Visual outcomes associated with optical coherence tomography biomarkers in diabetic macular edema: A systematic review

We evaluated the value of baseline structural optical coherence tomography (OCT) biomarkers in determining functional treatment response at 6,12-, and 24-months following treatment initiation in patients undergoing anti-vascular endothelial growth factor, steroid, or laser treatment for diabetic macular edema (DME). Ovid MEDLINE, EMBASE, and Web of Science databases were searched from inception for studies evaluating the association between baseline OCT biomarkers and best-recorded central visual acuity (VA). A synthesis using vote counting based on the direction of effect in relation to a five-letter minimally important difference was used. GRADE guidelines informed the certainty of evidence. Ninety-six studies evaluating 29 biomarkers were included. No biomarker with at least ‘Low’ certainty was associated with improved VA. Greater baseline ellipsoid zone (EZ) disruption and hyperreflective foci were associated with decreased VA at 6 months with “Low” certainty of evidence. There was also “Low” certainty that increased baseline disorganization of the retinal inner layers, increased baseline disruption of the external limiting membrane or EZ were associated with decreased VA at 12 months. No biomarker was associated with a poor prognosis with at least ‘Moderate’ certainty. The certainty was downgraded due to inadequately controlling for confounders and a lack of standardization regarding how biomarkers were defined and outcomes were measured.