Glaucoma- congenital
Overview
There are various forms of congenital glaucoma. Some arise in the context of other abnormalities (e.g. Reiger's syndrome, Sturge-Weber syndrome and neurofibromatosis) but the commonest type of infantile glaucoma is in fact primary congenital glaucoma. In 90% of cases, this is sporadic and in the remaining 10% of cases, there is an autosomal dominant pattern of inheritance
Symptoms
* Corneal changes including oedema which causes haziness. This may be the first abnormality noticed by the parents. * Globe enlargement (if the IOP rises before the age of 2), known as buphthalmos. This is not generally noticed by parents unless it is unilateral or markedly asymmetrical, when they may report that their child has a 'large eye'. * Other highly significant symptoms are photophobia, epiphora and blepharospasm.
Causes
Most cases of primary congenital glaucoma are sporadic in occurrence. However, evidence exists suggesting that the disease may be transmitted through an autosomal recessive pattern, with variable penetrance, or a polygenic inheritance pattern. CYP1B1, the gene encoding cytochrome P4501B1, is associated with primary congenital glaucoma. GLC3B located on band 1p36 and GLC3C located on band 14q24.3 are loci that are linked to primary congenital glaucoma, but the genes are unknown.
Diagnosis
* Cloudy cornea at birth - birth trauma, intrauterine rubella, some metabolic disorders (e.g. mucopolysaccharidoses), congenital corneal dystrophies. * Large cornea - very high myopia, megalocornea. * Epiphora - delayed canalisation of the nasolacrimal duct (very common). * Raised IOP - tumours (e.g. retinoblastoma), retinopathy of prematurity, intraocular inflammation, trauma.
Prognosis
The corneal oedema may persist for several weeks but often resolves as does the optic disc cupping (unlike adults). However, parents (and eventually, patients) need to be aware that there is always a risk of the pressure rising again and they will need life-long monitoring. About 50% of patients are left with a degree of visual loss2 which may be due to persistent oedema, persistent optic disc cupping, nystagmus, large refractive errors or amblyopia. An enlarged globe will also be more susceptible to damage in the future.
Treatment
* Primary care - any child presenting with symptoms or signs suggestive of glaucoma should be referred to the ophthalmologists. If the child appears to be systemically unwell (irritable, not feeding), referral should be immediate. If the symptoms have been going on a while, discuss it with the duty ophthalmologist. * Medical4 - this is usually temporary and initiated on diagnosis whilst awaiting surgery. It may involve the use of topical beta-blockers ± systemic carbonic anhydrase inhibitors. * SurgicalSurgery is the definitive treatment and can involve one or more of the following: * Goniotomy - this is usually performed at the initial examination under anaesthetic once the diagnosis is confirmed. It involves opening Schlemm's canal (which drains the aqueous) via an incision into the trabecular meshwork. This procedure may need to be repeated more than once.