To investigate the quantification of metamorphopsia with a novel method that uses Monpack One (Metrovision, Perenchies, France) and to compare the relationship between metamorphopsia score and spectral-domain optical coherence tomography (SD-OCT) findings in patients with epiretinal membrane (ERM).

This study included 37 eyes of 35 patients with idiopathic ERM. We examined the patients using SD-OCT and quantified the degree of metamorphopsia using the Monpack One. On the topographic map of the Early Treatment Diabetic Retinopathy (ETDRS) grid, central retinal thickness at the fovea (1 mm), and parafovea (3 mm) was measured with the SD-OCT software. The correlation between these factors was analyzed. We repeated the metamorphopsia test twice in 22 eyes of 11 healthy subjects in order to calculate intraclass correlation coefficients (ICCs) and evaluate the reproducibility and reliability of the new metamorphopsia test.

On the ETDRS grid, the retinal thickness (µm) of the central, superior, inferior, nasal, and temporal subfields was 495 ± 102, 428 ± 98, 454 ± 78, 434 ± 83, and 463 ± 95, respectively. The mean total metamorphopsia score was 24.8 ± 13.9, while those for the superior, inferior, nasal, and temporal subfields were 14.7 ± 9.1, 15.1 ± 8.6, 15.9 ± 8.9, and 14.6 ± 8.6, respectively. Linear regression analysis revealed that total metamorphopsia score was significantly related to central retinal thickness ( p = 0.01). Moreover, each subfield of parafoveal retinal thickness positively correlated with metamorphopsia subfield score ( p < 0.01–0.023). The ICCs for the metamorphopsia tests of the healthy individuals showed almost perfect repeatability (>0.9) in all subfields.

The degree of metamorphopsia in ERM could be quantified objectively on each subfield using the Monpack One metamorphopsia test. The degree of metamorphopsia significantly correlated with retinal thickness measurements based on SD-OCT.