Cataract in children

Choosing to operate in cases of paediatric cataract depends on a range of factors

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Writing in 1982, Noel Rice and David Taylor said that “bilateral congenital cataract is the most common cause of potentially treatable blindness in infancy”. That remains the case, according to Chris Lloyd MD, who was speaking at the Annual Conference of the Irish College of Ophthalmologists in Galway, Ireland. Studies have suggested that the incidence of cataract in infants is about 2.5 per 10,000, increasing to about 3.5 per 10,000 by the age of 15. Cataract is not a diagnosis, however, said Dr Lloyd, who is Consultant paediatric ophthalmologist at Great Ormond Street Hospital for Children in London, UK. “Cataract is derived from the Greek word for waterfall, and it tells you there’s a whitish opacity in the lens. But the severity of the opacity can vary,” he said. “Prolonged early monocular visual deprivation in infancy causes irreversible neurological changes – you develop an abnormal lateral geniculate nucleus and an abnormal occipital cortex,” said Dr Lloyd. Early intervention – of some kind – is therefore crucial. The density of the cataract will determine whether it requires conservative management or surgical intervention, and studies have shown that with surgery, results were best where children with unilateral cataract had surgery by six-to-eight weeks, while in the bilateral group results were best at eight-to-10 weeks (Birch et al, J AAPOS. 2009 Feb; 13(1): 67–71). GOLD STANDARD Lensectomy – removing the lens without inserting an implant lens – remains the gold standard procedure for young infants, said Dr Lloyd, who expressed uncertainty about the benefit of implanting intraocular lenses in infants. “Infant eyes are small, they have a hypoplastic and vascular iris, they’ve got an immature trabecular meshwork, the anterior chamber is shallow, and the eyes are floppy – the sclera is not rigid.” Studies such as the IOLunder2 and the Infant Aphakia Treatment Study (IATS) suggest that visual acuity results were not significantly different between patients that received a lens and those that did not. There were, however, more reoperations in the implant group, while strabismus was slightly increased in children that received contact lenses. If a child is put to sleep, Dr Lloyd is adamant that the anaesthetic not be wasted. Checking intraocular pressure, corneal diameters, B-scan ultrasonography, pachymetry, keratometry, biometry – are all things that should be done while the opportunity is there. In children under 5, a surgical posterior capsulorhexis and anterior vitrectomy is essential: “If you don’t do this, the visual axis will opacify within weeks and you’ll end up having to come back to carry out a YAG or a surgical capsulotomy.” Where lenses are required, allowances must be made for myopic shift related to growth of the eye, and Dr Lloyd recommends a table produced by Dr Scott McClatchey from San Diego that helps calculate appropriate IOL power.