The correlation between retinal sensitivity assessed by microperimetry and contrast sensitivity in diabetic macular oedema

Abstract

Aim To investigate the relationship between contrast sensitivity (CS) and retinal sensitivity (RS) assessed by microperimetry (MP) in diabetic retinopathy (DR) with clinically significant macular oedema (CSME). Methods A retrospective study was performed with 35 eyes of 35 patients with DR and CSME. Retinal thickness (RT) and MP were tested with the spectral SD-optical coherence topography/scanning laser ophthalmoscope system. Mean central RT at the fovea centre's 1 mm zone (CRT) and at the fixation centre's 1 mm zone (FCRT) was measured. RS was tested at the fixation centre, within 2 degrees and 4 degrees areas. CS was measured with six target sizes (6.3 degrees, 4.0 degrees, 2.5 degrees, 1.6 degrees, 1.0 degrees, 0.64 degrees) with a contrast glare tester. Results The mean CRT and FCRT were 344.3 +/- 136.2 and 359.9 +/- 135.5 mu m, respectively. Mean log CSs (-log10) with the six target sizes ranged from 0.19 to 1.32. The mean RS at the fixation centre, within 2 degrees, and within 4 degrees area were 8.51 +/- 4.81 dB, 8.58 +/- 3.88 dB and 9.22 +/- 3.56 dB, respectively. RS at all tested areas were significantly correlated to log CS with all target sizes (range, r=0.366-0.755; =0.0001-0.030). CRT and FCRT were not significantly correlated to log CS or RS. Conclusions CS and RS showed moderately significant correlations in CSME. However, neither CS nor RS was correlated with RT in patients with CSME. It could be that CS and MP are complementary to each other and are useful tools in the evaluation of functional vision.