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Cyclorefraction and its
Hira Nath Dahal
What is cycloplegia?
• It is the paralysis of the
ciliary muscle of the
eye ,resulting in the loss
of visual accommodation.
• Accommodation is the
ability of the lens to
change its refractive
power to view the near
• It is brought about by the
contraction of the ciliary
What are cycloplegics?
• Agents causing cycloplegia .
• Cycloplegics inhibit the action of the
acetylcholine on the effectors sites
innervated by the autonomic nerves.
• They block the muscarinic receptor sites.
• They are also called as anti- muscarinics,
Cholinergic innervations to eye
• Originate within the Edinger – Westphal nucles located
within the mesencephalon.
• The preganglionic parasympathetic fibers emerge from
the EWN ,exit the CNS , through the third cranial nerve
and proceed to ciliary ganglion.
• Synapses takes place with post ganglionic fibres at the
ganglion .The post ganglionic fibres enter the globe
through the short ciliary nerve and terminate on the iris
sphincter muscle and the ciliary body.
• Neurotransmitter in the effectors site is acetylcholine
Parasympathetic action in eye
• The pupil size is determined predominantly by the
varying degree of the parasympathetic innervations to
the sphincter muscles.
• The contraction of the sphincter muscle cause the
constriction of the pupil.
• The innervation to ciliary body cause contraction of the
ciliary muscle to induce accommodation.
• The degree of the parasympathetic innervations to the
sphincter in iris and the ciliary muscle is governed by the
impact of the pupillary reflex, the light reflex and the near
• The cholinergic rceptors in human eye have been found
in the iris sphincter and the ciliary body.
• It is of the muscarinic type.Other is nicotinic receptor
mainly found in the skeletal muscles.
• Five sub types of muscarinic receptors(M1-M5)have
• The muscarinic agonist action at the receptor costricts
the pupil, contracts the ciliary muscles and in general
• The inhibition of these receptors by the cholinergic
antagonist induce the
paralysis of accommodation
• It is the procedure to objectively determine
the refractive status of the eye when the
accommodative action of the eye is totally
• Commonly called as cyclorefraction or wet
• Reviewed by Bannon in 1947
• He noted that Pliny(23-79AD) discussed the use of various herbs to
dilate pupil for the treatment of corneal ulcers, cataracts and other
• During 18th
century atropine and other dilating drops were used for
• It was only in 1811 that the cycloplegic action of atropine was noted.
• It was known only when Dr William Wells ,a london oculist , found
that a patient whose pupil were dilated was also found to have
failure of accommodation.
• He found the change in accommodation from 7.00 to 1.00 in less
that 45 minutes and that the power of accommodation did not
returned for 8 days after he instilled belladona to young physicians
• Cycloplegic refraction was put in scientific
basis by Donders .
• It was universally accepted after the
publication of the Donders the “ Anomalies
of accommodation and refraction of the
eye” in 1864.
Currently five mydriatic- cycloplegic
cholinergic antagonist are available for
• Naturally occuring alkaloid
• First isolated from the belladona plant(atropa
• Non selective muscarinic antagonist.
• Most potent mydriatic and cycloplegic agent
• Depending on concentration mydriatic may last
upto 10 days and cycloplegia for 7to 12 days.
• Commercially available as the sulphate
derivative in 1% solution or 1% ointment.
Action parameters of atropine
• Cycloplegia begin within 12 to 18 minutes
• Reach to maxium in 106 minutes.
• Accommdation began to retain in 42 hours
• Full accommodation ability usually
attained within 8 days.
• Mydriatic effect begain in 12 minutes,
reach maxium in 26 minutes and reach
initial stage in 10 days.
• Often used for cycloplegic refraction in young ,
actively accommodating children with suspected
latent hyperopia or accommodative esotropia.
• It is not typically used for the routine cycloplegic
refraction in school aged children or adults due
to the prolonged paralysis of accommodation
that cause patient handicapped in near vision.
• The use is warranted in the case of esotropia
with suspected accommodative component.This
may lead to the permanent deviation.
Treatment of myopia
use of atropine may
prevent or slow down the
progession of myopia by
avoiding the tension due to
Treatment of amblyopia.
used for mild and
moderate amblyopia as and
alternative to occlusion.It is
Ocular side effects
• Direct irritation from the drug itself.
• Allergic contact dermatitis.
• Risk of angle closure glaucoma .
• Elevation of IOP in patients with open
• In the literature it is mentioned that
death of six reported cases have
occurred in children 3 years of age or
• Hypersensitivity to the belladona alkaloid.
