Longitudinal changes in vessel density and retinal nerve fiber layer thickness after acute primary angle closure

To evaluate the initial and longitudinal alterations of peripapillary optic disc vessel index in eyes with a history of acute primary angle closure (APAC) and to explore the better predictor of glaucoma progression. Twenty-one consecutive Chinese patients who were successfully treated for a unilateral episode of APAC were included in the study. The observation group consisted of eyes with the history of acute episode, while the contralateral eyes without an attack served as the control group. All APAC eyes underwent phacoemulsification cataract extraction, intraocular lens implantation and goniosynechialysis one day after the remission of episode. Moreover, the contralateral eyes were performed laser peripheral iridotomy (LPI). Patients were followed-up at 1 day after remission of APAC and 1 week, 1 month, 3 months, 6 months, and 1 year after surgery. All participants underwent ophthalmic examinations after remission of the acute episode but before surgery, including best-corrected visual acuity (BCVA), intraocular pressure (IOP), axial length (AL), visual field (VF), and retinal nerve fiber layer (RNFL) thickness and circumpapillary vessel density (cpVD) obtained by swept-source optical coherence tomography(SS-OCT). Correlation analysis was performed to identify the cpVD as a predictor of glaucoma progression. The vascular network was visibly attenuated and focal capillary dropout was evident in APAC eyes. The cpVD 1 day after APAC episode and 1 week postsurgery in APAC eyes was 45.96% (45.96 ± 3.41), and 46.19% (46.19 ± 3.15) which were significantly (P=0.020 and P༝0.035) reduced compared to 48.35% in the unaffected eyes. However, it remained stable during the follow-up in the subsequent year. The retinal nerve fiber layer (RNFL) thickness initially showed thickening at 1 day (P༝0.05), and followed by a progressive thinning from 1 week (P༝0.04) to 6 months (P༝0.02), and eventually reached a stable state. At the last follow-up in APAC eyes, peripapillary retinal VD was positively correlated with RNFL thickness (P༝0.01) and negatively correlated with VF mean deviation (P༝0.04). In APAC eyes, the circumpapillary VD decreased significantly 1 day after the APAC episode was fully resolved, and remained stable during the follow-up. However, the RNFL thickness ultimately plateaued at a stable level at 6 months. Thus, cpVD may be the more sensitive predictor than the RNFL thickness for the glaucomatous progression of APAC patients. Not applicable. •What is known: • The previous studies demonstrate that an initial increase in RNFL thickness after a single APAC episode, followed by a subsequent decrease. • The high IOP has a greater impact on the changes in vessel density parameters after an APAC episode. •What is new: • The study demonstrates that the cpVD decreased significantly 1 day after the APAC episode was fully resolved, and remained stable during the follow-up. • The study demonstrates that the cpVD was the more sensitive predictor than the RNFL thickness for the glaucomatous progression of APAC patients.