Background: The short-wavelength-sensitive (SWS) cone-mediated sensitivity is a sensitive indicator of functional changes of the macula in diabetic maculopathy. This study was performed to investigate whether functional losses of the macula are detectable in patients without a significant macular edema.
Methods: In 45 patients with diabetes mellitus with clear optical media and no macular edema, conventional white-on-white perimetry (WWP) and short-wavelength automated perimetry (SWAP) were performed in the central 10-deg field. Fifty-eight healthy subjects ranging in age from 16 to 62 years served as controls. The two groups did not differ in age.
Results: Variance analysis (ANOVA) revealed significantly lower sensitivity in patients with diabetes than in controls. SWAP thresholds were significantly more greatly reduced by diabetes than those of WWP (ANOVA interaction: P=0.003). Post-hoc testing revealed a sensitivity reduction of 2.8 dB ( P=0.0003) in patients with diabetes for SWAP versus 0.46 for WWP ( P=0.15). Subgroup analysis revealed that mean thresholds of SWAP and WWP predominantly were reduced in patients with advanced disease. In patients with no retinopathy, sensitivity was not affected at all.
Conclusion: SWS sensitivity may be affected in patients with diabetic retinopathy without clinically significant macular edema. Sensitivity loss was pronounced with increasing severity of retinopathy, reflecting the global status of the eye.