Causes of Diplopia in Patients With Epiretinal Membranes

Abstract

Purpose: To describe the causes of diplopia in patients with an epiretinal membrane (ERM) and presenting diplopia.

Design: Retrospective observational case series.

Methods: We reviewed patients diagnosed with an ERM, who had been seen by both retinal and strabismus specialists in a tertiary medical center. Data recorded: orthoptic evaluation, retinal misregistration (optotype-frame test, and synoptophore central peripheral superimposition slides at 5 and 10 degrees), and cause of any diplopia (retinal misregistration vs strabismus vs optical/refractive error). We defined central-peripheral rivalry-type diplopia as presenting symptomatic diplopia with evidence of retinal misregistration, and where other causes did not fully explain diplopia. The frequency of each cause of diplopia in patients with ERM was determined.

Results: Of 50 patients with ERM, 25 had symptomatic diplopia and 25 had no diplopia. Eleven of 25 diplopic patients (44%) had retinal misregistration as the sole cause (central-peripheral rivalry-type diplopia), 7 (28%) strabismus (1 of 7 initally appeared to have central-peripheral rivalry-type diplopia), 1 (4%) optical/refractive error (monocular diplopia), 2 (8%) mixed retinal misregistration (central-peripheral rivalry-type diplopia) and strabismus, and for 4 (16%) diplopia cause was indeterminate. Unexpectedly, 15 of 25 patients without diplopia (60%) had evidence of retinal misregistration.

Conclusions: Patients with ERM and presenting diplopia may have 1 of several causes of diplopia, most commonly retinal misregistration (central-peripheral rivalry-type diplopia). Nevertheless, diplopic patients with retinal misregistration may also have treatable strabismus or optical/refractive error as the primary barrier to single vision and therefore many potential barriers to single vision should be considered.

Figure 1

The Optotype-Frame Test, displaying a single, uncrowded Snellen optotype on a computer monitor. The optotype falls on central retina while the monitor frame falls on peripheral retina. Possible outcomes of the test include (Top left) single optotype with single frame, indicating no diplopia, (Top right) double optotype with a single frame, indicating retinal misregistration, (Bottom left) single optoptype with a double frame, also indicating retinal misregistration, and (Bottom right) double optoptype with a double screen, consistent with binocular diplopia caused by strabismus.

Figure 2

Synoptophore slides to evaluate retinal misregistration (10-degree targets pictured). One eye views five boxes, with four boxes oriented at the ends of a plus sign (Top). The other eye views 5 ×'s positioned to exacly superimpose on the five boxes (Middle). When the 4 periperal ×'s superimpose the 4 peripheral boxes, no retinal misregistration is present. When one of more of the peripheral ×'s do not align with the boxes (Bottom), retinal misregistration is present.