Background: Intermittent exotropia is the most frequent indication for surgical correction of exodeviations in childhood. Overcorrection with prolongated or persistent consecutive esotropia can impair binocular vision particularly in early childhood. We wanted to investigate this potential risk and the dose/effect relation of recess-resect surgery on children.

Patients and Methods: 120 children up to ten years of age underwent recess-resect surgery for intermittent exotropia in our clinic from 1991 to 1999 (< 2 % of the surgical cases). The cycloplegic refraction was spectacle corrected with a reduction of 0.5 dpt. Preoperatively, a diagnostic occlusion was performed for three days. The amount of surgery was calculated using our dosage schedules based on effects one week postoperatively. The squint angles as measured by the alternate prism and cover test at 5 m and 0.3 m pre- and 3 months postoperatively and the binocular functions as measured by the Bagolini striated glasses, Titmus, Randot, TNO, or Lang tests were evaluated.

Results: (Medians) Squint angles in primary position were: preoperative: distance (5 m) -15, near (0.3 m) -16"; postoperative (n = 104): distance - 4 degrees, near - 3 degrees. Effectivity of surgery: distance: 1.3 degrees /mm, near 1.4 degrees /mm. Consecutive esotropia requiring surgical correction occurred in 1 child. Second surgery for intermittent exotropia in the years 1991 to 1999 was necessary in 5 children. Binocular functions (n=95): Preoperative=postoperative: 61 %, postoperative > preoperative 21%, postoperative < preoperative 18 %. The diagnostic occlusion was helpful to differentiate "pseudo-divergence excess type" from "divergence excess type" exotropia. The average deviation did not increase under the diagnostic occlusion. The effectivity of surgery (/mm) in the children group was lower than in a compared group of older patients (>10 years) with intermittent exotropia.

Conclusion: Using our own dosage schedules and surgical technique, residual exodeviations are common after recess-resect surgery in childhood. The risk of consecutive esotropia or persistent impairment of binocular vision is low.