Purpose
Diabetic retinopathy is among the leading causes of preventable vision loss in working-aged individuals, and early diagnosis may prevent progression to advanced disease. Our objective was to study the potential use of a retinal acuity meter (RAM) with a brightness acuity meter (BAM) [AMA Optics, Fair Oaks, California, United States of America] as a screening tool to identify patients with early diabetic macular edema.
Methods
Diabetic patients were recruited in the ophthalmology clinic at Bellevue Hospital Center, New York. We performed the following exams: hemoglobin A1c (HbA1c), central foveal thickness (CFT) by spectral domain optical coherence tomography (SD-OCT) with the Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, DE) and visual acuity with the RAM. Macular edema was defined as CFT greater than 300 µm. After a 15-second macular photostress (MP) using the BAM, recovery time to RAM baseline visual acuity was measured without knowledge of the OCT data.
Results
A total of 47 eyes from 26 patients were analyzed. 17 eyes had macular edema and among these 35.5% were female, with a mean age of 60.8 years, mean HbA1c of 8.6%, mean recovery time of 24 sec and mean CFT of 327 µm. 30 eyes were without macular edema and among these 36.7% were female, with a mean age of 52.9 years and a mean HbA1c of 8.4%, mean recovery time of 19 sec and mean CFT of 264 µm. Retinal acuity ranged from 20/20 to 20/400 and MP recovery time ranged from 5 to 42 seconds. There was a significant correlation between recovery time greater than 21 secs and CFT by OCT greater than 300 µm (Chi square test = 5.8 , p = 0.02, Figure). The relationships between CFT or MP recovery and HbA1c did not show significant correlation.
Conclusions
Diabetic patients with central foveal thickness by OCT greater than 300 µm demonstrated significantly delayed MP recovery time as measured by the retinal and brightness acuity meters. Given the ease of use, these instruments could serve non-ophthalmologists, e.g., internists, as screening tools of macular function in patients with diabetes. Early referrals to ophthalmologists based on these screening results may result in prevention of irreversible vision loss.
Keywords: 499 diabetic retinopathy •
585 macula/fovea