AMBLYOPIA

AMBLYOPIA - Robert M.Kershner, MD
BASICS
DESCRIPTION
Amblyopia is the reduction in visual acuity in an eye due to not receiving adequate usage in early childhood; there is no structural or pathological abnormality of the eye, and it cannot be corrected by eye glasses or contact lens. Strabismus is the inability to align both eyes simultaneously under normal conditions.
• When seen in the geriatric population, the diagnosis has usually been made early in childhood.
• System(s) Affected: Nervous
• Synonym(s): Lazy eye
ALERT
Pediatric Considerations
More commonly seen in the pediatric age group early in life
GENERAL PREVENTION
None
EPIDEMIOLOGY
• Predominant age: May be present from birth or may be detected at any age
• Predominant sex: Male = Female
Prevalence
~2-2.5% in the general population
RISK FACTORS
None identified
Genetics
Increased incidence in children with one parent with a history of amblyopia
PATHOPHYSIOLOGY
• Strabismic amblyopia is a loss of visual acuity in an individual due to suppression of the images in an eye, which turns out or in.
• Anisometropic amblyopia is present when 1 eye has a significantly different refractive error than the fellow eye, leading to visual blurring.
• Refractive amblyopia is due to uncorrected high refractive error, resulting in visual blurring in either or both eyes.
• Deprivation amblyopia (amblyopia ex anopsia) is due to relatively complete visual deprivation in one eye, which may be caused by a congenital abnormality such as a corneal scar or cataract.
• Deficiency amblyopia is also known as nutritional optic neuropathy or tobacco-alcohol amblyopia. Deficiencies of vitamins B1 or B12, or riboflavin, may be responsible.
ETIOLOGY
• See "Pathophysiology."
ASSOCIATED CONDITIONS
• Amblyopia is more common in families with a history of unequal refractive errors, high uncorrected refractive errors, and strabismus.


DIAGNOSIS
SIGNS AND SYMPTOMS
History
• Rubbing the eyes
• Sitting close to television or computer screen
• Problems in sports
• Preference for front-row seating
• Covering or closing an eye
• Squinting eye in bright light
• Eye turns "in" or "out"; wandering eye
• Poor vision in one eye without apparent explanation
• Poor vision that does not correct with glasses
Physical Exam
• Examination by an ophthalmologist to screen for unequal refractive error, outward or inward turning of the eye (strabismic amblyopia), and proper vision testing of the eye under monocular conditions.
• All children should have complete visual examinations prior to starting school, with each eye tested individually. Children from families with a known history of amblyopia or strabismus should have special exams by an ophthalmologist.
TESTS
Diagnostic Procedures/Surgery
A complete slit lamp and dilated funduscopic examination is necessary to exclude an organic cause for the decreased visual acuity.
DIFFERENTIAL DIAGNOSIS
The diagnosis of amblyopia can be confused with an organic lesion causing decreased visual acuity, and this must always be excluded before the diagnosis of amblyopia is considered.
TREATMENT
STABILIZATION
Outpatient treatment
GENERAL MEASURES
• Correction of the underlying disorder should be instituted at the earliest opportunity.
• Full refractive correction and/or patching of the stronger eye to encourage visual development of the amblyopic eye is warranted.
• Amblyopia never corrects itself spontaneously and will always require treatment. Children do not outgrow amblyopia.
• Deficiency amblyopia: Balanced diet, vitamins, and avoidance of alcohol and tobacco
Diet
No special diet
Activity
No restrictions
SURGERY
Surgical correction of an abnormal eye position may be required.
FOLLOW-UP
PROGNOSIS
A treatable condition in most cases if the diagnosis is made early
• Patching therapy, eyeglasses, and surgical correction of abnormal eye positions can result in near normalcy of vision when instituted early.
• Visual development occurs during 1st several years of life, and amblyopia therapy can be effective until ~age 12.
COMPLICATIONS
If there is failure to institute proper therapy early, permanent and profound visual loss can be expected.
PATIENT MONITORING
Once the diagnosis of amblyopia is made, the patient needs to be seen frequently at the discretion of the ophthalmologist until complete resolution of the problem occurs.
REFERENCES
1. American Academy of Ophthalmology. Binocular Vision and Ocular Motility, 1985-1986 (Ophthalmology Basic and Clinical Science Course, Section 6). San Francisco: American Academy of Ophthalmology, 1985.
2. Harley RD. Pediatric Ophthalmology. Philadelphia PA: Saunders,1983.