Purpose: To test the hypothesis that eye muscle surgery in patients with infantile nystagmus syndrome improves contrast sensitivity function.Methods: This is a prospective, interventional case series analysis of clinical data before and after eye muscle surgery in 113 patients who had no previous surgical treatment. Outcome measures included: 1) Routine demography and clinical characteristics, 2) Binocular best-corrected visual acuity in the null position and 3) Contrast sensitivity function. All patients data was collected for this study immediately pre-surgery and 2 to 6 months after surgery. Parametric and non-parametric statistical analysis of outcome measure data collected for this study were performed using standard software on grouped data using computerized software.