Quantification of retinal tangential movement in epiretinal membranes

To describe a technique of quantifying retinal vessel movement in eyes with epiretinal membrane (ERM) and correlate the retinal vessel movement with changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), and patients' subjective reports about experienced symptoms (symptoms).

Retrospective, observational, comparative case series.

A total of 206 eyes of 113 patients: 142 eyes with ERM and 64 healthy fellow eyes.

All patients were examined as part of a screening protocol for a randomized clinical trial on ERM. Heidelberg Spectralis (Heidelberg Engineering Inc, Carlsbad, CA) optical coherence tomography (OCT) scanning had been performed twice or more in all patients. Eyes with ERM and healthy fellow eyes were examined. For each eye, the 2 fundus images were aligned using Heidelberg's AutoRescan feature. The macular area was divided into 9 subfields, and retinal vessel movements were calculated. For each eye, the total length of the 9 vectors was summed to describe the total retinal vessel movement (retinal tangential movement [RTM]).

To quantify retinal vessel movements associated with ERM. The secondary outcome was to correlate measured retinal vessel movement with changes in BCVA, CMT, and patients' subjective symptoms.

The study found significantly greater RTM in ERM eyes compared with healthy eyes (P<0.001). Among ERM eyes, the RTM was significantly greater in patients with worsening of symptoms compared with ERM eyes with unchanged assessment of symptoms. There were statistically significant correlations between increased RTM and reduction in BCVA (P = 0.024), increased CMT (P<0.001), and time between visits (P<0.001).

This study showed that ERM is not a static retinal disease but a dynamic condition in which retinal vessel movement associated with ERM was measureable, even in patients who had stable BCVA and CMT. The retinal vessel movements correlated to worsening of BCVA and increased CMT, and were more pronounced in patients with worsening of symptoms.