Clinical experiences with a new apparatus for bedside use in the eye tracking test

Abstract

When a human subject follows a moving object with his eyes, two different types of movement are noted : smooth pursuit movements and rapid, jerky changes of position known as saccades. Smooth pursuit movements enable the fovea to be maintained on a continuously moving object, whereas saccades serve to bring the fovea promptly on to an eccentric point in the visual field.
Eye tracking test (ETT) for investigation of smooth pursuit movements is nowadays one of routine tests in neurotological or neuro-ophthalmological clinics and various apparatuses have been used. However, as patients have to sit in front of them during the test, most serious patients in the neuro-surgical ward cannot be examined before surgery. For this reason one of the authors (Y. Chiba) designed a new handy apparatus for ETT at the bedside, and Mr. Shyosuke Matsuoka (Director of Mochizuki Electric Co. Ltd.) developed it as shown in Figures 1 and 2.
The apparatus has 64 light targets using L.E.D. As the light targets line up straight and a red light is turned on and off, one by one, the red target seems to move smoothly and continuosly on a line back and forth due to residual light.
The procured records are as accurate as those obtained with apparatus in neurotological clinics, and clinical experiences demonstrated several merits :
1) As it is small and portable, it can be easily used either at the bedside or in an outpatient clinic.
2) It can be used at the bedside even in patients who cannot be easily transported because of severe increased intracranial pressure or marked vertigo.
3) Even infants can follow a red target with interest, because the target moves back and forth automatically.
4) Vertical smooth pursuit movements can also be easily examined by turning the apparatus 90°.
5) Patients can also be examined while in a sitting position when the grip part of the apparatus is connected with the attached stand.
6) The price is reasonable.