Strabismus, Amblyopia & Leukocoria

Strabismus, Strabismus, Amblyopia & Amblyopia & LeukocoriaLeukocoria

Dr. Hessah Alodan, Dr. Hessah Alodan,

Pediatric Opthalmology Dept, Pediatric Opthalmology Dept, KAUHKAUH

Why Two Eyes ?Why Two Eyes ?

You can demonstrate to a patient the difference in their field or their child's field with one eye compared to two. With two eyes you can also demonstrate the peripheral field and the central fusion.

Why Two Eyes ?Why Two Eyes ?

Total binocular field is nearly 170 degrees (varies according to configuration of orbits)

Left Eye Monocular

Binocular

Right Eye Monocular

Why Two Eyes ?Why Two Eyes ?Two Pencils Test

With both eyes open the patient who uses both eyes producing stereopsis can put his pencil accurately on the examiner's pencil if stereopsis is present

The same person with one eye closed or with manifest strabismus or no stereopsis will miss the examiner's pencil initially and place it correctly only after the second or third try.

Visual Axis

Imaginary line between fovea and the object

Binocular Vision

If the visual axises from both eyes intersect at the object, binocular vision occurs

Sensory Fusion

Supper imposed images from each corresponding retinal area in binocular cells at the level of the occipital cortex

1. Same images2. Similar in size3. Similar in clarity

Motor Fusion

Ability to physically move the eyes so that they are pointing in the same direction allowing the corresponding areas of the retina in each eye to be pointing at the object of regard

Visual Axes Misalignment lead to:

1.Confusion

Superimposition of the two different images stimulating corresponding retinal points

2.Diplopia

One object stimulating two none corresponding retinal points

Compensatory mechanism to misalignment of VA :

1.Suppression

Subconscious active neglect of one eye input that occurs only when both eyes are open

2.Amblyopia

Action of extraocular muscles

Muscle Action

All obliques

Abduct

Horizontal Recti

Adduct

All superior muscles

Intort

All inferior

muscles Extort

Action Muscles

Dextroelevation

OD: Superior RectusOS: Inferior Oblique

Dextrodepression

OD: Inferior Rectus OS: Superior Oblique

Levoelevation

OD: Inferior Oblique OS: Superior Rectus

Levodepression

OD: Superior Oblique OS: Inferior Rectus

Right gaze

OD: Lateral Rectus OS: Medial Rectus

Left gaze

OD: Medial Rectus OS: Lateral Rectus

What is Strabismus ?What is Strabismus ?

Ocular misalignment due to abnormality in binocular vision or anomalies in neuromuscular control of ocular motility

Classification of Strabismus:

According to fusion status

1. Phoria Latent tendency of the eye to deviate and

controlled by fusional mechanism

2. Intermittent Phoria Fusion control is present part of the time

3. TropiaManifest misalignment of the eye all the time


According to fixation

1. Alternating Spontaneous alternation of fixation from one

eye to the other

2. Monocular Preference of fixation with one eye


According to type of deviation

1. Horizontal Esodeviation Exodeviation

2. Vertical Hyperdeviation Hypodeviation

3. Torsional Incyclodeviation Excyclodeviation

4. Combined


According to age of onset

1. Congenital

2. Acquired


According to variation of the deviation with gaze position or fixing eye

1. Comitant Same deviation in different direction of gaze

2. IncomitantVariable deviation in different direction of

gaze usually in paralytic or restrictive type of strabismus

Examination

1. History

2. Inspection

3. Assessment of monocular eye function

Visual acuity

Preverbal children

CSMOKNPreferential lookingVisual evoked potential

Examination

Assessment of monocular eye function

Visual acuity

Verbal children

Symbol testsSingle illiterate EAllen pictures H O T V letters

Examination

Assessment of binocular eye function

1. Hirschberg test

2. Krimski’s test

3. Cover test

4. Alternate cover test

5. Prism cover test

Examination

Fundoscopy

Cycloplegic refraction

• Tropicamide

• Cyclopentolate

• Atropin

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Type of Strabismus

Esotropia

• Pseudoesotopia • Infantile esotropia• Accommodative esotropia • Partially accommodative esotropia

