American Journal of Ophthalmology, March 2017
Govetto et al. reviewed the records of 172 patients (194 eyes) diagnosed with epiretinal membranes (ERMs). Based on findings from spectral-domain optical coherence tomography (SD-OCT), they identified a novel clinical entity associated with substantial vision loss: ectopic inner foveal layers.
The authors also proposed a 4-stage classification system for ERMs. Stage 1 ERMs are thin, with a foveal depression, and have readily distinguishable retinal layers. Stage 2 membranes lack a foveal depression and exhibit retinal distortion, with stretching or widening of the outer nuclear layer, although retinal layers still are distinct. Stage 3 denotes emergence of continuous ectopic inner foveal layers and maintenance of observable retinal layers. Stage 4 ERMs are thick, with a disrupted macula, distorted and indistinguishable retinal layers, and continuous ectopic inner foveal layers.
The ERMs in this study were graded as follows: stage 1, 43 eyes (22.1%); stage 2, 88 eyes (45.4%); stage 3, 51 eyes (26.3%); and stage 4, 12 eyes (6.2%). Continuous ectopic inner foveal layers were detected in 63 eyes (32.5%).
Successive ERM stages were associated with progressively reduced best-corrected visual acuity (BCVA), thickening of the central fovea, and greater prevalence of tractional cystoid macular edema and ellipsoid disruption. The presence of ectopic inner foveal layers correlated with poorer BCVA, even when controlled for other potential causes of reduced BCVA.
Sixty-three eyes were scheduled for surgery. During follow-up (mean, 22 months) of the nonsurgical eyes, 9 of 32 ERMs progressed from stage 1 to 2, 10 of 77 from stage 2 to 3, and 2 of 17 from stage 3 to 4. In all cases, progression was accompanied by a significant decline in BCVA. No progression was seen in 108 eyes.
The authors concluded that the presence of continuous ectopic inner foveal layers, as revealed on SD-OCT, is a prognostic factor for significant visual loss; and they proposed an OCT-based grading system for ERMs. Their study confirmed that the inner retinal layers of the macula may be particularly sensitive to tractional stress and demonstrated that ERM formation may significantly alter the microanatomy of the inner fovea.
The original article can be found here.