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International consensus: Pressure-related damage defines childhood glaucoma
New classification system aims to establish a shared language for collaboration and research.
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Ophthalmologists have different opinions on precisely what constitutes childhood glaucoma, with some concluding that elevated IOP alone indicates the disease.
While certainly a risk factor, elevated IOP alone does not signify childhood glaucoma, according to Allen D. Beck, MD, point person for developing the Glaucoma Research Network/World Glaucoma Association childhood glaucoma classification system.
To move toward greater consensus, the Childhood Glaucoma Research Network, an international collaboration of pediatric ophthalmologists and glaucoma specialists who look after children with glaucoma, enlisted Beck and a team of experts to produce a classification system that would streamline how childhood glaucoma is defined and categorized, with the aim of providing a framework for future research.
Beck and colleagues developed a new definition based on their knowledge of the similarities and differences between adult and childhood glaucoma.
“We came up with a new way of defining glaucoma … as pressure-related damage to the eye,” Beck said, adding that the damage is to the “whole eye, not just the optic nerve, because the infant eye can stretch and there can be corneal findings associated with at least the early onset of childhood glaucoma.”
Despite their strong merits and clinical applicability, childhood glaucoma classification systems have not achieved national, let alone universal, consensus, Beck said.
“Part of the problem is that, at least internationally, we don’t speak the same way,” he said.
The classification
“The aim of the new classification was for it to be simple, logical and easily remembered,” Maria Papadopoulos, MB BS, FRACO, said. “Instead of it being populated with every cause of childhood glaucoma, we deliberately made the categories simple and listed only the most common causes of childhood glaucoma but provided guidance to assist with the categorization of rarer conditions not listed.”
Papadopoulos, one of the editors of the World Glaucoma Association Consensus on Childhood Glaucoma, a book in which the new classification system is detailed, highlighted the system’s simplicity, clarity and broad categorization.
The classification system divides childhood glaucoma into primary childhood glaucoma, encompassing primary congenital glaucoma and juvenile open-angle glaucoma, and secondary childhood glaucoma, encompassing glaucoma associated with non-acquired ocular anomalies, glaucoma associated with non-acquired systemic disease or syndrome, glaucoma associated with acquired conditions and glaucoma after cataract surgery.
Glaucoma after cataract surgery was given its own category because of its significant association with glaucoma, especially congenital cataracts.
“Congenital cataracts are relatively rare, but it is still one of the most common mechanisms by which kids develop glaucoma,” Beck said. “If we do nothing else but heighten awareness of the increased risk for glaucoma following cataract surgery and that they need to be watched for life, that would be huge in terms of screening and management of childhood glaucoma.”
Improved diagnosis, referral
While the classification system does not reduce treatment challenges, it enhances the diagnosis and referral process, Papadopoulos said.
“The new definition and classification impacts the diagnosis and classification of [childhood glaucoma] for clinical and research needs,” she said. “It allows us to all ‘sing from the same hymn sheet,’ so to speak, so that we are calling the same thing childhood glaucoma, and it encourages the use of the same term internationally to describe a condition, for example, primary congenital glaucoma.”
Beck said the tendency among general practitioners has been to group all childhood glaucomas into the category of primary congenital glaucoma, which generally requires surgery soon after detection.
“It gives [physicians] some way of framing the diseases and thinking about it in a broader context rather than just putting it in one box,” he said.
Moving forward
So far, Beck said, the response to the new classification system has been mixed, with some institutions adopting it for training and other professionals using it in their clinical practice, noting its accessibility and practicality. But he acknowledged that not all childhood glaucoma specialists have referred to it positively, with some describing the terminology of the new classification system as “clunky” and others questioning the need for a new classification system at all.
“My response is that simplicity of the new system is a big advantage and the new terms are more specific,” Beck said.
The classification system is succinct enough to allow for changes resulting from future studies, which hinge on knowing who works in the childhood glaucoma field and sharing a common language about childhood glaucoma, he said. But more work is needed to more completely disseminate it.
“The classification system is a step forward toward trying to get to a better place where we can study childhood glaucoma with a goal of developing outcome data that help both the eye care providers and the parents and guardians of the children that have the disease,” Beck said. “That may be a big goal, but we have a lot more work to do, and to me this is a stepping stone to making that happen.” – by Steve Ahern