Peripapillary Vessel Density and Retinal Nerve Fiber Layer Thickness in Patients with Unilateral Primary Angle Closure Glaucoma with Superior Hemifield Defect

Abstract

Purpose: To evaluate peripapillary retinal nerve fiber layer (RNFL) thickness and radial peripapillary capillary (RPC) vessel density (VD) in the eyes with unilateral primary angle-closure glaucoma (PACG) with the visual field (VF) defect confined to the superior hemifield and compare these parameters with the corresponding perimetrically intact regions of the fellow eye with primary angle-closure (PAC) and normal control eyes, using optical coherence tomography angiography (OCTA).

Materials and methods: This prospective, cross-sectional study included 28 eyes with unilateral PACG, with VF defects restricted to the superior hemifield, 28 fellow eyes with PAC, and 30 age-matched normal controls. Peripapillary RNFL thickness and RPC VD were measured in the eight peripapillary sectors, using OCTA, and these parameters were compared among the corresponding sectors of PACG, PAC, and healthy eyes using analysis of variance (ANOVA) with the Bonferroni post hoc analysis.

Results: In PACG eyes, there was a significant difference in the RNFL thickness (p < 0.0001) and RPC VD (p = 0.001) between the superior and the inferior hemifield. In PAC and normal eyes, there was no significant difference in the RNFL thickness and RPC VD between the superior and the inferior hemifield. Within the perimetrically intact regions of the PACG eyes, the mean RNFL thickness was significantly reduced in the superonasal (SN) and upper nasal (UN) sectors (p = 0.02), but the VD did not show any significant difference, when compared to the fellow PAC eyes. In PACG eyes, the mean RNFL thickness was significantly reduced in the perimetrically normal SN and UN sectors (p < 0.0001) and the VD was reduced in the UN sector (p = 0.01), when compared to the normal eyes. When comparing the peripapillary sectors of the PAC and healthy eyes, RNFL thickness was reduced in UN (p = 0.02), lower nasal (LN) (p = 0.01), inferonasal (IN) (p = 0.02), and inferotemporal (IT) sectors (p = 0.03) and there was no significant difference in the VD in any of the sectors. Inside disc capillaries were preserved in all the three groups.

Conclusion: Sector-wise RNFL thinning seems to precede the vascular changes and functional loss in the PAC and PACG eyes.

How to cite this article: Mansoori T, Balakrishna N. Peripapillary Vessel Density and Retinal Nerve Fiber Layer Thickness in Patients with Unilateral Primary Angle Closure Glaucoma with Superior Hemifield Defect. J Curr Glaucoma Pract 2019;13(1):21-27.

Keywords: OCT angiography; Primary angle-closure; Primary angle-closure glaucoma; RPC vessel density; Retinal nerve fiber layer thickness; Superior hemifield loss.

Figs 1A to E

OCTA image of the optic disc in a normal eye; (A) Structural en face image of the healthy optic disc; (B) Humphrey VF analyzer 24-2 Swedish interactive threshold algorithm standard PDPP, shows intact superior and inferior hemifield; (C) Peripapillary RNFL measurement shows a normal RNFL thickness profile and the peripapillary region is divided into eight sectors based on the modified Garway-Heath of 2–4 mm grid. Inner ellipse indicates the optic disc boundary and the outer ellipse indicates the outer border of the peripapillary region; (D) OCTA scan of the peripapillary region showing VD of healthy eye. VD is measured in the sectors based on the modified Garway-Heath sector of 2–4 mm grid; (E) OCTA en face image shows dense radial peripapillary microvascular network around the optic disc

Figs 2A to E

PACG eye with a superior hemifield defect; (A) OCTA structural en face image of the optic disc shows focal inferior temporal notch with corresponding RNFL defect at the peripapillary IT region (red arrows); (B) Humphrey VF analyzer 24-2 Swedish interactive threshold algorithm standard, PDPP shows a superior hemifield VF defect and normal inferior hemifield; (C) Peripapillary RNFL shows a reduced RNFL thickness at the IT and lower temporal sectors; (D) OCTA of PACG eye showing reduced VD in IT and lower temporal sectors; (E) OCTA en face image shows focal RPC dropout at the IT and lower temporal sectors

Figs 3A to D

PACG eye with a superior hemifield defect; (A) OCTA structural en face image of optic disc shows focal inferior temporal notch with corresponding RNFL defect at the peripapillary IT region (red arrows); (B) Peripapillary RNFL shows reduced RNFL thickness in IT, lower temporal, and inferior nasal sectors; (C) OCTA of PACG eye showing reduced VD in IT, lower temporal, and inferior nasal sectors; (D) OCTA en face image shows wide RPC dropout at the IT, lower temporal, and inferior nasal sectors