Pseudoesotropia

• Occur in patients with flat broad nasal bridge and prominent epicanthal fold

• Gradually disappear with age

• Hirschberg test differentiate it from true esotropia

Infantile Esotropia

• Common comitant esotropia occur before six month of age

• Deviation is often large more than 40 prism diopter

• Frequently associated with nystagmus and inferior oblique over action

• Treatment

Correction of refractive errorTreat amblyopiaSurgical correction of strabismus

Accommodative Esotropia

• Occur around 2 ½ years of age

• Start as intermittent then become constant

• High hypermetropia

• Treatment

Full cycloplegic correctionTreat amblyopia

Partially Accommodative Esotropia

• Improve partially with glasses

• Treatment

Full cycloplegic correctionTreat amblyopiaSurgical correction of strabismus

Type of Strabismus

Exotropia

• Intermittent exotropia • Constant exotropia • Sensory exotropia

Intermittent exotropia

• Onset of deviation within the first year of age• Closing one eye in bright light • Usually not associated with any refractive error • Usually not associated with amblyopia

• Treatment

Correction of any refractive error Surgical correction of strabismus

Constant exotropia

• Maybe present at birth or maybe progress from intermittent exotropia

• Treatment

Correction of any refractive errorCorrection of amblyopia Surgical correction of strabismus

Sensory exotropia

• Constant exotropia that occur following loss of vision in one eye e.g trauma

• Treatment

Correction of any organic lesion of the eyeCorrection of amblyopia Surgical correction of strabismus

Types of Strabismus

Paralytic strabismus

• 6th nerve palsy • 4th nerve palsy• 3rd nerve palsy

6th Nerve Palsy

• Incomitant esotropia

• Limitation of abduction

• Abnormal head position

4th Nerve Palsy

• Congenital or acquired

• Hypertropia of the affected eye with excyclotropia

• Abnormal head position

3rd Nerve Palsy

• Congenital or acquired

• Exotropia with Hypotropia of the affected eye

• In children caused by: trauma, inflammation, post viral and tumor

• In adult caused by: aneurysm, diabetes, neuritis, trauma, infection and tumor

Special Types of Strabismus

• Duane strabismus

• Brown syndrome

• Thyroid opthalmopathy

Duane Syndrome

• Limitation of abduction

• Mild limitation of adduction

• Retraction of the globe and narrowing of the palpebral fissure on adduction

• Upshoot or downshoot on adduction

• Pathology faulty innervation of the lateral rectus muscle by fibers from medial rectus leading to co-contraction of the medial rectus and lateral rectus muscles

Brown Syndrome

• Limitation of elevation on adduction

• Restriction of the sheath of the superior oblique tendon

• Treatment needed in abnormal head position or vertical deviation in primary position

Thyroid Ophthalmopathy

• Restrictive myopathy commonly involving inferior rectus, medial rectus and superior rectus

• Patients presents with hypotropia, esotropia or both

Surgery of Extraocular Muscle

• Recession : weakening procedure where the muscle disinserted and sutured posterior to its normal insertion

Surgery of Extraocular Muscle

• Resection : strengthening procedure where part of themuscle resected and sutured to its normal insertion

Complication of Extraocular Muscle Surgery

• Perforation of sclera

• Lost or slipped muscle

• Infection

• Anterior segment anesthesia

• Post operative diplopia

• Congectival granuloma and cyst

AmblyopiaAmblyopia

What is Amblyopia ?

Amblyopia refers to a decrease of vision, either

unilaterally or bilaterally, for which no cause can

be found by physical examination of the eye

Pathophysiology of Amblyopia

amblyopia is believed to result from disuse from inadequate foveal

or peripheral retinal stimulation and/or abnormal binocular

interaction that causes different visual input from the foveae

No retinal changes - ERG OK

Afferent pupil response has been reported but not common

Lateral geniculate layers subserving amblyopic eyes atrophic

Cortical ocular dominance columns representing amblyopic eye less responsive to stimulus and show changes microscopically

Amblyopia

Three critical periods of human visual acuity development have

been determined. During these time periods, vision can be

affected by the various mechanisms to cause or reverse

amblyopia. These periods are as follows:

• The development of visual acuity from the 20/200 range to

20/20, which occurs from birth to age 3-5 years.

• The period of the highest risk of deprivation amblyopia, from a few months to 7 or 8 years.

