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R. W. Hertle, D. Yang, K. Adams, R. Caterino; A Single Surgical Procedure for Treatment of Nystagmus and a Vertical Head Posture Associated With Infantile Nystagmus Syndrome (INS): Results in 24 Patients. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2835. doi: https://doi.org/.
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We will characterize clinical and electrophysiological effects following a single procedure for chin-up and chin-down postures due to a vertical eccentric gaze null position in 24 patients with INS.
This is a prospective, comparative, interventional case series. All had a multiplanar INS oscillation. 13 with a chin-down posture had a bilateral; superior rectus recession of 5.0 mm + inferior oblique myectomy + one horizontal rectus recession or tenotomy. 11 with a chin-up posture had a bilateral 5.0 mm superior oblique tenectomy + 5.0 mm inferior rectus recession + one horizontal rectus recession or tenotomy on previously unoperated extraocular muscles. 2 had a simultaneous horizontal head/face turn. All were followed for at least 6 months. Outcome measures included: Demography, Associated conditions, Pre- and Post-; Binocular Best Optically Corrected Acuity (BCA), Anomalous Head Posture (AHP), Null Zone Dynamics (NZD), Best Null Foveation Time (FOV) and INS waveform changes.
Patients ranged in age from 2.5-38 yrs, follow up averaged 14.0 mos, preoperative head postures ranged from 15 to 35 degrees. The most common associated ocular conditions were strabismus in 16 (66%), ammetropia in 23 (96%), amblyopia in 11 (46%) and optic nerve/foveal dysplasia associated with albinism in 13 (54%). Regardless of the amount of head posture in degrees, after surgery, all patients significantly (p < 0.05) improved in AHP amount and to within 8 degrees of straight in all without any over corrections. There were significant (p <0.05) improvements, NZD and FOV. The INS Waveforms favorably improved, especially in the NZ. BCA increased .1 LogMar to .4 LogMar in 20 of 24 patients. There was a clinically inconsequential and uniform limitation of vertical gaze in all patients with no induced cyclovertical or alphabet patterns except for one patient in the chin-up group who required a second operation for a restrictive hypertropia. There were no other complications other than a conjunctival suture related cyst in three eyes.
This study provides a uniform surgical approach to treatment of vertical AHP with or without strabismus due to an eccentric gaze null in patients with INS. A further finding is the unique association of a vertical gaze null in albinos with INS. This report also adds to the evidence from previous reports that surgery on previously unoperated extraocular muscles in patients with INS waveforms favorably changes their nystagmus. The improved head posture and nystagmus due to surgery improves acuity and other visual functions.
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