Abstract
Purpose: :
We developed a new piece of equipment for measuring the range of visual field (VF) in infants by using the ‘Orienting Reflex’ that may be observed as a reflexive head and eye movement when a light stimulus is presented within the range of the VF.
Methods: :
The equipment is consisted of a transparent hemispheric dome of 100 cm in diameter, 72 LEDs for light stimulus, and a small video display. The LEDs were installed on eight meridian lines with 10–degree intervals between them. The video display could show an attractive animation with voice for keeping infant’s central fixation. The LED was randomly switched on and off at an optional position while the infant was held by its mother at the distance of 30 cm from the dome equipment and watching the video display. A single examiner operates this LED–stimulation and observes infant’s behavior of the orienting reflex from a monitor which is set behind the equipment. In this study, we measured a horizontal range of VF with both eyes open in 30 normal infants between the ages of 5 months and 5 years; 5 normal adults were used as controls.
Results: :
The success rate of measurement was 96.7%. Horizontal range of VF of infants under 1 year (n=7, youngest one; 5months) was 82 degrees, 1 year old (n=7), 95 degrees, 2 years old (n=8), 111 degrees, 3 years old (n=6), 152 degrees, and 5 years old (n=2), 180 degrees.
Conclusions: :
The newly devised equipment for visual field measurement of infants easily induced fixation and observation of the orienting reflex, and could be used in a wide range of age from 5 months to 5 years old. The range of VF of 3–year–old infants approached that of adults, and reached it completely at 5 years old.
Keywords: visual fields • visual development: infancy and childhood • infant vision