Prevalence of habitual refractive errors and anisometropia among Dutch schoolchildren and hospital employees.
OBJECTIVE
Refractive error (RE) is suggested to cause not only visual impairment, but also functional problems such as aspecific health complaints and lower levels of school achievement. During the last few decades the prevalence of myopia has increased worldwide, especially in Asia. We investigated the prevalence of habitual RE and anisometropia in a Dutch population of children and employees.


METHODS
In a cross-sectional study, RE in both eyes of 520 children (aged 11-13 years) and 444 hospital employees (aged 17-60 years) were measured using an autorefractometer. The measurements were performed without using a cycloplegium. Pearson's correlation coefficient (r) was used to analyse correlations between the right and left eyes. Chi-square tests were used to test the differences between subgroups according to gender and age.


RESULTS
In schoolchildren 28% of right eyes were myopic (> 0.50 D) and 8% hyperopic (> 0.50 D). Pearson's r between right and left eyes for spherical equivalent power (SEP) was 0.93. The mean cylinder deviation in right eyes was 0.26 D (range 0.00-4.50 D). Anisometropia > 1.00 D was present in 4.6% of children; 22% of children were not optimally (> 0.50 D) corrected. In hospital employees, 30% of right eyes were myopic (> 0.50 D) and 10% hyperopic (> 0.50 D). Pearson's r between right and left eyes for SEP was 0.53. The mean cylinder deviation in right eyes was 0.35 D (range 0.00-5.75 D). Anisometropia > 1.00 D was present in 25% of employees. Anisometropia was more frequently present in employees aged 40-60 years, than in those aged 17-39 years (30% versus 18%; p = 0.02, Cramer's V = 0.15).


CONCLUSIONS
Refractive errors are common in children aged 11-13 years and in working adults aged 17-60 years. Distributions of sphere and cylinder deviations are similar for Dutch schoolchildren and hospital employees. Surprisingly, anisometropia proved to be more prevalent with age. In children many eyes are not optimally corrected. Increased attention should be paid to uncorrected and miscorrected REs.
Department of General Practice, Maastricht University, The Netherlands. theo.hendricks@hag.unimaas.nl
Theo J W
TJ
Hendricks
John
J
de Brabander
Marlou H P
MH
Vankan-Hendricks
Frans G
FG
van der Horst
Fred
F
Hendrikse
J Andre
JA
Knottnerus
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D015858:Anisometropia / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D006282:Health Personnel / Q000706:statistics & numerical data*; D006761:Hospitals / Q000706:statistics & numerical data*; D006801:Humans; D008875:Middle Aged; D009216:Myopia / Q000453:epidemiology; D009426:Netherlands / Q000453:epidemiology; D009907:Optometry / Q000379:methods; D015995:Prevalence; D012030:Refractive Errors / Q000175:diagnosis / Q000453:epidemiology*; D013334:Students / Q000706:statistics & numerical data*; D055815:Young Adult