SD-OCT-histopathological correlation of Schnabel’s cavernous optic nerve atrophy

Abstract

Purpose : To date Schnabel’s cavernous optic nerve atrophy (SCONA) is a solely histopathologic diagnosis demonstrating characteristic predominantly postlaminar located cavernous spaces filled with acid mucopolysaccharides in the optic nerve (ON). Here, we present – to the best of our knowledge - the first correlation of histopathological findings and spectral domain-optical coherence tomography (SD-OCT) imaging features in SCONA.

Methods : We investigated an index patient with a histopathologically identified SCONA who had received multimodal imaging before enucleation for iris ring melanoma. The histopathological findings were correlated with the SD-OCT images (Spectralis, Heidelberg Engineering, Inc., Heidelberg, Germany). The SD-OCT images of our index patient were compared to representative images from eyes with regular optic discs (n=28) and with glaucomatous atrophy (n=44). Additionally, we histopathologically examined three more enucleated eyes with SCONA using step sections.

Results : Histopathological examination of our index patient showed a pre- and retrolaminar extension of SCONA with up to 100% involvement of the ON diameter. Correlation with the SD-OCT images revealed the display mode of the optic nerve head (ONH) rim analysis scan as most suitable to depict ON morphology. Small hyporeflective pseudocysts were detected retrolaminar in multiple scans corresponding to the histologically affected areas of SCONA. These changes were neither depicted in scans of patients with glaucomatous atrophy nor with normal optic discs. Histopathological examination of the globes with SCONA revealed a prelaminar extension of SCONA in our index patient, the others had only retrolaminar changes. Atrophy of the inner retinal layers and ONH excavation was observed correlating to the extent of SCONA.

Conclusions : SCONA can hitherto not be diagnosed clinically or with a standardized imaging tool. We present the first correlation of histopathological findings and SD-OCT of SCONA. The ONH analysis scan, especially the display mode, might be a suitable modality to detect SCONA in vivo and to study this rare entity clinically with regard to its clinical course, risk factors and pathogenesis. However, more cases of SCONA with correlation of SD-OCT and histology are needed to confirm our findings.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.