Paediatric ophthalmology and Strabismus

Anatomy of the extraocular muscles

Muscle Origin Insertion Superior rectus Tendinous ring Sclera 7.7mm posterior to limbus superiorly

Inferior rectus Tendinous ring Sclera 6.5mm posterior to limbus inferiorly Lateral rectus Tendinous ring Sclera 6.9mm posterior

to limbus laterally

Medial rectus Tendinous ring Sclera 5.5mm posterior to limbus medially

Anatomy of the extraocular muscles

Muscle Origin Insertion

Superior oblique Superiomedial to optic canal

Sclera, posterior to equator superiorly

Inferior oblique Floor of orbit just posterior to orbital margin and lateral to nasolacrimal canal

Sclera, posterolateral aspect of eyeball inferiorly

Anatomy of the extraocular muscles

Levator palpebrae superiorisAction -- Raises the upper lidNerve supply – (main striated part), 3rd nerve(superior div.) -- (smooth muscle part),sympathetic nerves

from superior cervical ganglionOrigin -- inferior surface of the lesser wing of sphenoid

above and anterior to the optic canalInsertion – striated fibres, anterior surface of superior `

tarsal plate and skin -- smooth muscle fibres, upper edge of superior

tarsal plate

Anatomy of the extraocular muscles Muscle Nerve supply Action Superior rectus 3rd nerve(superior div.) Elevation +

adduction and intortion Inferior rectus 3rd nerve(inferior div.) Depression +

adduction and extortion Lateral rectus 6th nerve Abduction

Medial rectus 3rd nerve Adduction

Superior oblique 4th nerve Depression + abduction and intortion

Inferior oblique 3rd nerve(inferior div.) Elevation + abduction and extortion

Cranial nerve palsies and extraocular muscles

Cranial nerve palsy Position of eye3RD Nerve Out and down with limitation

of adduction, elevation and depression

4th nerve Eye elevated, head tilted to opposite side, and chin down

6th nerve Eye in with limitation of abduction

PAEDIATRIC OPHTHALMOLOGY

Full history, family/birth.Examination• Lids • Corneas• Red reflex• Lens• Eye movements/squint• Dilated pupil examination – vitreous, lens, optic

nerve and retina• May need examination under anaesthesia

Checking visual acuity in children• Check for fixation in each eye• Hundreds and thousands• K pictures2-4 years• Cardiff cards• Sheridan Gardner chart 3-5 years• Snellen chart 4 years and upwards

Sheridan Gardner testBooklet used at distance of 6 meters Card given to child

Amblyopia

• Decreased visual acuity in one eye( usually), due to lack of stimulation of the eye.• Develops in early childhood and must be corrected before 8-10 years of age.• Vision is not improved with glasses and the fundus looks normal. Causes Anisometropia –difference in refractive error between the two eyes

Squint PtosisOrganic -Opacity in media –Cataract.

Corneal scar

Bilateral amblyopia occurs if there is a high refractive error in both eyes that is not corrected with glasses in early childhood.

Amblyopia needs early referral as the sooner it is treated the easier it is to reverse

SquintsNormally, when viewing an object, both eyes point directly at

the object being viewed. An image of the object is focused upon the macula of each eye, and the brain merges the two retinal images into one Sometimes, however, due to some type of extraocular muscle imbalance, one eye is not aligned with the other eye, resulting in a squint or heterotropia

With squint, while one eye is fixating upon a particular object, the other eye is turned in another direction, relative to the first eye

The deviating eye is not stimulated and becomes lazy or amblyopic, resulting in decreased vision in that eye.

Diagnosis of squint

Check vision - in most cases visual acuity is decreased in the squinting eye

Corneal light reflex- look for any deviation of reflex

Cover test- see videoFully dilated fundal examinationCheck for refractive error

Squint in a child= early referral

Treatment of squintPrescribe corrective lens if requiredPatch good eye to reverse the amblyopia of the

squinting eye (vision does not improve if child is over 8 years of age and the earlier treatment of amblyopia is started the easier it is to improve vision)

Ideal position is when vision is equal in each eye and squint then often alternates between each eye

Surgery may be needed get binocular function or for cosmetic reasons

Types of squints

Esotropia (Eye deviates inwards)

