Clinical review
Myopia
Douglas R Fredrick Department of Ophthalmology,
University of California, 10 Koret Way, San Francisco, CA 94143-0730, USA dfred{at}itsa.ucsf.edu
Shortsightedness is becoming more common. Douglas Fredrick
describes recent research into this condition and discusses future management of patients
Myopia is a leading cause of loss of vision
throughout the world, and its prevalence is increasing. Although most
researchers agree that people's refractive status is in large part
genetically determined, a growing body of evidence shows that visual
experiences early in life may affect ocular growth and eventual
refractive status. This review describes recent human and animal
research into the pathogenesis of myopia and discusses implications for the management of patients.
This review article was prepared by searching Medline for
citations of articles in English using the keyword "myopia." In addition, abstracts from the annual meetings of the Association for
Research in Vision and Ophthalmology were reviewed.
Myopia, commonly referred to as shortsightedness, is a common cause of
visual disability throughout the world. The World Health Organization
has grouped myopia and uncorrected refractive error with cataract,
macular degeneration, infectious disease, and vitamin A deficiency
among the leading causes of blindness and vision impairment in the
world.1 People with myopia can be classified in two
groups, those with low to modest degrees of myopia (referred to as
"simple" or "school" myopia, 0 to The prevalence of myopia varies by country and by ethnic group,
reaching as high as 70-90% in some Asian populations.
2 3
In Japan it is estimated that more than one million people suffer from
vision impairment associated with high myopia.4 According to epidemiological evidence the prevalence of myopia is increasing, especially in Asian populations.5 The prevalence of
pathological myopia is estimated at 1-3% in population based
studies.6 In addition to the human cost of visual
disability, there is a profound economic cost to society. In the United
States, for example, the treatment of myopia costs an estimated $250m
(£173m, To obtain clear vision, the eye must accurately focus an image in
space on the retina. The main ocular determinants of refraction are the
focusing power of the cornea and crystalline lens and the length of the
eye. In myopia, the image is focused in front of the retina because the
cornea or lens curvature is too strong or the eye is too long (axial
myopia). When the optical components focus the image perfectly on the
retina, this is described as emmetropia, and when the eye focuses the
image behind the retina, this is described as hyperopia. Refractive
error is measured in dioptres (D), and myopia is designated with a
minus sign. Mild myopia is 0 D to The two lines of research that support the idea that myopia and
refractive errors are in large part genetically determined come from
twin studies and studies of refractive errors in parents and their
children. Two well conducted and well controlled studies show that
refractive errors are much more strongly correlated in monozygotic
twins than in dizygotic twins.
9 10
A study of the
correlation between refractive error in parents and siblings showed
stronger correlations than would be expected by chance.11 Zadnik et al conducted perhaps the best longitudinal prospective study
into refractive errors in parents and children.12 All components of refraction were measured in children, and refractive error was measured in parents. The study showed that children with
myopic parents, although not yet myopic themselves, tended to have
longer eyes than children with non-myopic parents, resulting in a
predisposition to becoming myopic later in life. Genetic studies of
families with a strong history of pathological myopia have uncovered
two polymorphisms and two separate loci for high myopia, indicating an
autosomal dominant predisposition for the development of pathological
myopia.
13 14
Additional evidence supporting the role of genetics in the development
of myopia includes the wide variability of the prevalence of myopia in
different ethnic groups.15 The prevalence of myopia in
Asia is as high as 70-90%, in Europe and America 30-40%, and in
Africa 10-20%.
People who wear spectacles for myopia may remember being told that
they would ruin their eyes if they read in the dark or in a moving car
or held the book too close to their faces (fig 2). The idea that the
way in which we use our eyes early in life can affect ocular growth and
refractive error is gaining scientific credence. It has been
hypothesised that prolonged reading or the retinal blur of prolonged
near work leads to the development of myopia. This is supported by
evidence showing an increase in the prevalence of myopia from near 0%
to rates found in the Western population in aboriginal peoples exposed
to a Western curriculum of education.16 The correlation
between level of academic achievement and the prevalence and progress
of myopic refractive errors is strong; people whose professions entail
much reading during either training or performance of the occupation
(lawyers, physicians, microscopists, and editors) have higher degrees
of myopia, and the myopia may progress not just in people's
teenage years but throughout their 20s and 30s.
3 17-20
Although it has been presumed that people with higher intelligence have
higher degrees of myopia, these studies have been confounded by the
higher degrees of educational attainment and cumulative amount of near
work in patients with a higher IQ, and intelligence per se thus cannot
be correlated strongly with myopia.
