Because of the relationship between accommodation and ocular convergence, refraction with cycloplegic agents is a particularly important test in the evaluation of any patient who has issues relating to binocular vision and ocular motility.
Refraction is generally performed after cycloplegia. The ophthalmologist’s working distance and the child’s visual axis are important considerations. To be accurate, retinoscopy must be performed on axis. The 2 main methods for refraction are loose lenses for infants and younger children and the phoropter for those old enough to sit in an examination chair.
Cyclopentolate hydrochloride (1%) is the preferred cycloplegic drug for routine use in children. Use of a weaker concentration of cyclopentolate (0.2% to 0.5%) is suggested in infants. Tropicamide (0.5% or 1%) is usually not potent enough for effective cycloplegia in children. Many ophthalmologists use a combination of cyclopentolate, tropicamide, and/or phenylephrine to achieve maximum pupil dilatation. Atropine (1%) drops or ointment is used by some ophthalmologists, particularly in young children with esotropia or dark irides, but this drug causes prolonged blurring and is more often associated with adverse effects (see the section “Adverse effects of cycloplegic agents”). Some ophthalmologists choose atropine to ensure complete cycloplegia in select cases of accommodative esotropia.
Table 1-2 gives the administration schedule and onset of action for commonly used cycloplegics. The duration of action varies greatly, and the pupillary effect occurs earlier and lasts longer than the cycloplegic effect; thus, a dilated pupil does not necessarily indicate complete cycloplegia. For patients with accommodative esodeviations, repeated cycloplegic examinations are essential when control of strabismus is precarious.
Eyedrops in children
Most young children are apprehensive about eyedrops. Fortunately, there are many approaches to administering eyedrops. If possible, to improve the child’s cooperation for the remainder of the examination, someone other than the physician should instill the drops, which can be described to the child as being “like a splash of swimming pool water” that will “feel funny.” Some practitioners administer a topical anesthetic drop first, while others use the cycloplegic drops alone; some use a compounded cycloplegic spray from an atomizer.
Adverse effects of cycloplegic agents
Adverse reactions to cycloplegic agents include allergic (or hypersensitivity) reaction with conjunctivitis, edematous eyelids, and dermatitis. These reactions are more common with atropine than with the other agents. Cycloplegic agents may also cause systemic symptoms, including fever, dry mouth, flushing, tachycardia, constipation, urinary retention, nausea, dizziness, and delirium. Treatment is discontinuation of the drug, with supportive measures as necessary. If the reaction is severe, physostigmine may be given. One drop of atropine, 1%, contains 0.5 mg of atropine. See also BCSC Section 2, Fundamentals and Principles of Ophthalmology, Part V: Ocular Pharmacology.
Table 1-2 Administration of Commonly Used Cycloplegic Agents
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.