to evaluate effect of combined recession with tenotomy and 4-muscle tenotomy on visual function and eye movement records in patients with INS without AHP, and to compare their results.

it was a prospective interventional case0series of 14 patients with INS with no AHP or eccentric null point. Patients underwent tenotomy alone or in combination with recession according to the presence of strabismus. Outcome measures included best corrected visual acuity and nystagmus intensity from eye movement recordings pre and post operatively. Data were compared between patients with strabismus and those without.

Overall Nystagmus amplitude and velocity was decreased 28.7% and 21.9% respectively. Visual outcome of combined procedure in patients with INS and strabismus was less comparing with 4-muscle tenotomy. All ocular deviations were surgically corrected and there was no undercorrection or complication. Visual acuity showed improvement in patients who had more impaired pre-operation vision. Most patients were satisfied with cosmetic outcomes.

Tenotomy alone and combined with recession improves both visual function and eye movement records in INS. The procedures show better results in more visually impaired patients. We should consider patients’ pre-op VA and their visual potential as prognostic factors for their visual gain. Although visual outcomes are not advanced in all patients, nystagmus