gms | German Medical Science

Optical Coherence tomography (OCT) as a high-resolution imaging technique was used to evaluate the prognostic value of quantitative and qualitative morphologic features in idiopathic (PG) and secondary epiretinal membranes (SG).

Between 1996 and 2003, a total of 293 patients with epiretinal membrane had an eye examination including slit-lamp examination, fluorescein angiography (FLA) and OCT. The diagnosis was made based on funduscopy. Patients with diabetes were excluded. In a retrospective study, visual acuity was correlated with retinal thickness in patients with PG and SG who underwent surgery (n=141) or no treatment (n=75). The results were compared to the findings in the healthy fellow eyes. The percentage of eyes in which epiretinal membranes and intraretinal cysts could be detected by OCT was determined.

On OCT, epiretinal membranes separated from the inner-limiting membrane were found in 25% of the eyes. In the remaining 75% of eyes, OCT revealed epiretinal membranes adherent to the highly reflective nerve fiber layer, but a precise quantitative measurement of membrane thickness was not possible in these cases. A diffuse foveal and parafoveal thickening with good preservation of the foveal structure was found in 45% of cases. Intraretinal cysts were detectable on OCT in 26% of cases. There were two types of cysts: multiple small cysts in the inner nerve fiber layer (detectable only on OCT) and few large cysts in the outer retinal layer (correlation of leakage in FLA). In all eyes with epiretinal membranes, the foveal thickness was significantly higher compared to the healthy fellow eyes. Retinal thickness decreased significantly after removal of the epiretinal membrane in PG and SG, but it did not reach normal values. The follow-up time was from 2 days to 6 years. The preoperative visual acuity correlated with the foveal thickness.

Biomorphometric analyses using OCT are helpful in the differential diagnosis of macular pseudohole formation in epiretinal membranes and idiopathic macular hole. Structural features such as presence of an epiretinal membrane, thickening of the retina, absence of the foveal depression and intraretinal cysts are valuable prognostic parameters for macular surgery. Our findings confirm the results described in the literature that the foveal thickness does not normalize postoperatively. This explains why in some cases the anatomic success does not correlate with the functional findings.