Classification of Eye Deviations Flashcards
(21 cards)
What is orthophoria and how does it relate to eye deviations?
Orthophoria is the condition where there is no deviation in the eyes when they are open and both eyes are fixating. It is considered normal eye alignment, and no fusional vergence is needed for alignment
What is heterophoria, and when does it become noticeable?
Heterophoria (latent deviation) is a condition where the eyes are misaligned when dissociated (e.g., one eye covered). It is usually compensated by the fusional vergence system, and the misalignment is not apparent when both eyes are open and functioning together.
How is heterotropia different from heterophoria?
: Heterotropia (manifest deviation) is when one eye is misaligned even when both eyes are open and fixating on an object, leading to binocular vision impairment. Heterophoria, on the other hand, is latent and only becomes apparent when one eye is covered.
What are the two types of eye deviations based on their manifestation?
Heterophoria: Latent deviation, visible only when one eye is covered or the eyes are dissociated.
Heterotropia: Manifest deviation, visible when both eyes are open and fixating on an object.
What are the types of heterophorias based on direction?
Esophoria (SOP): Eyes tend to converge when dissociated.
Exophoria (XOP): Eyes tend to diverge when dissociated.
Hyperphoria: One eye is elevated compared to the other.
Hypophoria: One eye is depressed compared to the other.
Cyclophoria: Rotational misalignment of the eyes, with either incyclophoria or excyclophoria.
How is magnitude of a heterophoria measured?
The magnitude of a heterophoria is measured in prism dioptres (∆) for horizontal and vertical deviations and in degrees (°) for cyclophorias.
What is the fixation distance, and how does it affect heterophoria?
The fixation distance refers to whether the misalignment is measured at near or distance. The magnitude of a heterophoria can change depending on the distance at which the person is viewing, with near deviations often being greater than distance deviations.
What does it mean if a heterophoria is compensated vs. uncompensated?
Compensated: The person has sufficient fusional vergence to maintain binocular single vision and the misalignment is not symptomatic.
Uncompensated: The person has insufficient fusional vergence, leading to symptoms like asthenopia (eye strain) and potential double vision.
What are the classifications for heterotropia based on its direction?
Esotropia (SOT): One eye is convergent relative to the other.
Exotropia (XOT): One eye is divergent relative to the other.
Hypertropia (Hyper T): One eye is elevated relative to the other.
Hypotropia (Hypo T): One eye is depressed relative to the other.
Incyclotropia: The upper pole of the cornea rotates inward.
Excyclotropia: The upper pole of the cornea rotates outward.
What does comitancy refer to in heterotropia?
Comitancy refers to whether the degree of misalignment remains constant in all gaze directions.
Comitant: The deviation is the same in all gaze directions.
Incomitant: The deviation changes with the direction of gaze, often seen in paralytic or paretic strabismus.
How are constant and intermittent heterotropias different?
Constant heterotropia: The misalignment is always present, regardless of fixation conditions.
Intermittent heterotropia: The misalignment occurs only at certain times, and the person may have binocular fusion at other times, compensating for the deviation.
What is the clinical significance of alternating heterotropia?
Alternating heterotropia means that either eye can act as the fixating eye, and the misaligned eye alternates between the two eyes. This condition is less likely to lead to amblyopia compared to unilateral heterotropia.
How is ocular deviation classified by magnitude in heterotropia?
The magnitude of heterotropia is measured in prism dioptres (∆), with deviations ranging from mild (small deviation) to severe (large deviation). Prism correction can be used to help manage the deviation.
What is the role of fusion in the management of eye deviations?
Fusion is the process of merging the visual images from both eyes into a single perception. In heterophoria, fusion compensates for small misalignments, while in heterotropia, fusion is either absent or insufficient, leading to binocular vision issues.
How is convergence involved in the management of eye deviations?
: Convergence is the inward movement of both eyes to maintain single vision when viewing near objects. Conditions like convergence insufficiency or convergence excess can affect eye alignment, leading to horizontal heterophoria or heterotropia.
How does accommodation affect eye deviations?
Accommodation refers to the eye’s ability to focus on near objects. In conditions like accommodative esotropia, an uncorrected hyperopia leads to convergence during accommodation, resulting in esotropia at near distances.
What is the clinical significance of prism testing in diagnosing eye deviations?
Prism testing helps quantify the magnitude and direction of eye deviations in both heterophoria and heterotropia. The test involves covering one eye and measuring the prism dioptre needed to realign the eyes.
How do fusional vergences help correct eye deviations?
Fusional vergences are the eye’s ability to adjust the alignment of the eyes to maintain single vision. For heterophoria, fusional vergences compensate for small misalignments. For heterotropia, corrective measures like prisms or surgery may be needed.
What is the significance of convergence and divergence in managing eye deviations?
Convergence and divergence are types of vergence movements that help maintain binocular vision. They play a role in diagnosing and treating heterophorias and heterotropias, especially when there is an imbalance between the two systems (e.g., convergence insufficiency).
What is the relationship between age and the development of heterotropia?
Congenital heterotropia often develops within the first year of life, while acquired heterotropia can occur at any age, often due to factors like trauma, neurological conditions, or uncorrected refractive errors.
: How does binocular vision affect the prognosis of eye deviations?
Binocular vision helps maintain proper eye alignment and can compensate for small deviations (heterophorias). If heterotropia is left untreated, it can lead to suppression, amblyopia, and permanent visual dysfunction.
