Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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Is it Myopia?
- Nabil E Habib (17 May 2002)
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Myopia Possible LInk to Increased Refined Carbohydrate Intake and Hyperinsulinemia
- Joseph Mercola (18 May 2002)
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Exposed by optics!
- Jonathan D Rossiter (18 May 2002)
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Myopia query
- ANDREW KERR HENDERSON (18 May 2002)
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That cover photograph!
- Tony Ledwaba-Chapman (18 May 2002)
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Refractive Error?
- Jonnathan S Bhargava (18 May 2002)
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Short-sighted statistics?
- Robert M. Youngson (19 May 2002)
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Minus marks for myopia cover photo
- Jyotin C Pandit (19 May 2002)
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spectacles for myopia
- Denize Atan (19 May 2002)
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Refractive error
- Gillian Whitby (20 May 2002)
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Ignoring relevant data from the developing world?
- Lalit Dandona, Rakhi Dandona, Consultant, Administrative Staff College of India (20 May 2002)
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Shortsighted Graphics Editor?
- Melanie C Corbett (20 May 2002)
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No evidence for reading causing pathological myopia
- John J Sloper, Gillian G W Adams, Consultant, Strabismus and Paediatric Service, Moorfields Eye Hospital, Stuart Judge, Department of Physiology, University of Oxford. (21 May 2002)
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Absurd photograph
- Juliet A Thompson (22 May 2002)
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Myopia and Diet
- William J Jory, 21B Devonshire Pl, London, W1G 6HZ (22 May 2002)
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A Little Short Sighted?
- Caroline A Allum (22 May 2002)
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Photographs: Not necessarily wrong!
- Nikhil C Kaushik (23 May 2002)
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Myopia is not a disease.
- Michael J Gilkes (23 May 2002)
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shortsightedness only diagnosed when the need to read is there
- Veronica M Wilkie (23 May 2002)
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Re: Absurd photograph
- Christine Clark, Sarah Wenham (24 May 2002)
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CONGENITAL TOXOPLASMIC CORIORRETINITIS AND MYOPIA
- DENIS R. ESPINAL (27 May 2002)
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Re: Short-sighted statistics?
- Otis S. Brown, Dr. Stirling Colgate, Dr. David Guyton (28 May 2002)
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Myopia: The dangers of confusing myopia with hypermetropia
- Martin R Barnes, Tom Eke (30 May 2002)
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Myopia not always bad?
- David G Cottrell (30 May 2002)
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Wrong cover page photo
- Albert S. Khouri (11 June 2002)
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Convergence: a possible cause for the development of myopia
- Huseyin Bayramlar (10 September 2002)
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Nabil E Habib, Consultant Ophthalmic Surgeon Royal Eye Infirmary, Plymouth, PL4 6PL, UK
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Editor--It is interesting to note that the BMJ cover photograph chosen for an article on Myopia1 (short-sightedness) is showing a family with high hypermetropia (long-sightedness) as indicated by the thick convex spectacle lenses. This confirms that not only patients but also sometimes doctors may confuse the two conditions where the terminology (from Greek) is rather puzzling. Nabil Habib MBChB FRCOphth FRCS
1 Fredrick DR. Clinical review-Myopia. BMJ 2002;324:1195-9. The author has no competing interests. |
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Joseph Mercola, Medical Director Optimal Wellness Center Schaumburg, IL 60194
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Dr. Fredrick’s excellent review of myopia fails to acknowledge that diets high in refined starches such as breads and cereals increase insulin levels that can adversely affect ocular development and predisposition to myopia. Studies(1)carried out in hunter-gatherer societies and in recently westernized hunter-gatherer groups indicate that the prevalence of myopia normally occurs only in 0-2% of the population, and most refractive errors are less than minor. Moderate to high myopia is either non-existent or occurs in about one person out of a thousand. When these hunter-gatherer societies change their lifestyles and introduce grains and carbohydrates, they rapidly develop (within a single generation) myopia rates that equal or exceed those in western societies. Cordain’s review (1) of 229 hunter-gatherer societies found that although refined cereals and sugars were rarely if ever consumed by groups living in their traditional manner, these foods quickly became dietary staples following western contact. Hunter-gatherer diets are typically characterized by high levels of protein, moderate levels of fat and low levels of carbohydrate when compared to modern western diets. The carbohydrates present in