Paediatric glaucoma: Epidemiology and pathogenesis
Paediatric glaucoma is an important but under-represented subspecialist field of glaucoma. A child diagnosed today with congenital glaucoma has a five times longer life expectancy than a patient diagnosed with primary openangle glaucoma (POAG). Therefore, the impact of a blind child to the family, society as a whole and not least to the child themselves, is immense. It is, therefore, of the utmost importance that the treatments we offer allow these children, to enjoy a sighted and independent life. The importance of this disease is shown by the fact that 18% of children in blind institutions worldwide have glaucoma and it is responsible for 5% of childhood blindness.1
Paediatric glaucoma is an intraocular-dependent disease and the prognosis depends on early, accurate diagnosis, successful control of intraocular pressure (IOP), treatment of associated ocular abnormalities, including refractive error and prevention of amblyopia. There is currently debate as to how the childhood glaucomas should be classified but generally, they can be divided into primary glaucoma, which includes 'primary congenital glaucoma' (PCG), and juvenile-onset glaucoma. Secondary glaucoma, may have a purely ocular phenotype, or be part of a systemic disease, such as a metabolic, chromosomal or connective tissue disorder.
Much of the most uptodate information regarding the epidemiology of paediatric glaucoma comes from the British Infantile and Childhood Glaucoma Eye Study (BIG Eye) by Papadopoulos et al.2 This was a national, prospective, population-based study, performed as part of the British Ophthalmological Surveillance Unit programme (BOSU), which is aimed at collecting information on the management of rare ophthalmic disorders. The study involved active surveillance over a 12 month period, between December 2001 and November 2002, to identify children aged 16 years and younger with primary and secondary glaucoma and cases notified by consultant ophthalmologists in the UK. Eligible cases were re-evaluated 12 months after notification.
Of the children diagnosed with PCG, 94% required surgery and 75% had surgery within 4 weeks of diagnosis. The surgery of choice was either goniotomy or trabeculotomy in 87% of cases. In 50% of cases second surgery was required, 31% required 3 surgeries and 15% required 4 operations.
Of the children diagnosed with secondary glaucoma, the most frequent diagnosis was lensrelated (either aphakia or pseudophakia), 23% were secondary to the phacomatoses (most commonly SturgeWeber syndrome), 19% due to uveitis and 10% secondary to anterior segment dysgenesis. As opposed to PCG, most cases (67%) were unilateral and a lower proportion required surgery (64%).
A similar study from Toronto published in 1999 provided similar results, looking at all cases presenting to the Hospital for Sick Children over a 21year period. In this series, 98% of children with PCG required surgery and 50% of aphakic glaucoma cases required surgery, many being managed successfully with medical treatment.3