This group of articles are attempts to gain insights into the issue of myopia development by comparing many different original research articles. While not all research is expected to agree with other research, the overall trend in science will be to align our understanding of an issue with the preponderance of evidence.Daizong Wen, Jinhai Huang, Hao Chen, Fangjun Bao, et al. (2015) Efficacy and Acceptability of Orthokeratology for Slowing Myopic Progression in Children: A Systematic Review and Meta-Analysis. (ABSTRACT) Journal of Ophthalmology VOL 2015 (2015), Article ID 360806 http://dx.doi.org/10.1155/2015/360806 Accessed 08/30/2015
MyopiaPrevention.org comment: A summary of several studies showed orthokeratology had a 41% myopia control rate compared to control.Earl L. Smith III, Melanie C. W. Campbell, Elizabeth Irving. (2013) Does peripheral retinal input explain the promising myopia control effects of corneal reshaping therapy (CRT or ortho-K) & multifocal soft contact lenses? (FULL TEXT) Ophthalmic and Physiological Optics Volume 33, Issue 3, pages 379–384, May 2013 DOI: 10.1111/opo.12060
MyopiaPrevention.org comment: If it were possible to identify the factors responsible for myopic developement then treatment regimens could potentially be designed to maximise effectiveness of myopia control. Peripheral hyperopic focus in the form of bifocal contact lenses and orthokeratology has long been shown to be an effective method of such control and it appears that the extent of the treatment area is correlated with the effectiveness of such control. However, there is evidence to show that the peripheral hyperopia is not of sufficient quantity to be detectable by many eyes, that the peripheral changes do not preceed myopic development and the peripheral defocus varies with the meridian measured, among other confounding results. This point counter point article discusses these issues and possible implications. One option is to not consider peripheral hyperopia as a cause of myopia but rather to only consider creation of peripheral myopia as a treatment.Bruce H. Koffler. (2012) The Case for Myopia Control Now. (FULL TEXT) Refractive Eyecare November 2012
MyopiaPrevention.org comment: This article by one of the few ophthalmologists to write on this topic is an excellent summary of myopia research and current practice, with orthokeratology and atropine being the two current leading modalities. He encourages ophthalmologists to incorporate orthokeratology into their practices.D.I. Flitcroft. (2012) The complex interactions of retinal, optical and environmental factors in myopia aetiology. (ABSTRACT) JProgress in Retinal and Eye Research VOL 31 (2012) 622-660 doi: 10.1016/j.preteyeres.2012.06.004
MyopiaPrevention.org comment: This is an excellent paper describing where myopia research has been and where it needs to go. The author makes a strong case for there being no "safe" level of myopia in regards to development of glaucoma, retinal detachment, myopic degeneration and cataracts. He continues with discussion of the complexity of the optical environment that has been generally neglected in studies up to this point and argues for a more nuanced look at the optical performance of individual patients.Jeffrey Cooper, Erica Schulman and Nadine Jamal. (2012) Current Status on the Development and Treatment of Myopia. (FULL TEXT scroll to page 23 ) Optometry - Journal of the American Optometric Association Vos 83, No. 5, May 2012.
MyopiaPrevention.org comment: This is the best review to date of the various treatment modalites for myopia control. Combined with Jeffrey Walline's review (2011) the body of evidence to support anti-muscarinic medications (commonly atropine) and certain types of contact lenses (orthokeratology and specific multifocal soft lenses) as the primary methods of myopia treatment control is becoming clinically relevant. It must be remembered that low dose atropine is able to slow myopia without nearly all the side effects of normal dose atropine.The direct link to the article above is a pdf. This is the link to the journal page. Jeffrey J Walline, Kristina Lindsley, Satyanarayana S Vedula, Susan A Cotter, Donald O Mutti, J. Daniel Twelker. (2011) Interventions to slow progression of myopia in children. (ABSTRACT) The Cochrane Library Published Online 7 Dec 2011 doi: 10.1002/14651858.CD004916.pub3
MyopiaPrevention.org comment: Twenty three studies of randomized clinical trials for the purpose of controlling myopia were reviewed. The most effective treatment was anti-muscarinic medications (atropine, perenzepine, cyclopentolate). No randomized clinical trials existed to evaluate orthokeratology or bifocal-type soft contact lenses at the time of this article. There have been randomized trials since this article - see the submenus "Orthokeratology" and "Contact Lenses" under the Research tab above. Other methods (progressive addition spectacle lenses, bifocal spectacle lenses, rigid gas permeable contact lenses, and spectacle undercorrection) were found to have clinically limited effect or a worsening of myopia progression. The authors consider orthokeratology and bifocal-type soft lenses to be "promising".Siegwart, John T. Jr; Norton, Thomas T.(2011) Perspective: How Might Emmetropization and Genetic Factors Produce Myopia in Normal Eyes? (FULL TEXT) Optometry & Vision Science March 2011 - Volume 88 - Issue 3 - pp E365-E372 doi: 10.1097/OPX.0b013e31820b053d
