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4. Extra ocular movements and strabismus.pptx
- 1. EXTRA OCULAR MOVEMENTS AND STRABISMUS By: Qurat-ul-ain Ophthalmic Medical Technologist/ MBA Health & Hospital management
- 2. PREAMBLE • EOM and their innervation • Actions of EOM • Duction • Versions • Vergences • Strabismus
- 3. EXTRAOCULAR MUSCLES • Muscles of the eyeball are called as Extra-ocular muscles (EOM). • The eye-ball is chiefly moved by six extrinsic muscles. Distance between the insertion of muscles and limbus for each EOM varies: • Superior rectus 7.5 mm • Lateral rectus 7.0 mm • Inferior rectus 6.5 mm • Medial rectus 5.5 mm • :
- 4. INNERVATION • Superior rectus • Inferior rectus • Medial rectus • Inferior oblique Aforementioned muscles are innervated by the oculomotor nerve (CN3). • Superior oblique innervated by trochlear nerve (CN4) • Lateral rectus innervated by abducent nerve (CN6)
- 5. ACTIONS OF EOM: MUSCLES PRIMARY ACTION SECONDARY ACTIONS Medial Rectus Adduction - Lateral Rectus Abduction - Superior Rectus Elevation Adduction & Intorsion Inferior Rectus Depression Adduction & Extorsion Superior Oblique Intorsion Depression & Abduction Inferior Oblique Extorsion Elevation & Abduction
- 6. DUCTION: Agonist Primary action moving the eye in any one direction. Antagonist Muscles act in opposite to the Agonist muscles. Synergist Muscles that support the action of agonist muscles. Sherringtons Law of reciprocal innervations When agonist contracts, antagonists relax. Involves the movement of only eye. Actions includes: Adduction Abduction Supraduction Infraduction Incycloduction Excycloduction
- 7. VERSIONS: The four tertiary positions of gaze are: • Dextroelevation • Dextrodepression • Laevo elevation • Laevo depression Six cardinal positions of gaze: • Dextroversion • Laevoversion • Dextro elevation • Laevo elevation • Dextro depression • Laevo depression Binocular movements in the same direction. The four secondary positions of gaze are: • Dextroversion (right gaze) • Levoversion (left gaze) • Supraversion (Up gaze) • Infraversion (Down gaze)
- 8. • Yoke muscle: A muscle of one eye is paired with a muscle of the other eye while moving the eye into each of the six cardinal position of gaze. Dextroversion (LR of right eye and MR of left eye) Dextroelevation (SR of right eye and IO of left eye) • Herings law of equal innervation: It says that during any conjugate eye movement equal and simultaneous innervations follows to the yolk muscle. So, a paresis of one muscle is associated with over action of its yolk muscle or contra lateral synergist and it results in more secondary angle deviation in paralytic squint.
- 9. VERGENCES: Binocular movements but in the opposite directions (convergence & divergence). The convergence may be voluntary or reflux. The reflux convergences are of 4 types:
- 10. Tonic Due to inherent tone of medial recti muscle. Proximal Due to psychological awareness of a near object. Fusional Maintained by binocular single vision (BSV), so that similar images are projected onto the corresponding rertina. Accommodati ve Each diopter of accommodation is accompanied by a constant increment in accommodative convergence, giving the AC/A ratio. This is the amount of convergence in prism diopter per diopter. The normal value is 3-5 prism. This means that 1D of accommodation is associated with 3-5 prism of accommodative convergence.
- 11. SUPRA-NUCLEAR EYE MOVEMENT Saccadic Rapid- voluntary and refixating eye movements Pursuits Smooth following movements to maintain vision on a slow moving object. Vestibulo-ocular Vestibular nystagmus in caloric test.
- 12. STRABISMUS
- 13. TYPES OF STRABISMUS a) Pseudo-strabismus • It’s a clinical impression of ocular deviation when no squint is present. • Epicanthal folds • Abnormal interpupillary distance • Angle kappa b) Heterophoria • May present clinically with associated visual symptoms when the fusional amplitudes are insufficient to maintain alignment, particularly at times of stress or poor health.
- 14. c) VERGENCE ABNORMALITIES Convergence insufficiency (CI) Typically affects individuals with high near visual demand. SIGNS Remote near point of convergence (NPC) independent of any heterophoria & poor fusional convergence amplitudes. Accommodative Insufficiency (AI): Occasionally also present. May be idiopathic or post- viral. The minimum reading correction to give clear vision is prescribed. Divergence insufficiency Divergence paresis or paralysis is a rare condition typically associated with neurological disease, such as intra-cranial space- occupying lesions, cerebrovascular accidents, and head trauma. May be difficult to differentiate from 6th CN palsy & primarily a concomitant esodeviation. Near reflex insufficiency Presents as dual convergence & accommodation insufficiency. Mydriasis may be seen on attempted near fixation. Complete paralysis in which no convergence and accommodation can be initiated due to mid brain disease or after head trauma. Spasm of the near reflex It’s a functional condition affecting patients of all ages. Diplopia, blurred vision and head aches are the presenting symptoms. Signs: Esotropia, pseudomyopia, miosis Spasm may be triggered when testing ocular movements.
- 15. d) ESOTROPIA Accommodative Esotropia • Refractive Fully accommodative Partially accommodative • Non-refractive With convergence access With accommodation weakness Mixed Non-accommodative Esotropia • Early onset (congenital, essential infantile) • Microtropia • Basic • Convergence excess • Convergence spasm • Divergence insufficiency • Divergence paralysis • Sensory • Consecutive • Acute onset • Cyclic
- 16. EXOTROPIA • Constant (early onset) • Intermittent • Sensory exotropia • Consecutive exotropia
- 17. CONGENITAL CRANIAL DYS-INNERVATION DISORDERS • Duane retraction syndrome • Mobius syndrome • Congenital fibrosis of the EOM • Strabismus fixus ALPHABET PATTERNS V- pattern A- pattern
- 18. THANK YOU!