Association between choroidal thickness and diabetic macular edema: a meta-analysis

To evaluate the association between subfoveal choroidal thickness (SFCT) and diabetic macular edema (DME).

A systematic review and meta-analysis.

A retrospective or prospective study comparing SFCT in diabetic retinopathy (DR) patients with and without DME was included. The data were collected from published studies retrieved from PubMed, Web of Science, Embase, Ovid Medline, and Cochrane Library. The final search was conducted on July 2, 2023. Heterogeneity was assessed using I2 statistics, and a random-effects model was used for the meta analysis. This study calculated the weighted mean difference (WMD) and 95% confidence interval (CI) for SFCT.

A total of 26 relevant studies were identified, involving a combined sample size of 3201 eyes (1302 DR-DME eyes and 1899 DR-no DME eyes). The results showed no significance between DR-DME and DR-no DME (WMD = − 3.57 μm; 95% CI−26.54 to 19.41 μm; P = 0.76). Sub-analysis based on nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) subgroups showed that the SFCT of NPDR-DME was significantly thinner than that of NPDR-no DME eyes (WMD = − 19.80 μm; 95% CI − 34.55 to − 5.04 μm; P = 0.009), while there was no significance in SFCT between PDR-DME and PDR-no DME (WMD = − 26.45 μm; 95% CI − 104.00 to 51.11 μm; P = 0.50).

The SFCT was thinner in NPDR-DME eyes compared to NPDR-no DME eyes. Thinning SFCT might cause retinal hypoxia, and play an important role in DME occurrence. Additionally, this study highlights the importance of considering DR grades and treatment history when evaluating SFCT between DME and no DME.