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Eyesight tests and screening in young children

by

rachelmyers97The Sonksen logMAR Test

is a visual acuity test/vision screening test for very young children that was developed by a team of experts from the Institute of Child Health, University College London. It is suited to use with very young children, disabled children and adults, and those who do not speak English or are not familiar with the Roman alphabet

This children s eye test is straightforward to administer and can be used by all ophthalmic and healthcare professionals who work with children, including ophthalmologists, orthoptists, optometrists, paediatricians, health visitors and school nurses.

An original feature of the vision test is that it is published with centile charts of acuity which enable the tester to compare the child s results with norms for that age bracket to determine if further action or follow-up is required. These centile charts resemble those used for growth and provide scientifically validated data covering the ages from Two years nine months to seven years nine months – a time period of very rapid alterations in acuity.

Since its release the SLT has been taken up by many organisations in the UK and overseas, in a variety of settings. It is in common use for vision screening in schools and in primary care settings, and also as a diagnostic and monitoring tool in specialist ophthalmic centres such as eye hospitals and eye clinics.

Research has proven that even very young children are able to do the test. Almost 90% of 2.5 to 3 year olds and 96% of 3 to 3.5 year olds are able to do a linear binocular (both eyes) test and, if occlusion is accepted, a similar proportion of the youngest children are able to perform a linear monocular (one eye covered) test. Research has also proved that over 99% of children over 3.5 could complete the whole vision test using the SLT.

The test set contains everything the specialist requires in a handy long lasting and convenient case. It includes a keycard for matching, a training booklet along with a booklet of single letters to discover the level to begin the linear distant test in the youngest age bracket; two booklets with crowded linear displays up to logMAR 0.875 as well as logMAR near charts. A comprehensive manual explains in detail how to administer the test and interpret the findings, and a quick reference sheet contains the centile charts, an easy guide to conversion to Snellen or N equivalents and adjustment for different distances. A pointer and occlusion glasses are also included.

Booklet E (one single and two linear displays of logMAR 0.900 to 1.075) is available separately for use in eye and developmental clinics for children with severe visual impairment.

The Sonksen logMAR Test can be purchased online from

Novomed Ltd

. Or contact info@novomed.net for more information.

Scientific background

The Sonksen logMAR Test (SLT) is designed to calculate distant and near acuity in strict accord with specifications laid down for the logMAR scale. The logMAR scale currently is recognised as the global standard and recommended for the way of measuring visual acuity.

To guarantee consistent crowding of all test optotypes, crowding bars as described in the logMAR standard surround each test display. As a result measures obtained with the SLT are both significant and specifically equivalent with the international scale.

Generally there are rapid alterations in linear optotype acuity between 2 . 5 and 5.5 years with reduced though continuous progress until at least nine years. Age norms are consequently crucial for significant interpretation of measures in this age bracket.

The benefits of the logMAR over the Snellen standard are a regular progression (base 10) of both letter dimensions and spacing from one level to the next along with an identical number of letters at every level; scoring takes into account every letter correctly recognized by the testee, resulting in improved sensitivity and repeatability of measurement. An additional benefit is an increased amount of levels in a given acuity range which in turn allows for the rapid alterations in acuity of the under fives.

http://novomed.net/sonksen/index.php

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ArticleRich.com