hunter-gatherer diets are of a low glycemic index: they are slowly absorbed and produce a gradual and minimal rise in plasma glucose and insulin levels when compared to the sugars and refined starches in western diets. Studies of recently acculturated hunter-gatherer populations that have adopted western dietary patterns frequently show high levels of hyperglycemia, insulin resistance, hyperinsulinemia and type II diabetes. Conversely, hunter-gatherer populations in their native environments rarely exhibit these symptoms. In industrialized countries, this dietary shift from hunter-gatherers occurred more slowly over the 200 or so years since the advent of the industrial revolution as more and more refined sugars were gradually included in the diet along with increasingly greater levels of refined cereals. Although highly refined sugars and cereals are common elements of the modern urban diet, these carbohydrates were eaten sparingly or not at all by the average citizen in 17th and 18th century Europe and only started to become available to the masses after the industrial revolution. Only with the widespread introduction of steel roller mills in the late 19th century did fiber-depleted wheat flour of a low extraction become widely available. Hence, over the last 200-250 years the average glycemic load of foods in urban areas of industrialized countries has risen steadily, primarily because of increasing consumption of refined cereals and sugars. This increase in sugars is clearly related to increased levels of insulin. While reading may play a role, it does not explain why the incidence of myopia has remained low in societies that have adopted Western lifestyles but not Western diets. In the islands of Vanuatu they have eight hours of compulsory schooling a day, yet the rate of myopia in these children is only two per cent. The difference is that Vanuatuans eat fish, yam and coconut rather than white bread and cereals. The theory is also consistent with observations that people are more likely to develop myopia if they are overweight or have adult-onset diabetes, both of which involve elevated insulin levels. The progression of myopia has also been shown to be slower in children whose protein consumption is increased. This elevated level of insulin from consumption of excess grains and sugars will serve to increase free insulin like growth factor (IGF-1) which can then accelerate scleral tissue growth during critical developmental stages thus leading to myopia. A number of studies (1) also suggest that high carbohydrate diets may cause permanent changes in the development and progression of refractive errors, particularly during periods of early growth and development. High insulin levels from the carbohydrate loads could disturb the delicate choreography that normally coordinates eyeball lengthening and lens growth. And if the eyeball grows too long, the lens can no longer flatten itself enough to focus a sharp image on the retina, Population studies have demonstrated that people of Asian and Chinese descent tend to be more insulin resistant than people of European descent. The prevalence of myopia is also higher in Asian populations than it is in European populations; it is possible that the higher rates of myopia in Asian populations may, in part, be due to their increased genetic susceptibility to insulin resistance. (1) Cordain L, Eaton SB, Brand Miller J, et. al. An evolutionary analysis of the aetiology and pathogenesis of juvenile-onset myopia. Acta Ophthalmol Scand. 2002 Apr;80(2):125-35. National Library of Medicine Link http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11952477&dopt=Abstract |
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Jonathan D Rossiter, SpR in Ophthalmology Bournemouth Eye Unit, Royal Bournemouth Hospital, Castle Lane East, Bournemouth, Dorset. BH7 7DW
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Editor, As an ophthalmologist, I thoroughly enjoyed the comprehensive clinical review on Myopia by Fredrick. However I would like to point out that, although a pleasant composition, the choice of photograph for your cover was unfortunate. It is quite clear that the man and his younger son are in fact hypermetropic and not myopic as the title suggests! This can be seen by the magnification of the subjects' eyes from the 'plus' (or convex) lenses in their spectacles. In Myopia, as Fredrick points out, "the image is focused in front of the retina because the cornea or lens curvature is too strong or the eye is too long". A minus lens, which diverges light rays, is therefore required to correctly place the image onto the retina. Since minus lenses cause images to appear diminished1, the eyes of myopes look small behind their glasses. This, of course, did not detract from the excellent review! 1 Elkington AR, Frank HF,Greaney MJ. Clinical Optics, 3rd ed. Blackwell Sceince, 1999. |
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ANDREW KERR HENDERSON, Consultant Physician Lorn & Islands Ditrict General Hospital, Glengallan Road, OBAN, PA34 4HH
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Editor - I was interested to read the article on myopia by Douglas R Frederick in the BMJ 18/05/02. I think it was unfortunate that the photograph on the cover of the same issue, highlighting the article, showed a group of 3, probably father and 2 sons. Two of the three were wearing spectacles. These spectacles were obviously correcting hyperopia and not myopia. Was the little boy without spectacles supposed to be the myope? Dr Andrew K Henderson Consultant Physician Lorn & Islands DGH Glengallan Road OBAN PA34 4HH Tel 01631 567511/fax 01631 567510 |
