OCT and histopathological analysis of the tractional abnormalities of the central foveal bouquet associated with epiretinal membrane formation

Abstract

Purpose : To study the pathoanatomy of the central bouquet and assess the inter-relationship of Muller cells with central cone photoreceptors in the development of tractional complications in eyes with idiopathic epiretinal membranes (ERM).

Methods : ERMs were classified according to a recently published 4-stage grading system. The central bouquet (CB) was defined as a circular area of approximately 100 mm composed of densely packed cones (and Muller cells) in the central fovea. Tractional abnormalities of the CB were identified and studied with spectral-domain optical coherence tomography (OCT). Ex vivo histopathologic analysis was performed to better understand the inter-relationship of Muller cells with central cone photoreceptors in the CB. A model of the tractional mechnisms that take place in the CB in association with ERM is proposed.

Results : In this study, 263 eyes with ERMs were included. Mean follow-up was 21.2 ± 16.7 months. At baseline, tractional abnormalities of the CB were diagnosed in 58 out of 263 eyes (22%) and divided into 3 categories: cotton ball sign (defined as a fuzzy hyperreflective area between the ellipsoid zone and the interdigitation zone in the central fovea), foveolar detachment, and acquired vitelliform lesion. Visual acuity was highest in association with the cotton ball sign and lowest in the acquired vitelliform lesion groups (P < 0.001). Progressive enlargement in the dimensions of the 3 abnormalities were noted (P < 0.001) and sequential morphologic progression was identified in 7 eyes. Ex vivo histopathologic analysis illustrated characteristic staining patterns supporting a potential mechanism of traction by Muller cells in the CB leading to these characteristic central abnormalities. Presence of ectopic inner foveal layers was negatively correlated with the presence of CB tractional abnormalities (P = 0.002) and a proposed static model adhering to the forces of Hooke's Law is proposed.

Conclusions : The cotton ball sign, foveolar detachment, and acquired vitelliform lesion may comprise a continuum in the same clinical spectrum and may represent subsequent stages of central bouquet (CB) abnormalities complicating the development of ERM formation. Muller cells may play an integral role in the transmission of mechanical forces to the central foveal cones in eyes with ERM and other macular diseases.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.