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Why does early surgical alignment improve stereoacuity outcomes in infantile esotropia?,☆☆

Presented at the 25th Annual Meeting of the American Association of Pediatric Ophthalmology and Strabismus, Toronto, Ontario, April 157-18, 1999.
https://doi.org/10.1016/S1091-8531(00)90005-3Get rights and content

Abstract

Purpose: Recent studies of infantile esotropia suggest that early surgical alignment may enhance stereopsis and that alignment during the first 6 months of life may be optimal. Early surgery both establishes alignment during an early critical period for the development of stereopsis and minimizes the duration of misalignment. Here we examine the role of these 2 factors in promoting improved stereopsis outcomes. Methods: Participants were 129 consecutive patients enrolled in a prospective study of infantile esotropia who were followed up for a minimum of 5 years. At ages 5 to 9 years, Randot stereopsis was evaluated. Results: Multiple linear regression indicated that duration of misalignment, but not age at alignment or age at onset, was a significant factor in determining random dot stereopsis outcomes. Moreover, patients with stereopsis were less likely to have a loss of horizontal eye alignment requiring surgery than patients without stereopsis (14% versus 32%; z = 1.96, P = .05). Patients with stereopsis were also less likely to have dissociated vertical deviation than patients without stereopsis (25% versus 63%; z = 3.36, P <.001). Conclusions: The results suggest that early surgical alignment is associated with better stereopsis in those patients with infantile esotropia who were treated during the first 24 months of life, because early surgery minimizes the duration of misalignment, not because alignment is achieved during an early critical period of visual maturation. Random dot stereopsis can also be achieved in patients with alignment provided that the duration of misalignment is not prolonged. Improved outcomes of random dot stereopsis are associated with more stable long-term alignment outcomes. (J AAPOS 2000;4:10-4)

Section snippets

Subjects

Participants were 129 consecutive patients enrolled in a prospective study of infantile esotropia at the time of diagnosis and were followed up for a minimum of 5 years. All patients had constant esodeviations of ≥40 PD on the initial visit, usually measured at near with prism and cover testing. Some of the youngest infants were measured with the modified Krimsky method. All were remeasured on at least 1 occasion before surgery and either maintained the same angle of deviation (within 5 PD) or

Results

Overall, 36.4% of patients demonstrated some stereopsis, 21.7% passed the Randot stereotest at 500" or better, and an additional 14.7% passed the Titmus fly stereotest (3000"). A summary of the prevalence of stereopsis as a function of each of the independent variables is shown in Figure 1.

. Prevalence of stereopsis after surgical alignment at ages 3 to 24 months. Prevalence is shown as a function of age of onset (A), age at alignment (B), and duration of misalignment (C). The horizontal line in

Discussion

Although both age at alignment and duration of misalignment are correlated with long-term stereoacuity outcome, the results suggest that early surgical alignment of patients with infantile esotropia is associated with better random dot stereoacuity outcomes primarily because early surgery minimizes the duration of misalignment. Random dot stereopsis can be achieved in patients with later surgery provided that the duration of misalignment is not prolonged. “Later surgery” does not refer to

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  • Cited by (0)

    Supported in part by NIH grant EY05236.

    ☆☆

    Reprint requests: Eileen E. Birch, PhD, Retina Foundation of the Southwest, 9900 N Central Expressway, Suite 400, Dallas, TX 75231 (e-mail: [email protected]).

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