Characteristics of optical coherence tomography in patients with iron deficiency anemia : a systematic review and meta-analysis

Abstract Objective The primary objective of this systematic review and meta-analysis was to assess the association between iron deficiency anemia (IDA) and retinal changes via optical coherence tomography (OCT). Methods The search was conducted in MEDLINE, Scopus, Embase, Web of Science, and Google Scholar until February 1, 2024. Two independent researchers included the articles based on the inclusion and exclusion criteria. Data regarding the study design, patient characteristics, number of patients with and without IDA, mean and SD of the retinal nerve fiber layer (RNFL), C/D ratio, foveal avascular zone (FAZ) area and perimeter, foveal density and superficial and deep capillary plexus (SCP and DCP) vascular density (VD) were collected. STATA version 17.0 was used to compute pooled measures of the standardized mean difference. I2 and chi-square tests were used to assess heterogeneity between studies. Results We found 1378 nonduplicate studies, 35 of which were potentially relevant. 19 articles met the inclusion criteria and were included in the review. The meta-analysis confirmed that there was a statistically significant association between IDA and RNFL thickness reduction (SMD = -0.76, 95% CI: -1.09 to -0.44 ; p-value = 0.001, I2 = 86.88%), FAZ area (SMD =-0.35, 95% CI: -0.67 to -0.02; p value = 0.04, I2 = 59.76%) and SCP VD (SMD = -1.12, 95% CI: -1.85 to -0.39; p-value = 0.001, I2 = 83.15%). The associations between IDA and the C/D ratio (SMD = 0.07, 95% CI: -0.13 to 0.28; p value = 0.49, I2 = 0.0%) and DCP VD (SMD = -0.30, 95% CI: -0.89 to 0.29; ,p-value = 0.32 ,I2 = 77.20%) were not significant. There was no considerable publication bias. Conclusion The results of this meta-analysis demonstrated that, compared with healthy controls, individuals with IDA presented a thinner RNFL, a smaller FAZ, and lower SCP and DCP vascular densities. However, further studies are needed to reach more conclusive results.