Cycloplegic refraction is the gold standard for epidemiological studies

Abstract

ABSTRACT. Many studies on children have shown that lack of cycloplegia is associated with slight overestimation of myopia and marked errors in estimates of the prevalence of emmetropia and hyperopia. Non-cycloplegic refraction is particularly problematic for studies of associations with risk factors. The consensus around the importance of cycloplegia in children left undefined at what age, if any, cycloplegia became unnecessary. It was often implicitly assumed that cycloplegia is not necessary beyond childhood or early adulthood, and thus, the protocol for the classical studies of refraction in older adults did not include cycloplegia. Now that population studies of refractive error are beginning to fill the gap between schoolchildren and older adults, whether cycloplegia is required for measuring refractive error in this age range, needs to be defined. Data from the Tehran Eye Study show that, without cycloplegia, there are errors in the estimation of myopia, emmetropia and hyperopia in the age range 20-50, just as in children. Similar results have been reported in an analysis of data from the Beaver Dam Offspring Eye Study. If the only important outcome measure of a particular study is the prevalence of myopia, then cycloplegia may not be crucial in some cases. But, without cycloplegia, measurements of other refractive categories as well as spherical equivalent are unreliable. In summary, the current evidence suggests that cycloplegic refraction should be considered as the gold standard for epidemiological studies of refraction, not only in children, but in adults up to the age of 50.

Distribution of the Crystalline Lens Power In Vivo as a Function of Age

“…The lack of cycloplegia in the current study may have caused some of our subjects below the age of 50 to accommodate during measurement, which would increase lens power in the younger age categories, thus steepening the lens power decrease on the left-hand side of Figure 2. The influence of this effect can be estimated by referring to a recent article by Morgan et al, 26 who found that in subjects aged 20 to 50 years the mean difference between cycloplegic and noncycloplegic refraction can be up to 0.20 to 0.25 D for myopes and emmetropes, and up to 0.50 to 0.65 D for hypermetropes. This corresponds with lens power increases of 0.37 and 0.95 D for myopes/emmetropes and hypermetropes, respectively.…”

“…This may have introduced a small refractive shift, especially in the subjects below the age of 50. 26 …”

Cycloplegic refraction by 1% cyclopentolate in young adults: is it the gold standard? The Anyang University Students Eye Study (AUSES)

“…All three readings had to be at most 0.50D apart in both the spherical and cylinder components. One per cent cyclopentolate was used to achieve full cycloplegia,6 due to the difficulty of achieving complete cycloplegia in younger subjects with darker irises 4. For each student, one drop of 1% cyclopentolate (Alcon) was administered first, followed by one drop of Mydrin P (Tropicamide 0.5%, phenylephrine HCl 0.5%; Santen Pharmaceutical, Shiga, Japan) and then a second drop of 1% cyclopentolate at 5 min interval between each of the drops 21.…”

“…It is thus an important indicator in paediatric ophthalmology,1 cataract2 and refractive surgery,3 and many epidemiological studies of refractive status have been performed 4. As the capacity for accommodation exists, it is challenging to accurately measure refractive status without cycloplegia 4. However, in epidemiological studies, cycloplegia is particularly more challenging than in clinical situations, because of the time involved and the side-effects associated with cycloplegia, such as blurred vision and photophobia.…”

Effects of pupil dilation on objective refraction

“…However, the condition of cycloplegia is required for studying refraction in patients until the age of 20 years (Sanfilippo et al 2014). Moreover, the condition of cycloplegia is also required for epidemiological studies of refraction in patients aged over 50 years (Morgan et al 2015). Therefore, we need to examine how pupil dilation due to covering one eye affects the refraction in the condition of cycloplegic refraction.…”