Preliminary vision tests

Parents' alertness to their baby's visual behavior is important and helps in identifying and diagnosing the vision problem early. 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 old vision is .
By: Prof. Kent Caslow, Professional Director at ELI – an association specializing in the care of infants, toddlers and children with blindness or visual impairments.
In the first months of a 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), a smile to familiar figures, eye contact, interest in nearby toys, a bottle, etc., are all important signs that indicate the normal development of the visual system. Occasionally, the parents, or during follow-up tests on the milk droplets or even a caregiver staff at the daycare notice that these gestures are not properly observed. When there is a suspicion of abnormal development of the visual system, it is important to seek a vision test.

Poor early childhood tests make it possible to monitor the development of the visual system and diagnose visual impairments at an early stage, if 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, so the 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 in identifying and diagnosing the vision problem early. 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 a "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 can be done with infants and toddlers aged one month, six months or even two years ?
In the past, vision in infants and toddlers checked whether the baby was staring (fixation) and following an object.
But later a test came in with an "opto-kinetic drum", this is a cylinder with a series of stripes in black and white colors 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 density of the stripes that caused a jitter in the poor gives a measure of visual acuity.
Today there are 2 more reliable tests that can be performed for newborns and infants, which do not require much cooperation and they give quality results.
One is an electrophysiological test: VEP (VISUAL EVOKED POTENTIALS) – a 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.
The second is a behavioral test-preferential looking test . The source of this test is the "Teller Acuity Cards" method. This method is based on the fact that studies have shown that if an infant is shown an empty target and a target with an example next to it, the infant will turn his gaze (preference to gaze) to a stimulus with an example. The example of a stripe of varying density is most often used. Compared to gray irritation this method is very useful from the age of 3 months to 2 years of age and also usually possible until the age of 3. Usually from the age of 3 and up the stripes will not arouse enough interest to employ the children and therefore was found to be ineffective.
It is important to pay attention and monitor a baby's visual behavior already in the early stages of development. If you suspect that there are signs of abnormal development in the visual system, it is important to consult a ophthalmologist or pediatric optometrist for more information. It is important to remember that even in early childhood and although the baby is unable to answer questions in words, there are today the tools to check visual acuity in toddlers and know what he is seeing.

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