Bacillary detachment (BD) in nAMD: Incidence, clinical features, and response to anti-VEGF therapy

Abstract

Purpose : BD is a unique OCT signature identified in the outer retina. To our knowledge, it has not been described in nAMD. This preliminary analysis evaluates the incidence of BD in nAMD and response to anti-VEGF therapy.

Methods : A post hoc OCT image analysis was performed on the OSPREY phase II, prospective randomized clinical trial of anti-VEGF therapy in nAMD. BD was defined on OCT as a hyporeflective space above a hyperreflective linear structure continuous with the ellipsoid zone (EZ) band. Machine-learning-augmented feature extraction enabled characterization of parameters including retinal and sub-retinal pigment epithelium (RPE) compartment metrics, and retinal fluid volumes. This hypothesis-generating analysis was conducted without adjustment for multiple comparisons and was treatment agnostic.

Results : BD was identified in 6/81 eyes (7.4%) at Baseline. Baseline BCVA was similar between eyes with and without BD. At Baseline, BD eyes showed significantly higher mean central subfield thickness (CST, 610µm vs 479µm; p<0.05), total retinal fluid volume (0.95mm3 vs 0.37mm3; p<0.01), macular total retinal fluid index (TRFI, 7.8% vs 3.3%; p<0.05), total EZ attenuation (51% vs 30%; p<0.05), and sub-RPE compartment volume (1.80mm3 vs 0.78mm3; p<0.0001) compared to eyes without BD.

Compared to Baseline, macular TRFI was 0.03% (p=0.034) and CST was 331µm (p=0.006) in the BD group at Week 4. At the end of the loading phase, 83% of eyes with BD had minimal to no fluid (i.e., volume <0.001mm3) vs 68% of eyes without BD. By Week 56, total macular EZ attenuation remained higher in eyes with BD compared to eyes without BD (40% vs 16%). At Week 56, eyes with BD did not demonstrate VA improvement (-1.7 letters; p=0.838), while eyes without BD showed significant VA improvement (+6.9 letters; p<0.001).

Conclusions : BD is identifiable in a proportion of nAMD eyes which have higher baseline fluid volumes and CST. Preliminary findings suggest that eyes with BD are responsive to anti-VEGF therapy (fluid resolution and CST reduction), yet persistent significant EZ attenuation may limit VA recovery. More data are needed to further validate the findings; however, this is important for understanding visual prognosis and enriching clinical trials.

This is a 2021 ARVO Annual Meeting abstract.

 

A: B-scan; B: SRF (green) & IRF (blue) map; C: EZ attenuation map; D: ILM-RPE map; E: RPE-BM thickness map of a patient with BD