Summer holiday rush: which test should I use?

As we pass the midway point of the summer holidays, the rush is on for parents to get their children’s eyes examined before the start of term.

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Author: Daniel Hardiman-McCartney MCOptom, Clinical Adviser
Date: 18 August 2015

It’s that time of year and, as we are past the midway point of the summer holidays, the rush is on for parents to get their children’s eyes examined before the start of term. On Saturday, as expected, more than half my clinic was booked with under 12s. With my retinoscope poised and pocket Frisby stereo test to hand I was ready for what is always a very enjoyable and rewarding aspect of primary care practice: the summer holiday rush.  

Recently I was presented with an interesting case where a five year old’s visual acuity had apparently deteriorated, with vision reducing from RE 6/6- and LE 6/6 the previous year to 0.22 and 0.1 that day, (equivalent to roughly 6/9.5 and 6/7.5 in Snellen notation). Reviewing the notes from the last test, I read that the previous optometrist had helpfully recorded that they had used the consulting room’s projection chart pictures, whereas I was using a different acuity test, the Sonksen, which is a crowed logMAR test. The child, who was both enthusiastic and very competent for his age, was very much enjoying the magician's box of tests that we all use, so on the wave of this enthusiasm, I repeated the visual acuity test using the projection chart with its pictures, and found a visual acuity of 6/6- and 6/5, similar, perhaps slightly better to that found the previous year and markedly different from the findings of my logMAR test!  So the two tests of visual acuity produced quite different results. I suspect that the reason for this is that the use of single pictures on the projection chart overestimated this child’s visual acuity, when compared with a crowed letter chart, probably masking mild amblyopia in his right eye. His eyes were straight and following a cylcoplegic refraction I prescribed a mild anisometropic prescription, and look forward with interest to his next appointment. 

There are a handful of different issues you could discuss based on the results of this isolated eye examination: Should you perform a cycloplegic refraction at every child’s first eye examination? What is the most age appropriate and repeatable stereo test? What is a clinically significant difference in VA? What should the interval be for children’s eye examinations? For me, the key question is the importance of a robust measure of visual acuity. I would guess that single picture projection charts are very common across the UK and I would not like to estimate how many optometrists use them as the only method of assessing a child’s visual acuity, potentially overestimating it in the process. For an examination of a child to be fit for purpose, I challenge every practice owner to ask if their consulting room is equipped with a suitably robust (validated) method for measuring a child’s visual acuity.

In this edition of the College's In Focus magazine I thoroughly recommend the article by Yvonne Norgett: her top tips and guide about which tests you should use will ensure your battery of examination methods are fit for purpose and every child receives the robust eye examination they undoubtedly deserve.  

Important note: There are a number of validated charts available in addition to the Sonsken

Useful links: 

In Focus Autumn 2015 - Top Tips for examining children by Yvonne Norgett.

Crowding in Children's Visual Acuity Tests-Effect of Test Design and Age.

Improving the reliability of visual acuity measures in young children.

Daniel Hardiman-McCartney MCOptom
Clinical Adviser, College of Optometrists

Daniel graduated from Anglia Ruskin University, where he won the Haag Strait prize for best dissertation. Before joining the College, he was Managing Director of an independent practice in Cambridge and a visiting clinician at Anglia Ruskin University. He has also worked as a senior glaucoma optometrist with Addenbrooke’s Hospital in Cambridge and as a diabetic retinopathy screening optometrist. Daniel was a member of Cambridgeshire LOC from 2007 to 2015 and a member of the College of Optometrists Council, representing its Eastern region, from 2009 to 2014.  

Daniel has an interest in the effects of vision in art and is known throughout the industry as a passionate advocate of iconic and artisan eyewear. He currently practises part time in independent practice, is a locum, a glaucoma specialist optometrist across East Anglia with Newmedica and is clinical adviser to the College of Optometrists.

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