Epiretinal Membrane May Affect OCT Measurement Reproducibility

Retinal layer thickness obtained by optical coherence tomography (OCT) may show poor short-term reproducibility in patients with epiretinal membrane, particularly with respect to outer retinal layer thickness measurements, according to research published in Eye and Vision. The presence of ectopic inner foveal layers may affect short-term reproducibility even further, and show poor term reproducibility in both the inner and outer retinal layer thickness measurements. In patients with both epiretinal membrane and ectopic inner foveal layers, thicker central macular thickness (CMT) correlates with lower reproducibility for inner retinal layer thickness measurements, according to the report. 

Researchers performed a retroscopic analysis of patients with epiretinal membrane who underwent pars plana vitrectomy between 2018 and 2021 — both with ectopic inner foveal layers (eyes, 120; mean age, 67.0 years; 40.8% men) and without ectopic inner foveal layers (eyes, 53; mean age, 64.2 years; 45.3% men). The team assessed the reproducibility of OCT measurements twice within 1 week before participants underwent the procedure and determined reproducibility by assessing intraclass correlation coefficient (ICC) and coefficient of variation (CV) values.

“The preoperative thickness of each retinal layer, including the inner retinal layer and [outer nuclear layer], is a significant factor in the postoperative visual prognosis of [epiretinal membrane] patients.” according to the study authors. “Thus, accurate measurement of each thickness is crucial.”

OCT measurements demonstrated poor reproducibility in patients with ectopic inner foveal layers in both the inner and outer retinal layers, evidenced by CVs and ICCs for the nerve fiber layer (22.39% and 0.431, respectively), ganglion cell layer (13.12% and 0.550, respectively), inner plexiform layer (13.37% and 0.440, respectively), inner nuclear layer (13.21% and 0.286, respectively), outer plexiform layer (15.09% and 0.279, respectively), and outer nuclear layer (11.94% and 0.503, respectively).

Reproducibility for outer retinal layer measurements was poor regardless of the presence of ectopic inner foveal layers. Thicker CMT in patients with ectopic inner foveal layers was associated with lower reproducibility of the inner retinal layer thickness measurements, but patients without ectopic inner foveal layers were less affected by CMT, according to the report.  

“The short-term reproducibility of the inner retinal layer thickness measurements in [epiretinal membrane] patients with [ectopic inner foveal layers] was lower than in patients without [ectopic inner foveal layers], and the short-term reproducibility of the outer retinal layer thickness measurements, including outer plexiform layer and outer nuclear layer, was poor, regardless of the presence of [ectopic inner foveal layer],” according to the researchers. “Physicians should consider the low reliability of outer retinal layer thickness measurements in [epiretinal membrane] patients, and inner retinal layer thickness measurements in patients with [ectopic inner foveal layers], especially those with severely thickened central macular thicknesses.”

Study limitations include the use of only 1 type of OCT device, a retrospective nature, and the assessment of short-term reproducibility within a 1-week period.