Prof. Kent Caslo, Professional Director of ELI
In the first months of the baby's life, the visual system and the system of connections to the brain develop, which is responsible for the functioning and coordination of the visual system, such as: hand-eye coordination, poor coordination, visual information processing, decoding ability, depth vision and more.
Since during the development of the visual system, the baby is unable to speak or express his intentions clearly, it is advisable to pay attention to the baby's visual behavior, whether the baby is looking in the direction of light and interested in toys or his immediate environment. Toddlers with normal vision are not indifferent to their environment and will express interest in it; Blinking in exposure to strong light (sun), smiling at familiar figures, eye contact, interest in nearby toys, bottle and the like.
Poor early childhood tests make it possible to monitor the development of the visual system and diagnose visual impairments at an early stage, if there are any..Vision affects all areas of development, it is the organizing sense that pushes us to connect with the environment, stimulates curiosity and through it we perceive and understand the world. Vision affects motor, cognitive and behavioral ability, severity and character of visual impairment, are the important factors in the effect of visual impairment on development.
Parents' alertness to their baby's visual behavior is important and helps identify and diagnose the vision problem early on. But even if we know there are visual impairments, all of us, parents and professionals, we would like to have a more accurate understanding of the visual impairment and in a more positive tone to understand how much vision there is.
How to test the eyesight of newborns and infants?
The standard measurement is called visual acuity test.
It is usually measured in what is called a Sanlan fracture – 6/6, 6/12, 6/30 and the like (vision 6/6 – a bone measuring 1 cm from a distance of 6 m). This measurement describes how far a bone of a certain size can be identified. For older children and adults a board of letters, numbers, shapes or even pictures can be used to perform the test.
But what do you do at the age of a month, half a year or even two years?
In the past, it was checked and recorded whether the baby was staring (fixation) and following an object. Later a test came in with a " opto-kinetic drum " roll with a series of black and white stripes of varying thickness. When rotating the cylinder and provided the baby sees the stripes and there is no blurring of vision there will be a jitter of the poor (nystagmus). The degree of stripe density following which jitter was caused in the poor gives a measure of visual acuity.
There are currently 2 better tests that can be performed for newborns and infants, do not require much cooperation and give quality results.
- Electrophysiological test:
– Visual brain response). In this test, the toddler sits, held in front of a computer screen that radiates alternating stimuli for a short time. Attached to the toddler's head are 2 electrodes (one on the earlobe and the other located posteriorly on the baby's head), which record the activity taking place in the brain at this time in the part dealing with central vision. If there is not enough cooperation you can also use flashes of light on the screen and you can test a baby even while sleeping. The test does not measure visual acuity unless the pathway communication between the eye and the brain is normal. This test is called Flash VEP . If possible, it is better to use stripes or squares (such as a checkerboard) of different sizes, and then it is possible to measure the visual acuity and it can be compared to the standard drawing (a fracture of a snare). This test is called Sweep VEP.
- Behavioral Examination – Preferential Looking ) The first version of this method was Teller Cards ( > Teller Acuity Cards ). This method is based on the fact that studies have shown that if an infant is shown an empty target with a sample next to it, the baby will turn his gaze (gaze preference) to a stimulus with a sample. The example of stripes with varying density compared to gray irritation is usually used. This method is very useful from the age of 3 months to 2 years and is usually possible until the age of 3. For most ages 3 and up the stripes will not arouse enough interest to employ children. This method also gives a result of visual acuity and the results can be compared to a standard test.
To summarize: We recommend monitoring and paying attention to the baby's visual behavior during its developmental stages. If you feel that there may be a visual impairment, it is important to contact a pediatrician for a vision test and get more information. It is important to remember that even in early childhood and even though the baby is unable to answer questions in words today have the tools to test visual acuity in toddlers and know what he is seeing.