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Br J Ophthalmol. 2007 June; 91(6): 845.
PMCID: PMC1955595

Overestimation of uncorrected refractive error in Singapore teenagers

We read with interest the recent article by Ho et al.1 The authors present a study of teenagers who underwent visual acuity testing, non‐cycloplegic autorefraction (AR) and habitual refraction. The authors define myopia as a spherical equivalent (SE) of at least –1.00 diopters (D).

It has been reported that AR can overestimate myopia in paediatric patients without cycloplegia.2 Recently we saw a 17‐year‐old girl with a visual acuity of 20/40 in each eye without correction. A non‐cycloplegic AR using a Topcon Elite KR‐7000P (Topcon, Paramus, New Jersey, USA) revealed –7.75+0.50×011 in the right eye, and –8.75+0.75×156 in the left eye. Subjective refraction (SR) starting from the AR results showed 20/20 acuity in each eye. Her SR did not change with fogging. After cycloplegia, her SR and AR were –1.25+1.00×015 (20/20) in the right eye and –1.25+0.25×152 (20/20) in the left eye. This patient's spherical equivalent was –0.75 and –1.00 D in the right and left eyes, respectively. Her non‐cycloplegic AR overestimated her myopia by 6.75 D in the right eye and 7.25 D in the left eye, but acuities were 20/20 in each eye.

In the discussion, Ho et al state that their uncorrected refractive error rate of 22.3% is more than double the rates seen in several other countries. They suggest that the difference could be attributed to the high refractive error rates in the Singapore population. It is probable that the authors began their refractions using the results of the AR, which likely overestimated myopia, and then performed SR without cycloplegia. Although the authors acknowledge that the lack of cycloplegia was a limitation in their study, it likely affects the results significantly.


Competing interests: None declared.


1. Ho C S D, Ng C B C, Chan E. et al Uncorrected refractive error in Singapore teenagers. Br J Ophthalmol 2006. 90202–207.207 [PMC free article] [PubMed]
2. Choong Y F, Chen A H, Goh P P. A comparison of autorefraction and subjective refraction with and without cycloplegia in primary school children. Am J Ophthalmol 2006. 14268–74.74 [PubMed]

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