Short-wavelength Automated Perimetry and Capillary Density in Early Diabetic Maculopathy

Purpose: To correlate short-wavelength cone-mediated sensitivity (SWS) assessed by blue-on-yellow perimetry with alterations of the perifoveal vascular bed in early diabetic maculopathy.

Methods: Thirty-one patients (21 M, 10 F; mean age, 35 +/- 12 years; no lens opacities) with no clinically significant macular edema were included in this study. All patients underwent short-wavelength automated perimetry (SWAP) and conventional white-on-white perimetry (Humphrey, 10-2). In digitized video fluorescein angiograms (Scanning Laser Ophthalmoscope), the size of the foveal avascular zone (FAZ) and the mean perifoveal intercapillary area (PIA) as a measure of capillary density were quantified interactively.

Results: Mean thresholds of SWAP were significantly correlated with increasing size of FAZ (r = -0.51, P = 0.003) and PIA (r = -0.47, P = 0.01), whereas visual acuity expressed by log MAR (FAZ: r = 0.15, P = 0.41; PIA: r = 0.06, P = 0.76) and mean thresholds assessed with white-on-white perimetry (FAZ: r = -0.25, P = 0.20; PIA: r = -0.31, P = 0.14) were unrelated to diabetic changes of the perifoveal capillary network.

Conclusions: The alterations of the perifoveal network are related to selective disturbances of visual function as measured by blue-on-yellow-perimetry. SWAP may act as an early detector of visual function loss in early diabetic maculopathy and serve as a helpful technique to predict early ischemic damage of the macula and to monitor therapy.