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Cycloplegic Refraction
PURPOSE To measure a patient’s refractive error in the absence of accommodation．This is accomplished through the use of cycloplegic drugs that paralyze the ciliary body．
INDICATIONS
This test is useful when it is suspected that the patient has latent hyperopia, a strabismus of accommodative etiology, or an accommodative spasm．Cycloplegic refractions are most frequently used for examining children , and some authors recommend that the procedure be performed on all children under the age of three．The examiner who elects to perform cycloplegic refractions must be aware of the contraindications and side effects of the drug selected for this purpose．
Note: Parental consent should be obtained prior to performing this technique on a child．
EQUIPMENT
·Retinoscope．
·Phoropter．
·Distance visual acuity chart．
·Topical anesthetic．
·Cycloplegic agent：A 1%cyclopentolate solution is recommended. Other agents that may be used include cyclopentolate 0.5% (particularly with infants)，atropine 0.5% or 1.0%, scopolamine 0.25%, and homatropine 2% or 5%．
SET-UP
·A complete eye exam，including a “dry”(ie, done without cycloplegic ) refraction，should be conducted prior to cycloplegia．A cycloplegic refraction is often done at a second visit．
STEP-BY-STEP PROCEDURE
1．Check the IOP and the anterior chamber angles of both eyes prior to instilling drops．These tests serve to rule out the risk of angle closure due to the mydriatic effect of cycloplegic agents．If the anterior chamber angle is estimated at less than 1/4:1 using the van Herick angle estimation technique，gonioscopy must be performed prior to inducing cycloplegia．
2．Instill one drop of topical anesthetic into the inferior cul-de-sac of each eye．
3．Instill two drops(gtts)of 1.0% cyclopentolate．Allow 5 minutes between drops．Maximum cycloplegia with cyclopentolate occurs 10 to 40 minutes after the instillation of drops．
4．Check each eye for cycloplegia after 30 minutes．There are several ways this may be done．Two are described here．
a．Ask the patient to focus on an accommodative target set at a distance of one meter．Determine the accommodative near point using a push- amplitude of accommodation technique．If there is adequate cycloplegia there should be less than two diopters of accommodation remaining prior to beginning the refraction．
b．If the patient is too young to respond to the above procedure，the examiner can screen for accommodative activity with a retinoscope．
5．Perform retinoscopy or a monocular subjective refraction on both eyes using routine techniques．
6．Following the cycloplegic refraction recheck the intraocular pressure in both eyes．
RECORDING
·When using pharmacological agents always record the agent，concentration, number of drops, and time administered．
·Record the refraction technique，the correction found，and the resulting VA.
EXAMPLE
·Cycloplegic refraction：
1 gtt Ophthaine 0.5%，2 gtts Cyclogel 1% @ 10:00 AM
Static 0D +8.50 = -1.50×95 20/30+
0S +7.O0 = -1.00×90 20/20
Subj： 0D +8.00 = -1.O0×90 20/20
0S +7.O0 = -1.O0×90 20/20
0U 20/20
EXPECTED FINDINGS
·If routine refractive techniques were unable to relax the accommodative system，additional plus will be found in the spherical component of the patient’s refraction under cycloplegia．
·Because of the high level of accommodative activity found in many children，the cylinder power measured during retinoscopy without cycloplegia is frequently inaccurate．The amount of cylinder found using cycloplegic drugs is likely to be more accurate． |