• Have open angle or angle closer
• Have tendency towards IOP elevation.
• One tenth as potent as atropine.
• Shorter duration of mydriasis and
• It is not the drug of choice for the
cycloplegic refraction because of its
prolonged mydriatic and cycloplegic
• Non selective antagonist
• Maxium cycloplegic occurs in 40 minutes.
• Last for 90 minutes and by the third day
accommodation come to normal.
• Not a drug of choice.
• Introduced in clinical practice in 1951
• Commercially available as 0.5%,1%,and 2% solution.
• drug of choice for the routine in nearly all age group,
especially infants and young children.
• Faster onset of action and shorter duration of effect.
• Equally effective as atropine in the case of older
• Full recovery of mydriasis and cycloplegia occur within
• Cycloplegia occurs in 30-45 minutes of instillation.
• For children under the age of 6 one or two drops of 1% is
used and for children above 6 , 0.5% is used.
Side effects of cyclopentolate
• Ocular side effects
• Transient stinging on initial instilation.
• Allergic reaction to cyclopentolate are rare and may be
unrecognized by practioner.
• Symptoms of irritation and diffuse redness , facial rash that
develope within minutes to hour of instillation.
• Lacrimation ,stringy white mucus discharge and blurred vision are
• Systemic effects
• Distrubance in speech
• Visual hallucination.
• Short duration cycloplegic available in 0.5
and 1% solution.
• Cycloplegia in about 30 minutes.
• Recovery occurs within 2-6 hours.
• It is considered inadequate for children
• Widely used as mydriatic agent.
Choice of cycloplegic agents
The choice of drug depends on its
duration of action
duration of effect
Which drug do you choose for cycloplegia?
When is cycloplegia ready for
• The completeness of the cycloplegia is determined by
assessing the residual accommodation by push up test.
• The mydriasis and cycloplegia do not complete at the
• Unlike homatropine and tropiamide in the case of
cyclopentolate the cycloplegia is completed prior to
mydriasis, so often when there is complete mydriasis the
cycloplegia is considerd to be complete for the refraction.
• If pupillary dilatation is used to determine whether
cycloplegia is at the level of refraction , the refraction
may be unnecessarily delayed or additional drug may be
Indications for cyclorefraction
The main aim of cyclorefraction is to revel the latent hyperopia
that creats problem.
Types of hyperopia
Absolute hyperopia- that which cannot be corrected by accommodation.
Axial hyperopia- due to axial length
Faculcative hyperopia- that which can be entirely corrected by accommodation.
Latent hyperopia- the degree of total hyperopia that is corrected by the physiological tone of
Manifest hyperopia-total hyperopia not corrected by physiological tonus of ciliary muscle.
Total hyperopia- manifest and latent combination.
Old patients- the need of cyclorefraction
decrease makdely with age
• The patient beyond 40 is not expected to
have latent hyperopia.
Young adults- only if latent hyperopia is
a problem.Suspected if asthenopia is
complained for near work, but do not have
uncorrected hyperopia and other refractive
and binocular abnormalities.
if a child often preschool is seen with
convergent strabismus, to find if it is
associated with accommodative
child having the significant esophoria ,
should also be undergone cyclorefraction,
to find uncorrected hyperopia.
• The child uncoperative for the dry retinoscopy.
• If the difference in the refractive error of the eyes
is unusually greater.
• In the case of oblique astigmatism to determine
the exact orientation of power axis.
• If the unusually high astigmatism detected
during dry retinoscopy.
• If the retinoscopy finding is much greater than
excepted in the case of hyperopic patient.
Post mydriatic treatment(PMT)
• Assessment of the finding of
cyclorefraction by subjective means after
the effect of cycloplegia is eliminated.
• If atropine is used ciliary tonus should be
• Not necessary in the case of
• If blurring is complained with full power
obtained from cyclo then?
Cycloplegic and non cycloplegic
• Bannon(1947) did research taking 500 patients.
in the younger age group more percentage showed more
hyperopia in cyclorefraction.
cases in which the cycloplegic and non cycloplegic were same
was lower in younger group and highest in older group.
certain showed less hyperopia.
• In recent research done by Grosvenor and others taking 60
second year optometry students in 1984.
the refractive finding under maxium cycloplegia was within +/-0.25
D of the non cycloplegic finding for 41 students.
In 19 subjects the cycloplegic refraction was found to be 0.5 to1.25D
more than non cycloplegic refraction.