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Tony Ledwaba-Chapman, Community Eye Physician St James's Hospital, Leeds LS9 7TFThat cover
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I couldn't agree more with Mr Habib. The photograph of the child reading in the body of the article of course shows a girl clearly wearing spectacles for myopia. The rule of thumb for the non-ophthalmologist is that if the eyes appear to fill the lenses the wearer is hypermetropic, if you can see the lines of the temples within the lenses (the "Douglas Hurd appearance") the wearer is a myope. |
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Jonnathan S Bhargava, Locum Specialist Registrar in Ophthalmology Eye, Ear, Nose and Throat Centre, Queen's Medical Centre, Nottingham, NG7
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Dear Sir, I found the article entitled 'Myopia' by Douglas R Frederick to be a very interesting and concise review of current knowledge about this potentially disabling condition. However, I presume the Author did not choose the photograph that adorned the front page of the BMJ this week, as this shows a man and a child who are wearing spectacles that magnify their eyes (convex lenses) and they are therefore hyperopic and not myopic as the article suggests. A quick look at a patients spectacles allows one to easily discover a patient's refractive error which is important in treating ocular disease. Yours Sincerely Jonathan Bhargava |
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Robert M. Youngson, Retired Consultant ophthalmologist
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 EDITOR - Estimates of the prevalence of myopia based on the number of people in a population wearing glasses are liable to an error that may be significant. Lenses appropriate for the correction of myopia are known as minus lenses. If a person with no refractive error looks though a minus lens, accommodation is induced and the image appears sharper. Focusing for distant objects is now possible as the accommodation can be exerted or relaxed around a fixed correction point. And if glasses are prescribed on the basis of purely subjective tests there is the risk that people with normal refraction will be considered myopic. Plus lenses, of the kind appropriate for hypermetropia or presbyopia diminish the reflex accommodation, and, if too strong, will blur the distant image. There is thus a built-in bias in favour of minus lenses for people who don’t need glasses. Fredrick’s figures for myopia of 70% to90% in some Asian populations may possibly be exaggerated. Robert M. Youngson 16 St Leonard’s Avenue Blandford Forum, Dorset DT11 7NY I have no competing interests in this matter |
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Jyotin C Pandit, Consultant Ophthalmic Surgeon The Birkdale Clinic, Prem House, 2 Park Road, Waterloo, Crosby, Merseyside L22 3XF
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Dear Sir, I was very pleased to see the BMJ carrying a review on a subject much misunderstood by the lay public and medical practitioners and one which is close to my heart. However, I was surprised to see the cover photograph in this week's BMJ which showed a hypermetropic man with his two sons, one of whom was also hypermetropic. It was immediately clear that the purpose of the review had not been fully served, namely to educate people about the concept of myopia. All distant light rays have to be brought to a sharp focus on the back of the eye in order to see clearly. The cornea and the natural lens of the eye (both acting as convex "plus" lenses) normally provide enough focussing power to bring light rays to a focus on the retina. However, if the cornea is too steeply curved, if the natural lens is too fat or if the distance from the natural lens to the cornea is too great, then light rays will be brought to a focal point somewhere inside the vitreous body of the eye. A blurred image will be cast upon the retina. An optical lens that diverges the light rays (concave "minus" lens) before they enter the eye will reduce the overall power of the cornea/natural lens system and therefore the focal point can once again be on the retina. A concave lens has the effect of reducing the size of objects seen through it, therfore the eyes of individuals wearing spectacles to correct myopia always appear smaller than in reality. In hypermetropia, the opposite situation exists. I found the following sentence most useful in remembering the correct combination when I was studying: In myopia, "minus" lenses minimise the eyes. Respectfully, Jyotin C Pandit FRCSEd Consultant Ophthalmic Surgeon Specialising in Cataract and Refractive Surgery The Birkdale Clinic Crobsy, Merseyside |
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Denize Atan, SHO ophthalmology Oxford Eye Hospital,Oxford OX2 6HE
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EDITOR- I was very interested in the review article of myopia in this week's issue of the BMJ, both as someone who is myopic and a practising ophthalmologist. However, the photograph on the front cover of the journal clearly shows a father and son wearing prescription spectacles to correct hypermetropia, commonly referred to as long-sightedness. These plus-dioptre lenses have a magnifying effect on the appearance of the eyes (in fact, magnifiers used for reading are simply high plus-dioptre lenses) whereas the minus- dioptre lenses used to correct myopia, or short-sightedness, would have the opposite effect. |
