Outer Retinal Columnar Abnormalities (ORCA): a novel optical coherence tomography sign of CRB1 maculopathy?

Purpose: To report a novel optical coherence tomography (OCT) sign in the context of CRB1-related maculopathy, termed outer retinal columnar abnormalities (ORCA).

Methods: Retrospective, multicenter observational case series of 14 eyes of 8 patients with molecularly confirmed CRB1-related maculopathy and ORCA. Multimodal imaging scans and medical records patients with CRB1-related maculopathy were reviewed. Outcome measures included best-corrected visual acuity (BCVA), central subfield thickness on spectral-domain OCT (SD-OCT), presence of ORCAs and analysis of their change in appearance over time.

Results: At baseline, mean age was 18 +/- 10 years (range 9-36). All patients had an isolated macular dystrophy except for 1 case harboring a triallelic pathogenic variant. Variant c.498_506del was found in 9 cases (88%). At presentation, ORCA were visible on macular SD-OCT in all cases as multiform, vertical hyperreflective columnar alterations extending from the ellipsoid to the outer plexiform layer, with a variable degree of hyporeflective cystic spaces in the outer and inner nuclear layers. Over 6 +/- 4.7 follow-up years, the presence of ORCA varied greatly with a decrease in ORCA associated with sequential development of retinal atrophy.

Conclusions: A high suspicion for CRB1-associated retinal dystrophy should arise in the presence of ORCA on SD-OCT, prompting genetic testing.