GROWING BURDEN

A dramatic rise in myopia prevalence in countries throughout the world is driving a need to better understand the public health consequences of this trend and research on methods for controlling myopia. Kathryn Rose PhD and Brien A Holden PhD, DSc discussed these topics at the 2015 annual meeting of the Association for Research in Vision and Ophthalmology in Denver, USA.

According to the findings of a recently completed analysis of temporal trends, Dr Holden and colleagues project that by 2050, half of the world’s population will be myopic.

“More importantly, however, there will be an increased prevalence of high myopia (5.0D and above). We predict that in 2050, 10 per cent of the world’s population, or about one billion people, will be high myopes,” said Dr Holden, Chief Executive Officer of the Brien Holden Vision Institute, Sydney, Australia.

The significance of the latter estimate has to do in large part with the association between high myopia and increased risk of blinding eye disease. Although there is a need for better information to quantify how much visual impairment and blindness is attributable to high myopia, available data indicate that myopic macular degeneration is the leading cause of blindness in Japan and the fifth most common cause in the USA, said Dr Holden. It was also found to be the most important cause of impaired vision among persons aged less than 75 years in the Rotterdam Eye Study.

Dr Rose, Head of Discipline (Orthoptics), University of Technology Sydney, Australia, pointed out, however, that even lower levels of myopia (i.e less than 3D) are associated with an increased likelihood of glaucoma, cataract and, most worrisome, retinal detachment. In addition, she cited a study that reported retinal changes were already present among children and teens with -8 to -10D of myopia. (Analysis of High Myopic Maculopathy Based on Fundus Photos: Zhongshan Ophthalmic Center-Brien Holden Vision Institute High Myopia Registry; Ou X, Xinxing G, Mingguang H)

Dr Rose also noted that there is a need for better information on the costs associated with undercorrection and uncorrection of myopia. Results of a recent study by Congdon and colleagues showing that providing free glasses improved academic performance of primary school age children in rural China indicate that such cost analyses may need to factor in the impact on educational outcomes, she said.

EARLY INTERVENTION

Since younger age of onset of myopia is associated with greater annual progression and an increased risk of developing high myopia, there is great interest in interventions that delay the development of myopia and/or slow its progression.

“If we can start controlling myopia progression in any child who is a -1.0D myope and reduce its rate of increase by 50 per cent, we could eliminate 89 per cent of cases of high myopia,” said
Dr Holden.

Discussing methods for controlling myopia, Dr Holden emphasised the need for both halting the use of techniques that seem to worsen myopia progression and implementing effective interventions. Modalities to avoid include undercorrection and the use of conventional single-vision spectacles or contact lenses.

Methods that can reduce the incidence of high myopia include increasing outdoor activity, treatment with atropine or 7-methylxanthine, orthokeratology, and novel myopia control spectacles and contact lenses that shift the peripheral image in front of the retina or that shift parts of the retinal image forward. Dr Holden postulated, however, that the pharmacological methods in contrast to the optical-based methods are likely to be associated with a rebound effect.

Dr Rose observed that school-based programmes appear to have the greatest potential for success in getting children to spend more time outdoors. Now, however, the obstacle remains to gain support from policymakers to implement that strategy.

Ideally, the future will bring ways to identify at a young age those children who are fast-growing myopes and at greatest risk for developing high myopia. Still, it remains to be seen if it is possible to control the progression of a child destined for high myopia and its pathological consequences, Dr Holden said.

Kathryn Rose: kathryn.rose@uts.edu.au

EuroTimes wishes to extend our sincere condolences to the family, friends and colleagues of Dr Brien A Holden, who has sadly passed away since speaking at this year’s ARVO annual meeting. For tributes to Dr Holden’s life and work, visit:
www.brienholdenvision.org