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Gillian Whitby, Optometrist Whitby & Co, 29 Fleet Street, London EC4Y 1AA
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EDITOR – Above the headline “Myopia: Does reading damage your eyes?” (BMJ 18th May 2002), your cover photograph shows a father and son who are plainly suffering not from myopia, but from hyperopia (longsightedness). And on the first page of the review article to which the headline refers (1), Figure 1 is a photograph of an only minimally myopic young girl, above the caption “High (pathological) myopia…” Someone in your picture library appears to need an eye examination 1. Fredrick D, Review Article - Myopia, BMJ 2002; 324: 1195-9 |
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Lalit Dandona, Director, Health Policy Administrative Staff College of India, Hyderabad - 500 082, India, Rakhi Dandona, Consultant, Administrative Staff College of India
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The review of myopia(1) by Douglas Fredrick in the BMJ of 18 May 2002 addresses an important cause of visual impairment worldwide. This paper is a clinical review focusing on the pathogenesis and management of myopia. To highlight the importance of myopia as a public health problem this paper mentions prevalence of myopia and visual impairment due to myopia by citing some data from studies from developed countries, i.e. Australia, Japan and Singapore. However, recent population-based data on the prevalence of myopia and visual impairment due to myopia from India published in peer-reviewed journals are not cited. Since this review was prepared by searching Medline for ‘myopia’(1), and the latest paper cited in this review was published in April 2002, we searched Medline for four years preceding this, i.e. 1 April 1998 to 31 March 2002. This search for ‘myopia’ revealed 1,892 items, of which 171 were for ‘myopia’ and ‘epidemiology’. Of the latter, eight items were identified if the term ‘India’ was specified. These included four papers from population-based studies that were published in Investigative Ophthalmology and Visual Science (2-5), which has one of the highest impact factors among vision journals. Among these four papers, one published in April 2001 specifically mentions that 0.21% of an Indian population was reversibly blind due to myopia (presenting distance visual acuity less than 6/60 in the better eye which could be improved with spectacles) and another 0.03% of this population was irreversibly blind due to myopic retinal degeneration (3). In fact, the prevalence of 0.24% myopia-related blindness in this population is probably higher than the prevalence of blindness from all causes together in the populations of most developed countries (6). If one were to look at only the abstract of this paper on Medline, it mentions that 16.3% of the 1.84% prevalence of blindness was caused by refractive error (3). A review of the available worldwide data on blindness due to refractive error was also published in the March 2001 issue of the Bulletin of the World Health Organization (7). One might assume that since the focus of this review paper was pathogenesis and management of myopia, specific attention to epidemiology may not have been considered necessary. However, reference to prevalence data from developed countries was made to highlight the public health importance of myopia. One wonders then why relevant data published from the developing world, even in a prestigious journal, was ignored. One hopes that this was an innocuous oversight. In any case, there is increasing concern over the need for adequate attention to developing country issues and information on health, as noted in the recent debate on 10/90 gap in health research (8). In an increasingly inter-connected world, an important part of addressing this issue would have to be more widespread awareness among developed country academics about the relevance of developing country health issues and information for optimal long-term human development. Lalit Dandona, MD, MPH
Rakhi Dandona, PhD
Centre for Social Services,
Administrative Staff College of India,
Bella Vista, Raj Bhavan Road,
Hyderabad - 500 082, India
References: 1. Fredrick DR. Myopia. BMJ 2002;324:1195-9. 2. Dandona R, Dandona L, Naduvilath TJ, et al. Refractive errors in an urban population in southern India: the Andhra Pradesh Eye Disease Study. Invest Ophthalmol Vis Sci 1999;40:2810-8. 3. Dandona L, Dandona R, Srinivas M, et al. Blindness in the Indian state of Andhra Pradesh. Invest Ophthalmol Vis Sci 2001;42:908-16. 4. Dandona R, Dandona L, Srinivas M, et al. Refractive error in children in a rural population in India. Invest Ophthalmol Vis Sci 2002;43:615-22. 5. Murthy GV, Gupta SK, Ellwein LB, et al. Refractive error in children in an urban population in New Delhi. Invest Ophthalmol Vis Sci 2002;43:623- 31. 6. Dandona L, Foster A. Patterns of blindness. In: Tasman W, Jaeger EA, editors. Duane’s clinical ophthalmology. Philadelphia: Lippincott Williams & Wilkins, 2002. 7. Dandona R, Dandona L. Refractive error blindness. Bull World Health Organ 2001;79:237-43. 8. Global Forum for Health Research. The 10/90 report on health research 2001-2002. Geneva: Global Forum for Health Research, 2002. |
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Melanie C Corbett, Consultant Ophthalmic Surgeon The Western Eye Hospital, Marylebone Road, London NW1 5YE.
