Delineation of capillary dropout in the deep retinal capillary plexus using optical coherence tomography angiography in a patient with Purtscher’s retinopathy exhibiting normal fluorescein angiography findings: a case report

BACKGROUND Fat embolism in the deep retinal capillary plexus is one of the reported mechanisms underlying central/paracentral scotoma in patients with Purtscher's retinopathy. Here we report the clear delineation of capillary dropout in the deep capillary plexus using optical coherence tomography angiography (OCTA) in a chronic case of unexplained scotoma that developed after femoral fracture. The patient exhibited normal fluorescein angiography (FA) findings and a normal retinal appearance. CASE PRESENTATION A 42-year-old Japanese man with a history of bilateral, unexplained paracentral scotoma that developed after femoral fracture and pulmonary fat embolism due to a car accident 20 years ago was referred to our outpatient clinic. Initial ophthalmological examination revealed unremarkable retinal findings. Goldmann perimetry, FA, and full field electroretinography showed no pathological changes. Although fat embolism in the retinal vasculature was suspected, psychosomatic visual field defects could not be ruled out. We performed OCTA, which clearly delineated capillary dropout in the deep retinal capillary plexus. A final diagnosis of paracentral acute middle maculopathy secondary to Purtscher's retinopathy was made on the basis of this finding. CONCLUSIONS Our findings suggest that OCTA clearly and noninvasively delineates the deep retinal capillary plexus and the superficial capillary plexus. Because conventional FA provides limited depth resolution, capillary dropout restricted within the deep capillary plexus cannot be detected, particularly when the superficial capillary plexus is well preserved. Thus, OCTA can be a useful tool for the detection of capillary dropout in the deep retinal capillary plexus.