Xiang F, He M, Morgan IG.State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China; ARC Centre of Excellence in Vision Science and Visual Sciences Group, Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, Australia.Ophthalmology. 2012 May 9
In this study, participants had their eyes examined every year from 2006 to 2010 -- kids who developed myopia were followed. The question is, why do children develop myopia, especially if there is a low or no genetic predisposition? Animals generally seem to not develop myopia in their natural environments (but in the lab, they can become myopic under certain conditions); I read an article that said that dogs can become myopic naturally... In this study, it is suggested that myopic defocus possibly slows myopic development, though it does not stop it. According to this theory, becoming myopic and experiencing defocus sends a signal to the eye to slow down axial growth. In most infants these visual input is enough to direct the eye towards emmetropic refraction: unaided good vision at near and far. Why does this process fail in myopic children?
From the text:"Children who were not myopic at the first examination and myopic in at least 1 subsequent examination from 2006 to 2010 were included in the analysis. Annual change in SER increased slowly from 4 years before the first detection of myopia to 2 years before myopia onset (-0.25 to -0.4 diopter [D]). The rate of progression was the highest during the year of onset (-0.92 D). After the first detection of myopia, the rate of progression decreased to -0.71 D in the following year and kept decreasing. Annual change in axial length showed a similar, but inverse, shape to that of SER. Annual change in lens power did not change significantly around the onset of myopia.Before the onset of myopia, axial elongation and progression accelerate. After a myopic refraction is established, axial elongation and progression decrease. We suggest that the increases before myopia may be due to increased intensity of study and decreased time outdoors. In contrast, the rapid slowing after the onset of myopia may represent an inhibitory effect of myopic defocus on eye growth."
Link to abstract:
http://www.ncbi.nlm.nih.gov/pubmed/22578257