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EDITOR – I write with reference to your cover illustration on the 18th May 2002 issue, relating to an article about the aetiology of myopia 1. I was surprised to see that it portrayed individuals who were hyperopic (longsighted) rather than myopic (shortsighted). It is possible to diagnose the type of refractive error because the positive (convex) lenses required to correct hyperopia make the patients’ eyes appear larger that normal. In contrast, the negative (concave) lenses which would correct myopia give the appearance of smaller eyes. There are a significant number of patients who do not know their refractive status. Eyecare professionals are able to measure the refractive error of the eye or the strength of the spectacle lenses using either an autorefractor or focimeter respectively. However, general practitioners and others without this equipment have to rely upon more basic observations, such as those outlined above. In patients with low degrees of refractive error the apparent magnification or minification of the eyes behind the spectacles may not be as obvious. If this is the case, a quick way of making the diagnosis is to hold the patient’s spectacles about 5-10cm in front of some print, and move the spectacles to compare the size of the image looking through the lens and without. In astigmatism the magnification or minification will be different in two perpendicular meridians. This is most easily detected by rotating the spectacles through 90° and back whilst still looking through the lens. Identification of the refractive status can be important as different errors have different associations, prognoses and responses to refractive surgery. |
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John J Sloper, Consultant, Strabismus and Paediatric Service Moorfields Eye Hospital, City Road, london EC1V 2PD, Gillian G W Adams, Consultant, Strabismus and Paediatric Service, Moorfields Eye Hospital, Stuart Judge, Department of Physiology, University of Oxford.
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Sir. We read with concern the recent clinical review of myopia by Fredrick1 and its associated coverage in the BMJ. The cover photograph shows a father and son wearing hypermetropic glasses over a caption stating "Myopia: does reading damage your eyes? Probably". This leads the reader to expect a report of statistical evidence for such a risk factor. No such evidence is presented. While Fredrick's article summarises some of the recent evidence on the role of genes and environment in ocular growth and re fractive development, no evidence whatsoever is presented to support the author's key concern that the incidence of pathological myopia may rise in parallel with the rise in simple or school myopia. This is not to say that this issue is not a legitimate concern, but to emphasise that Fredrick cites no data addressing this issue. We are particularly concerned by the implications contained in the illustrations to the review. Fig. 1 shows a young girl wearing what is clearly a low myopic spectacle correction over a caption reading "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". This is misleading because it suggests a relationship between low myopia, the use of spectacles and the development of pathological myopia for which no evidence is cited. Fig. 2 shows a photograph of advanced myopic retinal degeneration over a caption stating "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". It would appear that the legends have been transposed, but nevertheless no evidence is cited to support the implication, repeated in Fig 4, that near work can lead to pathological myopia with its complications. The author himself states that "myopia and refractive errors are largely genetically determined". It is disappointing to find the BMJ publishing a review which so badly confuses evidence and supposition and moreover has the potential to cause unwarranted anxiety to parents and to precipitate referrals to an already overloaded paediatric hospital eye service. 1. Fredrick DR. Myopia. BMJ 2002; 324: 1195-1199.. |
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Juliet A Thompson, staff grade in ophthalmology West Kent Eye Centre, Farnborough Hospital, Orpington , Kent, BR6 8ND
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I was desparately disappointed at the choice of photograph used on the front cover of the BMJ, to draw attention to this article. I doubt the author was consulted. Why use a photograph of people wearing a high hypermetropic correction, the complete opposite to the subject of the article? While most of your intended audience will not have noticed the error, it was extremely irksome the those of us who did. |
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William J Jory, Consultant London Centre for Refractive Surgery, 21B Devonshire Pl, London, W1G 6HZ
