Optical Coherence Tomography and Visual Acuity in Patients With Birdshot Chorioretinopathy

Abstract

Purpose: : To assess the relationship between visual acuity and macular imaging by Optical Coherence Tomography (OCT) in patients with birdshot chorioretinopathy

Methods: : Cross–sectional analysis of 80 patients with Birdshot chorioretinopathy seen in a single center. OCT was performed with the Zeiss–Humphrey OCT–3 machine (macular thickness software). The following parameters were analyzed: morphology, foveal thickness, macular thickness and volume

Results: : There were 29 males and 51 females and the mean age was 55.6 years at the time of the study. Median best corrected visual acuity (BCVA) was 0.8 (range counting fingers to 1.2). The mean central foveal thickness was 187 ± 98.5 µm (range 85 – 768), the mean macular thickness in a 0.5 mm radius was 224.3 ± 87.3 µm (range 146 – 262) and the mean macular volume was 6.84 ± 1.38 mm³ (4.59 – 14.71). Epiretinal membranes were seen in 30 eyes of 21 patients and choroidal neovascularisation in two eyes. The mean central foveal thickness was greater in Birdshot patients than the normal value reported in the literature. BCVA correlated with foveal thickness (R=0.57, P<0.001) and macular volume (R=0.54, P<0.001). All eyes with a BCVA of ≥1.0 had a macular volume within one standard deviation of the mean for the cohort (5.63–8.04), and a best–fit curve showed decreasing BCVA with both increasing and decreasing macular thickness. In eyes with low visual acuity, macular volume correlated better with visual acuity then did foveal thickness, possibly due to foveal thickness measurements being more sensitive to loss of fixation.

Conclusions: : Optical Coherence Tomography imaging was helpful to determine causes of decreased visual acuity in patients with birdshot chorioretinopathy. Retinal thinning and retinal thickening, particularly as defined by macular volume, were both associated with reduced visual acuity.

Keywords: autoimmune disease • retinochoroiditis • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)