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 μm at baseline and was significantly decreased to 126.7 ± 114.4 μm at 1 month, to 110.5 ± 103.4 μm at 3 months, and to 110.4 ± 89.6 μm at 6 months (all P < 0.001). NSRDFT was 409.5 ± 173.1 μm at baseline and was significantly decreased to 274.1 ± 140.4 μm at 1 month, to 249.1 ± 95.9 μm at 3 months, and to 254.1 ± 90.4 μm 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.