Relation of interdigitation zone changes and right-angle vessels in Macular Telangiectasia Type-2 (MacTel).

Background: To study the relation between interdigitation zone (IDZ) and right-angle vessel (RAV) in Macular Telangiectasia Type-2 (MacTel).

Methods: A total of 43 eyes of 38 patients with presence of definite RAV on colour fundus photograph (Gass and Blodi-only stage-3) were confirmed on multimodal imaging. The relation of IDZ changes and associated ellipsoid zone (EZ) alterations on spectral-domain optical coherence tomography (OCT) with RAV were studied at baseline and these OCT changes were followed up in 15 eyes over a mean of 3.86 years.

Results: A total of 58 RAVs were found in the 43 eyes and 53/58 (91.3%) RAVs were associated with IDZ alterations in 39 eyes. On follow-up, IDZ attenuation progressed to IDZ loss and subsequent EZ attenuation and loss. A pre-existing IDZ loss was associated with subsequent EZ defect (P = 0.002). In 36 eyes that had OCT angiography, eyes with RAV showed deep capillary plexus telangiectasia in all 36 (100%) eyes and 32/36 (89%) eyes showed IDZ changes with or without EZ loss.

Conclusions: IDZ attenuation and/or loss are associated with RAV and may serve as predictor of EZ loss in MacTel.