• The period during which recovery from amblyopia can be obtained, from the time of deprivation up to the teenage years or even sometimes the adult years

Amblyopia

Diagnosis of amblyopia usually requires a 2-line difference of

visual acuity between the eyes

Crowding phenomenon: A common characteristic of

amblyopic eyes is difficulty in distinguishing optotypes that

are close together. Visual acuity often is better when the

patient is presented with single letters rather than a line of

letters

to 20/70

An amblyopic eye with 20/70 full line vision

may be able to see as well20/30 viewing a single optotype

Causes of Amblyopia

Many causes of amblyopia exist; the most important causes are as follows:

Anisometropia

• Inhibition of the fovea occurs to eliminate the

abnormal binocular interaction caused by one

defocused image and one focused image.

• This type of amblyopia is more common in

patients with anisohypermetropia than

anisomyopia. Small amounts of hyperopic

anisometropia, such as 1-2 diopters, can

induce amblyopia. In myopia, mild myopic

anisometropia up to -3.00 diopters usually

does not cause amblyopia.

Causes of Amblyopia

Strabismus

The patient favors fixation strongly with one eye and does not alternate fixation. This leads to inhibition of visual input to the retinocortical pathways.

Incidence of amblyopia is greater in esotropic patients than in exotropic patients

Alternation with alternate suppression avoids amblyopia

Causes of Amblyopia

Visual deprivation

Amblyopia results from disuse or understimulation of the retina. This condition may be unilateral or bilateral. Examples include cataract, corneal opacities, ptosis, and surgical lid closure

Deprivation Amblyopia

Bilateral Deprivation Amblyopia

Causes of Amblyopia

Organic

Structural abnormalities of the retina or the optic nerve

may be present. Functional amblyopia may be

superimposed on the organic visual loss

Causes of Amblyopia

Ametropic Amblyopia

Uncorrected high hyperopia is an example of this bilateral amblyopia.

Treatment

The clinician must first rule out an organic cause and

treat any obstacle to vision (eg, cataract, occlusion

of the eye from other etiologies).

Remove cataracts in the first 2 months of life, and

aphakic correction must occur quickly

Treatment of anisometropia and refractive errors must occur next

The next step is forcing the use of the amblyopic eye by occlusion therapy

LeukocoriaLeukocoria

Causes of LeukocoriaCauses of Leukocoria

CataractCataract RetinoblastomaRetinoblastoma ToxocariasisToxocariasis Coat´s diseaseCoat´s disease ROPROP PHPVPHPV Retinal detachmentRetinal detachment ColobomaColoboma Retinal dysplasiaRetinal dysplasia Norrie´s diseaseNorrie´s disease

• opacification of the lens.

• Congenital cataracts usually are diagnosed at birth.

• If a cataract goes undetected in an infant,

permanent visual loss may ensue.

cataractcataract

Unilateral cataracts are

usually isolated sporadic

incidents

• Bilateral cataracts are often inherited and associated with other diseases.

•They require a full metabolic, infectious, systemic, and genetic workup.

•The common causes are hypoglycemia, trisomy (eg, Down, Edward, and Patau syndromes), myotonic

dystrophy, infectious diseases

(eg, toxoplasmosis, rubella, cytomegalovirus, and herpes simplex [TORCH]), and prematurity

RETINOBLASTOMARETINOBLASTOMA

CLINICALCLINICAL

MANIFESTATIONSMANIFESTATIONS Leukocoria (60%)Leukocoria (60%) Strabismus (20%)Strabismus (20%)

OTHER- Uveitis, Orbital OTHER- Uveitis, Orbital

cellulitis, Hyphaema, cellulitis, Hyphaema, Heterochromia, Heterochromia, Glaucoma, Bupthalmos Glaucoma, Bupthalmos

Retinoblastoma is the most common intraocular tumor of Retinoblastoma is the most common intraocular tumor of childhood.childhood.

RETINOBLASTOMARETINOBLASTOMA

RetinoblastomaRetinoblastoma The disease is bilateral in approximately 30% of cases. The disease is bilateral in approximately 30% of cases.

