Quantification of Retinal Microvascular Density Using Optic Coherence Tomography Angiography in Primary Angle Closure Disease.

Purpose: To evaluate the microvascular density of the peripapillary and parafoveal areas of the eyes with primary angle closure disease (PACD) using optical coherence tomography angiography (OCTA).Materials and methods: An observational study was conducted with 76 PACD patients (29 eyes with primary angle closure suspect, 22 eyes with primary angle closure [PAC], and 25 eyes with primary angle closure glaucoma [PACG]) and 27 control eyes. OCTA was performed for all subjects to acquire a 4.5 × 4.5 mm scanning area centered on the optic discs and a 3 × 3 mm parafoveal cubes. Peripapillary and parafoveal vessel density (VD) were compared between these four groups, and the relationship between VD values and structural and functional changes was evaluated.

Results

Among all four groups, the peripapillary VD of the PACG eyes was the lowest in all six sections (all P < .01), while the parafoveal VD was lower than that of the normal group only in the average, superior, and inferior areas (all P < .05). The PAC group had lower peripapillary VD than the normal group (62.6[55.2-67.4] vs. 66.7[54.7-69.3], P = .01), while their retinal nerve fiber layer (RNFL) and ganglion cell complex thickness were not significantly different than those of the control group (all P > .05). In addition, the stages of PACD, visual field mean deviation, and RNFL thickness were shown to be predictors of the peripapillary VD in the multiple linear regression analysis.

Conclusions

The PAC eyes had lower peripapillary VD than normal eyes when their RNFL and GCC thickness did not differ. This suggests that a reduction in retinal VD may occur before structural loss in PAC eyes. Retinal VD measurement may be a useful tool for the assessment of PACD.