Procedure corrects small-angle strabismus and removes need for prism glasses
Reviewed by Yi Ning J. Strube, MD, MS, FRCSC, DABO, FAAP
Data presented at the Canadian Ophthalmological Society Annual Meeting suggest central plication on vertical rectus muscles represents a viable surgical approach to resolving diplopia that develops secondary to small-angle vertical strabismus.
“This is the first study looking at the dose response of central plication on vertical rectus muscles,” said Yi Ning J. Strube, MD, MS, FRCSC, DABO, FAAP, the presenting author at the event, held recently at the Québec City Convention Centre in Canada. Strube is the director of pediatric ophthalmology and adult strabismus service at Kingston Health Sciences Center and Hotel Dieu Hospital and associate professor, Pediatric Ophthalmology and Adult Strabismus, Queen’s University, Departments of Ophthalmology and Pediatrics, Queen’s University, Kingston, Ontario, Canada.
According to Strube, central plication was originally reported in 2012, and the original study by Leenheer and Wright in 2012 described central plication in 9 patients, with only 2 patients in that study treated for vertical strabismus.1 To demonstrate the efficacy of the procedure in correcting vertical strabismus, Strube and colleagues conducted a retrospective review of procedural outcomes performed over a 5-year period involving 2 strabismus surgeons working in different practice settings.
The primary end point of the study was the amount of strabismus correction, measured in prism diopters (PD), per central plication on a vertical rectus muscle. Strube pointed out that in this study the patients included only had a central plication of a vertical rectus muscle, with no other concurrent procedures performed.
A total of 36 patients, who had an average age of 59.7 years and were followed up on average for 8.4 months, were evaluated. A total of 26 (72%) underwent inferior rectus central plication, and 16 (44%) had previous strabismus surgery. A total of 11 patients had idiopathic strabismus; 7 had congenital superior oblique palsy; 4 had dissociated vertical deviation; 2 had Brown syndrome; and the remainder had trauma, other ocular surgeries, or pathologies.
Of the 31 patients with diplopia before the procedure, 23 had no diplopia after the procedure and did not require prism glasses (74% resolution of diplopia; P < .001). Ten of 16 patients (62.5%) who required prisms preoperatively no longer required prisms postoperatively (P = .004).
Of the entire cohort, the mean vertical deviation change was 4.6 PD. The impact of surgery on deviation, however, was greater after excluding patients with congenital superior oblique palsy. After removing these patients from statistical analysis, the dose effect of surgery was 5.5 PD.
“It is not to say that I would not offer a patient who had that diagnosis (congenital superior oblique palsy) this procedure, but I would probably augment it with another procedure,” Strube said.
Small-angle vertical strabismus presents in childhood and in adulthood, with presentations in adults occurring after procedures like cataract surgery and refractive surgeries like laser-assisted in situ keratomileusis or photorefractive keratectomy. “They (adults) are often left with a small residual strabismus or a small deviation, which traditionally would be corrected with prism glasses,” Strube said.
Patients who have undergone refractive surgery, who have typically invested time and money to be free of spectacles, likely are not interested in having to wear prism glasses because of a small strabismus, Strube pointed out, adding that prism glasses are often not well tolerated. “The ability to offer this procedure to our patients is game-changing,” Strube noted. “We can now effectively and easily treat the growing number of adult patients we see with small-angle vertical strabismus, especially after refractive and cataract surgery, who are very motivated to be out of glasses.”
The procedure can be used for patients of all ages with small-angle strabismus. “We would not exclude anyone based on age,” she said.
A benefit of the central plication is that it can be performed with topical anesthesia, which makes it a fit for older patients, Strube said.
Strube pointed out her office has done the procedure with such patients while they are awake with just topical anesthesia, and it has gone very well. “The fact that it can be done under topical anesthesia opens up treatment options to many of our patients with medical comorbidities where general anesthesia is not safe,” Strube concluded. “It is a simple and quick surgical procedure that causes minimal pain, with quick postoperative recovery.”