Abstract
Purpose: :
To assess contrast sensitivity as a measure of visual function in patients with birdshot chorioretinopathy; and to identify relationships between contrast sensitivity and other measures of visual function (best corrected visual acuity, symptoms, color vision, visual field parameters) and clinical findings on examination.
Methods: :
We evaluated 63 patients (126 eyes) with a clinical diagnosis of birdshot chorioretinopathy in a single-center, cross-sectional study. Contrast sensitivity was measured at four spatial frequencies (3, 6, 12, and 18 cycles/degree [cpd]) in all patients, using the CSV-1000E instrument (VectorVision, Greenville, OH). The percentage of eyes with abnormal contrast sensitivity measurements (defined as 2 SD below the mean for population norms) were determined for each spatial frequency, with the intent to compare results at the spatial frequency having the highest prevalence of abnormal values to the following parameters in a per-eye analysis: best corrected visual acuity (BCVA), the presence or absence of eight specified symptoms; color confusion score (CCS); lens status (clear lens, cataract, pseudophakia); and ocular coherence tomography (OCT) parameters (central macular thickness, loss of the third highly reflective band). Results were adjusted for patient age, duration of disease, and treatment history.
Results: :
Contrast sensitivity values were abnormal in 31 eyes (25%) at a spatial frequency of 3 cpd; in 41 eyes (33%) at a spatial frequency of 6 cpd; in 103 eyes (82%) at a spatial frequency of 12 cpd; and in 49 (39%) at a spatial frequency of 18 cpd. Contrast sensitivity at 12 cpd was related to poor BCVA (p<0.0001), symptoms of blurry vision (p=0.019) and poor contrast, and presence of cataract (p=0.025). Among 38 eyes with normal Snellen acuity (≥ 1.0), 23 eyes (61%) had abnormal contrast sensitivity at a spatial frequency of 12 cpd.
Keywords: contrast sensitivity • clinical (human) or epidemiologic studies: prevalence/incidence • chorioretinitis