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How is amblyopia detected?
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How is amblyopia treated?
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What are the factors that may affect response to amblyopia treatment?
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My child has amblyopia and is currently patching his better eye. What is the
ideal number of hours of patching? How soon do we see an improvement in his
vision?
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What is penalization? Who undergo this amblyopia treatment option?
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Amblyopia is a reduction in best-corrected visual acuity that cannot be
attributed to any structural abnormality of the eye. It is commonly unilateral
but may be bilateral. It is caused by any abnormal visual experience early in
life due to strabismus (squint), uncorrected refractive error or visual
deprivation. These causes should be addressed as soon as possible by showing
the child to an ophthalmologist. Amblyopia, depending on the severity, may be
reversible if the underlying causes are identified and amblyopia treatment is
started early. This is why vision screening in preschool children is important
in identifying patients who are more likely to develop this condition.
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How
is amblyopia detected?
The primary care
physician or pediatrician should be able to detect risk factors for the
development of amblyopia during the first clinic visit. In preverbal children
and infants, the best method of screening is the simultaneous red reflex test or
“Bruckner” test. This test will detect amblyopic refractive errors and optical
media opacities such as cataracts. Older children (2 ˝ - 3 years of age) should
be able to cooperate with some form of visual acuity testing, usually a type of
picture card, or the E game. Early detection and early referral to the
pediatric ophthalmologist is critical to the treatment of amblyopia.
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How
is amblyopia treated?
The first and the
most important step in amblyopia therapy is to make sure that there is a clear
retinal image. Significant errors of refraction should be corrected with
spectacles or contact lenses, and visually significant opacities, such as
cataracts, must be surgically removed. Children with visually significant
cataracts are best treated during the first few weeks of life, while delaying
treatment past 3 or 4 months of age carries a relatively poor visual prognosis.
The next step is to
correct ocular dominance in patients with unilateral amblyopia by patching the
better eye. Patching the good eye forces the brain to use the amblyopic eye to
stimulate visual development. Part-time occlusion is recommended for very young
children, especially those under 1 year of age, to prevent the development of
occlusion amblyopia of the good eye. The earlier the intervention, the better
the visual prognosis. Penalization with atropine drops is an alternative option
for children who are not compliant with patching.
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What are the factors that may affect response to amblyopia treatment?
The response to
amblyopia treatment depends on the age of the child and the severity of the
amblyopia. The severity of the amblyopia depends on when the abnormal stimulus
begun, the length of exposure to abnormal stimulation, and the severity of the
image blur. The more severe the image blur, the earlier the onset, and the
longer the duration of a poor visual stimulus, the more severe the visual loss.
The first few months of life is the critical period of visual development when
children are most susceptible to amblyopia. Stimulation of a severely blurred
retinal image during the critical period of visual development results in dense,
often irreversible, amblyopia. This is why visually significant congenital
cataracts must be operated and visually rehabilitated within the first few weeks
of life for best visual results. Amblyopia can occur, however, in older
children. Acquired media opacity such as a cataract, or acquired strabismus,
can cause some amblyopia, even up to age 7 or 8 years of age, but of lesser
severity.
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My child has amblyopia and is currently patching his better eye. What is the
ideal number of hours of patching? How soon do we see an improvement in his
vision?
Occlusion therapy
or patching is still the mainstay in amblyopia treatment. The optimal dosage of
patching (hours of patching per day) needed for correction of amblyopia was not
known until recently, when several research studies had their results published
in medical literature.
The Pediatric Eye
Disease Investigator Group in the United States particularly compared the
improvement in visual acuity of young children undergoing different dosages of
patching. They found that the improvement in visual acuity in children with
severe amblyopia undergoing full time (all waking hours) and part-time (6 hours)
is approximately the same. Moreover, they found out in another study on
moderate amblyopes that 2 hours of daily patching produces an improvement in
visual acuity that is of similar magnitude to the improvement produced by 6
hours of daily patching.
Most recently,
another group of vision scientists from the United Kingdom found that the total
cumulative amount of patching needed to correct amblyopia is around 200 hours.
They also found out that a longer duration of patching (6 hours per day versus
shorter times) resulted in a more rapid improvement in vision. Another
important finding of their study was that younger children (less than 4 years
old) responded much faster to patching than older children (more than 6 years
old). This supports the argument for early treatment of amblyopia.
Theoretically, if a child is to undergo 2 hours of patching a day, it would take
approximately 3 months before an improvement in vision is seen. On the other
hand, 6 hours of patching would take a relatively shorter time before a maximal
improvement in vision is seen. Both patching regimens result in similar
magnitude of vision improvement. Therefore, occlusion therapy should be
individualized and the choice of patching regimen will ultimately depend on the
severity of the amblyopia and the age of the child. Regular follow-up with the
pediatric ophthalmologist despite good response to amblyopia treatment will help
the parents monitor amblyopia recurrence and visual development.
