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Questions and Answers
Which condition is characterized by a tendency of the eyes to deviate when fusion is blocked?
Which condition is characterized by a tendency of the eyes to deviate when fusion is blocked?
What kind of deviation does a hypertropia describe?
What kind of deviation does a hypertropia describe?
Which type of squint may be a result of a difference in refraction between the two eyes?
Which type of squint may be a result of a difference in refraction between the two eyes?
Which term describes a manifest deviation where the visual axes do not intersect at the point of fixation?
Which term describes a manifest deviation where the visual axes do not intersect at the point of fixation?
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In which condition might one eye's image be suppressed at the cortical level?
In which condition might one eye's image be suppressed at the cortical level?
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What anatomical feature is typically slightly temporal to the anatomical center of the posterior pole?
What anatomical feature is typically slightly temporal to the anatomical center of the posterior pole?
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Which term refers to the condition where there is an upward latent imbalance of the eyes?
Which term refers to the condition where there is an upward latent imbalance of the eyes?
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What is the most common form of strabismus regarding horizontal deviation?
What is the most common form of strabismus regarding horizontal deviation?
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Which of the following statements about orthophoria is true?
Which of the following statements about orthophoria is true?
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What primary factor may lead to decompensated phoria?
What primary factor may lead to decompensated phoria?
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Study Notes
Strabismus Introduction
- Visual axis passes from the fovea through the nodal point to the fixation point.
- In normal binocular vision, visual axes intersect at the fixation point.
- Images are aligned by the fusion reflex and combined by binocular cells.
- Orthophoria: perfect ocular alignment in the absence of fusion stimulus (uncommon).
- Heterophoria: tendency for eyes to deviate when fusion is blocked (latent squint).
- Slight phoria is common and overcome by fusion reflex.
- Can be inward (esophoria) or outward (exophoria) imbalance.
- Decompensating phoria causes binocular discomfort (asthenopia) or double vision (diplopia).
- Heterotropia: manifest deviation where visual axes do not intersect at the fixation point.
- Images are misaligned, often causing double vision, or the image from the deviating eye is suppressed.
- Childhood squint, can be caused by failure of binocular fusion, oculomotor imbalance, or differing eye refraction (anisometropia).
Anatomical Axis and Angle Kappa
- Anatomical axis: passes from the posterior pole through the center of the cornea.
- Visual axis is usually slightly temporal to the anatomical axis, due to foveal location.
- Angle kappa: measures the angle between the visual and anatomical axes (usually about 5°).
- Angle kappa is positive when the fovea is temporal to the posterior pole center
- resulting in nasal corneal reflex displacement.
- Negative angle kappa is when the fovea is nasal to the center.
- Large angle kappa can mimic a squint (pseudosquint), particularly in conditions like retinopathy of prematurity.
Other Strabismus Factors
- Failure of fusion, can lead to heterotropia in adults or strabismus in children.
- Factors can include weaknesses or restrictions in extraocular muscles or nerve damage/weakness.
- Horizontal deviation (latent or manifest) is common strabismus type.
- Upward, downward displacement of eyes are called hypertropia/hypotropia and hyperphoria/hypophoria, respectively.
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Description
This quiz explores the concept of strabismus, including the alignment of visual axes and different types of deviations like heterophoria and heterotropia. It covers topics such as binocular vision, ocular alignment, and common visual disorders related to strabismus. Test your knowledge on these essential aspects of eye health and vision.
