A cross sectional study of optical coherence tomography angiography biomarkers and best corrected visual acuity in epiretinal membrane eyes

BACKGROUND: To compare Optical Coherence Tomography Angiography (OCTA) biomarkers in epiretinal membrane (ERM) eyes and normal eyes, to investigate the association of each biomarker with best corrected visual acuity (BCVA), and to identify their optimal cut-off values for various best correct visual acuity in ERM eyes. METHODS: A cross-sectional observational population study of the right eye of 6011 participants aged above 50 was performed. Central subfield thickness (CST_A), foveal avascular zone (FAZ_A), mean vessel density (mVD_full) and mean capillary perfusion density(mCPD_full) were measured by OCTA. Welch's T-test was used to compare different mean values of parameters between normal eye and epiretinal membrane eyes. Multivariable linear regression test was used to assess the correlation between BCVA LogMAR and OCTA parameters. The cut-off values of biomarkers for best corrected visual acuity (BCVA LogMAR ≥ 0.18 / 0.3) in epiretinal membrane eyes were determined using receiver operating characteristic (ROC) and Area under curve (AUC) analysis. RESULTS: ERM eyes had a significantly higher CST_A than normal eyes (Normal: 249.437 (95% CI 248.845 to 250.029) vs. ERM: 308.202 (95% CI 299.915 to 316.489) P < 0.001) A smaller FAZ_A was found in ERM eyes than normal eyes (Normal: 0.269 (95%CI 0.266 to 0.273) vs. ERM: 0.225 (95%CI 0.202 to 0.248) P < 0.001). Both mVD_full and mCPD_full were lower in ERM eyes when compared with normal eyes (mVD_full Normal: 16.397 (95% CI 16.343 to 16.451) vs. ERM 15.610 (95% CI 15.372 to 16.048) (P < 0.001)) (mCPD Normal: 0.399 (95% CI 0.397 to 0.400) ERM: 0.381 (95% CI 0.373 to 0.390) (P < 0.001)). Among CST_A, FAZ_A, mVD_full and mCPD_full, only CST_A was found to be significantly associated with best corrected visual acuity (BCVA). Better visual outcome is associated with smaller CST_A (beta* =0.265). CST_A was found to have an acceptable AUC value for BCVA LogMar ≥ 0.3 in epiretinal membrane eyes (AUC value = 0.708). The AUROC values of other biomarkers were less than 0.7 in predicting BCVA in epiretinal membrane eyes. CONCLUSION: CST_A was found to be thicker in ERM eyes while mVD_full, mCPD_full and FAZ_A were lower in ERM eyes than normal eyes. CST_A was found to be significantly associated with BCVA in ERM eyes. The cut off value of CST_A was found to be 345.5, with an acceptable AUC value for discriminating BCVA LogMAR ≥ 0.3 in epiretinal membrane eyes.