Amblyopia Quiz and Flashcards: Test Your Knowledge

Study Notes

Amblyopia

A reduction of best-corrected visual acuity (unilateral or bilateral) that results from abnormal processing of visual images, leading to reduced visual acuity.
Clinically defined as a 2-4 logMAR line difference between both eyes or a visual acuity (AV) of < 0.5-0.6 in one eye that does not improve with correction.
Typically appears before the age of 6 and can be caused by lack of stimulation, strabismus, refractive error, or a combination of these.
Usually unilateral but can be bilateral in some cases.

Types of Amblyopia

Refractive Amblyopia: Caused by anisometropia, resulting in unstable central fixation and unilateral amblyopia. May also be isometropic if the refractive error is large in both eyes, leading to bilateral amblyopia. Has a better prognosis than strabismic amblyopia.
Strabismic Amblyopia: Associated with constant, unilateral, and early-onset strabismus, leading to unilateral amblyopia. Focal point can be central (more frequent in alternating or intermittent strabismus) or eccentric (more frequent in unilateral and constant strabismus).
Deprivation Amblyopia: Caused by complete or partial lack of visual stimulation due to pathological causes, making it the least frequent type.

Amblyogenic Mechanisms

Blurry Foveal Image: Lack of focused images affects the development of cortical mechanisms responsible for perception of form and contour. Results in fewer connections from the affected eye.
Suppression: A cortical mechanism that occurs to avoid double vision. More likely to occur in younger children.
Neural Plasticity: Amblyopia is a cortical problem, not limited to the eye. Significant loss of neural activity and reduced binocular cells in the primary visual cortex. Can be corrected until around age 8, but becomes increasingly difficult after that age.

Diagnosis and Treatment

Diagnosing amblyopia requires finding the underlying cause, not just low visual acuity.
Important to analyze the patient's history and symptoms, including the problem, affected eye, and duration of the problem.
Measurement of visual acuity should include the test, distance, and corrections used, as well as any peculiar head positioning.
LOGMAR is a better test than Snellen due to the crowding phenomenon.
The cover test is important for detecting amblyopia, and stereopsis is a good method for detecting problems.

Description

Ambliopia is a condition that reduces visual acuity, resulting from abnormal processing of visual images. It typically appears before the age of 6 and can be caused by lack of stimulation. Clinically, it's defined as a 2-4 logMAR difference between both eyes or a visual acuity of less than 0.5-0.6 in one eye.