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BINOCULAR VISION

BINOCULAR VISION . AND STRABISMUS. DEFINITIONS. Binocular vision is the ability to use both eyes simultaneously. Binocular single vision is the ability to use both eyes simultaneously with bifoveal fixation so that each eye contributes to a common single perception. CONDITIONS FOR BSV.

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BINOCULAR VISION

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  1. BINOCULAR VISION AND STRABISMUS

  2. DEFINITIONS • Binocular vision is the ability to use both eyes simultaneously. • Binocular single vision is the ability to use both eyes simultaneously with bifoveal fixation so that each eye contributes to a common single perception.

  3. CONDITIONS FOR BSV • Overlap of visual fields. • Correct neuromuscular development so that the visual axes are directed at the object. • Normal visual pathway. • Approx equal image clarity. • Corresponding retinal areas.

  4. STRABISMUS • Misalignment of the visual axes which initially results in confusion and diplopia. • Visual axis is the line which passes from the fovea to the point of fixation. The visual axes of the 2 eyes normally intersect at the point of fixation.

  5. CLASSIFICATION OF STRABISMUS • Esotropia (convergent squint) • Exotropia (divergent squint) • Phoria: Latent deviation seen when fusion is dissociated: exophoria,esophoria,orthophoria. • Angle of squint is measured with prisms.

  6. ESOTROPIA.. • Accommodative : • Refractive: due to excessive hypermetropiabw +4.00DS and +7.00DS but normal AC/A ratio. • Non refractive: excessive convergence wt high AC/A ratio, no sig .refractive error.

  7. MANAGEMENT OF ACCOMMODATIVE ESOTROPIA • Refraction • Bifocals (executive type) • Miotic therapy: 4% pilocarpine 4X daily x 6 wks. Then gradually reduce freq and strength to minimal effective dose. It induces peripheral accommodationso less acommodative effort is required for near vision resulting in less AC. • Amblyopia Rx • Surgery: Bilateral MR recession or recession/resection on amblyopic eye.

  8. NON-ACCOMMODATIVE ESOTROPIA • Essential infantile: develops 1st 6 months of life in a normal infant. • Large angle bw 30-70 prism diopters and stable(dist=near). • Alternating fixation at primary gaze. • Cross fixation in side gaze mimicking 6th nerve palsy with failure of abduction.

  9. MANAGEMENT • Eyes should be aligned: by 2 years . • Refract to r/o any possible errors. • Definitive Rx is surgery: bilateral medial rectus recession . • Acceptable goal: alignment within 10 prism diopters.

  10. EXOTROPIA • CONSTANT: congenital • Present at birth • Normal refraction • Large constant angle • Neurological anomalies frequently present. • RX: surgical: bilateral lateral rectus recession + resection of MR depending n the angle.

  11. CONSTANT EXOTROPIA contd.. • Sensory : • Result of binocular view disruption by acquired lesions eg: • Cataract or other media opacities. • In children < 5yrs or adults • RX : correction of amblyopia followed by surgery.

  12. INTERMITTENT EXOTROPIA • Presentation usually around 2 years of age. • May be due to divergence excess, convergence weakness. • May be precipitated by bright light, day dreaming, fatigue, illness, stress. • May degenerate, remains constant or rarely decrease.

  13. TREATMENT OF INTERMITTENT EXOTROPIA • Spectacle correction in myopes may correct it. • Orthoptic treatment: occlusion therapy, diplopia awareness and fusional convergence. • Surgery: necessary by 5 years: lateral rectus recession.

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