day 9 STRABISMUS squint.pptx

7/27/2019 day 9 STRABISMUS squint.pptx

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STRABISMUS/SQUINT

Dr. Nyoman Sunerti, Sp.MStrabismus Division, Opthalmology

Departement Udayana Medical Faculty


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Strabismus/Squint

Is a misalignment of the eyesMisalignment may be in any direction- inward - outward - upward - downward

Strabismus

: ocular misalignmentAbnormality of binocular vision

Anomalies of neuromuscular control of ocular motility


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Extraocular Muscle

There are six extra ocular muscle plays a role in eye position- Medial Rectus --------------- N III

- Superior Rectus --------------- N III- Inferior Rectus --------------- N III- Inferior Obliq --------------- N III

- Superior Obliq -------------- N IV- Lateral Rectus -------------- N VI


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Strabismus, Terms1. Fusional Status

Phoria, intermitten tropia, tropia2. Fixasi

Alternating, monocular 3. Type Deviasi

Horisontal: esodeviasi/exodeviasiVertical: hyperdeviasi/hipodeviasi

Torsional: incyclodeviasi/excyclodeviasiCombine: horisontal, vertical, torsional

4. Age onset: congenital, acquire d


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Functions of the ocular muscle


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Law of ocular motility

Yoke MusclesAre pairs of muscles, one in each eye, that

produce conjugate ocular movementHering LawOf equal innervation states that during any

conjugate eye movement, equal andsimultanius inervation flow to the yoke muscle


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Main fields of action ektraocularmuscle


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Yoke muscles in cardinal positions of gaze


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Examination of strabismus

History is important in the diagnosis of strabismusFamily historyStrabismus and ambliopia frequently found to occur infamilies

Age at onsetThe earlier the onsert of strabismus, the worse the

prognosisType of onsetThe onset my be gradual, sudden, or intermitentType of DeviationFixationOne eye may constantly deviate or aternating fixation


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Determination of angle of strabismus

A. Prisma and Cover testsB. Objective test

Cover test consist four parts

1. The cover test2. The un cover test3. The alternate cover test

4. The Prism cover test


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Cover test

The examiner observes one eyeA cover is placed in front of the other eye

If the observed eye moves to take up fixation


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COVER TEST

A. Normal

B. Right eye Normal

C. Left Eye NormalD. Right Eye Esotropia

E. Right Eye Eksotropia

F. Right Eye Hypertropia

G.Right Eye Hypotropia


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Objective test

Hirschberg MethodA pen torch is shone into the eyes and the

patient fixate the light.The corneal reflection of the light will becentered in the pupil of the fixating eye, butwill be decentered in a squinting eye.


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Hirschberg test Rough measure of deviation

Note location of corneal light reflex

Reflex at border of pupil = 15 Reflex at limbus = 45


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HIRSCHBERG TEST


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Sensory Changes in Strabismus

Up to age 7 or 8 the brain usually developrespons to ab normal binocular vision that mayoccur if the onset of strabismus is later.This canges include

diplopiasupresionAnomalous retinal correspondenceEccentric fixation


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AmbliopiaIs a unilateral or bilateral reduction of bestcorrected visual acuity, that caused beattributed to the effect abnormality of the eyeCaused by abnormal visual experience early in

life, resulting fromStrabismusAnisometropia (High bilateral refractive errors)Visual deprivation

Treatment : Occlusion therapy, the sound eye iscovered with patch to stimulate the ambliopic eye


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Treatment of Strabismus

Non surgical- Eye glasses

- OcclutionSurgical


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Principles of squint sugerys

RecesionSlackens of muscle bymoving its insertion to

ward its origin

ResectionShorten a muscle toenchance its effective

pull


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Esotropia

The most common type of strabismus morethan 50% of deviation in pediatric populationThe causes can result from abnormality of inervational, anatomical, mechanical,refractive and accommodative


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Mayor type of Esodeviation

1. Accomodative (Refraktive and NonRefraktive)

2. Non Accomodative (Basic, acute)3. Incomitant esotropia (Sixth cranial nerve

paralysis, medial rectus restriction)


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Exotropia

The most common type of exodeviation isintermittent exotropiaWhich is latent at time and manifest at other Onset is usually occurs early


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Classification

Basic type :Exodeviation approximately the same atdistance and near fixationDivergence excess typeExodeviation that is greater at distance fixationthan at near Convergence insufficiency typeIs Present when the exodeviation is greater at

near than at distance


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day 9 STRABISMUS squint.pptx

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