Observations by researchers that altering the visual experience of
young animals can affect the growth of the eye have led to the
experimental use of animals to investigate myopia. Whether using
primates (monkeys, marmosets, or tree shrews) or chickens, investigators have shown that when a clear, formed image is not allowed
to be focused on the retina (by suturing up eyelids or placement of
translucent goggles) high myopia will develop in the eyes of young
animals.21-24 The ocular growth seems to be focally controlled in birds' eyes, as hemiretinal occlusion leads to only hemiocular elongation (fig 3).
Summary points
The prevalence of pathological myopia leading to vision
impairment is increasing in many parts of the world
Animal models in multiple species show that early visual experience
affects growth of the eye and eventual refraction
Ocular growth is modulated by biochemical processes occurring in the
retina, choroid, and sclera
Topical medications and bifocal spectacle lenses or rigid lenses may
slow the progression of myopia but cannot prevent pathological myopia
Fig 1.
High (pathological) myopia often leads to
atrophy of the choroid and subsequent retinal macular degeneration,
with loss of central visual acuity and high incidence of retinal
detachment, glaucoma, and strabismus
Methods
6 dioptres) and those with
high or pathological myopia (greater than 6 dioptres). Simple myopia
can be corrected with spectacles or contact lenses, whereas "high"
(pathological) myopia is often associated with potentially blinding
conditions such as retinal detachment, macular degeneration, and
glaucoma (fig 1).
281m) per year.7 As the prevalence of simple
myopia increases, the incidence of pathological myopia may also
increase. Since no current treatments can reverse the structural
changes of pathological myopia, preventing myopia has long been a goal
of ophthalmologists and scientists researching vision. Understanding
the mechanisms and factors that affect ocular growth is prerequisite to
development of these therapeutic strategies.
Definition and epidemiology
1.5 D, moderate 1.5 D to 6.0
D, and high myopia 6.0 D or more. Pathological myopia occurs with
more than 8.0 D, although retinal disease, cataract, and
glaucoma
the associated threats to visioncan also occur in patients
with moderate and high myopia. At birth, most infants are hyperopic,
but when the eyes grow they usually become less hyperopic and by age
5-8 years emmetropic. This process, wherein the refractive state of
children's eyes shifts in magnitude and reduces in variance to reach
near emmetropia, is called emmetropisation. The question for
researchers is how much of this emmetropisation process is genetically
determined and how much it is modulated by early visual experience, and
epidemiological research into this question must be carefully
conducted. Historically, most research into myopia has been limited by
its retrospective nature; lack of measurement of ocular refractive
variables of patient and parents; lack of adequate randomisation,
control group, and follow up; and poor therapeutic compliance. In the
past decade, well designed epidemiological protocols have been used to
investigate the epidemiology of myopia.8
Genetic factors and refractive status
Visual experience and ocular growth
Fig 2.
Epidemiological research confirms a strong
correlation between near work, such as reading, and progression of
myopia. This process may continue through the third decade of life and
is not limited to simple "school myopia"
Animal models of myopia
View larger version (20K):
[in a new window]
Fig 3.
Chick model of form deprivation myopia. In the
avian model of experimental myopia, hemiocular occlusion leads to
hemiretinal visual deprivation. This visual deprivation leads to focal
elongation of the eye, indicating local control of scleral growth
controlled by the visual experience at the level of the retina and
sclera
Top
Methods
Definition and epidemiologyThe chicken model has been used to try to characterise the possible signal that triggers retinal, choroidal, and scleral growth. Possible modulators of growth include acetylcholine, dopamine, vasoactive intestinal polypeptide, and glucagon.25 Altering the visual environment leads to changes in the synthesis of mRNA and the concentration of matrix metalloproteinase. Further elucidation of the biochemical processes in these animal models of myopia may have implications for treating myopia in humans.
Before we conclude that myopia in humans is analogous to experimentally
induced myopia in animal models, we should bear in mind that naturally
occurring disease processes causing deprivation of formed vision do
affect human infants. In periocular haemangiomas and congenital
cataracts, the two conditions that have been most studied, occlusion of
the visual axis occurs in the first few months of
life.
26 27
In eyes that are not treated promptly, axial
elongation and myopia develop. Other conditions that are associated
with myopia include congenital ptosis; perinatal, vitreal, and retinal
haemorrhages; and inflammatory keratitis. These naturally occurring
experiments of deprivation of formed vision are consistent with the
animal models previously described.
| |
Models for the development of myopia |
|---|
Retinal blur
On the basis of epidemiological studies of myopia, experimental
animal models of myopia, and analysis of people with visual deprivation
early in life, a model of myopia development can be postulated (fig 4).