Exotropia ( Eye deviates outwards)

Hypertropia (Eye deviates upwards)

Hypotropia (Eye deviates downwards)

Left esotropia

Right exotropiaNote position of light reflexIn centre of pupil in left eyeTo nasal side of pupil in right

Leucocoria (general term meaning white pupil)

Causes• Retinoblastoma –under 3 years of age- uni and

binocular (see lecture on intratumours)• Toxocariasis -3-10 years of age- uniocular• Persistant hyperplastic primary vitreous -

uniocular• Cataract- uni and binocular• Retinopathy of prematurity -binocular

Examination for leucocoria• Red reflex is extinguished and replaced by

white pupil• C.T. and /or MRI is helpful if full fundal exam is

not possible• Examination under anaesthesia may be

necessary

• Any child with leucocoria needs very urgent referral to out rule retinoblastoma

Leucocoria

Left convergent squint(esotropia) and left leucocoria

Congenital cataract

Signs - Leucocoria Nystagmus if bilateralCauses - Hereditary Idiopathic

Galactosaemia- bilateral Persistant hyperplastic primary vitreous-

unilateral Rubella - bilateral, • Delay in treating congenital cataract may lead to

irreversible amblyopia• Treatment – lens aspiration +/- intraocular lens

placement

Retinopathy of prematurity

Risk factors - < 36 weeks gestation

Birth weight < 1500gmsSupplemental oxygen therapyPremature twin

Retinopathy of prematurityPathology and Signs –

Avascularity of peripheral retina –(retinal periphery is only fully vascularised close to term)

A ridge develops between normal, and poorly vascularised retina..

Ischaemia leads to development of neovascularisation. New vessels can bleed into retina and vitreous. Dilated retinal veins and tortuosity of retinal arteries in

posterior pole. Fibrovascular proliferation Retinal detachment Leucocoria

Retinopathy of prematurity

Early diagnosis is essential. Bilateral dilated ocular exam at 4-6 weeks after birth. This is repeated at 2 weekly intervals until 14 weeks of

age and then 1-2 monthly. If no retinopathy at 14 weeks of age – very low risk

after this.

Treatment – Laser photocoagulation ,

Cryotherapy.

Retinopathy of prematurity

Retinal periphery which has been treated by laser photocoagulation

Congenital defects

Congenital naso lacrimal duct obstruction.• Tearing +/- conjunctivitis• Usually opens spontaneously by one year of

age, if not needs syringing and probing under GA.

Congenital defectsCongenital glaucoma or Bupthalmos• Photophobia, tearing, blepharospasm• Corneal diameter >12mm before 1 year of age• Corneal oedema• Increased I.O.P.• Cupped disc• May be uni or binocular• Treatment is surgical +/- topical Rx

Bupthalmos

• Note enlarged right cornea with normal left cornea

Infections in children Ophthalmia Neonatorum • A discharging, red, one or both eyes within the first

four weeks of life.• Accurate diagnosis is imperative- conjunctival swabs Causes –• Chlamydia trachomatis - 5 to 14 days after birth

• Neisseria gonorrhea - 1 to 3 days after birth• Bacteria – staph, strep or gram negative• Herpes simplex virus - 5 to 7 days after birth

Ophthalmia Neonatorum

• Treatment - initially broad spectrum topical antibiotics until swab results obtained.

• Chlamydia-systemic erythromycin 2-3 weeks +topical erythromycin. May effect joints, blood, and C.N.S.

• Neisseria gonorrhea-systemic penicillin 2weeks + topical Rx.

Above infections are notifiable and patients need to be referred to neonatal paediatrician. Mother and partner also need investigation.

• Herpes simplex-vesicles on lids or keratitis -.topical +/- systemic Acyclovir. May cause encephalitis.

Infections in children• Toxocariasis-nematode infection, usually

uniocular .Transmitted via oral-faecal route from dogs.

• Preseptal cellulitis-systemic antibiotics• Orbital cellulitis- rapid onset, unilateral,

chemosis, fever, proptosis, pain. Requires urgent admission; IV antibiotics; CT ;MRI, ENT opinion.• Molluscum contageosum – causes

recurrent sterile conjunctivitis, Rx cautery under GA

Orbital cellulitis