Eye Problems in Babies

Eye problems in babies may be divided into congenital or acquired.

These can either be due to developmental problems, mainly secondary to genetic conditions, or to intrauterine damage from such factors as drugs or infection.

Defects of the globe

• Anophthalmos - complete failure of development of the optic vesicle
• Congenital cystic eye - failure of development of the globe
• Coloboma - failure of complete closure that can affect the iris, retina or choroid
• Nanophthalmos - small eye with normal function
• Microphthalmos - small eye without normal function (e.g. cataract, coloboma, congenital cyst)

Defects of the lids

• Congenital ptosis - this is usually due to defective muscles of the upper lid but may also be due to Horner's syndrome and 3rd nerve palsy
• Eyelid colobomata - often associated with specific craniofacial syndromes

Defects of the cornea

Corneal opacity

This can be partial or complete and caused by:

• Congenital glaucoma (commonest with abnormally large eye)
• Forceps damage
• Endothelial development abnormalities
• Persistent attachment of lens
• Intrauterine inflammation
• Interstitial keratitis
• Megalocornea - an X-linked inherited defect associated with an abnormally large, but clear, cornea

Defects of the iris and pupil

• Corectopia - this is inappropriately positioned pupils. The condition is relatively common. The pupils are usually positioned upwards and outwards.
• Polycoria - two or more pupils may exist in one iris.
• Coloboma of iris - this is usually seen in the lower part of the iris towards nose, but defects may affect other parts of the eye.
• Aniridia - this is a rare genetic defect with absent iris often with secondary glaucoma (in the absence of a family history, it may be associated with Wilm's tumour).
• Albinism - patients may also have poor eyesight and nystagmus.
• Heterochromia - irises of different colours may be associated with normal function or may occur with congenital Horner's syndrome.
• Congenital cataracts may be secondary to maternal rubella infection or be an inherited defect. Small opacities may not cause visual problems, large ones may cause nystagmus and amblyopia requiring surgery within a few weeks of birth and long-term wearing of contact lenses. There is a high risk of glaucoma associated with surgery before 4 weeks.²

Other lens and anterior segment defects

Lens defects include colobomata and subluxation as occurs in Marfan's syndrome. Rarely, incorrect development of the neural crest can cause a number of syndromes which affect the anterior segment. An example is Axenfeld-Rieger's anomaly, which consists of small eyes (microphthalmia), hypoplastic irises, polycoria (iris tears), and abnormal patterning of the chamber angle between the cornea and the iris. Glaucoma often is an important complication.³

Vitreous defects

• The remains of the hyaloid artery may appear on the optic disc (Bergmeister's papilla) or of the lens (Mittendorf's dots).
• White pupil (leukocoria) can be caused by:
  • Persistent hyperplastic primary vitreous
  • Stage V retinopathy of prematurity (retrolental hyperplasia)
  • Severe posterior uvitis/vitritis

Defects of choroid and retina

• A number of rare syndromes can cause these, including colobomata and aicardia syndrome (severe psychomotor retardation, corpus callosum agenesis, chorioretinal lacunae, and early-onset infantile spasms).⁴
• Scarring can result from congenital toxoplasmosis.

Benign abnormalities are frequently seen as in:

• Minor defects of retinal vessels at nerve head
• Tilted disc from unusual angle of nerve entry

More severe defects include:

• Central coloboma of the disc - this is also called Morning glory syndrome. The optic nerve head is funnel-shaped with a white dot in the center, an elevated ring of pigment around the disk, and vessels radiating out from the ring like spokes. It thus resembles the Morning glory flower.⁵
• Optic nerve hypoplasia - this may be uni- or bi-lateral and is a non-progressive condition. It is now realised to be relatively common with many cases causing only minor visual impairment that may only become apparent later in life. However, in severe cases can produce a range of visual defects including total blindness. It can be difficult to diagnose and is often associated with congenital defects of the brain and facies.

Extra-ocular defects

• Dermoids - these are most frequently seen superolaterally
• Obstruction of nasolacrimal duct - this causes epiphoria in up to 30% neonates. It is thought to be caused by colonisation with bacteria (50% Gram negative, 50% Gram positive). Ofloxacin topical drops are the treatment of choice. Persistent epiphoria will need probing.^6,7
• Craniofacial anomalies -a number of these can affect vision (e.g. craniosynostosis with downslanting palpebral fissures)⁸

Poor vision with no apparent cause

Main causes include:

• Leber's congenital amaurosis (retinal dystrophy)
• Cone dystrophy
• Oculomotor apraxia (a difficulty in controlling horizontal eye movement)
• Delayed visual maturation - defined as absence of visual response in a child under three months due to gestational immaturity⁹

Congenital glaucoma

This is often bilateral and associated with other defects. Early diagnosis is necessary to avoid irreversible blindness. Signs include:

• Severe photophobia
• Corneal haze
• Corneal opacity
• Increased corneal diameter
• Increased size of eye (due to raised intra-ocular pressure and non-rigid sclera)

Ophthalmia neonatorum¹⁰

Neonatal conjunctivitis can be caused by a number of agents including:

• Chlamydia - this is common cause of neonatal conjunctivitis. The incubation period is 5-14 days. It is diagnosed by laboratory studies of conjunctival scrapings. The infection can vary from mild self-limiting inflammation to a severe condition causing blindness. Treatment is with systemic erythromycin, as topical treatment is not sufficient.
• Bacteria - infection presents at age 2-5 days. Treatment needs to be based on examination of conjunctival smears. Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus viridans, and Staphylococcus epidermidis are common Gram-positive organisms. Neisseria gonorrhoea can penetrate the cornea and cause severe inflammation. Pseudomonas spp.. infection is rare but also carries significant risk of corneal damage.
• Herpes simplex - this is diagnosed on examination of conjunctival smears. It is mostly acquired from maternal genital infection during the birthing process, and can be avoided if the condition is recognised and Caesarian delivery is instituted. The condition is usually mild, but in babies with immune deficiency, serious complications such as encephalitis can develop. Topical or systemic antiviral therapy may be necessary.

Retinopathy of prematurity (retrolental fibroplasias)⁶

This occurs when there is disruption of the vascularity of the retina. 80% of babies are less than 1kg in weight, and the condition is associated with prolonged administration of oxygen. Abnormal vessels develop in areas where vascular and avascular tissue meet. The condition sometimes resolves spontaneously but may require laser therapy or surgery.

Strabismus

Also known as squint, this occurs in less than 2% of babies. If it persists longer than 3 months of age, referral is indicated. It can be an early presenting feature of retinoblastoma.¹¹

Amblyopia

This is defined as unilateral reduced visual acuity that cannot be corrected with lenses, with no obvious cause. It is associated with conditions in which one eye fails to provide a visual signal over a long period of time. The longer the period of visual disability, the worse the prognosis in terms of visual acuity. Commonest causes are:

• Strabismus - secondary to suppression of images from affected eye to avoid double vision
• Anisometropia - failure to focus both eyes simultaneously

Shaken baby syndrome

This can cause intra-ocular haemorrhages, which may be the only sign of abuse.¹² Retinal haemorrhages, especially in children under the age of 3 with no head injury, are highly suggestive of shaking. However, other causes, such as blood dyscrasias and infections.¹³