Prolonged near work was thought to lead to progressive myopia through
the direct physical effect of prolonged accumulation, but according to
current theory prolonged near work leads to myopia via the blurred
retinal image that occurs during near focus. This retinal blur
initiates a biochemical process in the retina to stimulate biochemical
and structural changes in the sclera and choroid that lead to axial
elongation.28
Accommodation problems
People with shortsightedness have poorer ability to focus
accurately by accommodation, which leads to even more retinal blur and
defocus. In this model, the infant eye at birth is hyperopic or shorter
than it should be in order to focus incoming light properly. Early
visual experiences affect the growth of the eye. Deprivation of formed
vision leads to an eye that grows in uncontrolled fashion, ever
searching for a focal point, bypassing emmetropia, and developing axial
myopia. People who do not have a strong predisposition for myopiawho
have no family history of high myopia or who come from an ethnic group
with no strong preponderance of myopiaalso begin life hyperopic, and
emmetropisation occurs until the images are properly focused on the
retina, when the process stops. Further myopiogenic stimuli such as
prolonged reading or occupations that require extensive near work may
lead to mild myopia later in life.
Familial factors
In children with a familial or ethnic predisposition to myopia the
emmetropisation process continues, but they become mildly myopic early
in life (fig 4). When they are exposed to myopiogenic factors, such as
extensive near work, which produces blur and defocused images on the
retina, myopisation consequently proceeds unchecked, searching for a
focal point, which causes axial elongation and moderate myopia in late
adolescence. Additional myopiogenic factors such as extensive near work
in secondary or postgraduate school or in an occupation can lead to
higher degrees of myopia. This model raises the question whether any
interventions should be recommended to stop or slow this abnormal
process of myopisation.
|
| |
Therapeutic interventions to prevent myopia |
|---|
Most myopic children will develop only low to moderate levels of myopia, but some will progress rapidly to high myopia. Risk factors for the development of high myopia include ethnicity, parental refraction, and rate of progession of myopia. In those children at risk, interventions should be considered.
Efforts to prevent the progression of myopia date back centuries, and eye exercises, medications, and hygiene have been proposed to prevent weak eyes. Most modern efforts have been focused on decreasing the accommodative requirements of the eyes. Anticholinergics such as atropine have been used in combination with bifocals in an attempt to slow the progression of myopia. Although progression is slowed during treatment, the long term effects seem to be a difference of no more than 1-2 dioptres, and no cases of pathological myopia have been prevented with this treatment.
Anticholinergics may act by a direct affect on the retina. Pirenzepine is a selective antimuscarinic that has no anti-accommodative effects. It has been shown to retard experimental myopia in chickens through a direct effect on the retina and sclera, and its efficacy is currently being investigated in a multicentre trial. Other biochemical modulators of scleral growth are currently being investigated in animal models, and limited human trials are under way.
Accommodative effort and retinal blur can be minimised by bifocal glasses, which change the focal point for near work. Use of bifocals may slow the rate of progression of myopia; prospective randomised trials are addressing this question.29 Rigid or gas permeable contact lenses may offer a mode of treatment that may be effective in slowing the progression of myopia.30 The rate of progression of myopia is slower in patients using these contact lenses than in patients using lenses that are placed in spectacles.31 The exact mechanism by which rigid contact lenses prevent axial myopia from developing is unclear. Laser refractive surgery can eliminate the refractive condition of myopia, but it does not decrease the rate of the blinding conditions of retinal detachment, macular degeneration, and glaucoma associated with high myopia.32
Other interventions have included the use of vitamins, scleral surgery
to provide shortening of the eye, biofeedback, ocular hypotensives,
ocular relaxation techniques, and acupuncture, and proponents of these
treatments often make unsubstantiated and exaggerated claims of
success. Their efficacy has not been confirmed in randomised controlled trials.
| |
Conclusion |
|---|
Until these treatments have been developed further parents of
myopic children should ensure that refractive errors are corrected accurately as overcorrection may induce more myopia. Parents should consider the use of bifocal lenses to prevent retinal blur in patients
with known accommodative lag and provide adequate lighting for reading
and advocate a healthy balance of physical activity coupled with
encouragement to enjoy the activity of reading. Doctors should
encourage young shortsighted people to participate in clinical trials
investigating strategies to prevent myopia.
