Background: Children with developmental disorders and/or psychomotor delay may respond differently to strabismus surgery than children who develop normally, but the literature is conflicting.
Methods: We studied 37 patients with spasm, trisomy 21, prematurity, epilepsy, psychomotor retardation, and/or hydrocephalus (study group) and 67 control patients, all between 14 months and 14 years of age. All received a recession of one or both medial rectus muscles (Rc-surgery) or a monocular recession-resection of medial-lateral rectus muscles (RcRs-surgery) for esotropia. Rc-surgery was performed in cases with convergence excess. Spectacles were prescribed prior to surgery for all hyperopia > 2D, all partly accommodative esotropia, and all myopia.
Results: (effect per mm of surgery): For Rc-surgery, after 2 months follow-up, at 2.5 m fixation distance, the effects (change of angle per millimeter of surgery, mean + or - SD) were 2.07 + or - 0.82 degrees /mm (study group) and 1.07 + or - 0.74 degrees /mm (control group) (P < 0.001). At 30 cm fixation distance, the effects were 2.42 + or - 0.79 degrees /mm (study group) and 1.53 + or - 1.00 degrees /mm (control group) (P < 0.001). Effects at infinity were similar to those at 2.5 m. Because of this larger effect on near angles, convergence excess decreased after surgery in both study and control groups. For RcRs-surgery, at 2.5 m fixation distance, the effects were 1.78 + or - 0.43 degrees /mm (study group) and 1.78 + or - 0.42 degrees /mm (control group) (P = 0.741). At 30 cm fixation distance, the effects were 1.82 + or - 0.39 degrees /mm (study group) and 1.84 + or - 0.58 degrees /mm (control group) (P = 0.918). At fixation distance infinity, results were similar to those at 2.5 m. For both Rc-surgery and RcRs-surgery, reported differences were similar after one year follow-up. Success of surgery: After 2 months of follow-up, esotropia between 0-6 degrees was present, for Rc-surgery in 64% in the study group (with adjusted dosages) and 93% in the control group; and for RcRs-surgery in 66% in the study group and 88% in the control group.
Conclusions: Rc-surgery in children with developmental disorders and/or psychomotor delay has a larger effect per mm of surgery than in normal children. RcRs-surgery has a similar effect in delayed and normal children.