DONE BY:Kamal Sub-LabanMahmoud Salman

Mustafa Jaber

Anatomy Review•The eye layers:

1 -A tough outer coat (fibrous).

2 -A rich vascular coat (the choroid)

3 -innermost neural (retnia).

Medial and lateral recti horizontal eye movement

Superior and inferior recti vertical eye movement

Superior oblique depression during adduction

Inferior oblique elevation during adduction

Nerves responsible for eye movement are:

3rd , 4th and 6th Their nuclei are found in the brain stem.Together they have connections with

gaze center. And these connections ensure that both eyes are moving

together in a coordinated way.

Eye movements:Eye movements:

1. Ductions: monocular eye movement-Vertical axis Adduction: SR, IR, MR Abduction: IO, SO, LR-Horizontal axis Elevators: IO, SR Deppressors: SO, IR-Anteroposterior axis Medial rotators: SR, SO Lateral rotators: IR, IO

2.Versions: binocular eye movement in the same direction

Dextro=right , Levo=left Primary position Dextro (to the right): Elevation: RSR+ LIO Depression: RIR+ LSO Version: RLR+ LML Levo (to the left): Elevation: RIO+ LSR Depression: RSO+LIR Version: RMR+LLR

3 .Vergences: binocular eye movement in opposite direction

Convergence – inward

Divergence- outward

Amblyopia refers to diminished vision in either

one or both eyes. Amblyopia is the medical

term used when the vision in one of the

eyes is reduced because the eye and the

brain are not working together. The eye

itself looks normal, but it is not being used

normally because the brain favors the other

eye.

Most cases are asymptomatic, which make it

often goes undetected.

In severe cases:

1. poor depth perception may be found.

2. poor spatial acuity

3. low sensitivity to contrast

4. reduced sensitivity to motion

1. Strabismus: A misalignment of the eyes is the most

common cause of functional amblyopia. The two eyes

are looking in two different directions at the same time.

The eyes may turn in, out, up, or down. Strabismus may

be diagnosed at birth, or it may develop later in

childhood. The brain is sent two different images and

this creates confusion. Images from the misaligned or

"crossed" eye are turned off to avoid double vision.

2. Refractive or anisometropic Amblyopia:

A difference of refractive states exists

between the two eyes (in other words, a

difference in prescription between the two

eyes). Because the brain cannot fuse the

two images, the brain suppresses the

blurred image, causing the eye to become

amblyopic.

Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles that prevent bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely affect depth perception. Strabismus can be either a disorder of the brain coordinating the eyes or a disorder of one or more muscles, as in any process that causes a dysfunction of the usual direction and power of the muscle.

why squint is important ●A squint may show that the acuity of the eye is

impaired ●A squint may itself cause amblyopia in a child

●A squint may be a sign of a life threatening condition like retinoblastoma

CLASSIFICATION OF CLASSIFICATION OF STRABISMUSSTRABISMUS

Strabismus can be classified in terms of:Strabismus can be classified in terms of:

1.DIRECTION OF DEVIATION1.DIRECTION OF DEVIATION- Hyper deviation- Hyper deviation- Hypo deviation- Hypo deviation- Divergent- Divergent- Convergent- Convergent

2. COMITANCY2. COMITANCY- concomitant / non-- concomitant / non-paralyticparalytic- incomitant / paralytic- incomitant / paralytic33 . .CONSTANCYCONSTANCY

- constant- constant- intermittent- intermittent

The movement of both eyes are full (there is no paresis) but only one eye is directed towards the fixated target.

The angle of deviation is constant and unrelated to the direction of gaze.

It is the common squint that is seen in childhood.

Under age of 6, it is rarely caused by serious neurological disease. It’s usually primary in this age group.

Strabismus arising later in life may have a specific and serious neurological basis.

The degree of misalignment varies with direction of the gaze.

One or more of the extraocular muscles or nerves may not be functioning properly, or normal movement may be restricted mechanically.

This type of strabismus may indicate either a nerve palsy or extraocular muscle disease.

Vascular disease..ex Dm, hypertension Orbital disease…ex neoplasia Trauma..most common cause of palsy of

4th,6th Neoplasia… glioma Raised intracranial pressure may cause a

3rd or 6th nerve palsy Inflammation… sarcoidosis

Dysthyroid eye disease Myasthenia gravis Ocular myositis Ocular myopathy Browns syndrome

Heterophoria is a latent tendency for misalignment of the two eyes that becomes a manifest only if binocular vision is interrupted such as by covering one eye

A minor degree of heterophoria is normal for most individuals

Esotropia=inward movement Exotropia=outward movement Hypertropia=upward movement Hypotropia=downward movement prefix+phoria=(latent)the tendency to

have squint when there is no concentration on a certain object….most common is exophoria

Corneal inspection Hirschberg corneal light reflex test Cover-uncover test

Have the patient look at the six cardinal positions of gaze to differentiate between concomitant and non-comitant

Objective assessment of ocular alignment In newborn and often in young children it

may be the only feasible method Normally the light is reflected on each

cornea symmetrically and in the same position relative to the pupil and visual axis on each side

In deviating eye the light reflection will be not centrally positioned and in direction opposite to that of the deviation

Example…pupil margin 15’,limbus 45’,iris 30’

Easy, requires no special equipment and detect almost every case of tropia

Can be used in patients >6yrs Have the patient look at the fixation point Note which eye seems to be fixating Cover it and observe the other If it moves to pick up the fixation=>this eye

was not directed toward the object of regard orginally

No shift on cover testing means there is no tropia

Two types of cover test help to reveal a squint, especially if it issmall and the examiner is unsure about the position of thecorneal reflections.● In the cover and uncover test, one eye is covered and theother eye is observed. If the uncovered eye moves to fix onthe object there is a squint that is present all the time—amanifest squint. The test should then be carried out on theother eye. A problem arises when the vision in the squintingeye is reduced, and the eye may not be able to take upfixation. This emphasizes the need to test the vision of anypatient with squint. If the cover and uncover test is normal(indicating no manifest squint) the alternate cover testshould be done.● In the alternate cover test, the occluder is moved to and frobetween the eyes. If the eye that has been uncovered moves,then there is a latent squint.

The patient complain of diplopia, there may be head posture to compensate for the eye to move in particular direction.

In third nerve palsy: failure of adduction, elevation and

depression of the eye. Ptosis in some cases, a dilated pupil due to involvement of autonomic fibres.

A fourth nerve palsy result in defective depression of eye when attempted in adduction.

A sixth nerve palsy results in faillure of abduction of the eye.

Early detection The most effective way to support

fusion(binocular vision) is to treat amblyopia (failure of normal visual development) and equalize vision

Glasses can treat some or all of the esotropia

In farsighted and may decrease deviation in near sided with myopia

Surgical corrections of misalignment may still be necessary for functional or cosmetic reasons

It must be stressed that surgery is not an alternative to glasses and patching when amblyopia

In paralytic strabimus treatment is directed to underlying pathology

Diplopia can be helped by fitting prisms to the patients glasses