Cycloplegic refraction involves using eye drops to paralyze the focusing muscles of the eye in order to get a more accurate measurement of a person's refractive error without influence from accommodation. It is particularly useful for children, people with hyperopia or esotropia, those with presbyopia symptoms at a young age, and for evaluating candidates for refractive surgery. While the drops cause temporary blurry vision and light sensitivity, they allow the full refractive error to be determined and properly corrected.
2. Cycloplegic refraction is performed to ascertain the cause of a refractive error
without any adjustment of the focus by the person being tested.
For example, when refraction is performed without cycloplegic eye drops, there
could a conscious or unconscious influence on the readings by the patient.
Sometimes the patient may be subconsciously over-focusing. This may make
someone appear more nearsighted or less farsighted than they actually are.
Cycloplegic drops paralyze the focusing muscles of the eye and prevent the
accommodating reflex by which focus is automatically adjusted. Doing so ensures a
more accurate diagnosis and prescription
3. Sometimes when people come in for an eye examination, things are not always
what they seem. An example of this that occurs with fluctuating prescriptions. Let's
say that a person comes for refraction. The examination goes smoothly and a new
prescription for eyeglasses is made. A few days later, the person comes back in
claiming that the glasses helped a little but that the eyes are extremely tired and
the glasses "did not seem right." Upon hearing the news, you recheck the
prescription by performing regular refraction. However, this time around, the
patient is able to see 6/6 through a variety of lens powers.
In instances like this, you realize that the patient was indeed farsighted but had a
large amplitude of accommodation. This means that the patient was able to
compensate for the farsightedness by adjusting the accommodation (focus) of the
eye
4. While the drops can cause short-term blurriness and light sensitivity, it allows you
to measure the entire amount of farsightedness. In this way true refractive error can
be measured and prescription adjusted accordingly.
6. Indications
Cycloplegic drops are not needed by everyone searching for a new pair of
eyeglasses. They are used for a very specific purpose in those with a large
amplitude of accommodation. There are four groups of people that cycloplegic
refraction may benefit with.
7. Children
A cycloplegic refraction is often performed on children. Children have the ability to
accommodate a great deal.
Also, children tend to focus at a close range and are unable to control their
focusing when they are supposed to be looking at a far distance during an
examination.
8. Hyperopia. Uncorrected hypermetropia can result in accommodative esotropia,
strabismic amblyopia and isometropic amblyopia. Children with >3.50ds of
hypermetropia have a 13 times greater risk of developing strabismus or amblyopia.
Esotropia. New onset of/ previously well-controlled accommodative esotrope is an
indication for cycloplegic refraction. This allows us to determine whether the eye
turn has an accommodative component.
Anisometropia is a very powerful amblyogenic risk factor. Over +1.00ds difference
between two eyes can put a child at risk of developing anisometropic amblopia. It
is not surprising to find a much larger difference in refractive error between the two
eyes after cyclodilation. If you don’t prescribe the full anisometropic difference
between the two eyes, the amblyopia/reduced acuity may not fully resolve despite
occlusion therapy/patching. Treatment of anisometropia should consist of
symmetric reduction of hypermetropia of up to 2.00 D.
9. Accommodative Spasm. In older children and young adults, cycloplegic refraction
can confirm the diagnosis of accommodative spasm, which is a constant or
intermittent, involuntary increase in ciliary contraction. Patients with low hyperopia
may present as myopic during examination; this so-called pseudomyopia can be
identified by cycloplegic evaluation.
Asthenopia with near work. This applies for children and young adults. A study of
young adults18-21 years old showed that they possessed +1 to +2 D of latent
hypermetropia. Should they complain of headaches with near work and asthenopia,
10. Pre-Presbyopia
Presbyopia is a condition that affects all of us around the age of 40 to 45. It is when
we begin to lose our ability to focus on near objects. This is why people over 40 are
often using reading glasses or wearing a bifocal.
However, in some people, symptoms may develop much earlier (a condition
referred to as pre-presbyopia). They will be unable to focus quickly from near to far
distance or be unable to focus properly at night. The best way to isolate the
problem is for the doctor to perform cycloplegic refraction
11. LASIK Candidates
People who decide to have laser vision correction (LASIK) or other refractive
surgery must undergo cycloplegic refraction.
This is performed to ensure that their accommodation does not interfere with the
results. The surgeon needs to know exactly how much of the person's vision
problem to correct with the laser
12. Side Effects
Cycloplegic eye drops do tend to sting for a few seconds when first applied to the
eye. Depending on the type of drop used, they can cause blurriness and light
sensitivity for several hours. Some people may even continue to have blurriness the
next day.
Protective disposable sunglasses are typically provided to prevent squinting and
discomfort as well as to protect the eye from sun damage.
Cycloplegic eye drops can also cause an acute angle-closure glaucoma attack in
people with very narrow angles. It should be checked to make sure you are not at
risk for glaucoma before instilling the eye drops.
