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In patients with diabetic macular edema, the absence of disorganization of the retinal inner layers (DRIL) and preservation of the ellipsoid zone\/external limiting membrane (EZ\/ELM) were associated with a better final visual acuity and improved response to intravitreal injections.\u00a0Photo: Jay Haynie, OD.\u00a0Click image to enlarge.<\/p>\n
A literature review published in the Journal of Vitreoretinal Diseases identified several OCT findings that may offer clues about visual prognosis and treatment response in patients with diabetic macular edema (DME). Its authors reviewed studies evaluating a range of OCT biomarkers and their associations with visual acuity (VA) and response to intravitreal anti-VEGF and corticosteroid therapy. The most useful markers included disorganization of the retinal inner layers (DRIL), epiretinal membrane (ERM), ellipsoid zone (EZ) integrity and external limiting membrane (ELM) continuity.<\/p>\n
DRIL acted as one of the strongest predictors of visual outcomes. Its presence at baseline was associated with poorer post-treatment VA and reduced VA gains, while a lack of DRIL was linked to \u201ca gain in BCVA of more than five letters,\u201d as reported by the researchers in the study. Extensive DRIL exceeding 500\u00b5m was also associated with \u201cfunctional and anatomic\u201d resistance to anti-VEGF therapy.<\/p>\n
Photoreceptor-related biomarkers were also relevant factors. Disruption of the EZ or ELM was generally associated with poorer VA and smaller visual gains. Patients who responded well to anti-VEGF therapy gained at least 10 ETDRS letters and had substantially less EZ and ELM disruption at baseline than poor responders. EZ integrity was also associated with a favorable response to dexamethasone implants.<\/p>\n
Other biomarkers showed more nuanced relationships with treatment. Hyperreflective dots, thought to represent inflammatory cells such as microglia, were associated with visual or anatomic improvements in several studies, particularly following corticosteroid treatment, although findings were inconsistent. Results for subretinal fluid were also inconsistent, with some studies linking its presence to improved treatment responses while others found little predictive value. Persistent subretinal fluid presence, however, has been associated with damage to the retinal pigment epithelium and photoreceptors.<\/p>\n
The study also noted that choroidal vascularity index may be a promising emerging marker. Higher baseline values were associated with greater VA gains following anti-VEGF therapy, while lower values were linked to better corticosteroid responses in one study.<\/p>\n
The authors emphasized that although OCT biomarkers could eventually help individualize DME treatment, many remain understudied, and future research may help determine which ones clinicians can reliably use when making treatment-related decisions.<\/p>\n