ophthalmology SGD copy.pptx...............

Strabismus

1. Incomitant strabismus

2. It’s a type of heterotropia ( manifest squint) in which the amount of deviation varies in different direction of gaze.it include following conditions Paralytic squint A and V pattern heterotropia Restrictive squint Paralytic strabismus It refers to ocular deviation resulting from complete or incomplete paralysis of one or more extraocular muscles The lesion may be neurogenic, myogenic or at the level of neuromuscular junction Neurogenic lesions Lesions at the level of nerve nucleus,nerve root,or any part of nerve in its course Nuclear ophthalmoplegia refers to paralysis of extraocular muscles due to lesion of 3 Rd CN It’s often bilateral.

3. Common causes : Congenital hypoplasia or absence of nucleus is a known cause of 3 Rd and 6 th CN palsies Inflammatory lesions include encephalitis, meningitis, peripheral neuritis Vascular lesions: hypertension,DM , atherosclerosis in the form of haemorrhage , thrombosis, embolism, aneurysm, vascular occlusion Traumatic lesions: head injury Toxic lesions: CO poisoning,diphtheria toxin, alcoholic and lead poisoning Demyelinating lesions: multiple sclerosis and diffuse sclerosis.

4. 2. Myogenic lesions: Congenital lesions: absence ,hypoplasia, mal insertion, weakness,musculofacial anomalies Traumatic lesions Inflammatory lesions: myositis due to influeza , measles, other viral fevers Myopathies: thyroid myopathies,carcinomatous myopathies Bilateral ptosis Diplopia

5. 3. Neuromuscular junction lesions Myasthenia gravis Clinical features Symptoms: Diplopia Confusion Nausea and vertigo Ocular deviation

6. Signs Primary deviation: Deviation of affected eye and is away from the action of paralysed muscle Eg : if LR is Paralysed the eye is converged Secondary deviation: Deviation of normal eye seen under cover ,when the patient is made to fix with the squinting eye . Limitations of ocular movement Compensatory head posture False projection or orientation

7. Clinical varities of ocular palsies Isolated muscle paralysis LR and SO most common muscles to be paralysed Paralysis of 3 Rd CN

8. Clinical features: Ptosis: due to paralysis of LPS Deviation: eyeballs turned down,out,intorted ( due to LR and SO) Limited ocular movements Pupils fixed and dilated Accomodation is completely lost Crossed diplopia elicited on rising the eyelids

9. Double elevator palsy: Also known as monocular elevation deficiency (MED) It is a congenital condition caused by supranuclear defects,charecterised by paresis of SR and IO Classic presentation of unilateral limitations of upgaze above midline with hypotropia on the affected side. Total ophthalmoplegia : All EOM including LPS and IOM viz sphincter pupillae and ciliary muscles are paralysed Results from combined paralysis of 3 Rd ,4 th &6 th CN Common feature cavernous sinus thrombosis

10. External ophthalmoplegia : All extraocular muscles are paralysed sparing the intraocular muscles Lesion at the level of motor nuclei sparing the edinger westpal nucleus. Inter nuclear ophthalmoplegia : Lesion of the medial longitudinal fasciculus( MLF) Charecterised by defective action of MR on the side of lesion Horizontal abducting nystagmus of opposite eye

11. INVESTIGATIONS Every case of squint should be evaluated as previously mentioned. Inspection Ocular movements Pupillary reactions  Fundus examination Refraction Direct cover test Alternate cover test Examination of angle of deviation Tests for the grade of binocular vision

12. Diplopia charting

13. HESS SCREEN TEST

14. INVESTIGATIONS TO FIND OUT THE CAUSE OF PARALYSIS ORBITAL USG ORBITAL AND SKULL CT SCANNING NEUROLOGICAL INVESTIGATIONS

15. DIFFERENCES BETWEEN PARALYTIC & NON-PARALYTIC SQUINT  FEATURES PARALYTIC SQUINT NON-PARALYTIC SQUINT Onset Usually sudden Usually slow Diplopia Usually present Usually absent Ocular Movements Limited in the direction of action of paralysed muscle Full False Projection Positive Negative

16. MANAGEMENT Treatment of the cause Conservative measures - Wait and watch for 6 months. Vitamin B complex Systemic steroids Treatment of annoying diplopia - Use of occluder on the affected eye, with intermittent use of both eyes with changed head posture to avoid suppression amblyopia. Surgical treatment

17. 'A' AND 'V' PATTERN HETEROPHORIA It is labelled when the amount of deviation in squinting eye varies by more than 10° and 15° respectively, between upward and downward gaze. 'A' AND 'V' ESOTROPIA - In 'A' esotropia the amount of deviation increases in upward gaze & decreases in downward gaze. The reverse occur in 'V' esotropia. 'A' AND 'V' EXOTROPIA - In 'A' exotropia the amount of deviation decreases in upward gaze & increases in downward gaze. The reverse occur in 'V' exotropia . C/F - It refers to vertically incomitant stabismus associated with horizontally concomitant strabismus

18. STRABISMUS SURGERY Strabismus surgery is surgery on the extraocular muscles to correct the misalignment of the eyes. Eye muscle surgeries typically correct strabismus and include the following: Loosening / weakening procedures Recession involves moving the insertion of a muscle posteriorly towards its origin.  Myectomy  Myotomy  Tenectomy  Tenotomy

19. Tightening / strengthening procedures Resection involves detaching one of the eye muscles, removing a portion of the muscle from the distal end of the muscle and reattaching the muscle to the eye. Tucking Advancement is the movement of an eye muscle from its original place of attachment on the eyeball to a more forward position. Transposition / repositioning procedures Adjustable suture surgery is a method of reattaching an extraocular muscle by means of a stitch that can be shortened or lengthened within the first post-operative day, to obtain better ocular alignment. Posterior fixation suture (FADEN OPERATION) to correct dissociated vertical deviation. Transplantation of muscles in paralytic squint.

20. STEPS OF RECESSION Muscle is exposed by reflecting a flap of overlying conjunctiva and Tenons capsule. Two vicryl sutures are passed through the outer quarters of the muscle tendon insertion The muscle tendon is disinserted from the sclera with the help of tenotomy scissors. The amount of recession is measured with the callipers and marked on the sclera. The muscle tendon is sutured with the sclera at the marked site posterior to original insertion. Conjunctival flap is sutured back.

21. STEPS OF RESECTION Muscle is exposed as for recession and the amount to be resected is measured by callipers and marked. Two absorbable sutures are passed to the outer qaurters of the muscles at the marked site. The muscle tendon is disinserted from sclera and the portion of the muscle anterior to the sutures is excised. The muscle stump is sutured with the sclera at the original insertion site. Conjunctival flap is sutured back.

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