Be aware of post-surgical diplopia risk

Baltimore-A careful history taking-with special attention to risk factors-may aid ophthalmologists in the prevention of diplopia after surgical procedures, said Anya Trumler, MD.

“Diplopia is a disabling complication of any ocular surgery and should be included in the surgical consent, especially in those at risk,” said Dr. Trumler, assistant professor of ophthalmology, division of pediatric ophthalmology and adult strabismus at The Krieger Children’s Eye Center, The Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore. “It is important for the surgeon to understand the risk factors and mechanism to prevent diplopia complications.”

Of the 1.6 million cataract surgeries performed in the United States each year, the incidence of complications ranges from 0.1% to 6.8%.  These complications can include endophthalmitis, retinal detachment, and cystoid macular edema.

The causes of diplopia may be mechanical, neuromuscular, nerve related, disorder- or toxin-induced, and can include fixation switch, concurrent onset of systemic illness, and tilting of the IOL.

One of the possible causes of diplopia after surgery is the nerve block, Dr. Trumler said.

The reasons for this are unknown, she said, but are hypothesized to include needle injury to the muscle, possible ischemia caused by injection in a perimuscular space causing compression, and neurogenic injury.

“All anesthetic agents directly injected into muscle are myotoxic,” Dr. Trumler said. “Bupivacaine is the most, and procaine the least.”

Treatment includes observation, Fresnel and ground in prisms, and strabismus surgery, she said.

Diplopia is also a well-known complication of scleral buckling for retinal detachment, Dr. Trumler said, and occurs after pars plana vitrectomy without scleral buckle.

Factors that predispose these patients include underlying strabismus, disinsertion of EOM with faulty repositioning, cryotherapy, and multiple reoperations.

The types of diplopia that occur in these patients include hypertropia (58%), horizontal deviation (17%), and torsional (46%).

Aniseikonia from macular disease may cause a separation or compression of photoceptions, or rivalry between central and peripheral fusion. Dragged-fovea diplopia may result from rivalry between central and peripheral fusion as well.

“One treatment option is removal of the scleral buckle,” she said. “(But) wait at least 6 months before doing so.”

Exoplant removal, however, has minimal effects on improving strabismus, and the re-detachment rate ranges from 4% to 33% for various reasons, Dr. Trumler said.

In addition, there seems to have been an increase in the incidence of diplopia related to amniotic graft syndrome, she said.

The increase may be due to several factors, including changes in techniques, more frequent surgical intervention for cosmesis, and more aggressive excision with conjunctival autografts.

Prevention of recurrence includes intraoperative steroid use and avoidance of fibrin blue.

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