Abstract
Purpose:
To evaluate the presence of relative afferent pupillary defect (RAPD) in asymmetric macular disease and quantify it using an automated binocular infrared computerized pupillometer (RAPDx, Konan Medical USA Inc., Irvine, CA), We also correlated the inter-eye difference in magnitude of RAPD with the inter-eye difference in macular lesion size measured on Fundus Auto-fluorescence (FAF) and Color Fundus Photos (FP).
Methods:
22 patients with asymmetric macular disease (20 with age-related macular degeneration, 1 with pattern dystrophy, 1 with pigment mottling) were prospectively enrolled and their pupil responses were tested using the RAPDx. Testing was conducted under dark room conditions using the full field stimulus testing strategy extending to ~18 degrees from fixation. They also underwent FP (Topcon, Tokyo, Japan) and FAF (Heidelberg, Carlsbad, CA). Patients with glaucomatous optic neuropathy, other optic nerve disease, or retinal vascular diseases were excluded. The RAPD score, an index of the direction and magnitude of pupil response asymmetry of the two eyes was calculated. The surface area of macular lesions visualized on both FP and FAF was measured using ImageJ software (NIH, Bethesda, MD) after determining an appropriate scale (11.36um/pixel for FAF and 13.56 μm/pixel for FP).
Results:
Mean RAPD score was 0.55 ± 0.66 units, mean FAF lesion size was 17.45 ±15.52mm2 and mean lesion size on FP was 10.67 ±9.63mm2. Mean inter-eye difference in lesion size on FAF was 9.01 ±10.50mm2 and on FP was 5.48 ±4.97mm2. RAPD score had a significant positive correlation with the inter-eye difference in lesion size on both FAF (r=0.75, p<0.001) and FP (r=0.68, p<0.0002). 8/22 patients (36.3%, 4 male, 4 female) had an RAPD score ≥0.5 and were considered positive for an APD. Among these 8 patients, there was a trend towards correlation of RAPD score with inter-eye difference in lesion size on FAF (r=0.61, p=0.05) and FP (r=0.38, p=0.17). 1/22 had an APD on the swinging flash light test.
Conclusions:
Macular pathology has the potential to cause clinical and sub-clinical RAPD when a sufficient portion of the retina is involved and there is a high degree of asymmetry. The inter-eye difference in the surface area of macular lesions correlates with the RAPD score, detected using an automated pupillometer.
Keywords: 668 pupillary reflex •
585 macula/fovea •
613 neuro-ophthalmology: optic nerve