Abstract
Purpose:
Primary isolated divergence insufficiency (DI) is an acquired esotropia that most commonly occurs in individuals older than 50 years and causes diplopia, worse with distance fixation. Treatment of diplopia is achieved with base-out prisms in small angle deviations and surgery in cases of larger angle esotropias. As the world population continues to age and quality of life expectations rise, a thorough knowledge regarding the treatment and outcomes of this condition is essential. Our study objective is to provide a better understanding of the surgical treatment of DI.
Methods:
Clinical characteristics were collected from patients with DI who underwent surgical correction over a 15-year period at a large academic center. Treatment success was defined as resolution of diplopia and a deviation in primary position (near and distance) of ≤ 10 prism diopters (PD).
Results:
Thirty-four patients (ages 27-79, mean 61 years) underwent surgical correction. All patients experienced diplopia, and 82 % utilized prism correction prior to surgery. Average pre-operative deviation was 22 PD at distance and 15 PD at near. An ipsilateral recess/resect procedure was used in 62%, unilateral medial rectus recession in 23%, and bilateral medial rectus recessions in 15%. Adjustable sutures were employed in 96%, with 50% requiring adjustment on the day of surgery. Of those requiring adjustment, 47% were advanced (average advancement 1.7 millimeters) and 53% were recessed (average recession 1.6 millimeters). Diplopia in primary position resolved in 89% of patients, with no difference in treatment success between the three operations. Only four patients (12%) required further surgery; three of them after unilateral medial rectus recession.
Conclusions:
Initial treatment of DI is usually with prism correction; however surgical correction for larger deviations and persistent diplopia is indicated and very successful. Multiple surgical approaches combined with adjustable sutures achieve excellent outcomes. Compared to a large review of adult-onset esotropia of multiple etiologies at our institution, patients with DI required a larger amount of post-op adjustments. This may indicate that routine surgical algorithms do not apply as well to DI patients. Additionally, our study demonstrated a higher rate of re-intervention in unilateral medial rectus recessions, suggesting that this procedure should not be the preferred primary surgery for DI.