MyopiaPrevention.org comment: The basic question is why doesn't emmetropization overcome a genetic tendency for myopia in some eyes? For example, having two myopic parents increases the risk that a child is myopic, which means that the emmetropization process somehow breaks down.Earl L. Smith III, Donald O. Mutti.(2011) Contact Lenses and Myopia Control: Evidence Versus Hype. (FULL TEXT) Contact Lens Spectrum June 2011
MyopiaPrevention.org comment: This article takes the format of a point-counter-point presentation: "Correcting Lenses Can Alter Refractive Development" (Smith) vs "Peripheral Myopic Defocus May Not be the Answer" (Mutti). While Smith lays out the argument that controlling peripheral focus appears to slow myopia, Mutti argues that "the human data suggest that peripheral defocus is no better than foveal defocus as a growth signal for human myopia onset or progression (Mutti et al, 2011)"Seo-Wei Leo, Terri L. Young. (2011) An evidence-based update on myopia and interventions to retard its progression. (ABSTRACT) Journal of AAPOS Volume 15, Issue 2, Pages 181-189 (April 2011) "Presented as a workshop at the 35th Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, San Francisco, California, April 17 to 21, 2009."
MyopiaPrevention.org comment: This is a fairly extensive but compact review with 109 references. After a background of several topics, multiple interventions are mentioned:
Atropine: reviews the ATOM study. (discussed on this web site - 77% myopic progression reduction)
Pirenzepine: approximately 50% reduction; not available.
Bifocals: No slowing of myopia
Progressive Addition Lenses(COMET study): PALs are "not clinically meaningful"
Contact lenses (RGP): "not effective for myopia control"
Orthokeratology: "...no evidence for long-term efficacy of orthokeratology in reducing myopia progression...A gold standard randomized controlled trial with sufficient subject numbers still needs to be conducted..."
Undercorrection: makes things worse. "This means that myopes may have an abnormal mechanism for detecting the direction of optical defocus of the retinal image."
Part time lens wear: No effect seen. Larger study called for.
NeuroVision: A commercial internet based system of training. Premliminary results compared to age matched normals of another study showed slowing of myopia. A randomized controlled trial is needed.
EyeRelax: "a microscope-like device". No evidence it can retard myopia.
Pinhole Glasses: No evidence it can retard myopia.
Bates Method: "Bates' anecdotal reports of improved vision have not been evaluated in trials.
Increased outdoor play: a "promising but yet to be tested therapy..."
He concludes with the statement "Peripheral refraction interventions to retard myopia progression may also be possible in the near future."Weihua Meng, Jacqueline Butterworth, François Malecaze, Patrick Calvas.(2011) Axial Length of Myopia: A Review of Current Research. (FULL TEXT) Ophthalmologica 2011;225:127-134 DOI: 10.1159/000317072
MyopiaPrevention.org comment: The title promises more than the article delivers. A good review of incidence of myopia in different populations, a discusssion of some genetic components and some animal models. No mention is made of peripheral hyperopia, outdoor time or any lens treatment studies of myopia control.Charman, W. Neil.(2011) Keeping the World in Focus: How Might This Be Achieved?. (FULL TEXT) Optometry & Vision Science March 2011 - Volume 88 - Issue 3 - pp 373-376 doi: 10.1097/OPX.0b013e31820b052b
MyopiaPrevention.org comment: The author makes the case for emmetropization, controlled by imagery in the peripheral retina, by necessity requiring the detection of the visual image as being under or over corrected. The method by which the eye can determine this sign of defocus is postulated to be controlled by oblique astigmatism in the peripheral retina, creating two images that are selectively in focus depending on whether the eye is too short or too long for an accurate axial, spherical focus to take place.
Since there is evidence for neurons tuned to different orientations in the peripheral retina, they could selectively signal the eye to grow or stop growing depending on which sends the stronger signal along a yet unidentified pathway.
The interesting point is that such a system only works if the image across the field of view is relatively flat optically, such as an outdoor environment. An indoor environment has many objects at many different distances so that the peripheral retina may often receive a very different signal than the central focus which would confuse the emetropization process.
