Clinical features and surgical treatment of double elevator palsy in young children.

Aim: To describe the clinical features of congenital double elevator palsy (CDEP) and to evaluate various surgical outcomes between the standard Knapp and augmented Knapp procedures, based on improvements in primary eye position and ocular motility.

Methods: Twenty-two patients with CDEP at Shanghai Children's Hospital were enrolled from July 2014 to January 2018. The forced duction test (FDT) was negative in 21 patients, aged 8mo to 12y (mean 5.4y). Patients were divided into two treatment groups: 16 patients underwent the standard Knapp procedure (group A), with or without horizontal squint procedure; and 5 patients underwent the augmented Knapp procedure (Foster procedure; group B). One patient underwent inferior rectus recession in the affected eye and superior rectus recession in the sound eye because of a positive FDT. The pre- and postoperative vertical deviations in the primary position and ocular motility were compared in the two groups.

Results: Twenty-one eyes of the 22 patients (95%) were aligned within 10 prism diopters (PD), and all patients (100%) reached ≥25% elevation improvement after surgery. The average corrected vertical deviation in group B was statistically better than that of group A. For group A, the vertical deviation in the primary position decreased from 24.75Δ±8.35Δ to 4.56Δ±8.07Δ after surgery, for an improvement of 23.06Δ±6.51Δ (<0.05). In group B, the decrease was from 35.00Δ±5.00Δ (range 30Δ-40Δ) to 1.00Δ±2.24Δ, for an improvement of 34.00Δ±4.18Δ (<0.05). There were significant differences between the pre- and postoperative elevation in each group (group A, <0.05; group B, <0.05). The average scale of improved elevation in group B (1.80±0.45) was not significantly better than that of group A (1.69±0.87; =-0.732, =0.548). The average follow-up periods lasted 21mo in group A and 18mo in group B.

Conclusion: For vertical deviations <30Δ, the standard Knapp procedure can be chosen. For deviations greater than 30Δ-40Δ, the Foster procedure should be chosen. Because of our early interference, the inferior rectus (IR) muscle did not show mechanical restriction. Monocular elevation deficiency (MED) should be diagnosed early so that complications will be reduced and the procedure will be easier for the surgeon.