Peripheral vision can influence eye growth and refractive development in infant monkeys.

Peripheral vision can influence eye growth and refractive development in infant monkeys.
Smith EL 3rd, Kee CS, Ramamirtham R, Qiao-Grider Y, Hung LF.
Invest Ophthalmol Vis Sci. 2005 Nov;46(11):3965-72.
College of Optometry, University of Houston, TX 


This study investigated the role of peripheral vision in the development of induced myopia in monkeys.  The monkeys in the experiment had their peripheral vision obstructed and were allowed to have clear central vision, and they developed myopia under these conditions.  Once the obstruction was removed (helmets with spectacles) the monkeys recovered from myopia.  


Refractive error at the periphery varies from vision at the center.  People with myopia tend to be hyperopic (blurred vision at near distances) in the periphery and myopic (blurred vision at far distances) in the center.  So an optical correction that is best for the center may be actually detrimental for the periphery.   This is the idea behind the MyoVision by Zeiss lenses that are available currently in Asia.  The center corrects for myopia and the periphery has a lower prescription, like a concentric bifocal.


From the text:
"On the one hand, the peripheral retina can contribute to emmetropizing responses and to ametropias produced by an abnormal visual experience. On the other hand, unrestricted central vision is not sufficient to ensure normal refractive development, and the fovea is not essential for emmetropizing responses."

Link to article:
http://www.iovs.org/content/46/11/3965.full

Monovision slows juvenile myopia progression unilaterally

Monovision slows juvenile myopia progression unilaterally.

Br J Ophthalmol. 2005 Sep;89(9):1196-200.
Monovision slows juvenile myopia progression unilaterally.
Phillips JR.
Department of Optometry and Vision Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.

I've read in various articles and websites that undercorrection (wearing a lower spectacle prescription than the one that gives the sharpest vision at 20 feet) may  improve, may worsen and may not have any impact on myopia progression.  I found every argument and study to be persuasive to some degree.

The purpose of this study was to find if monovision (wearing one lens corrected for distance and another for near vision), would reduce accommodation (the work required to focus) in children with myopia.  It was expected that the children would use  the near corrected eye (undercorrected for distance)  for near activities like reading, and the distance corrected eye for their distance vision, but instead they used the distance corrected eye for both near and far vision.   The result was that myopia progression in the near-corrected eye was slower than in the distance-corrected eye.  So the eye that was corrected for distance vision ended up becoming more myopic under the conditions of this study (monovision).

From the text:

"A significant finding was that the rate of myopia progression was slower in the near corrected eyes than in the distance corrected eyes. While participant dropout is of some concern, the demonstrated effect in 13 participants suggests that it can be generalised to at least 75% of the equivalent myopic population (p = 0.05).²⁶ Although it is probable that the difference in progression rates can be attributed to a slowing of progression in the near corrected eyes because of sustained myopic defocus, the possibility of some increase in progression rate in the distance corrected eyes cannot be ruled out. Progression is typically most rapid during the initial stages of myopia development and slows to a stable refraction over a number of years.²⁷Accordingly, Grice et al²⁸ reported a mean progression rate in the first year after myopia onset of −0.87 D/year in a group of 19 children, whereas children with longer standing myopia (for example, those wearing single vision lenses as controls in PAL studies) typically have progression rates between 0.5–0.7 D/year.^4–6,29 Therefore, while the progression rate in distance corrected eyes of −0.72 D/year found in the present study is to be expected, that of −0.32 D/year in near corrected eyes is lower than expected for children who had only recently developed myopia and were receiving their first optical correction.

For all eyes myopia progression was closely correlated with changes in VCD. The slopes of the relations were comparable to the theoretical value of −2.70 D/mm³⁰ suggesting that most of the difference in progression rate between the eyes could be accounted for by the difference in their vitreous chamber elongation rates.

In conclusion, monovision is not effective in reducing accommodation in juvenile myopia. However, the results suggest that myopic retinal defocus acts as an anti-myopiagenic stimulus that counters abnormal axial elongation of the human eye. This conclusion is the opposite of that reached after bilateral undercorrection of children with myopia⁹ but it is consistent with the results of animal studies.^1,2,31 "

Link:

http://www.ncbi.nlm.nih.gov/pubmed/16113381

How genetic is school myopia?

How genetic is school myopia?
Morgan I, Rose K.
Visual Sciences Group, Research School of Biological Sciences and Centre for Visual Science, Australian National University
Prog Retin Eye Res. 2005 Jan;24(1):1-38.

Myopia that is detected during childhood is often referred to as school myopia.  Though there is a clear genetic component to myopia and there are several studies that have shown this, the author of this article finds that some of the data is contestable, and that the environment may play an even greater role.  There's a strong link with increased education and urbanization, for example.

Link to abstract:
http://www.ncbi.nlm.nih.gov/pubmed/15555525