Contrast Sensitivity Loss in Diabetic Pregnancy Correlates with Thickening of the Central Macula

Abstract

Abstract: : Purpose: To evaluate the correlation between contrast sensitivity and macular topography in diabetic women during pregnancy. Methods: Forty six diabetic and 11 non-diabetic women were prospectively followed throughout pregnancy and post-partum period. Fundus photography, clinical eye examination and contrast sensitivity (Vistech 6500) and Heidelberg Retinal Tomograph examination were performed at the 1st and 3rd trimesters and 3 months post partum. Results: Measured with the 1.5 mm circle refrence plane, the volume above refrence plane (VARP) in diabetics was 0.084+0.064(SD) at the 1st trimester, 0.080+0.056 at the 3rd and 0.087+0.067 3 months post partum. The corresponding values in non-diabetic pregnant women were 0.069+0.040, 0.054+0.024 and 0.036+0.020 (p=0.036). Contrast sensitivity values at 3 cpd in diabetics were 105+48, 133+50 and 136+45 and in non- diabetics 131+44, 162+26 and 170+30 (p=0.012) at the same time points. At 6 cpd the contrast sensitivity values were 95+51, 113+50 and 115+51 in diabetics and 116+50, 137+44 and 146+51 in non-diabetics (p=0.043). There was a negative correlation between VARP at the 3rd trimester and contrast sensitivity at 6 cpd (r= -0.446, p=0.002) in diabetic women. The correlation persisted when only patients with normal VA and biomicroscopically normal maculae were included (r = 0.424, p=0.005). In multivariate linear regression analysis with contrast sensitivity at 6 cpd as a dependent variable, only VARP measurement met the inclusion criteria for the model (R² = 0.175, p=0.003), whereas blood pressure, duration of diabetes, glycohemoglobin, or retinopathy grade or progression did not qualify. Conclusions: Loss of contrast sensitivity has been reported to precede the appearance of clinically detectable diabetic retinopathy. These results suggest that the mechanism for the loss of contrast sensitivity is related to subclinical thickening of the central macula, occuring before any retinopathy is present.

Keywords: diabetic retinopathy • contrast sensitivity • macula/fovea