Optical Coherence Tomography Angiography of the Peripapillary Retina in Primary Angle-Closure Glaucoma

Abstract

Purpose: To measure the change of peripapillary retinal vessel density (VD) in eyes with a history of acute primary angle-closure glaucoma (PACG).

Design: Case-control study.

Methods: Twenty-one consecutive Chinese patients with history of unilateral acute PACG were enrolled. Eyes with acute PACG constituted the case group, while the contralateral eyes without attack constituted the control. All patients underwent ophthalmic examinations including best-corrected visual acuity, intraocular pressure, and visual field (VF). Spectral-domain optical coherence tomography (SD-OCT) was used to obtain both structural OCT and OCT angiography (OCTA). Structural OCT scans provided thickness measurements of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC). OCTA was used to measure all-plexus peripapillary retinal VD.

Results: In unaffected eyes, a dense microvascular network surrounded the disc on all-plexus retinal OCTA. The vascular network was visibly attenuated and focal capillary dropout was evident in acute PACG eyes. The peripapillary VD in acute PACG eyes was 66.6% ± 17.3% (mean ± standard deviation), which was significantly (P < .01) reduced compared to 87.2% ± 8.6% in the unaffected eyes. In acute PACG eyes, peripapillary retinal VD was positively correlated with RNFL and GCC thicknesses (P < .001 each) and negatively correlated with VF mean deviation (P = .002) and cup-to-disc ratio (P = .0064). In unaffected eyes, there were no correlations between peripapillary retinal VD and glaucoma-related parameters.

Conclusions: In acute PACG eyes, peripapillary retinal VD decreased significantly compared with the contralateral unaffected eyes. Peripapillary retinal VD was significantly correlated with other glaucomatous changes.

FIGURE 1.

A series of correlated peripapillary pathologic changes were present in acute primary angle-closure glaucoma (PACG) eyes when compared with the contralateral unaffected eyes. The left eye (Top row) of this patient is the unaffected eye and the right eye (Bottom row) is the acute PACG eye. Color fundus photographs: The acute PACG eye had enlarged cup-to-disc ratio. En face angiograms (4.5 × 4.5 mm): En face image of the all-plexus peripapillary retinal circulation. The all-plexus inner retina was defined as the layers between the internal limiting membrane (shown in pink dashed line) and the outer plexiform layer (shown in yellow dashed line). In the acute PACG eye, the peripapillary capillary network was obviously attenuated. Cross-sectional angiograms: Cross-sectional optical coherence tomography angiography (OCTA) was taken at the position of the yellow arrow on the en face OCTA. Blood flow signal of the inner retina (between the pink dashed line and the yellow dashed line) is shown in purple. Blood flow signal of the choroid is shown in red. There was obvious reduction of both flow signals and thicknesses in the retinal nerve fiber layer (RNFL) in the acute PACG eye when compared with the contralateral unaffected eye. RNFL thickness: Peripapillary RNFL thickness decreased significantly in acute PACG eye compared to the contralateral normal eye.

FIGURE 2.

Comparison of peripapillary retinal vessel density in the acute primary angle-closure glaucoma (PACG) eyes and the contralateral eyes. The Mann-Whitney test showed a significant reduction in peripapillary retinal vessel density in acute PACG eyes compared with contralateral eyes.

FIGURE 3.

Correlations of peripapillary vessel density with visual field and nerve fiber layer thickness in acute primary angle-closure glaucoma (PACG) eyes. Simple linear regression showed a negative correlation of peripapillary vessel density with the visual field mean deviation (MD) and a positive correlation with the mean retinal nerve fiber layer (RNFL) thickness in acute PACG eyes.