The average age at diagnosis is 18 months and 90% of The average age at diagnosis is 18 months and 90% of

patients are diagnosed before the age of 3 years. Less patients are diagnosed before the age of 3 years. Less

than 10% of retinoblastoma suffers have a family history than 10% of retinoblastoma suffers have a family history

of the disorder, 90% of cases areof the disorder, 90% of cases are sporadic sporadic. Of the . Of the

sporadicsporadic cases, the responsible mutation is in a germ cases, the responsible mutation is in a germ

cell in 25% of cases and in a somatic cell in 75% of cell in 25% of cases and in a somatic cell in 75% of

casescases

GENETICSGENETICS

Retinoblastoma gene is a recessive oncogene of 180,000 kilobases.Retinoblastoma gene is a recessive oncogene of 180,000 kilobases.

Located chromosome- 13q14Located chromosome- 13q14

Knudson Knudson two hittwo hit hypothesis: hypothesis:

Germinal cells have one defective and one normal RB gene.Germinal cells have one defective and one normal RB gene.

A somatic mutation results in loss of the normal RB gene and hence retinoblastoma develops A somatic mutation results in loss of the normal RB gene and hence retinoblastoma develops

(somatic mutations occur frequently enough in the developing retina, therefore lesions usually (somatic mutations occur frequently enough in the developing retina, therefore lesions usually

affect both eyes)affect both eyes)

In addition, the first child of a parent who had had a unilateral retinoblastoma has a 4% chance In addition, the first child of a parent who had had a unilateral retinoblastoma has a 4% chance

of developing the diseaseof developing the disease

PATHOLOGYPATHOLOGY

Arise in primitive photoreceptor cells.Characteristic histology:Arise in primitive photoreceptor cells.Characteristic histology:

Retinoblastomas are composed of poorly differentiated neuroblastic Retinoblastomas are composed of poorly differentiated neuroblastic

cells with scanty cytoplasm and prominent basophilic nuclei.cells with scanty cytoplasm and prominent basophilic nuclei.

The tumour proliferates rapidly, with a tendency to outgrow its blood The tumour proliferates rapidly, with a tendency to outgrow its blood

supply and undergo spontaneous necrosis. Necrotic tumour being supply and undergo spontaneous necrosis. Necrotic tumour being

eosinophilic stain pink.eosinophilic stain pink.

Characteristic Flexner-Wintersteiner rosettes represent an attempt Characteristic Flexner-Wintersteiner rosettes represent an attempt

at retinal differentiation. Histologically, a ring of cuboidal cells is at retinal differentiation. Histologically, a ring of cuboidal cells is

seen surrounding a central lumen. Cuboidal tumour cells with seen surrounding a central lumen. Cuboidal tumour cells with

basally oriented nuclei arranged around a central lumen.basally oriented nuclei arranged around a central lumen.

RetinoblastomaRetinoblastomaCalcification is another

feature of retinoblastomas,

usually occurring in necrotic

areas. Calcium stains with

H&E. It is worth identifying

calcium in suspect eyes by

ultrasound, or CT scan to

differentiate retinoblastomas

from other tumours.

MANAGEMENTMANAGEMENT EMPIRICAL GENETIC COUNSELLINGEMPIRICAL GENETIC COUNSELLING

ENUCLEATIONENUCLEATION

unilateral, poor visual prognosisunilateral, poor visual prognosis

PLAQUEPLAQUE

4-12mm +/- vitreous seeding4-12mm +/- vitreous seeding

EXTERNAL BEAMEXTERNAL BEAM

>12mm, multiple foci, only eye>12mm, multiple foci, only eye

LASERLASER

consider- indirect, xenon arcconsider- indirect, xenon arc

cryotherapy if <2dd in sizecryotherapy if <2dd in size

CHEMOTHERAPY, if intracranial extensionCHEMOTHERAPY, if intracranial extension

Non-Retinoblastoma Non-Retinoblastoma MalignanciesMalignancies

Unfortunately, children who have genetic retinoblastoma Unfortunately, children who have genetic retinoblastoma

and survive their primary intraocular cancer have a and survive their primary intraocular cancer have a

substantially increased risk of death from one or more substantially increased risk of death from one or more

nonretinoblastoma malignancies over the course of their nonretinoblastoma malignancies over the course of their

lifetimes, up to 35% of children who have had a bliateral lifetimes, up to 35% of children who have had a bliateral

retinoblastoma and external beam radiation therapy will retinoblastoma and external beam radiation therapy will

develop a second cancer by age 25 yearsdevelop a second cancer by age 25 years

Congenital retinal Congenital retinal telangiectasis (Coats' telangiectasis (Coats'

disease)disease) Congenital retinal telangiectasis (Coats' disease) is an Congenital retinal telangiectasis (Coats' disease) is an

idiopathic retinal vascular disorder that usually affects idiopathic retinal vascular disorder that usually affects

young male patients unilaterally in their first or second young male patients unilaterally in their first or second

decade of life.. Patients may present with decreased decade of life.. Patients may present with decreased

vision, as well as strabismus or leukocoria in children. vision, as well as strabismus or leukocoria in children.

