Abstract
Purpose :
To describe the presence of continuous ectopic inner foveal layers associated with epiretinal membranes (ERMs). This novel observation is applied in the development of an updated spectral domain optical coherence tomography (SD-OCT) staging scheme for ERM evaluation.
Methods :
Clinical charts and SD-OCT images of 194 eyes of 172 consecutive patients diagnosed with idiophatic ERMs were carefully analyzed. OCT Agiography (OCT-A) was utilized to evaluate qualitatively the foveal avascular zone (FAZ) in eyes with ERMs,and to compare it with the fellow eye in patient with unilateral ERM.
Results :
The presence of continuous ectopic inner foveal layers was identified in 63 out of 194 eyes (32.5%) and their presence was significantly associated with lower visual acuity (p=0.001). ERMs were divided in four stages (Figure 1). Stage 1 (43/194 eyes, 22.1%) ERMs were mild, thin and with a foveal depression. Stage 2 (88/194 eyes, 45.4%) ERMs were associated with widening of the outer nuclear layer and loss of the foveal depression. Stage 3 (51/194 eyes, 26.3%) ERMs were associated with continuous ectopic inner foveal layers crossing the entire foveal area. In stages 1, 2 and 3 all retinal layers were clearly defined on OCT. Stage 4 ERMs (12/194 eyes, 6.2%) were thick and associated with continuous ectopic inner foveal layers and significant disruption of all retinal layers. Visual acuity progressively declined from stage 1 through stage 4 (p<0.001). The OCT-A was used to image the FAZ of 43 eyes, and showed marked alterations of the FAZ, ranging from a slight reduction in the area of the capillary-free zone to the near-complete disappearance in eyes with stage 3 and 4 ERMs and ectopic inner foveal layers (Figure 2).
Conclusions :
SD-OCT inner foveal layers are a frequent finding in ERM, are an independent risk factor for worse visual acuity and were the keystone of the proposed OCT staging scheme. Our results may be clinically significant and may influence visual prognosis. Further the findings of this study raise important questions regarding reactive cellular mechanisms in the middle retina.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.