Ophthalmology: Phoria and Tropia
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Questions and Answers

What is the term for the error of alignment that occurs when fusion is suspended?

  • Heterophoria (correct)
  • Phoria
  • Tropia
  • Orthophoria

    • In normal individuals, the eyes always remain exactly parallel on dissociation.

    False

    What is the purpose of the cover test?

    To diagnose the presence of a heterophoria and heterotropia

    Distance fixation represents the error between the position of the eyes produced by tonic convergence and _______________________.

    <p>parallelism</p> Signup and view all the answers

    What is the movement seen in esophoria during the alternate cover test?

    <p>The eye moves inward under the cover</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Phoria = A measure of the error between the desired alignment of the eyes Tropia = A manifest deviation of the visual axes Heterophoria = A latent deviation of the visual axes Orthophoria = A condition where the eyes remain exactly parallel on dissociation</p> Signup and view all the answers

    Heterophoria is a manifest deviation of the visual axes.

    <p>False</p> Signup and view all the answers

    What is the term for the reflex that maintains the correct alignment of the two eyes?

    <p>Fusion reflex</p> Signup and view all the answers

    What is the direction of movement of the uncovered eye in Hypertropia?

    <p>Downwards to fixate</p> Signup and view all the answers

    Incomitant Heterotropia is also known as non-paralytic strabismus.

    <p>False</p> Signup and view all the answers

    What is the term for the upper poles of the cornea deviating outwards?

    <p>Exyclotropia</p> Signup and view all the answers

    In Cyclotropia, Incyclotropia is characterized by the upper poles of the cornea deviating _____________.

    <p>inwards</p> Signup and view all the answers

    Match the type of Esotropia with its characteristic.

    <p>Primary Esotropia = Constant Esotropia Onset in infancy = Deviation increases with accommodation</p> Signup and view all the answers

    What happens to the secondary deviation in long-standing cases of Incomitant Heterotropia?

    <p>It equals the primary deviation</p> Signup and view all the answers

    What is the direction of the eye's movement in exophoria during the alternate cover test?

    <p>Outwards</p> Signup and view all the answers

    Esophoria is a type of heterophoria characterized by convergence excess.

    <p>True</p> Signup and view all the answers

    What is the difference between hyperphoria and hypophoria?

    <p>Hyperphoria is when the eye moves upwards under the cover, while hypophoria is when the eye moves downwards under the cover.</p> Signup and view all the answers

    Incomitant heterophoria is often seen in the presence of _______________________ or mechanical strabismus.

    <p>paralytic</p> Signup and view all the answers

    Match the following types of heterophoria with their characteristics:

    <p>Esophoria = Convergence excess Exophoria = Convergence weakness Hyperphoria = Eye moves upwards under the cover Hypophoria = Eye moves downwards under the cover</p> Signup and view all the answers

    Heterotropia can be present in both eyes at the same time.

    <p>False</p> Signup and view all the answers

    What is the sequence of events in the cover test for heterotropia?

    <p>Cover one eye, observe the other eye, and then remove the cover</p> Signup and view all the answers

    What is the term for the deviation that increases when the paretic eye is made to fixate and decreases when the fellow eye fixates?

    <p>Incomitant heterophoria</p> Signup and view all the answers

    Study Notes

    Heterophoria (Latent Squint)

    • Most binocular anomalies result in misalignment of the visual axes
    • Fusion reflex maintains correct alignment of the two eyes
    • Heterophoria is the error of alignment that takes place when fusion is suspended
    • Phoria represents the error between the desired alignment of the eyes and the position produced by tonic, accommodative, and proximal convergence

    Types of Phoria

    • Esophoria:
      • Convergence excess – deviation greater at near fixation
      • Divergence weakness – deviation greater at distance fixation
      • Non-specific – deviation similar at near and distance fixation
    • Exophoria:
      • Convergence weakness – deviation greater at near fixation
      • Divergence excess – deviation greater at distance fixation
      • Non-specific – deviation similar at near and distance fixation

    Vertical Heterophoria

    • Hyperphoria: the eye moves upwards under the cover and will then be seen to come down once the cover is removed
    • Hypophoria: the eye moves downwards under the cover and will then be seen to come up once the cover is removed
    • Nomenclature is determined by the high eye

    Incomitant Heterophoria

    • Dissociation deviation increases when one eye is made to fixate and decreases when the other eye fixates
    • Or, it increases and decreases when the eyes fixate in different positions of gaze
    • Aetiology: most are seen in the presence of paralytic or mechanical strabismus
    • Diagnosed according to underlying cause, e.g., esophoria in 6th nerve palsy or hypophoria in TED or Hyperphoria in 4th nerve palsy

    Heterotropia

    • When both eyes are open, one eye will fixate the target and the other will deviate
    • Cover Test (Cover – Uncover) is used to diagnose heterotropia
    • Horizontal and vertical squints can coexist
    • Can be in one eye or both (alternating) although not at the same time

    Types of Heterotropia

    • Esotropia:
      • Eye is deviated inwards (convergent)
      • Uncovered eye will move outwards (temporally) to take up fixation
    • Exotropia:
      • Eye is deviated outwards
      • Uncovered eye will move inwards (nasally) to take up fixation
    • Hypertropia:
      • Eye is elevated upwards
      • Uncovered eye moves downwards to fixate

    Vertical Heterotropia

    • Hypertropia: uncovered eye moves downwards to take up fixation
    • Hypotropia: uncovered eye moves upwards to take up fixation
    • Nomenclature is determined by the eye that shows manifest deviation

    Cyclotropia

    • Excyclotropia: upper poles of cornea deviate outwards
    • Incyclotropia: upper poles of cornea deviate inwards

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    Description

    Learn about phoria, tropia, and heterophoria, including the misalignment of visual axes and the fusion reflex in binocular vision.

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