However, one must
be cautious in understanding these studies. None of their patients had cataract
or glaucoma. The amblyopia in these disorders is different from that due to
strabismus or unequal refractive error. Amblyopia with glaucoma and cataract
can be much more difficult to treat especially when it starts on the first year
of life. Therefore, similar studies should be done to learn if the same
conclusions can be drawn about amblyopia in different kinds of childhood eye
disease.
PEDIG. A Randomized Trial of Patching Regimens for Treatment of Moderate
Amblyopia in Children. Arch Ophthalmol 2003; 121: 603-611.
PEDIG. A Randomized Trial of Prescribed Patching Regimens for Treatment of
Severe Amblyopia in Children. Ophthalmology 2003; 110: 2075-2087.
Stewart et al. Treatment dose-response in amblyopia therapy: the Monitored
Occlusion Treatment of Amblyopia Study (MOTAS). Invest Ophthalmol Vis Sci,
2004. 45(9):3048-3054.
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What is penalization? Who undergo this amblyopia treatment option?
Penalization is the
use of atropine drops in treating amblyopia. Topical atropine sulfate 1%
dilates the pupil and paralyses accommodation (focusing) of the good eye. This
forces the child to use the amblyopic eye. The blurring effect of atropine is
greatest for near vision and for eyes that are hyperopic. Atropine will not
significantly blur the vision if the eye is myopic or if there is no refractive
error. Thus, atropine penalization will not work unless the good eye is
significantly hyperopic. Most patients with amblyopia are best treated with
occlusion of the good eye, but penalization may be an option for those children
who are compliant to patching. A recent study showed that weekend application
is as effective as daily application of atropine sulfate 1%, claiming that the
magnitude of improvement in visual acuity is similar to that previously reported
for patching for either 2 or 6 hours per day. This is good news for those
children who show severe adverse reaction to this drug.
PEDIG. A Randomized Trial of Atropine Regimens for Treatment of Moderate
Amblyopia in Children. Ophthalmology 2004; 111: 2076-2085.
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There are several ways of reaching the ophthalmologists of EYE REPUBLIC Ophthalmology Clinic:
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ONLINE ACCESS
WEBSITES.
http://www.EyeRepublic.com.ph - EYE REPUBLIC
Ophthalmology Clinic
http://www.OCP.com.ph - Ophthalmic
Consultants Philippines Co. -
http://www.LASIK.com.ph - Refractive
Surgery Resource
http://www.Cataract.com.ph - Cataract Surgery Resource
http://www.Eye.com.ph - Eye
Information Online
http://www.EyeDoc4Kids.com.ph - Eye Information for Kids
http://www.Retina.com.ph - Retina
Surgery Resource
http://www.Glaucoma.com.ph - Glaucoma
Online
http://www.Uveitis.com.ph - Uveitis Online
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EYE REPUBLIC
Ophthalmology Atlas
CLINIC INFORMATION
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EYE REPUBLIC Ophthalmology Clinic
Manila
3/F Don Santiago Building Units 309-310
1344 Taft Avenue, Ermita
Manila, 1000 Philippines
Direct and Fax: (632) 536-2398
Trunk Line: (632) 523-8271 to 79 local 30
Mobile: (63917) 899-2020
Map and directions
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EYE REPUBLIC
Ophthalmology Clinic
Asian Hospital
and Medical Center
5/F Medical Office
Building (MOB) Suite 509
2205 Civic Drive,
Filinvest, Alabang
Muntinlupa City,
1781 Philippines
Direct:
(632) 771-9253
Direct and Fax:
(632) 771-9254
Mobile: (63917) 795-2020
Map and Directions
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EYE REPUBLIC Ophthalmology Clinic
Medical City
6/F Medical Arts Tower Inc (MATI) Suite 602
MERALCO Compound, Ortigas Avenue
Pasig City, 1604, Philippines
Direct and Fax: (632) 632-7846
Mobile: (63917) 537-2020
Map and directions
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EYE REPUBLIC
Ophthalmology Clinic
St. Luke's
Medical Center
6/F
Cathedral Heights Building Complex (CHBC)
North Tower Suite 614
279 E. Rodriguez
Sr. Boulevard
Quezon City, 1102
Philippines
Direct and Fax:
(632) 407-3883
Mobile: (63917) 855-2020
Map and directions
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CLINIC HOURS
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Monday to Saturday 9:00 AM to 6:00 PM
All clinics are closed on Sundays and Holidays
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AMBLYOPIA information compiled by
Dr. Barbara L. Roque
and initially uploaded on May 1, 2005.
Last updated on
September 13, 2007. |
