Published on June 16, 2016
1. Etiology of Heterophoria and Heterotropia Tukezban Huseynova, MD Specialist in Strabismus and Refractive Cornea, Briz-L Eye Clinic, Baku, Azerbaijan Tukezban@gmail.com
2. Orthoforia occurs where both visual axes are directed towards the fixation point and do not deviate on dissociation.
3. Factors that determine the relative position of the visual axes. Anatomical factors. Innervational factors.
4. Factors Responsible for the Manifestation of a Deviation Abnormalities of Fusion Mechanism Reflexologic Theories
6. Where heterophoria is presented, both visual axes are directed towards the fixation point but deviate on dissociation.
7. Classification. • Esophoria - convergence excess - divergence weakness - non-specific • Exophoria - conveargence weakness - divergence excess - non-specific • Hyperphoria/hypophoria • Alternating hyperphoria/hypophoria • Cyclophoria
8. Aetiology. Esophoria • Anatomical – enophthalmos, narrow IPD, extraocular muscle anomalies • Refractive – suprable hypermetropia, anisometropia • High AC/A ratio • Weak negative fusional reserves
9. Aetiology. Exophoria • Anatomical – exophthalmos, wide IPD, extraocular muscle anomalies • Refractive – acquired myopia, presbyopia, anisometropia • Weak positive fusional reserves • Passage of time
10. Aetiology. Hyperphoria/hypophoria • Refractive – high myopia (heavy eye syndrome) • Weak vertical fusional reserves • Anatomical – displaced globes, abnormal extraocular muscles, ptosis
12. Heterotropia is a condition in which one or other visual axis is not directed towards the fixation point.
13. There are a number of different forms of heterotropia: • Esotropia • Exotropia • Hypertropia • Hypotropia • Cyclotropia • Dissociated vertical deviation (DVD) • Dissiciated horizontal deviation (DHD)
14. Factors Causing the Deviation. Mechanical factors Structural anomalies of extraocular muscles Accommodation and refraction in comitant strabismus Fixation disparity Previous eye surgeries or brain surgeries
15. Factors Causing the Deviation. Other Innervational (Neurologic) Factors in Comitant Strabismus. Paretic elements Anomalies of the brainstem Anomalies of convergence and divergence Vestibular system Anomalies of the visual pathway Brain damage Embryopathy
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