gms | German Medical Science

Macular thickness was measured in 33 eyes with optical coherence tomography (OCT) using the Retinal Thickness Map during long-term follow-up (8±4 weeks, 12±2 months, and 46±13 months) after surgical peeling of idiopathic epiretinal membrames (IEM). Foveal structure was analysed 46±13 months postop using Fourier-domain OCT. Thickness of individual retinal layers was measured in the horizontal midline with a manual segmentation procedure aided by a customized computer program. At last follow-up, 12 of 33 eyes had a foveal pit. The photoreceptor complex with inner/outer segment junction was intact in all eyes. Retinal thickness remained increased in the central and nasal fields of the Retinal Thickness Map. Compared to age-matched normal controls retinal layers remained significantly thickened in the fovea and nasal parafovea between the outer nuclear and the ganglion cell+inner plexiform layers. The thickness of the retinal nerve fiber layer and the photoreceptor complex were not different from controls. Morphological changes were correlated with best-corrected near- and distance visual acuity, reading speed, and metamorphopsia. Best-corrected distance visual acuity (logMAR) was 0.1±0.1 at last follow-up. Complementary to the functional and morphological investigations we classified IEM clinically in accordance with epidemiological studies as either cellophane-type or premacular fibrosis. IEM of both types were analysed with light- and electronmicroscopy, immunogold-electronmicroscopy, immunohistochemistry, and Western blot. The presence of high amounts of collagen type VI in cellophane-type membranes and the relative absence of collagen types I and II is the major structural difference to premacular fibrosis. The molecular differences between the two membrane types indicate different pathogenetic mechanisms during their formation.