D009898:Optic Disk / Q000473:pathology*; D011446:Prospective Studies; D012372:ROC Curve; D012165:Retinal Ganglion Cells / Q000473:pathology; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods*; D014794:Visual Fields