RESUMO
AIMS: To evaluate the association between subfoveal choroidal thickness (SFCT) and diabetic macular edema (DME). DESIGN: A systematic review and meta-analysis. METHODS: 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. RESULTS: 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). CONCLUSION: 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.
RESUMO
BACKGROUND: High altitude (HA) is an extremely challenging environment for millions of people who either travel to HA regions or inhabit there permanently. SUMMARY: Significant progress has been made over the past decades in the understanding of physiological adaptations in HA conditions, and recently, more studies regarding its influence on metabolic disease have been published. However, the effect of HA on diabetic retinopathy (DR), the leading cause of blindness, remains unclear. KEY MESSAGES: The present article provides an overview of the changes in the principal physiology and clinical characteristics related to DR after HA exposure. Despite conflicting evidence, this review synthesizes the available studies and explores the potential mechanisms, such as genetic adaptations, glucose homeostasis, and related physiological changes, by which long-term exposure to HA may alleviate the progression of DR. By shedding light on this complex relationship, it also provides insights into the interplay between HA and DR, offering valuable implications for clinical practice and further research.
