·To investigate the retinal microvascular and thickness abnormalities in adult patients with constant exotropia using OCTA (optical coherence tomography angiography) device, and explore the clinical application value of OCTA in constant exotropic adults.

·A total of 29 adult patients with constant exotropia who visited the Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University from January to December 2019 were recruited as the experimental group. Twenty-seven eyes of 27 healthy volunteers who visited the hospital during the same period were included as the control group. All participants underwent a comprehensive ophthalmologic examination at the first visit, which included subjective refraction, intraocular pressure measurement, ocular motility and position test, cover test at distance and near, axial length, and slit-lamp examination. Pearson's chi-squared test was used to compare categorical variants. The vessel and thickness in 3 mm×3 mm macular area were detected by OCTA device by a single experienced technician. The average vessel density of superficial capillary plexus (SCP), deep capillary plexus (DCP), foveal avascular zone (FAZ) area and inner and full retina thickness were automatically calculated by software. The differences in OCTA parameters between the dominant eyes, non-dominant eyes and control eyes were compared by using t-test or Mann-Whitney U test. The OCTA data was corrected for axial length and refractive error using Littmann's formula. A value of P<0.05 was considered statistically significant.

·There was no significant difference in age and gender between the experimental group and the control group. All participants had normal eye movements and normal anterior and posterior segments of the ocular. There were no statistically significant differences in SE, BCVA, intraocular pressure, and axial length of the dominant, non-dominant and normal eyes. In the 3 mm×3 mm macular region, there was no significant difference in the average blood flow density of SCP, DCP and FAZ area in the dominant, non-dominant and control eyes. The fovea and temporal regions of full macular thickness of the non-dominant eyes were (248.61±19.84) μm and (320.44±17.05) μm respectively, significantly (P=0.018, P=0.018) thinner when compared with the dominant eyes [(251.61±19.37) μm, (323.44±15.82) μm].

·OCTA is an effective tool to quantitatively analyze the blood flow density, FAZ area and macular thickness of patients with constant exotropia. There are no significant differences in the average blood flow density of SCP, DCP and FAZ area in adult patients with constant exotropia; there are specific changes in the macular microstructure of the non-dominant eyes. The fovea and temporal regions of full macular thickness of the non-dominant eyes are significantly decreased.