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1 School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
2 Optometry Department, Oxford Eye Hospital, Oxford, UK
Correspondence to:
Dr Jez Guggenheim
School of Optometry and Vision Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, UK; guggenheim@cf.ac.uk
Accepted for publication 8 July 2004
Keywords: children; vision screening
Vision screening in children is aimed primarily at detecting non-strabismic amblyopia (other forms of vision defect are generally evident to parents). Such non-strabismic amblyopia occurs mostly as a result of uncorrected refractive errors.1,2 In the December 2003 report by the Child Health Sub-group3 it was recommended that all 4–5 year olds should receive vision screening. The Health For All Children 4 (HFAC4, 2003) "Hall Report"4 and the Children’s Eye Health Working Party guidelines5 similarly suggest vision screening should be undertaken in all 4–5 year olds. This advice is in accord with the results of the first randomised controlled trial of treatment for amblyopia,2 which found that treatment of moderate amblyopia (acuity 6/36–6/18) in preschool aged children was effective. However, currently the coverage of vision screening is patchy, and numbers of specialist screening personnel may be insufficient to meet demand if the recommendation to screen all 4–5 year olds were to be implemented.6 In districts where vision screening is not carried out, optometrists might act as an important safety net by providing an additional route for referral of non-strabismic amblyopes.
METHODS
As part of an investigation into the genetics of myopia,7 we investigated the age distribution of individuals attending for a sight test at 19 optometry practices in northern England during the period January 2000–December 2001. For subjects attending more than once, only the most recent visit was recorded. Of the 90 884 attendees, age was known for 90 750. None of the optometry practices operated in a manner that would be expected to discourage the attendance of children. The age distribution of this optometric cohort was compared with data from the census of England and Wales, conducted in 2000.
RESULTS
Figure 1 shows the age distribution of the optometric cohort compared with that of the year 2000 census. Although the optometry practices were not selected according to defined epidemiological sampling criteria, the high similarity in the age distribution of the two datasets after the age of 10 suggests the optometry attendees are generally representative of the UK population. However, there was a clear deficit in visits to optometrists in the preschool age group, which was highly significant (2 = 4186.4, df = 1; p<0.0001). Attendance to optometrists appeared to increase linearly until about age 11 when it reached adult levels (fig 1, inset). Our analysis suggests that only 7% of children aged 0–5 years visit an optometrist (1.48% of visits in the optometric cohort were for infants aged 0–5 years, and there were 16.6 million sight tests carried out in Great Britain in total,8 in the year 2000, suggesting 246 000 tests on the 3.7 million infants in this age group). Because infants in whom a refractive error has been detected are likely to visit their optometrist each subsequent year, this figure must be an overestimate of the proportion attending for the first time—that is, in a screening context.
Figure 1 Age distribution of subjects visiting optometric practices (n = 90 750) and in the 2000 population census for England and Wales (n = 52 041 916). Note the deficit in numbers of children under the age of 10 years (see inset figure for detail), and the increased attendance of patients >45 years old coinciding with the onset of presbyopia.
COMMENT
The fact that a visit to the optometrist is such an exception to the rule at this age underlines the importance of vision screening programmes, and suggests that every effort should be made to implement a comprehensive system of screening at age 4–5 in order to detect children likely to benefit from early treatment for amblyopia. However, where such programmes are not in place, we suggest that encouraging children to visit an optometrist should help in the early referral of non-strabismic amblyopes.
ACKNOWLEDGEMENTS
We are grateful to the staff of Conlons Opticians Ltd for access to anonymised patient record information. This work was supported by grants from the National Eye Research Centre (SCIAD015) and the Sir Jules Thorn Charitable Trust (RSC47).
References
Reeves BC. Taxonomy and epidemiology of amblyopia. In: Fielder AR, ed. Amblyopia: a multidisciplinary approach. Oxford: Butterworth-Heinemann, 2002:68–80.
Clarke MP, Wright CM, Hrisos S, et al. Randomised controlled trial of treatment of unilateral visual impairment detected at preschool vision screening. BMJ 2003;327:1251.
Child Health Sub-Group Report: Vision defects. 2003 (www.nelh.nhs.uk/screening/child_pps/vision_chsgr.html).
Hall DMB, Elliman D. Screening for vision defects. Health for all children. Oxford: Oxford University Press, 2003:230–44.
Children’s Eye Health Working Party. Guidelines for children’s eye care. 2002.
National Screening Committee. Vision Workshop of the Child Health Screening Sub-Group 2002.
Farbrother JE, Kirov G, Owen MJ, et al. Family aggregation of high myopia: estimation of the sibling recurrence risk ratio. Invest Ophthalmol Vis Sci 2004;45:2873–8.
Office for National Statistics. Sight tests volume and workforce survey (figure for combined private and NHS sight tests).