Refer this article as: Camaret, E., Drobe B., Lenses to slow the progression of myopia, Points de Vue, International Review of Ophthalmic Optics, N63, Autumn 2010
Lenses to slow the progression of myopia
An increase in myopia
Myopia remains, for the most part, a mystery. We know how to measure it, correct it, even operate upon it, but we are still largely in the dark as to its origin. The two main causes of myopia are heredity and environmental factors.
It has been shown that lifestyle, place of residence, cultural level and the number of years spent studying can play a role in the evolution or even the appearance of myopia in young people. Frequent use of near vision and a short working distance are also factors that encourage the onset of myopia as well as its progression. It is presumed that factors such as diet or the frequent use of computer screens could also be involved in the onset of myopia.
Over these past few years the number of myopes has increased considerably. American researchers have just established that the rate of myopia in the United States has increased from 25% in the seventies to almost 42% at the beginning of the year 2000 .
But it is most particularly found in Asia, where there are up to 80% of myopes in some countries. The first signs of myopia generally appear at around the age of 6 and progression can reach up to two dioptres per year. Progression usually stops when the child stops growing. In Asia, it is not unusual to see children with myopia of -8 dioptres or more.
Progressive myopia is due to abnormal lengthening of the eye. As well as the need for visual correction, myopia increases the risks of ocular pathologies, such as retinopathies, retinal detachment or glaucoma. High myopia therefore has major consequences on ocular health. These vision problems can also have an impact on social life: in China, policemen, soldiers and pilots have to have good vision to be able to do their jobs.
If the development of myopia could be reduced by half, we would then reduce the risks of retinal pathologies by a factor of 10.
Research and the first solutions
Since the eighties, Essilor has participated actively in various studies on the effect of power additions on myopia progression [2, 3, 4]. It is shown from these studies that progressive lenses can slow by upto 40% the progression of myopia amongst children with near point esophoria, that is about 1/3 of children. For the remaining 2/3, children with exophoria or near point orthophoria, the wearing of a power addition has no effect and may potentially increase their myopia  in the case of strong exophoria.
On the other hand, a recent study undertaken by Doctor Desmond Cheng in Canada, has shown that a prototype lens, combining a power addition with a “base-in” prism for near vision, could slow the progression of myopia by almost 60% in these same children with exophoria . This lens with prismatic addition is currently the most efficient noninvasive solution.
To assist the eye care professional, Essilor has created a very simple measuring tool known as Myopilux (Fig. 1). He can decide at a glance on the phoria of his young patient and thus prescribe the best equipment to slow the progression of myopia: progressive lenses or lenses with prismatic addition.
Since 2005, Essilor has been selling progressive lenses for children on the Asian market (China and Taiwan), known as “Essilor Junior”. A major advertising campaign was used at the Shanghai Optical Fair in 2006 to promote progressive lenses for children and inform parents of the potential risk of progressive myopia. The aim was also to train Chinese opticians in how to use the Myopilux and how to offer a progressive lens to a child, who corresponds strictly to inclusion criteria.
Further research undertaken by Essilor to design progressive lenses for children included measurements being taken on Chinese children, combining biometry, wear parameters and posture for near vision. In 2008 these resulted in a new prototype lens and in 2009 Essilor Asia put on the market the first progressive lens specifically created for Asian myopic children by the Singapore R&D department and protected by international patents, the “Essilor Junior NG”.
For many years Essilor's truly ethical approach has involved it in the control of myopia, particularly through programs and R&D partnerships dedicated to progressive myopia and active participation in wearer tests. As and when studies are carried out, new products will be launched in order to slow further still the progression of myopia in young people.