Kestenbaum and artificial divergence surgery for abnormal head turn secondary to nystagmus. Specific and nonspecific effects of artificial divergence.

Recommendations concerning the kind and dosage of eye muscle surgery for nystagmus vary in the literature. The present paper is an evaluation of the effects of Kestenbaum and artificial divergence surgery on abnormal head posture in a retrospective study. Exclusively patients with surgery for nystagmus-related horizontal head-turn (HT), with binocular vision and without previous eye muscle surgery were considered. Of the 78 patients, aged 3 to 68 years, 52 had a HT to the left side; 47 patients were male. In the Kestenbaum group (n = 31), the preoperative HT of 30 degrees (20-40) (median, 0.1-0.9 quantile) was reduced to 10 degrees (0-30) by surgery of 14 mm (10-20) on each eye. Four patients received further surgery. In the artificial divergence group (n = 27), the HT of 30 degrees (25-40) was reduced to 5 degrees (0-20) by recess-resect surgery of 10 mm (7-12) on the adducted eye. Seven patients needed further surgery. In the combined Kestenbaum plus artificial divergence group (n = 20), the HT of 30 degrees (25-40) was reduced to 7 degrees (-5-15) by surgery of 29 mm (21-37) on both eyes together. No further surgery was necessary. Kestenbaum surgery had a similar effect/dose ratio as recess-resect surgery for strabismus. If a test with base-out prisms suggests that artificial divergence is promising, this concept is preferable. It can be integrated into Kestenbaum surgery.