Congenital problems^[4]

Congenital problems may either conditions^[5], or to intrauterine damage from such factors as drugs or infection. There seem to be no common factors among mothers of babies with congenital eye problems.^[6][7] One study showed that cases with different isolated ocular congenital abnormalities had different maternal characteristics.^[8]

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 (eg 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 can be partial or complete and caused by:

• Congenital glaucoma (most common with abnormally large eye).
• Damage from forceps.
• 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 Wilms' 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 but large opacities may cause nystagmus and amblyopia requiring surgery within a few weeks of birth. There is a high risk of glaucoma associated with surgery in the first year of life.^[9] One study found that incidence was variable and suggested that factors other than the age at which surgery was undertaken were involved in the aetiology of this condition.^[10]
  • Glaucoma and vitreous haemorrhage (the other major complication) are also higher in babies with a family history of aphakic glaucoma, or who had nuclear cataract or persistent fetal vasculature syndrome. Such patients should be monitored closely postoperatively for the development of these conditions.^[11]

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 leading to the formation of more than one pupil in the iris ) and abnormal patterning of the chamber angle between the cornea and the iris. Glaucoma is often an important complication.^[12]

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 uveitis/vitritis.

Defects of choroid and retina

• A number of rare syndromes can cause these, including colobomata and Aicardi's syndrome (severe psychomotor retardation, corpus callosum agenesis, chorioretinal lacunae and early-onset infantile spasms).^[13]
• 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 centre, an elevated ring of pigment around the disc and vessels radiating out from the ring like spokes. It thus resembles the morning glory flower.^[14][15]
• Optic nerve hypoplasia - this may be unilateral or bilateral 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 it 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. See also separate article Septo-optic Dysplasia.

Extra-ocular defects

• Dermoids - these are most frequently seen superolaterally.
• Obstruction of nasolacrimal duct - this causes epiphora in up to 30% of neonates. It is thought to be caused by colonisation with bacteria (50% Gram-negative, 50% Gram-positive). Most cases resolve spontaneously, although persistent symptoms beyond the age of 12 months may require probing. Associated infection - eg conjunctivitis and dacryocystitis - may require antibiotics.^[16] Dacrocystitis can lead rapidly to generalised sepsis and an aggressive approach with intravenous antibiotics and surgical drainage is sometimes required.^[17]
• Craniofacial anomalies - a number of these can affect vision (eg craniosynostosis with downslanting palpebral fissures).^[18]

Poor vision with no apparent cause

The main causes include:

• Leber's congenital amaurosis (retinal dystrophy) - see also separate article Hereditary Retinal Dystrophies.
• Cone dystrophy.
• Oculomotor apraxia (a difficulty in controlling horizontal eye movement).
• Delayed visual maturation - defined as absence of visual response in a child aged under three months, due to gestational immaturity.^[19]

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).

For more detail see separate article Congenital Primary Glaucoma.

Acquired problems

Ophthalmia neonatorum^[20]

This is a conjunctivitis occurring in the first 28 days of life. It is most commonly infective in origin: Neisseria gonorrhoeae, Chlamydia trachomatis, bacteria such as staphylococci, streptococci and viruses - notably the herpes simplex virus - but may also occur as a reaction to chemical irritants. Chlamydial and gonococcal infection can be life-threatening.

For more detail see separate article Ophthalmia Neonatorum.

Retinopathy of prematurity (retrolental fibroplasias)^[16]

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

For more detail see separate article Retinopathy of Prematurity.

Strabismus

Also known as squint, this occurs in less than 2% of babies. If it persists longer than three months of age, referral is indicated. It can be an early presenting feature of retinoblastoma (21% in one study).^[21]

For more detail see separate article Squints.

Amblyopia

This is defined as reduced visual function in one or both eyes, not improved by refraction or removal of pathological obstruction to vision. It is caused by sensory deprivation with or without abnormal binocular interaction during the sensitive or critical period of retinal development in the first 2-3 years of life. The longer the period of visual disability, the worse the prognosis in terms of visual acuity. The most common causes are:

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

For more detail see separate article Amblyopia.

Shaken baby syndrome

Intra-ocular haemorrhages produced by vigourous shaking of a baby may be the only sign of child abuse. Retinal haemorrhages, especially in children under the age of three years, are highly suggestive of shaking (unless there is a history of other head injury) - but there are other rare causes, such as blood dyscrasias and infections.^[22][23]