Non-surgical interventions—including Fresnel prisms and Bangerter filters—may be effective treatments in patients with central-peripheral rivalry-type diplopia, a Mayo Clinic study reports. On the surgical side, the investigation also found epiretinal membrane peeling was also a “surprising” success and should be considered.

Binocular diplopia due to central-peripheral rivalry associated with retinal misregistration in retinal disease—also known as “dragged fovea diplopia syndrome”—is an under-recognized problem which causes significantly impaired quality of life in many adults, says investigator Jonathan M. Holmes, MD, of the Mayo Clinic’s Department of Ophthalmology.

“The condition is most often associated with epiretinal membrane or macular degeneration and may present immediately following successful cataract surgery because the optical axis becomes clear enough to recognize the underlying problem,” he says.

Providers may often confuse this condition with either monocular diplopia or small-angle hypertropia associated with sagging eye syndrome, Dr. Holmes adds.

As such, if a provider is confused on the diagnosis (binocular diplopia due to central-peripheral rivalry associated with retinal misregistration), they may not offer any further treatment when optical correction fails, or they may erroneously prescribe multiple changes in ground prism, he says.

“The highest success rate in treating this condition was with epiretinal membrane peeling surgery to address the underlying retinal misregistration, although final success with surgery sometimes requires prescribing a small amount of prism postoperatively,” Dr. Holmes says.

The retrospective, interventional case series was set in an adult strabismus clinic at a tertiary medical center. The investigation enrolled 50 patients with retinal misregistration and central-peripheral rivalry-type diplopia—with minimum frequency of “sometimes” at distance and/or for reading— either caused by epiretinal membrane (44 patients) or other retinal disorders (six patients).

Researchers noted the following treatments were included in the study: Bangerter filter, tape, Fresnel prism, clear prism (incorporated into glasses or loose prism in office), iseikonic manipulation (using iseikonic lenses or contact lenses), MIN lens or epiretinal membrane peeling either alone or in any combination. However, not all treatments were trialed on every patient.

Investigators evaluated diplopia frequency using a questionnaire that tracked the success of distance and reading at approximately six months. 

The study reported 17 of the 50 patients (34 percent) were classified a success using the following treatments:

• Fresnel prism: four of seven patients (57 percent)
• Bangerter filter:four of 28 patients (14 percent)
• Epiretinal membrane peeling: eight out of 18 subjects (44 percent)
• Iseikonic manipulation using a contact lens: one out of 23 patients (four percent)

“Fresnel prism was found to be successful in some patients, in part probably due to the accompanying induced blur, whereas ground-in prism alone was unsuccessful in our cohort,” Dr. Holmes says. The study also found Bangerter filter or Satin Scotch tape were occasionally successful by inducing blur, he adds.

While aniseikonia was commonly associated with this condition, iseikonic lenses were rarely successful, which was likely due to local differences in magnification between the periphery and center versus overall aniseikonia, Dr. Holmes said.

“With epiretinal membrane peeling surgery, although the good news is that some patients’ diplopia is significantly improved, other patients experience no improvement, presumably because there is insufficient remodeling of the underlying retina, despite successful removal of the membrane,” he adds.  “Further research is ongoing to improve our ability to facilitate retinal remodeling.”

Dr. Holmes advises patients with intermittent or constant, typically vertical, binocular diplopia— which often occurs when staring at small images such as text on the TV or reading—should be evaluated for central-peripheral rivalry-type diplopia. “Both surgical and non-surgical treatments should be considered.”