|
Additional educational resources
Review articles Norton TT. Animal models of myopia: learning how vision controls the size of the eye. Inst Lab Anim Res J 1999;40:59-77. Smith EL, Hung LF. The role of optical defocus in regulating refractive development in infant monkeys. Vis Res 1999;39:1415-35. Goss DA, Zhai H. Clinical and laboratory investigations of the relationship of accommodation and convergence function with refractive error. A literature review. Doc Ophthalmol 1994;86:349-80. Ongoing studies Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) study (www.nei.nih.gov/neitrials/static/study72.htm) Contact Lens and Myopia Progression (CLAMP) study (www.nei.nih.gov/neitrials/static/study81.htm). Study of rigid contact lenses versus spectacles on progression of myopia Correction of Myopia Evaluation Trial (COMET) (www.nei.nih.gov/neitrials/static/study9.htm). Study of bifocals versus single vision lenses |
| |
Footnotes |
|---|
Competing interests: DRF has done consultancy work for Novartis.
| |
References |
|---|
| 1. |
Pararajasegaram R.
Vision 2020the right to sight: from strategies to action.
Am J Ophthalmol
1999;
182:
359-360.
|
| 2. | Chow YC, Dhillon B, Chew PT, Chew SJ. Refractive errors in Singapore medical students. Singapore Med J 1990; 31: 472-473[Medline]. |
| 3. | Wong TY, Foster PJ, Hee J, Ng TP, Tielsch JM, Chew SJ, et al. Prevalence and risk factors for refractive errors in an adult Chinese population in Singapore. Invest Ophthalmol Vis Sci 2000; 41: S324. |
| 4. | Takashima T, Yokoyama T, Futagami S, Ohno-Matsui K, Tanaka H, Tokoro T, et al. The quality of life in patients with pathologic myopia. Jpn J Ophthalmol 2001; 45: 84-92[CrossRef][Medline]. |
| 5. | Rajan U, Tan FT, Chan TK. Increasing prevalence of myopia in Singapore school children. In: Chew SJ, Weintraub J, eds. Proceedings of the fifth international conference on myopia, Toronto, Ontario, Canada, June 22-24, 1994. New York: Myopia International Research Foundation, 1995:41-46. |
| 6. | Vongphanit J, Mitchell P, Wang JJ. Prevalence and progression of myopic retinopathy in an older population. Ophthalmology 2002; 109: 704-711[CrossRef][ISI][Medline]. |
| 7. | Javitt JC, Chiang YP. The socioeconomic aspects of laser refractive surgery. Arch Ophthalmol 1994; 112: 526-530. |
| 8. | Negrel AD, Maul E, Pkharel GP, Zhao J, Ellwein LB. Refractive error study in children: sampling and measurement methods for a multi-country survey. Am J Ophthalmol 2000; 129: 421-426[CrossRef][ISI][Medline]. |
| 9. |
Hammond CJ, Snieder H, Gilbert CE, Spector TD.
Genes and environment in refractive error: the twin eye study.
Invest Ophthalmol Vis Sci
2001;
42:
1232-1236 |
| 10. | Teikari JM, O'Donnell J, Kaprio J, Koskenvuo M. Impact of heredity in myopia. Hum Hered 1991; 41: 151-151[ISI][Medline]. |
| 11. | Teikari J, O'Donnell J, Kaprio J, Koskenvuo M. Genetic and environmental effects on oculometric traits. Optom Vis Sci 1980; 66: 594-599. |
| 12. | Zadnik K, Satariano WA, Mutti DO, Sholtz RI, Adams AJ. The effect of parental history of myopia on children's eye size. JAMA 1994; 271: 1323-1322[Abstract]. |
| 13. | Young TL, Ronan SM, Drahozal LA, Wildenberg SC, Alvear AB, Oetting WS, et al. Evidence that a locus for familial high myopia maps to chromosome 18p. Am J Hum Genet 1998; 63: 109-119[CrossRef][ISI][Medline]. |
| 14. | Young TL, Ronan SM, Alvear AB, Wildenberg SC, Oetting WS, Attwood LD, et al. A second locus for familial high myopia maps to chromosome 12q. Am J Hum Genet 1998; 63: 1419-1424[CrossRef][ISI][Medline]. |
| 15. |
Saw SM, Katz J, Schein OD, Chew SJ, Chan TK.
Epidemiology of myopia.
