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BY D- MOHAMED WAHDAN Professor of ophthalmology

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ILOS   (intended lecture outcome) At the end of this lecture you will be able to know  Ocular muscles and their actions Normal ocular motility Abnormal  ocular motility

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Bony orbit  Angle  of the medial and lateral walls of the orbit  is 45° so the optical axis forms  approximately  23  ° with  both medial &lateral walls.  The  medial walls of the 2 orbits are parallel to each other.

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Extra ocular muscles (EOM):- Four  recti :        Superior rectus     Inferior  rectus       Medial  rectus          Lateral  rectus Two  oblique muscles :        Superior  oblique       Inferior  oblique

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In addition:  Levator palpebrae  superioris  it  inserts into upper eye lid for elevating  upper eye  lid .

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The  4 rectii arises from fibrous ring (annulus of  Zinn ) around  optic foramen . Vertical recti(sup.& inf . Rectus ) run in line with orbital axis & are  inserted  in front of  equator.

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Obliques are  inserted behind equator & form an angle of 51° with visual axis.

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Nerve Supply of EOMs
3rd 4th , and 6th cranial nerves.
• The 3rd (oculomotor nerve) supplies:
All EONIs
except
Latera] Recti-B ff)LBdJe
Abducent newel
Superior ObJlcjue
Trochlear nerve

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Uniocular movements Ductions  – only one eye is  open tested  by asking the pt. to follow a target in each direction of gaze .

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Binocular movements    Versions :-both eyes  open, attempting  to fixate a target &moving in same direction.    Abduction  of one eye accompanied by adduction of other eye is called conjugate movements.

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Vergences :binocular, simultaneous movements  (opp . direction )                 Convergence – simultaneous adduction                 Divergence – outward  movement

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Actions of EOM ACTION PRIMARY SECONDARY TERTIARY MR                ADDUCTION   -- LR                  ABDUCTION   -- SR       ELEVATION  INTORSION ADDUCTION IR        DEPRESSION  EXTORSION ADDUCTION SO      INTORSION  DEPRESSION ABDUCTION IO       EXTORSION  ELEVATION ABDUCTION

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Diagnostic positions of gaze :- 9 Primary  position of gaze:-assumed by eyes when fixating a distant object with head erect. 6  cardinal  positions :- to test 12 EOM in their main field of  action.

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A. Esotropia
B. Exotropia
C. Hypertropia
D. Hypotropia

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ETIOLOGY  OF STRABISMUS 1 .  High Refractive errors ( anisometropia ) - High degree of uncorrected hyperopia in children may cause excessive convergence of the eyes and may lead to the convergent strabismus.

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2. Ocular eye conditions  such as  uniocular  opacities in children that are dense  eg . Cataract, corneal opacities and macular  disease.

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3. Family History Some types of squints run in families and are presented mostly as inherited cases.

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4. Acquired This can either be brought about by trauma or any lesion affecting the EOM’s or CN’s especially no.  III.

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1-Apparent Strabismus Definition:   There is an  appearance of squint ,  but it is  not a true squint  because the  two visual axes are normally directed.

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1-  Apparent  esotropia : Epicanthus. High myopia [negative angle alpha]. Narrow inter-pupillary distance (IPD). Enophthalmos .

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2-   Apparent  exotropia : Lateral  tarsorrhaphy . Hypermetropia  [positive angle alpha]. Wide inter-pupillary distance. Exophthalmos.

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3-  Apparent  hypertropia : Due to ptosis. 4- Apparent  hypotropia : Due to  coloboma  of upper eyelid.

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LATANT SQUENT State of muscle imbalance   in which there is  tendency for eye deviation ,  BUT this tendency is  checked  for the interest of   binocular vision

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Aetiology  of  heterophoria : Errors  of refraction:          Hypermetropia     esophoria .         Myopia   exophoria . Muscle weakness.

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Symptoms of  heterophoria Eye  strain  [muscular  asthenopia ]. Running of letters  together during reading. Diplopia  after prolonged work.

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Diagnosis of  heterophoria : The  principle  is to  abolish fusion   by dissociating the two eyes using: Cover test. Maddox rod test. Maddox wing test.

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Correct  errors of refraction. Exercising prism. Relieving prism [in  hyperphoria  only]. Surgery if  heterophoria  becomes manifest.

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Abnormal deviation of visual axis. [  Abnormal deviation of one visual  axis  in  relation to the other visual  axis ,   from  normal physiologic position ].

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Esotropia (convergent).
Exotropia (djyergent).
Hypertropia (upyyard
Hypotropia (downward dey]don).

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Aetiology Errors  of refraction:     Hypermetropia     esotropia .    Myopia   exotropia . Organic cause of the eye:    Opacity of the media [cornea & lens].    Disease of macula.    Retinoblastoma [ glioma  retinae]. Idiopathic.

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Refraction & fundus
Glasses &
visual acuity
Occlusion
amblyopia
Orthoptic
Surgery not cured].

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Unilateral comitant esotropia:
NJecJjaJ recd!E recæjon I-Y LR rzectjon],
Alternating esotropia:
B]nnecJjaJ recd!E recæjon,

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Unilateral exotropia:
Latera] recd!E recæjon rzectjon],
Alternating exotropia:
B]JateraJ latera] recd!E recæjon,

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Paralytic Strabismus Abnormal  deviation of visual axis,  due to  paralysis  or  paresis  of one or more of  extra-ocular muscles.

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Diplopia, vertigo & headache.
Characters of diplopia:
B]nocuJar,
Hor]zonuJ or
or crczecJ,
Paralytic esotropia d]pJopja,
Paralytic exotropia crczecJ d]pJopja,

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Limitation of ocular movements.
False projection Ifaße or]enutjon],
Secondary angle of deviation > primary.
Abnormal ocular deviation.
Abnormal head posture locular

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Diagnosis of the cause:
Neurological examination
Laboratory investigations' blood sugar,
Imaging
sen & of bra]nj orbit & S]nusæ
Diagnosis of paralyzed muscle:
Diplopia chart.
Hess screen.

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Treatment of the cause.
Surgical treatment:
Wait for 6 months
before surgeny for
of sponunec)1E jnnproyennenl
Strengthen the paralyzed muscle by:
Rzectjon & tendon trarEpJanutjon,
Recession of direct antagonist.
Recession of yoke muscle.

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