Abstract
Purpose:
To evaluate SD-OCT findings in patients with birdshot chorioretinopathy and correlate them with visual acuity, kinetic perimetry, and electroretinography.
Methods:
We performed a retrospective analysis of patients with clinical diagnosis of birdshot chorioretinopathy who had concurrent OCT, kinetic perimetry, and ERG. All OCT scans were evaluated for external limiting membrane (ELM) integrity, ellipsoid zone (EZ) integrity, and presence of cystoid macular edema (CME). These were compared to select functional measures - rod and cone function on ERG, visual acuity, and visual field abnormalities.
Results:
Thirteen encounters of eleven patients were analyzed. 12 (46.2%) OCT images showed ELM disruption; 14 (53.9%) images showed EZ disruption; 9 (35.6%) images showed CME. 20 Goldman visual fields (76.9%) showed abnormalities, including enlarged blind spots and areas of relative scotomas. On ERG, 14 studies had normal rod function (53.9%) and 3 had normal cone function (11.5%). 7 studies had mild rod dysfunction (26.9%), 3 moderate (11.5%) and 2 severe (7.7%). 6 studies had mild cone dysfunction (23.1%), 15 moderate (23.1%), and 2 severe (7.7%). Visual acuities were categorized as normal (20/20 Snellen acuity), mild impairment (20/25-20/40), moderate impairment (20/50-20/150), or severe (20/200 or below). 5 studies were normal (19.2%), 10 had mild impairment (38.5%), and 11 had moderate impairment (42.3%). The relationship between EZ disruption and visual acuity (p=0.023) and the relationship between EZ disruption and cone function on ERG testing (p=0.025) appeared statistically significant by Chi-square test of independence. The relationship between ELM disruption and presence of visual field loss (p=0.017) appeared statistically significant by Fisher’s exact test. The relationship between ELM disruption and visual acuity (p=0.051) and the relationship between presence of CME and visual acuity (p=0.051) approached statistical significance.
Conclusions:
SD-OCT imaging of the fovea can be a useful adjunct test in birdshot chorioretinopathy. Changes in ELM and EZ on OCT may relate to important functional measures, including visual field loss and visual acuity impairment. However, some functional changes appear to be independent of the anatomical changes noted on foveal OCT.