Epidemiol Rev
1996;
18:
175-187 |
| 16. | Young FA, Leary GA, Baldwin GR. The transmission of refractive errors within Eskimo families. Am J Optom Physiol Optics 1969; 46: 676-685. |
| 17. | Tay MT, Au Eong KG, Ng CY, Lim MK. Myopia and educational attainment in 421,116 young Singaporean males. Ann Acad Ed Singapore 1992; 21: 785-791. |
| 18. | Saw S, Neito FJ, Katz J, Schein OD, Levy B, Chew S. factors related to the progression of myopia in Singaporean children. Optom Vis Sci 2000; 77: 549-554[ISI][Medline]. |
| 19. | Teasdale TW, Schmidt E. Myopia and its relationship to education, intelligence and height: preliminary results from an on-going study of Danish draftees. Acta Ophthalmol Suppl 1988; 185: 41-43. |
| 20. | Dunphy EB, Stoll MR, King SH. Myopia among American male graduate students. Am J Ophthalmol 1968; 65: 518-521[ISI][Medline]. |
| 21. | Raviola E, Wiesel TN. An animal model of myopia. N Engl J Med 1985; 312: 1609-1615[Abstract]. |
| 22. |
Wallman J, Turkel J, Trachtman J.
Extreme myopia produced by modest change in early visual experience.
Science
1978;
201:
1249-1251 |
| 23. | Siegwart Jr JT, Norton TT. The susceptible period for deprivation-induced myopia in tree shrew. Vision Res 1998; 38: 3505-3515[CrossRef][ISI][Medline]. |
| 24. | Whatham AR, Judge S. Compensatory changes in eye growth and refraction induced by daily wear of soft contact lenses in young marmosets. Vision Res 2001; 41: 267[CrossRef][ISI][Medline]. |
| 25. | Crewther DP. The role of photoreceptors in the control of refractive state. Prog Retina Eye Res 2000; 19: 421-457[CrossRef][ISI][Medline]. |
| 26. | Hoyt CS, Stone RD, Fromer C, Billson FA. Monocular axial myopia associated with neonatal eyelid closure in human infants. Am J Ophthalmol 1981; 91: 197-200[ISI][Medline]. |
| 27. | Robb RM. Refractive errors associated with hemangiomas of the eyelids and orbit in infancy. Am J Ophthalmol 1977; 83: 52-58[ISI][Medline]. |
| 28. |
Diether S, Gekeler F, Schaeffel F.
Changes in contrast sensitivity induced by defocus and their possible relations to emmetropization in the chicken.
Invest Ophthalmol Vis Sci
2001;
42:
3072-3079 |
| 29. | Hyman L, Gwiazda J, Marsh-Tootle WL, Norton TT, Hussein M, the COMET Group. The correction of myopia evaluation trial (COMET), design and general baseline characteristics. Control Clin Trials 2001; 22: 573-592[CrossRef][ISI][Medline]. |
| 30. | Walline JJ, Mutti DO, Jones LA, Rah MJ, Nicholls KK, Watson R, et al. The contact lens and myopia progression (CLAMP) study: design and baseline data. Optom Vis Sci 2001; 78: 223-233[ISI][Medline]. |
| 31. | Khoo CY, Chong J, Rajan U. A 3-year study on the effect of RGP contact lenses on myopic children. Singapore Med J 1999; 40: 230-237[Medline]. |
| 32. | Zadnik K. It's the retina, stupid. Optom Vis Sci 2001; 78: 179-180[ISI][Medline]. |
© BMJ 2002
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Relevant Articles
- Myopia
- Martin Barnes, Tom Eke, and Huseyin Bayramlar
BMJ 2002 325: 1035.[Extract] [Full Text]
-
Visual experience and genes cause myopia
BMJ 2002 324: 0.[Full Text] [PDF]
-
Myopia and the private finance initiative
BMJ 2002 324: i.[Full Text] [PDF]
- Website of the week: Eye sites
- Anna Ellis
BMJ 2002 324: 1224.[Full Text]
This article has been cited by other articles:
-
Cumberland, P. M, Peckham, C. S, Rahi, J. S
(2007). Inferring myopia over the lifecourse from uncorrected distance visual acuity in childhood. Br. J. Ophthalmol.
91: 151-153
[Abstract] [Full text] -
Zhang, Q, Guo, X, Xiao, X, Jia, X, Li, S, Hejtmancik, J F
(2006). Novel locus for X linked recessive high myopia maps to Xq23-q25 but outside MYP1.. J. Med. Genet.
43: e20-e20
[Abstract] [Full text] -
McCarty, C A
(2006). Uncorrected refractive error. Br. J. Ophthalmol.
