Cycloplegic and Noncycloplegic Refraction
Ideally, refractive error is measured with accommodation relaxed. The amount of habitual accommodative tone varies from person to person, and even within an individual it varies at times and decreases with age. Because determining this variable may not always be possible, cycloplegic drugs are sometimes used. The indication and appropriate dosage for a specific cycloplegic drug depend on the patient’s age, accommodative amplitude, and refractive error.
A practical approach to obtaining satisfactory refraction is to perform a careful noncycloplegic (or manifest) refraction, ensuring relaxed accommodation with fogging or other nonpharmacologic techniques. If the results are inconsistent or variable, a cycloplegic refraction should be performed. If the findings of these 2 refractions are similar, the prescription may be based on the manifest refraction. If there is a disparity, a postcycloplegic evaluation (performed at a time after the cycloplegic effects have abated, usually several days later) may be necessary. Most children require cycloplegic refraction because of their high amplitude of accommodation. For more details on the cycloplegic drugs used in adults and children, please refer to BCSC Section 2, Fundamentals and Principles of Ophthalmology.
Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.