Visual determinants of myopia:
Over the past 30 years, research in animal models of
myopia have provided abundant information on the mechanisms of "visual control of eye growth".
In summary, perhaps the most crucial discovery from animals studies has been that eye
growth is controlled by visual experience. This conclusion has stimulated many
epidemiological studies in children. Major observations have been that a correlation of
myopia exists (in most studies) with the amount of "near work", with the educational level,
with the educational level of the parents, and with a lack of "outdoor activity and sports" (e.g.
Mutti et al, Invest Ophthalmol Vis Sci. 2002, 43, 3633-3640). A recent large review by Rose & Morgan
(2005) has accumulated considerable evidence for a major environmental contribution to
myopia in industrialized nations which cannot be explained by changes in the genetic
background.
It is surprising that the mechanisms that link near work to myopia are still not well defined.
The most common hypothesis is that insufficient accommodation ("lag of accommodation")
places the focal plane behind the retina and that this condition drives axial eye growth. To
reduce or even reverse the lag of accommodation, progressive addition lenses (reading glasses
with smoothly increasing plus power in the lower visual field) were tested in children (COMET
study, USA, Invest Ophthalmol Vis Sci. 2004, 45, 2143-2151). Their effects on myopia progression
were smaller than expected, although statistically significant. This could indicate that visual
input is not as important in children as in animal models. However, it equally likely that it
indicates that reading glasses do not provide the best optical condition to slow down myopia
progression.
Therefore, it is important to develop an optical correction paradigm that is more
effective against myopia progression:
Project 1/1 Schaeffel - peripheral defocus and
myopia development, Germany
Project 1/2 Artal - advanced optical technologies to
evaluate central and peripheral retinal image quality, Spain
Project 1/3 Rodenstock GmbH - development of advanced spectacle lenses with control of the
peripheral refractive errors, Germany.
About the genetic determinants of myopia [>>]
