Intraocular vascular analysis using optical coherence tomography angiography in patients with vascular paralytic strabismus

Purpose To investigate changes in peripapillary and macular vessel density (VD) in vascular paralytic strabismus using optical coherence tomography angiography (OCTA). Methods Medical records of patients who recovered from monocular vascular paralytic strabismus were retrospectively analyzed. Age, sex, presence of underlying diseases, strabismus type and severity, time to recovery, and visual acuity at diagnosis were evaluated. VD in the optic disc area and macular capillary plexus density were estimated using OCTA. The effect of paralytic strabismus on intraocular VD was investigated by comparing VD between the paralysis and contralateral eyes. To analyze hemodynamic changes, VD changes in the paralysis eye during the attack and recovery were compared. Results Thirty-one patients (mean age, 64.1±13.0 years; 21 males, 10 females) were included and mean recovery time was 3.0±1.6 months. The most common paralysis was sixth nerve palsy (54.8%). When comparing OCTA results between the paralysis and contralateral non-paralysis eyes, foveal VD in the superficial capillary plexus (SCP) was significantly lower in the paralysis eye (P = 0.034); however, VD in the optic disc area was not different. In the paralysis eye, foveal VD in the SCP significantly increased after paralysis recovery (P = 0.04). During attack, the maximal deviation angle and severity of duction limitation were significantly related to foveal VD in SCP. The greater the deviation angle and the more severe the eye movement restriction, the lower the foveal VD in SCP. Conclusions Transient retinal ischemia of the paralysis eye was observed in a patient with paralytic strabismus, which corresponded to the degree of deviation angle and ocular motor restriction. Ischemic factors, which are the etiology of vascular paralytic strabismus, affect intraocular blood flow.