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Sir, Professor Fredrick has rightly described myopia as a leading cause of loss of vision throughout the World with increasing prevalence. He also discussed the possible causes of myopia, to which I would like to add my own clinical experience. In the early 1980s I was the resident Ophthalmologist in North West British Columbia. When my wife and I examined the school children I found that by the age of 15, 60% of them had become myopic. Their parents traced their ancestry to Mongolia, their forbears having wandered across the Aleutian Land Bridge as it was then, from Asia to North America about 4000 years BC. These childrens' parents retained the short, stocky, rather muscular build of their forbears. By contrast, their children were much taller and the prevalence of myopia was striking. My wife and I deduced that this sudden alteration with an incease in long bone measurement and coincidentally an increase in the axial length of the eye causing myopia, was due to a sudden change of diet from high protein meat and fish to high carbohydrate western style diet in a single generation. It was noteworthy that the further these tribes lived from a western style fast food outlet, the lower the incidence of myopia. Thus we deduced that dietary change, in a single generation, was the cause of the myopia. Yours sincerely,
References 1. Jory, WJ. Eyecare for North Coast Pacific Indians. Submitted to Canadian Federal Government 1981. 2. Frederick, DR. Myopia. BMJ 2002;324:1195-1199. |
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Caroline A Allum, specialist registrar radiology Royal Free Hospital NW3 2QG
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I thought the clinical review article by Douglas Frederick was excellent, but was surprised that the illustration on the front page of the BMJ was of a hyperopic family. Just a little short sighted? |
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Nikhil C Kaushik, Consultant Ophthalmic Surgeon North East Wales Trust Hospital, Wrexham, North Wales LL13 7TD
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Your technical editors have come under fire for the choice of the photographs supporting this interesting article indeed, but they can defend themselves by proposing that they wished to make the point that not all myopes need miunus (Concave) lenses these days. The cover photograph may be representing a family that has had corrective surgery that has gone wrong. One could argue that they have had LASIK performed that has overcorrected myopia to an extent that they now need plus (Convex) lenses in order to see properly. By the same token the picture of the girl in the main article may be that of a patient whose high myopia was reduced by Surgery so she now needs thinner lenses. The point then is that we should not get surprised when we find a fundus picture suggestive of high myopia, but the patient sees 6/6 without glasses, and they forget to state that they have had corrective surgery for shortsightedness. It may interest your readers to know that there is a genuine concern in the Ophthalmic community about the future of myopes who are undergoing LASER and other kinds of refractive surgey with astonishing enthusiasm. There is serious concern about what the future holds for such eyes when and if they develop Glaucoma, develop a retinal problem and indeed the difficulties in dealing with such eyes when they develop cataracts. These are uncertain and interesting times, and that is just what these pictures may have intended to depict! |
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Michael J Gilkes, Retired consultant ophthalmologist Home
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I despair at the article by Fredrick in the current BMJ. Are we to revert to a hundred ears ago when Fuchs and others attrbuted mopia to "venery and the excessive eating of meat" The work of Sorsby (1957, 1960. 1991) clearly estalished that refractive VARIATIONS are just that and simply reflect normal procsses of growth and inheritance. There is still far too widespread and ignorant public anxiety about eyes and vision for the unleshing of of very old chestnut which requires the most rigorous validation. The very serious economic implications will not have escaped the notice of the providers and suppliers of refractive appliances. Michael Gilkes F.R.C.S. Reference. Problems of Refraction. M.J.Gilkes.1966. Trans.O,S.U.K. LXXXVI, 657-666. |
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Veronica M Wilkie, GP The Corbett Medical practice, 36 Corbett Avenue Droitwich, worcs UK DY11 7TE
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I read this overview with interest and wondered whether the research findings that shortsightedness being more common when societies learn to read is due to the fact that near vision is not used as much in populations that do not read/write. ie that individuals/societies do not realise they are short sighted until they start to read! |