MyopiaPrevention.org comment: Abstract: "On July 26 to 29, 2010, the 13th International Myopia Conference was held in Tübingen, Germany, and featured 4 key note lectures, 17 targeted symposia, and 98 poster presentations..."
It is difficult to get a good overview of the expanse of the data presented because there are 76 papers and 60 posters of data by my count! (Posters are literally poster boards where data from a study is summarized for quick review.) Each of seven topics have multiple symposiums which have multiple papers. Use the link above to see the names of the various sections and papers. The posters (98 of them) are all also listed with links to the actual pdf file of the board available for 60 of them. The pdf files at the bottom of the page are all of the available posters grouped into nine files.The actual papers are found in the next articles of the journal: Myopia (FULL TEXT)
I am considering how to best summarize the studies, but for now your best bet is to investigate the offerings yourself. It is a large expanse of data.W. Neil Charman, Hema Radhakrishnan. (2010) Peripheral refraction and the development of refractive error: a review. (FULL TEXT) Ophthalmic and Physiological Optics 2010 Jul;30(4):321-38. DOI: 10.1111/j.1475-1313.2010.00746.x
MyopiaPrevention.org comment: Although the idea that peripheral hyperopia causes myopia has been discussed for several years, the proof generally remains in animal models and is yet to be proven in human studies, even if the available data "support the possibility of an interaction between the states of focus on axis and in the periphery". This review covers animal studies, peripheral refraction as a predictor of myopic development in humans, peripheral refraction in ametropes, depth of focus and accommodation.
The authors argue that peripheral myopia may be the result of myopic development, rather than the cause, a view that not all agree with. While it has yet to be proven that relative peripheral hyperopia causes myopia in humans, peripheral focus does influence central focus. This is an excellent article to for those interested in a summary of curent research.Roger W Beuerman, ed.(2010) Myopia - Animal Models to Clinical Trials. Book published: April 2010; 420 pages (Link to info page)
MyopiaPrevention.org comment: This book, coordinated by the Singapore National Eye Centre, discusses epidemiology, clinical studies, genetics, animal models and interventions. The clinical studies are short on human refractive error information and the interventions section could have been expanded, but overall the text is a useful reference. The linked page above contains links to the book's Table of Contents, Foreward and Chapter One.Gwiazda, Jane (2009) Treatment Options for Myopia (FULL TEXT) Optometry and Vision Science: June 2009 - Volume 86 - Issue 6 - pp 624-628
MyopiaPrevention.org comment: Discusses various treatments to control myopia, including single vision lenses, bifocals, progressive addition lenses, contact lenses, atropine, pirenzepine and a discussion about the fact that many treatments seem to work for a year and then less in future years. Most treatments had "small benefits that last for a relatively short period of time" although orthokeratology results were "significant". The need for more studies was expressed.Jerome A. Legerton, and Brian Chou, (2009) Myopia Regulation: Myth or Megatrend? (FULL TEXT) (Release Date: August 2009, Expiration Date: August 31, 2012) Review of Optometry CE Lesson, August 2009
MyopiaPrevention.org comment: A review of some myopia prevention techniques, including contact lenses, undercorrection, drugs, vision training and orthokeratology. "Accumulating evidence" may reach a "critical mass" in the next few years in our understanding of how to prevent myopia.McBrien, Neville A.; Morgan, Ian G.; Mutti, Donald O. (2009) What's Hot in Myopia Research-The 12th International Myopia Conference Australia, July 2008 (FULL TEXT) Optometry and Vision Science Guest Editorial January 2009 - Volume 86 - Issue 1 - pp 2-3
MyopiaPrevention.org comment: A summary of the conference. Children who spend more time outdoors have less myopic progression, regardless of time spent reading, ethnicity, or activity levels. Animal studies have shown peripheral defocus able to control myopic progression but human studies are just now being done. Genetic factors are not well defined at this time. Use of atropine eye drops with all their side effects "remains the only consistently effective treatment for myopia in humans."McBrien, Neville A., Morgan, Ian G. (2009) Myopia: Proceedings of the 12th International Conference (FULL TEXT) Optometry and Vision Science: January 2009 - Volume 86 - Issue 1 - pp E67-E73 doi: 10.1097/01.opx.0000344145.17236.cb
MyopiaPrevention.org comment: This is the Report of the 12th International Myopia Conference held on July 8-12, 2008 in Queensland, Australia. A large number of studies. Don't miss the attachments at the end of the article. The next International Myopia Conference is July 26-29, 2010 in Tübingen, Germany. International Myopia Conference 2010Kenneth J. Ciuffreda, Balamurali Vasudevan.(2008) Nearwork-induced transient myopia (NITM) and permanent myopia – is there a link?. (FULL TEXT) Ophthalmic and Physiological Optics Volume 28, Issue 2, pages 103–114, March 2008 DOI: 10.1111/j.1475-1313.2008.00550.x