90: 521-522
[Full text] -
McCarty, C A
(2004). Refining the aetiology of myopia through negative results. Br. J. Ophthalmol.
88: 1-1
[Full text] -
Hadj-Rabia, S., Froidevaux, D., Bodak, N., Hamel-Teillac, D., Smahi, A., Touil, Y., Fraitag, S., de Prost, Y., Bodemer, C.
(2003). Clinical Study of 40 Cases of Incontinentia Pigmenti. Arch Dermatol
139: 1163-1170
[Abstract] [Full text] -
Barnes, M., Eke, T., Bayramlar, H.
(2002). Myopia. BMJ
325: 1035-1035
[Full text]
Rapid Responses:
Read all Rapid Responses
- Is it Myopia?
- Nabil E Habib
bmj.com, 17 May 2002 [Full text] - Myopia Possible LInk to Increased Refined Carbohydrate Intake and Hyperinsulinemia
- Joseph Mercola
bmj.com, 18 May 2002 [Full text] - Exposed by optics!
- Jonathan D Rossiter
bmj.com, 18 May 2002 [Full text] - Myopia query
- ANDREW KERR HENDERSON
bmj.com, 18 May 2002 [Full text] - That cover photograph!
- Tony Ledwaba-Chapman
bmj.com, 18 May 2002 [Full text] - Refractive Error?
- Jonnathan S Bhargava
bmj.com, 18 May 2002 [Full text] - Short-sighted statistics?
- Robert M. Youngson
bmj.com, 19 May 2002 [Full text] - Minus marks for myopia cover photo
- Jyotin C Pandit
bmj.com, 19 May 2002 [Full text] - spectacles for myopia
- Denize Atan
bmj.com, 19 May 2002 [Full text] - Refractive error
- Gillian Whitby
bmj.com, 20 May 2002 [Full text] - Ignoring relevant data from the developing world?
- Lalit Dandona, et al.
bmj.com, 20 May 2002 [Full text] - Shortsighted Graphics Editor?
- Melanie C Corbett
bmj.com, 20 May 2002 [Full text] - No evidence for reading causing pathological myopia
- John J Sloper, et al.
bmj.com, 21 May 2002 [Full text] - Absurd photograph
- Juliet A Thompson
bmj.com, 22 May 2002 [Full text] - Myopia and Diet
- William J Jory, et al.
bmj.com, 22 May 2002 [Full text] - A Little Short Sighted?
- Caroline A Allum
bmj.com, 22 May 2002 [Full text] - Photographs: Not necessarily wrong!
- Nikhil C Kaushik
bmj.com, 23 May 2002 [Full text] - Myopia is not a disease.
- Michael J Gilkes
bmj.com, 23 May 2002 [Full text] - shortsightedness only diagnosed when the need to read is there
- Veronica M Wilkie
bmj.com, 23 May 2002 [Full text] - Re: Absurd photograph
- Christine Clark, et al.
bmj.com, 24 May 2002 [Full text] - CONGENITAL TOXOPLASMIC CORIORRETINITIS AND MYOPIA
- DENIS R. ESPINAL
bmj.com, 27 May 2002 [Full text] - Re: Short-sighted statistics?
- Otis S. Brown, et al.
bmj.com, 28 May 2002 [Full text] - Myopia: The dangers of confusing myopia with hypermetropia
- Martin R Barnes, et al.
bmj.com, 30 May 2002 [Full text] - Myopia not always bad?
- David G Cottrell
bmj.com, 30 May 2002 [Full text] - Wrong cover page photo
- Albert S. Khouri
bmj.com, 11 Jun 2002 [Full text] - Convergence: a possible cause for the development of myopia
- Huseyin Bayramlar
bmj.com, 10 Sep 2002 [Full text]
This article
-
Extract
- Respond to this article
- Read responses to this article
- Alert me when this article is cited
- Alert me when responses are posted
- Alert me when a correction is posted
- View citation map
Services
- Email this article to a friend
- Find similar articles in BMJ
- Find similar articles in ISI Web of Science
- Find similar articles in PubMed
- Add article to my folders
- Download to citation manager
- Request Permissions
Citing Articles
- Read articles citing this article
- Citing Articles via ISI Web of Science (28)
- Citing Articles via Google Scholar
Google Scholar
PubMed
Related content
Bookmark with
What's new
Latest blogs
Services
Tools
Online poll
Resources
Rapid responses for this article
Most read last week
Print issues