The hallmark feature of congenital retinal telangiectasis The hallmark feature of congenital retinal telangiectasis

is localized fusiform aneurysmal dilations of the retinal is localized fusiform aneurysmal dilations of the retinal

vessels reminiscent of tiny light bulbsvessels reminiscent of tiny light bulbs

Persistent hyperplastic Persistent hyperplastic primary vitreous (PHPV)primary vitreous (PHPV)

Persistent hyperplastic primary vitreous (PHPV) is a Persistent hyperplastic primary vitreous (PHPV) is a

congenital anomaly in which the primary vitreous fails to congenital anomaly in which the primary vitreous fails to

regress in utero. Highly vascular mesenchymal tissue regress in utero. Highly vascular mesenchymal tissue

nurtures the developing lens during intrauterine life. In nurtures the developing lens during intrauterine life. In

PHPV, the mesenchymal tissue forms a mass behind the PHPV, the mesenchymal tissue forms a mass behind the

lens.lens.

Persistent hyperplastic Persistent hyperplastic primary vitreous (PHPV)primary vitreous (PHPV)

A gray-yellow retrolental membrane may produce A gray-yellow retrolental membrane may produce

leukocoria, with the subsequent suspicion of leukocoria, with the subsequent suspicion of

retinoblastoma. retinoblastoma.

In PHPV, the globe is white and slightly microphthalmic. In PHPV, the globe is white and slightly microphthalmic.

Patients have no history of prematurity or oxygen Patients have no history of prematurity or oxygen

administration.administration.

RETINOPATHY OF PREMATURITY RETINOPATHY OF PREMATURITY (ROP)(ROP)

Vasoproliferative retinopathy affecting premature infants Vasoproliferative retinopathy affecting premature infants

exposed to high oxygenexposed to high oxygen

INCIDENCEINCIDENCE

Prematurity (<32/40)Prematurity (<32/40)

Birth weight (30% < 1000gm affected)Birth weight (30% < 1000gm affected)

Oxygen durationOxygen duration

90% ROP regresses spontaneously, 5% blindness90% ROP regresses spontaneously, 5% blindness

Signs include:

• neovascularization,

• fibrous bands

• retinal detachments

• vitreous hemorrhage

• leukocoria

RETINOPATHY OF PREMATURITY RETINOPATHY OF PREMATURITY (ROP)(ROP)

Retinal detachment in Retinal detachment in childhoodchildhood

Retinal detachment in childhood can be confused with Retinal detachment in childhood can be confused with

retinoblastoma, and vice versa. The possibility of an retinoblastoma, and vice versa. The possibility of an

underlying retinoblastoma should always be considered underlying retinoblastoma should always be considered

when a child presents with retinal detachment and when a child presents with retinal detachment and

vitreous hemorrhage, even when a history of trauma is vitreous hemorrhage, even when a history of trauma is

obtained. obtained.

Risk factors:Risk factors:

Trauma Trauma

SurgerySurgery

vitreous detachmentvitreous detachment

high myopiahigh myopia

retinal breaks or tears retinal breaks or tears

retinal vascular diseaseretinal vascular disease

history of detachment in the other eyehistory of detachment in the other eye


SymptomsSymptoms

flashes of lightflashes of light

floatersfloaters

curtain-like decrease in visioncurtain-like decrease in vision


COLOBOMACOLOBOMA

Optic Disc ColobomaOptic Disc Coloboma Due to failure of closure of Due to failure of closure of

foetal fissure inferiorlyfoetal fissure inferiorly

May be isolated disc or May be isolated disc or

associated chorioretinal associated chorioretinal

colobomacoloboma

Usually sporadic, some ADUsually sporadic, some AD

Can be bilateralCan be bilateral

Visual acuity varies from Visual acuity varies from

normal to NPL.normal to NPL.

Strabismus, Amblyopia & Leukocoria

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