Comparison of clinical outcomes of different components of diabetic macular edema on optical coherence tomography

Purpose To evaluate the edema reduction after intravitreal injection of ranibizumab (IVR) in two diabetic macular edema (DME) components in the same eye using optical coherence tomography (OCT). Methods Totally 113 eyes with mixed OCT pattern of DME were included. All the eyes underwent best-corrected visual acuity (BCVA) examination and OCT scanning at baseline and follow-up visits (1, 3, and 6 months after 3 monthly consecutive IVR). The mixed OCT pattern of DME was classified into 2 OCT components: serous retinal detachment (SRD) component and non-SRD component. Foveal thickness of the SRD component (SRDFT) and the non-SRD component (NSRDFT) was compared between baseline and follow-up visits. Reduction and reduction ratio of the SRDFT and the NSRDFT at each follow-up were compared. When calculating the NSRDFT reduction ratio, we innovatively optimized a commonly used formula by subtracting the normal foveal thickness from the baseline NSRDFT. Results SRDFT was 265.6 +/- 175.4 mu m at baseline and was significantly decreased to 126.7 +/- 114.4 mu m at 1 month, to 110.5 +/- 103.4 mu m at 3 months, and to 110.4 +/- 89.6 mu m at 6 months (all P < 0.001). NSRDFT was 409.5 +/- 173.1 mu m at baseline and was significantly decreased to 274.1 +/- 140.4 mu m at 1 month, to 249.1 +/- 95.9 mu m at 3 months, and to 254.1 +/- 90.4 mu m at 6 months (all P < 0.001). There was no significant difference in reduction or reduction ratio between NSRDFT and SRDFT during follow-up (all P > 0.05). The correlation between BCVA and SRDFT was most significant at baseline (r = 0.366, P < 0.001) and the correlation between BCVA and NSRDFT was most significant at 6 months (r = 0.426, P < 0.001). BCVA improvement was more significantly correlated with reduction or reduction ratio of SRDFT at each follow-up timepoint (r = 0.271-0.426, all P < 0.01). Conclusions IVR was effective in reducing both the SRD and non-SRD components of DME according to our optimized formula. The association between BCVA improvement and edema reduction was more significant in the SRD component.