Abstract
Purpose:
Recent evidence suggests that neuronal loss plays a key role in the development of diabetic retinopathy. As microaneursyms are the initial hallmark of diabetic retinopathy, we sought to correlate the number of microaneurysms with retinal thickness in patients with early diabetic retinopathy.
Methods:
80 patients with microaneurysms within 1 disc diameter of the fovea in at least one eye were recruited. Fundus photography and Heidelberg Spectralis Spectral Domain Optical Coherence Topography (SD-OCT) were carried out in each patient. The number of microaneurysms within 3 mm of the fovea were manually counted by 2 independent observers. If there was a significant discrepancy then a third observer would do a re-count. The average of the 2 observers, or the re-count were used for the analysis. The retinal area analyzed was divided into 4 sections: superior, temporal, inferior and nasal. These were analyzed separately in each eye by non-linear regression analysis using a negative binomial method.
Results:
The total number of microaneurysms in the 4 quadrants was 474, 792, 418, and 262 in the superior, temporal, inferior, and nasal quadrants respectively. The average sectorial thickness on SD-OCT was 318, 314, 310 and 332 in the superior, temporal, inferior, and nasal quadrants respectively. In all analyzed sectors of each eye, the number of microaneurysms was found to be statistically significantly higher with thinner retina. The best fit model for the number of microaneurysms in the right eye was -10.26 + 0.034 x thickness (p<0.0001), -8.32 + 0.03 x thickness (p<0.0001), -4.43 + 0.015 x thickness (p<0.003) & -4.47 + 0.013 x thickness (p<0.003) in the superior, temporal, inferior, and nasal quadrants respectively. The best fit model for the number of microaneurysms in the left eye was -6.87 + 0.023 x thickness (p<0.006), -8.41 + 0.031 x thickness (p<0.0001), -13.6 + 0.044 x thickness (p<0.0001) & -9.88 + 0.03 x thickness (p<0.0001) in the superior, temporal, inferior, and nasal quadrants respectively.
Conclusions:
We have found a significant correlation between higher numbers of microaneurysms and lower retinal thickness, even after accounting for regional differences in microaneurysm distribution. This is consistent with our hypothesis that neuronal loss might play a role in the pathogenesis of microaneurysms. Our results also support the previously reported finding that the temporal retina has the highest number of microaneuysms.
Keywords: 499 diabetic retinopathy •
688 retina