Saccadic Eye Movements in Patients With Niemann-Pick Type C Disease

This study is done in conjunction with a trial, conducted at Columbia University College of
Physicians and Surgeons in New York and the Royal Manchester Children's Hospital in England,
to examine the effectiveness of a new drug called OGT 918 for treating Niemann-Pick Type C
(NPC) disease. Patients with this genetic disorder do not transport lipids (fatty
substances) in their cells, resulting in problems of the liver, spleen and brain. An early
sign of NPC is a reduced ability to move the eyes rapidly up and down or from side to side.
These voluntary eye movements are called saccades. Patients in the OGT 918 trial who
participate in this sub-study will have their saccadic eye movements measured to see if
improvement occurs with OGT 918 treatment.

Patients with Niemann-Pick Type C disease 12 years of age and older who are enrolled in the
OGT 918 trial described above may be eligible for this study.

Participants will have both vertical (up and down) and horizontal (side to side) saccadic
eye movements measured at two time points before starting treatment with OGT 918 and after
12 months of treatment. For the test, patients sit in a chair with their head positioned as
for a regular eye examination (steadied by a chin cup and headrest) and follow with their
eyes a series of lights or laser spots moving on a screen at a distance of 1 meter (3 feet).
During the test, patients wear either special recording glasses, infrared goggles, or
special contact lenses for measuring eye movements. A full eye evaluation lasts about 1
hour, and each eye is evaluated twice. The evaluations are separated in time by at least an
hour, and possibly a day.