Vision Screening Online Training Program
Module 6: Visual Acuity
(C&TC: Usually performed by a nurse or medical assistant)
Vision screening is most often associated with visual acuity testing using eye charts. The purpose of visual acuity testing is to test for refractive errors in a child’s sight; specifically nearsightedness (myopia) and astigmatism. Research also has revealed that diseases such as strabismus and amblyopia often present with refractive errors making visual acuity testing a means of screening for amblyogenic and strabismic risk factors. Studies have shown that near-sightedness is most commonly detected once a child reaches puberty. However, children may start developing refractive errors at a young age, which will especially inhibit their learning ability. For this reason, it is important that visual acuity testing is performed consistently starting at the age of three.
There are 5 different charts recommended for screening by the Minnesota Department of Health. These include the MassVat 10’ Lea or HOTV charts, Minnesota Early Childhood Visual Acuity Chart, 20’ or 10’ Sloan Chart and the 20’ Snellen Chart. These various acuity charts are used for different populations. For instance, the 10’ Lea and HOTV charts are best used for children who are illiterate, generally between the ages of 3 and 5 years old. These charts are also useful for immigrant populations where children have not yet learned the English alphabet. The 20’ Sloan and Snellen charts however, are best used when the child being screened is literate or at least knows their letters and numbers. Lastly, sometimes children are difficult to test using the traditional wall charts, which is why a visual acuity flip chart has been added to the MDH vision screening tools. This flip chart was designed specifically for Minnesota’s screening standards leading to the chart’s name as the Minnesota Early Childhood Visual Acuity Test. This chart is generally used at 10’ feet, and is useful because it is less “busy” than wall charts allowing children to pay better attention.
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