An advanced device to measure the field of vision of infants has been developed by scientists at L.V. Prasad Eye Institute, Hyderabad. The device, named paediatric perimeter, can be used to test the eyesight of infants between two and 12 months.
Currently, there is no specific perimeter device to measure the field of vision in infants. As a result, most of the eye defects arising during infancy get detected only in adulthood.
The paediatric perimeter helps to measure the area of vision and also the reaction time of infants. The innovation was recently published in Translational Vision Science and Technology.
Most doctors and optometrists use a crude way of assessing visual fields by bringing bright toys from the side of the eye to the centre and see if the infant is attracted.
The device can also be used on patients with special needs where testing using conventional perimeters is not possible.
The device consists of a hemispherical dome fitted with LEDs in all directions which are controlled using a computer program. The infant is placed inside the dome in the lying down position. The baby’s eye and head movements when the LED is switched on randomly are monitored by an infrared camera mounted on the top of the dome. The test takes only 6-10 minutes .The reaction time (time taken for the infant to look at the LED after it is switched on) measured helps identifying infants with developmental delay — healthy infants react within 380 milliseconds and those with developmental delay took 663 milliseconds.
To measure the area of vision, the LED was switched along the dome starting from the left and right sides to the centre, and also from front to back. The infants gaze was monitored by the camera and the degree of eye movements along with the reaction time was calculated to identify visual field defects. Many neurological factors can cause impairments in the vision of an infant.
The device was validated using adults with normal vision and those with glaucoma and retinal defects.
“The device is the result of collaborative effort of optometrists, ophthalmologists, engineers and designers from all over the world at Srujana Center for Innovation at the institute,” says Mr. Koteswararao Chillakala, Embedded Systems Engineer from the Srujana Centre for Innovation at L.V. Prasad Eye Institute, Hyderabad in an e-mail to The Hindu.