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Most
children 1) are
farsighted and 2) have sufficiently strong capacity to accommodate
that they can bring the focus of both of their eyes clearly on near as
well as distant objects. The degree of farsightedness (hyperopia) is determined
by refracting the eye after instillation of a cycloplegic eye drop. This
is called a cycloplegic refraction- a critical component of a confirmatory
eye exam.
When cycloplegic drops are placed in Farsighted eyes that are not fully
corrected by spectacles or contact the vision is blurred, especially for
near. The amount of blur is related to the amount of farsightedness(1).
This principal can be used to “penalize” the better eye and
treat amblyopia.
Compared to patching treatment for amblyopia, penalization has potential
advantages of:
A) Improved compliance
B) Maintained binocularity
Potential disadvantages of penalization are:
A) the better (sound) eye is blurred all day
B) the patient may more sensitive to bright light
C) the appearance of the eyes is different, especially with light blue
eyes
Dilating drops have different durations of cycloplegic effect:
Atropine 4-7 days dilated 1-2 days blurred
Scopolamine 3-4 days dilated 1 day blurred(2)
Homatropine 3-4 days dilated 1 day blurred
Tropicamide 3-4 hours dilated minimal blur
Phenylephrine 3-4 hours dilated least blur
The Amblyopia Treatment Studies have shown
that:
Daily atropine 1% works similarly to part-time patching(3)
Weekend atropine 1% works similarly to daily atropine(4)
Families found atropine slightly preferable to patching(5)
Reducing “plus” spectacles may enhance the treatment with
atropiine(6)
References:
1. Arnold RW, Gionet EG, Hickel J, Owen M, Armitage MD. Duration and effect
of single-dose atropine: paralysis of accommodation in penalization treatment
of functional amblyopia. Binoc Vis and Strabismus Quart. Spring-Fall 2003;19(2):81-86.
2. Arnold RW, Ellis F, Helveston E. Diplopia and Transdermal Scopolamine:
A case report. Am Orthoptic J. 1992;42:183-184.
3. PEDIG. A randomized trial of atropine vs. patching for treatment of
moderate amblyopia in children. Arch Ophthalmol. 2002;120(3):268-278.
4. PEDIG, Repka MX, Cotter SA, et al. A randomized trial of atropine regimens
for treatment of moderate amblyopia in children. Ophthalmology. Dec 2004;111(11):2076-2085.
5. PEDIG, Holmes JM, Beck RW, et al. Impact of patching and atropine treatment
on the child and family in the amblyopia treatment study. Arch Ophthalmol.
Nov 2003;121(11):1625-1632.
6. PEDIG. The course of moderate amblyopia treated with atropine in children:
experience of the amblyopia treatment study. Am J Ophthalmol. Oct 2003;136(4):630-639. |
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