New Treatments for Infantile and Other Forms of Nystagmus

Abstract

Abstract Our objective was to translate the past 40 years of infantile nystagmus syndrome (INS) research (i.e., ocular motor recording and control-systems analysis) into a therapeutic approach. Our eye movement recordings use infrared reflection, magnetic search coil, and high-speed digital video systems. Each eye was calibrated during monocular fixation (fellow-eye occluded). We analyzed and displayed all data using software developed and written in our laboratory in the MATLAB (MathWorks, Natick, MA) environment, including the eXpanded Nystagmus Acuity Function (NAFX). Analysis of A 1000 INS subjects over 40 years revealed waveform characteristics that can be exploited therapeutically. Analysis of postoperative INS data suggested that tenotomy and resuture (at the original insertions) of the extraocular muscles in the plane of the IN would improve foveation. The NAFX across normal gaze angles showed both peak-value increases and NAFX-curve broadening. We have concluded that all patients with nystagmus should have eye movement recording and analysis. The resulting accurate diagnosis and documentation of INS characteristics (undetectable by clinical observation) identify the best therapy. NAFX analysis allows estimation of postoperative acuities and determination of the most appropriate therapies. This eye movement–based procedure is the first to provide both the physician and patient with a posttherapeutic estimation of specific improvements in visual function that is not possible from acuity measurements alone.