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Introduction to Comitant strabismus.pptx
- 1. CONCOMITANT STRABISMUS Dr. RituChaturvedi HOD, Department of Ophthalmology SRVS, Medical College
- 2. A type ofmanifest squint in which the amount of deviation in the squinting eye remains constant in all directions of gaze; and there is no associated limitation of ocular movements
- 3. ETIOLOG Y • Binocular visionand coordination of ocular movements are not present since birth but are acquired in the early childhood. • The process starts by the age of 3-6 months and is completed up to 5-6 years. Therefore, any obstacle to the development of these processes may result in concomitant squint.
- 4. ETIOLOG Y Sensory obstacles • Refractiveerrors • Prolonged use of incorrect spectacles • Anisometropia • Corneal opacities • Lenticular opacities • Diseases of macula • Optic atrophy • Obstruction in the pupillary area due to congenital ptosis Motor obstacles • Congenital abnormalities of the shape and size of the orbit • Abnormalities of extraocular muscles • Abnormalities of accommodation, convergence and AC/A ratio Central obstacles • Deficient development of fusion faculty • Abnormalities of cortical control of ocular movements, and hyperexcitability of the CNS during teething
- 5. CLINICAL FEATURES IN GENERAL 1. OCULARDEVIATION • Unilateral or alternating • Inward deviation or outward deviation or vertical deviation • Primary deviation is equal to secondary deviation • Ocular deviation is equal in all directions of gaze
- 6. 2. OCULAR MOVEMENT •Not limited in any direction 3. REFRACTIVE ERROR • May or may not be associated 4. SUPPRESSION AND AMBLYOPIA • May be develop as sensory adaptation to strabismus • Amblyopia develops in monocular strabismus only and is responsible for poor visual acuity 5. A-V PATTERNS • May be observed in horizontal strabismus. • when this patterns associated, the horizontal concomitant strabismus becomes vertically incomitant
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- 9. • Denotes inwarddeviation of one eye and is the most common type of squint in children. • Unilateral or alternating CONVERGENT SQUINT
- 10. 1. INFANTILE ESOTROPIA •Age of onset, usually 1-2 months, but may occur during first 6 months of life • Angle of deviation is constant and fairly large (>30 degree) • Fixation pattern • Binocular vision does not develop and there is alternate fixation in primary gaze and cross fixation in the lateral gaze • Amblyopia in 25-40% cases • Treatment • Amblyopia treatment by patching the normal eye should always be done before performing surgery • Recession of both medial recti is preferred over unilateral recess-resect procedure • Surgery should be done between 6 months – 2 years; preferably <1 year
- 11. 2. ACCOMMODATIVE ESOTROPIA •Occurs due to overaction of convergence associated with accommodation reflex • 3 types • Refractive accommodative esotropia • Associated with high hypermetropia (+4 to +7D) • Fully correctable by use of spectacles • Non-refractive accommodative esotropia • Caused by AC/A ratio • Esotropia is greater for near than that for distance • Fully corrected by bifocal glasses with add +3DS for near vision • Mixed accommodative esotropia • Caused by combination of hypermetropia and high AC/A ratio • Esotropia for distance is corrected by correction of hypermetropia; and the residual esotropia for near is corrected by addition of +3DS lens
- 12. 3. ACQUIRED NON-ACCOMMODATIVEESOTROPIAS • Includes all those acquired primary esodeviations in which amount of deviation is not affected by the state of accommodation 4. SENSORY ESOTROPIA • Results from monocular lesions in childhood which either prevent the development of normal binocular vision or interfere with its maintenance 5. CONSECUTIVE ESOTROPIA • Result from surgical overcorrection of exotropia
- 13. • Characterised byoutward deviation of one eye while the other eye fixates DIVERGENT SQUINT Types – Congenital exotropia – Primary exotropia – Secondary exotropia – Consecutive exotropia Rare, almost present at birth
- 14. EVALUATION • History • Examination: -inspection - ocular movements - pupillary reactions - media & fundus examination - testing of vision & refractive error - cover tests (direct and alternate) - estimation of angle of deviation - tests for grade of binocular vision and sensory functions • confirms the presence of manifest squint ii. iii. iv.
- 17. TREATMENT • Goals oftreatments: - To achieve good cosmetic correction - To improve visual acuity - To maintain binocular single vision • Treatment modalities: - spectacles with full correction of refractive error - occlusion therapy - preoperative orthoptic exercises - squint surgery - postoperative orthoptic exercises
- 18. • Squint surgery –Should always be instituted after the correction of refractive error, treatment of amblyopia and orthoptic exercises. Basic principles: These are to weaken the strong muscle by recession (shifting the insertion posteriorly) or to strengthen the weak muscle by resection (shortening the muscle).
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