Purpose:
In
children under 20 years, refractive development targets a
cycloplegic refractive error of +0.5 to +1.5D, while presbyopes over 40 years generally have non-
cycloplegic errors of ≥ +1D. Some
papers suggest these periods are
separated by a period of myopic
refractive error (i.e., ≤ 0.50D), but this remains unclear. Hence, this
work investigates the mean
cycloplegic refractive error in
adults aged between 20 40 years.
Methods:
In 2002 a
cross-sectional study with stratified
cluster sampling was performed on the
population of Tehran, providing
cycloplegic and non-
cycloplegic refractive error data for the right
eyes of 3,576 participants,
aged 30.6 ± 18.6 years (range 186 years). After grouping these data into
age groups of 5 years, the
refractive error histogram of each group was fitted to a Bigaussian function. The mean of the central, emmetropized peak was used to estimate the mean
refractive error without the influence of
myopia.
Results:
The mean
cycloplegic refractive error at the emmetropized peak decreased from +1.10 ± 0.11D (95 %
confidence interval) to +0.50 ± 0.04D before 20 years and remains stable at that value until the age of 50 years. The non-
cycloplegic refractive error also sees a stable phase at 0.00 ± 0.04D between 15 45 years. After 45 50 years both
cycloplegic and non-
cycloplegic refractive error become more hypermetropic over
time, +1.14 ± 0.12D at 75 years.
Conclusions:
The
cycloplegic refractive error in
adults is about +0.50D between 20 50 years, disproving the existence of the myopic period at those ages.(AU)