MyopiaPrevention.org comment: This article is a review and discussion of the literature on near work (reading) causing myopia (NITM). The authors consider how long NITM persists (several minutes to over an hour), are myopes more likely to have NITM (yes), are progressive myopes more likely to have NITM than stable myopes (yes), does myopic defocus cause myopia in humans (yes, as shown in studies where myopes are undercorrected), and is there a mechanism that could relate NITM to permanent mypopia (yes, but not an excellent model). They conclude with a suggested protocol for treatment. This is a thoughtful review worth reading.Jeffrey J. Walline (2007) Slowing Myopia Progression with Lenses (FULL TEXT) Contact Lens Spectrum June 2007
MyopiaPrevention.org comment: A review of some treatment options. Most don't work well for various reasons, orthokeratology is the "most promising".Seo-Wei Leo, Seo-Wei Leo, Seo-Wei Leo, Seo-Wei Leo. (2007) Report of the National Myopia Prevention and Control Workgroup 2006: A Summary. (FULL TEXT) Annals, Academy of Medicine Singapore October 2007
MyopiaPrevention.org comment: I've included this review for historical interest. Most of the information has been updated in the 2011 update by Seo-Wei Leo "An evidence-based update on myopia and interventions to retard its progression" listed in this section.Morgan I, Rose K. (2005) How genetic is school myopia? (ABSTRACT) Prog Retin Eye Res 24(1): 1-38.
MyopiaPrevention.org comment: I've actually listed this article twice - once here and once under the Environment section. This is an excellent, extensive review article with over 300 references. Don't miss reading it if you are serious about myopia, its incidence and what causes it. Quoting from the abstract: "Overall, while there may be a small genetic contribution to school myopia, detectable under conditions of low environmental variation, environmental change appears to be the major factor increasing the prevalence of myopia around the world. There is, moreover, little evidence to support the idea that individuals or populations differ in their susceptibility to environmental risk factors." The "environment" that is discussed is not necessarily the amount of reading. Quoting further: "...near work has been documented as a risk factor in almost all studies that have examined the issue, although the association is weak..." (section 5.2.1) A risk factor does not mean causality.Thorn F, Gwiazda J, Held R. (2005) Myopia progression is specified by a double exponential growth function. (FULL TEXT) Optom Vis Sci. 2005 Apr;82(4):286-97.
MyopiaPrevention.org comment: A very interesting article about measuring and predicting the progression of myopia, specifically that the plot of person's myopic changes from start to stabilization can be defined by a double exponential function with variables specific to that person. The process of myopiazation begins with a period of accelerating change (not an instantaneous change) followed by a period of relatively constant change and then a deceleration and leveling off. The mean (average) refraction before myopiazation began was +.34 (hyperopic) and maximum rate of change was .79 diopters/year which occurs at 10.5 years of age. If a point at which the acceleration of change had reached half it's maximum rate is chosen as when myopia starts, the onset of myopia is a full 2 years prior to a criteria of -.50 diopters being used. Although the data could be used to predict the course of progression for an individual knowing their beginning refractive findings, it is not exact enough in that it occasionally significantly overshoots end points. One of the main results of finding that a double exponential function can fit the curve of an individual's changes is that it indicates that some mechanism is at work separate from the emmetropization process until a critical point is reached, rapid change starts and the child passes into myopia within a year. Inhibitory mechanisms build up and the process slows. It would indicate that interventional processes, such as ortho-k, bifocal contacts and PALs might be most effective at the time of maximum change, before the child even becomes myopic. This may also be why various studies show that interventions help for the first year the most and then produce less change in successive years. The myopiazation process is already being inhibited by the time treatment is normally begun.Morgan I, Megaw P.(2004) Using natural STOP growth signals to prevent excessive axial elongation and the development of myopia. (FULL TEXT - pdf download) Ann Acad Med Singapore. Jan;33(1):16-20
