Purpose
Phase-variance OCT (pv-OCT) imaging uses SD-OCT instrumentation to allow non-invasive visualization of the retinal and choroidal flow in three-dimensions in vivo. The purpose of this study was to determine whether pv-OCT imaging can be used to detect choroidal perfusion abnormalities that may be associated with self-limiting inflammatory disorders of the retina and choroid, such as acute posterior multifocal placoid pigment epitheliopathy (APMPPE) and post-West Nile Virus chorioretinitis. These two conditions were studied since transient ischemia of the choriocapillaris from post-viral vasculitis has been postulated as a possible mechanism for pathogenesis of transient vision loss based on angiographic abnormalities.
Methods
Two eyes (1 subject) with acute APMPPE and two eyes (1 subject) with newly diagnosed post-West Nile chorioretinitis involving the macula were imaged at presentation and serially thereafter with fundus photography, fluorescein angiography, indocyanine green angiography, SD-OCT and research-grade phase-variance OCT until visual function recovered and stabilized.
Results
At presentation, both subjects had severe loss of vision with best corrected visual acuity of 20/400. Multiple macular lesions were noted in the study eyes. In all eyes studied, patchy hypoperfusion of the choriocapillaris was noted on pv-OCT during the acute presentation. These patches of hypoperfusion corresponded to the areas of hypofluorescence noted on fluorescein and indocyanine green angiography and outer retinal abnormalities noted on SD-OCT. The areas of choroidal hypoperfusion on pv-OCT were not associated with any shadowing artifacts on SD-OCT B-scans. Both patients were treated with oral prednisone with almost complete recovery of vision over the next several weeks. Recovery of choroidal perfusion abnormality detected on pv-OCT preceded recovery of visual acuity and outer retinal abnormalities noted on SD-OCT.
Conclusions
pv-OCT imaging allows visualization of transient perfusion abnormalities of the choriocapilaris associated with APMPPE and post-West Nile virus chorioretinitis. These transient perfusion changes at the level of the choriocapillaris may play a role in the pathogenesis of vision loss associated with both these inflammatory conditions.