Prof. Kent Cassello, Professional Director, Israel AYT
In the first months of the baby's life, the visual system and the brain connections system develops, which is responsible for functioning and coordinating the actions of the visual system, such as: coordination of the eye, coordination between the poor, processing visual information, ability to decipher, in-depth vision and more.
Since at the time of development of the visual system, the baby is unable to speak or express his intentions clearly, it is advisable to pay attention to the visual behavior of the baby, the baby looks towards the light and is interested in toys or in his immediate environment. Toddlers who see normally are not indifferent to their surroundings and will be interested in it ; Blinking in exposure to strong light (sun), smile to familiar figures, eye contact, interest in close toys, bottle, etc.
Poor early childhood tests allow to monitor the development of the visual system and diagnose visual impairments at the earliest 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, the severity and nature 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 visual problem early.But even if we know that there are visual impairments, all of us, parents and professionals, we would like to have a more accurate understanding of the visual impairment and a more positive note to understand how old vision is.
How do I test the visual ability of newborns and babies?
The conventional measurement is called a visual acuity test.
Usually measured in what is called a snellen fracture – 6/6, 6/12, 6/30, etc. (vision 6/6 – an object 1 cm in size from a distance of 6 meters). This measurement describes how far an object of a certain size can be identified. For older children and adults you can use a palt of letters, numbers, shapes or even images to perform the test.
But what do you do when you're a month, six months, or even two?
In the past, it has been examined and recorded whether the baby is staring (pixation) and following an object. Later, a test came in with an "optokinetic drum" cylinder with a series of black and white stripes of varying thickness. When rotating the cylinder, provided that the baby sees the stripes and there is no blurring of vision, the jiggle of the poor (Nistagmus) will be caused. The degree of band density that resulted in fables in the eyes provides a measure of visual acuity.
Today there are 2 better tests that can be performed for newborns and babies, do not require much cooperation and give quality results.
- Electrophysiological examination: VEP test (VISUAL EVOKED POTENTIALS- Brain and visual response). In this examination the toddler sits, held in front of a computer screen that radiates changing stimuli for a short time.The toddler's head will be attached to two electrodes (one on the earlobe and the other located back on the baby's head), which record the activity that occurs in the brain at this time in the part that deals with central vision. If there is not enough collaboration, flashes of light can also be used on the screen and a baby can be checked even while sleeping. The test does not measure visual acuity unless the route of communication between the eye and the brain is normal. This test is called Flash VEP. If possible, it is best to use striped flashes or squares (such as a checkers board) of different sizes, and then visual acuity can be measured and can be compared to the standard record (snellen fragment). This test is called Sweep VEP.
- Preferential Looking The first version of this method was Teller Acuity Cards. This method is based on the fact that it has been shown in studies that if the baby is shown an empty target and next to a goal with an example, the baby will turn his gaze (preference) to stimulation with an example. The example of variable density stripes is usually used compared to gray stimulation, this method is very useful from 3 months to 2 years of age and is also usually possible until age 3. For many aged 3 and over, the stripes will not stimulate enough interest to keep the children busy and therefore have been found to be ineffective. This method also results in visual acuity and the results can be compared to a standardized test.
In summary: We recommend following and paying attention to the visual behavior of the baby during its development. If you feel that there may be a visual impairment, it is important to contact a poor pediatrician for a vision test and get more information. It is important to remember that even in early childhood and although the baby is unable to answer words about questions there are now the tools to check visual acuity in toddlers and know what he sees.