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J. Felius, C. S. Cheng, X. Wang, D. R. Stager, Sr., E. E. Birch; Accommodative Convergence in Patients With Infantile Esotropia Before and After Surgery. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4867.
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© ARVO (1962-2015); The Authors (2016-present)
The high incidence of accommodative esotropia in children with a history of successfully treated infantile esotropia remains poorly understood. Here we investigate whether abnormalities in the convergence-accommodation crosslink exist before treatment for infantile esotropia and whether changes occur as a result of surgical alignment of the visual axes.
An infrared eccentric photoscreener was used to measure gaze position and refractive status while the infant viewed accommodative targets at distances of 1.0 to 0.25 meter. The response AC/A ratio was measured under free-viewing conditions (closed-loop) and under monocular viewing conditions (open-loop: eliminating the convergence-driven component of accommodation). Data are presented from 15 non-amblyopic patients with infantile esotropia (age 5-12 months) tested before (n=10) and/or after (n=12) surgery. For comparison, 12 normal infants were tested.
Normal infants showed a mean response AC/A ratio of 0.7 ma/D (closed loop; 95%-c.i., 0.33-1.4) and 0.4 ma/D (open loop; 95%-c.i., 0.0-0.98). Under closed-loop conditions, as many as 50% of patients showed abnormally high AC/A ratio before surgery, vs. 8% after surgery (P=0.043). Eight patients who were tested before and after surgery showed a mean decrease in AC/A ratio from 1.9 ma/D to 0.7 ma/D after surgery (P=0.014). However, none of the patients showed abnormal open-loop AC/A ratios before surgery, while 1 of 7 patients showed abnormally high AC/A after surgery.
Some patients may habitually under-accommodate in order to reduce over-convergence under free-viewing conditions, resulting in a high closed-loop AC/A. However, no abnormalities in strength of the physiological crosslink (open-loop AC/A) were found before surgery. After surgery, only one patient showed an abnormally high open-loop AC/A. Longitudinal data are being collected to monitor which patients ultimately develop accommodative esotropia by age 4 years.
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