MyopiaPrevention.org comment: A review article that discusses that the eye undergoes an emmetropization process of both "GO" signals to make the eye grow to the correct length for good focus, a reduction of that signal as the point is reached and in addition a "STOP" signal to stop growth if the eye overshoots in length. Yet it is clear that the process is somehow disturbed by environmental pressures such that the incidence of myopia is increasing rapidly. Possible solutions are discussed, specifically the use of plus lenses for undetermined but brief periods of time each day that may reduce myopic progression based on results from chick eyes.Wallman J, Winawer J. (2004) Homeostasis of eye growth and the question of myopia. (FULL TEXT) Neuron Vol. 43, 447–468, August 19, 2004
MyopiaPrevention.org comment: An excellent review article from 2004 discussing emmetropization and myopia. Detailed discussions of mechanisms.Ian G Morgan.(2003) The biological basis of myopic refractive error. (Invited Review)(FULL TEXT) Clin Exp Optom 86: 5: 276-288
MyopiaPrevention.org comment: quoting from the introduction: "This article treats the control of eye growth as a biological process. It attempts to explain the processes of emmetropisation and the development of myopia in humans in terms of understandings obtained from animal studies. It also reviews optical and pharmaceutical preventive treatments of myopia and outlines how studies on animal models may facilitate the further development of rational optical and pharmaceutical methods for the prevention of myopia."Saw SM, E.Shih-Yen, A.Koh, D.Tan (2002) Interventions to retard myopia progression in children: an evidence-based update (ABSTRACT) Ophthalmology, Volume 109, Issue 3, Pages 415-421
MyopiaPrevention.org comment: An article that states "The latest evidence from randomized clinical trials does not provide sufficient information to support interventions to prevent the progression of myopia."Saw SM, Gazzard G, Au Eong KG, Tan DT (2002). Attempts to arrest progression. (FULL TEXT) Br J Ophthalmol. 86: 1306-11.
MyopiaPrevention.org comment: A review of myopia prevention techniques. "...atropine eye drops appear the most promising."Seet B, et al. (2001). Myopia in Singapore: taking a public health approach. (ABSTRACT) Br J Ophthalmol. 85: 521-6.
MyopiaPrevention.org comment: Myopia as a public health concern.Crewther DP (2000). The role of photoreceptors in the control of refractive state. (ABSTRACT) Prog Retin Eye Res. 19: 421-457
MyopiaPrevention.org comment: A discussion of potential areas of research into emmetropization based on the anatomy of the eye and what would be required to modify the process.Norton TT. (1999) Animal Models of Myopia: Learning How Vision Controls the Size of the Eye. (FULL TEXT) ILAR Journal V40(2) 1999
MyopiaPrevention.org comment: A good review article (1999)of how myopia develops, emmetropization, communication from retina to sclera, role of accommodation and animals that have been shown to respond to manipulation of myopic progression.ZADNIK, KARLA (1997) Myopia Development in Childhood. (ABSTRACT; FULL TEXT as pdf download) Optometry and Vision Science August 1997 - Volume 74 - Issue 8
MyopiaPrevention.org comment: A partial report of the Orinda Longitudinal Study of Myopia. Children become emmetropic as the eye's axial length increases and the crystalline lens decreases in power. Parental history of myopia is the predominant factor for myopic development which is not due to myopic parents having an effect on near work activity.Gwiazda J, Thorn F, Bauer J, Held R. (1993) Emmetropization and the progression of manifest refraction in children followed from infancy to puberty. (No on-line link found) Clin Vision Sci 1993;8:337-44. (ABSTRACT)
MyopiaPrevention.org comment: Cited as showing that refractive error at 9-12 months of age was predictive of refractive error in high school. Although there is no on-line reference that I could find, the following is taken from the article's summary:
"1. The manifest refractions of 72 children were tracked at regular intervals starting soon after birth and continuing for 9-16 y. Near-retinoscopy, a non-cycloplegic refraction technique, was used for children aged 0-3 y, and non-cycloplegic distance retinoscopy after 3 y. Almost 1400 refractions have been obtained from this group.
"2. During the first 6 months the mean spherical equivalent of the group is negative by a small amount. By one year of age the children have an average of .5 D of hyperopia which they maintain until age 8 y. After 11 y the mean sperical equivalent once again becomes negative, largely because some of the children are becoming myopic.
"3. The dispersion of refractions is largest shortly after birth and smallest at 6 y, reflecting the process of emmetropization during the preschool years.
"4. The spherical equivalent at 1 y is most predictive of later spherical equivalents. Correlations of spherical equivalent at 1 y with other ages range from .43 during the period of emmetropization to .76 at some later ages.
"5. Children with a negative spherical equivalent in infancy in conjunction with either against-the-rule astigmatism or no astigmatism are more likely to be myopic at school age than children with infantile with-the-rule astigmatism.
"6. There is an increased incidence of myopia in children with two (compared to zero or one) myopic parents."