[Congenital nystagmus: indication, results and dosage of Kestenbaum surgery in 34 patients].

BACKGROUND

Abnormal, nystagmus related head postures can be treated by Kestenbaum's procedure, if the concept of artificial divergence (Cüppers procedure) is not expected to work. In this retrospective study, we evaluated the effects of Kestenbaum surgery in order to establish dosage recommendations.

PATIENTS AND METHODS

Solely patients who received Kestenbaum surgery (maximum 3 mm dosage difference between both eyes, i.e., without additional artificial divergence) for a horizontal head turn (HT) due to nystagmus were included in this study. Exclusion criteria were previous eye muscle surgery, strabismus, lacking binocular vision, and cerebral disease. The millimetres of surgery and the pre- and 3-6 months-postoperative findings (HT and visual acuity at 5 m distance, stereopsis) were evaluated.

RESULTS

Of the 34 patients, 21 had a HT to the left side and 20 were male. The age at surgery (median, 10%- and 90%-quantile) was 7 years (4-32), the total amount of surgery 32 mm (20-40), and the preoperative HT 30 degrees (20-40). Postoperatively (n = 31), the HT amounted to 7 degrees (0-20). The reduction of HT was 67% (25-100), the efficacy of surgery 0.8 degree (0.3-1.0) per millimetre total amount of surgery on both eyes together. Four patients needed further surgery due to residual HT. Postoperatively, the maximum visual acuity was available without HT or with significantly less HT than preoperatively. Stereopsis showed a trend of improvement.

CONCLUSIONS

The Kestenbaum procedure has a dose/effect ratio similar to that of recess/resect surgery for strabismus. Due to a long term efficacy of 1.5 degrees/mm, a dosage (in millimetres) on each eye of two thirds of the HT (in degrees) can be recommended. Physiological and methodical factors (false measurements) have to be discussed as an explanation for apparently low efficacy of surgery.