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Christine Clark, SpR O+G Ysbyty Gwynedd, LL57 2PW, Sarah Wenham
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As two highly myopic members of the BMA, we were rather disappointed to see the long sighted individuals advertising the article on myopia. We would have happily posed for the cover! Yours in Braille,
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DENIS R. ESPINAL, 05/25/2002 FACULTAD DE MEDICINA, UNAH
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IN MY COUNTRY THE CONGENITal CORIORRETINITIS CAUSED BY TOXOPLASMA IS ONE OF THE FIRST CAUSES OF BLINDNESS IN CHILDREN UNDER 10 YEARS, ALL THIS CHILDREN HAVE MYOPIA, MAYBE RELATED TO INDUCED SCLERAL GROWTH. Dr. DENIS ESPINAL
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Otis S. Brown, Electrical Engineer 11286 Weatherstone, Waynesboro, PA, 17268, Dr. Stirling Colgate, Dr. David Guyton
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I believe that the short-sighted statistics is even worse that was stated. If you check my site: http://geocities.com/otisbrown17268 under "Statistics" you will find that myopia runs about 95 percent for some (Item #6)of the medical community. |
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Martin R Barnes, SHO in ophthalmology Leicester Royal Infirmary, Leicester. LE1 5WW, Tom Eke
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EDITOR-The front cover of the BMJ on 18th May 2002 contained a significant error. Above the headline "Myopia: does reading damage your eyes?" was a photograph of a man and boy with hypermetropia, the ‘opposite’ condition. Hypermetropia, or long-sightedness, is corrected by spectacles with convex (magnifying) lenses that make the eyes appear larger, as demonstrated in the photograph. By contrast, myopia (near- sightedness) is corrected by concave lenses, which make the eyes appear smaller. Figure 1 of the article itself(1) did show a girl wearing myopic spectacles, though the degree of myopia was only modest, about -2 dioptres and certainly not the high (pathological) myopia referred to by the legend. It appears that the photographs for figures 1 and 2 were transposed. It is important for doctors to be able to distinguish hypermetropia from myopia. Hypermetropes are at increased risk of developing acute angle closure glaucoma (AACG), an unpleasant and sight threatening condition. In predisposed eyes, AACG may be induced by eye drops that dilate the pupils, or by drugs with pupil dilating side effects such as many antidepressants.(2) In contrast, iatrogenic angle closure is very rare in myopes. We teach our students to look at a patient’s spectacles as the first step in assessing the risk of iatrogenic AACG. For further practical help in assessing AACG risk, non-ophthalmologists should consult a general text.(3) Martin Barnes Tom Eke 1.Fredrick DR. Myopia. Br Med J 2002;324:1195-9. 2.Hitchings R. (2000) Glaucoma. London: BMJ Books, pp.159-6. 3.Chawla HB. (1999) Ophthalmology: A Symptom Based Approach. 3rd Ed. Oxford: Butterworth Heinemann, pp.33-4. Competing interests: none. |
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David G Cottrell, Consultant Ophthalmologist Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP
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Neither this article nor the responses to date have queried the presumption that myopia is inevitably undesirable. I contend that for the vast majority of people over the age of 40, mild to moderate myopia is a positive advantage over hypermetropia ("long-sight") or emmetropia ("normal sight"). Once presbyopia (the fixed focus of older age) sets in, the hypermetropic eye without optical correction is out of focus for all distances. The uncorrected moderately myopic eye, however, is still in perfect focus at a very useful distance (eg 33cm with 3 dioptres of error) for all sorts of activities including reading. The presbyopic emmetrope can still focus at a distance without glasses, but whenever closer focus is needed glasses are required. (One very often sees people in the supermarket fumbling to get out their glasses to read a price.) The (superior) myope will already have his/her glasses on; even if these are not bifocal or varifocal he/she needs only to peep over or under the lenses to read. I admit that I am biased in being a late-40s myope (-1.75 dioptres, but I would prefer to be -3 as my presbyopia increases). I am aware of several other myopic ophthalmologists who also greatly value their myopia. I know that surgery for presbyopia is now being performed, but as a myope there is no need for me even to consider it. Ref: Frederick, DR. Myopia. BMJ 2002;324:1195-1199. |
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Albert S. Khouri, Ophthalmology Service Consulting Clinics, POBox 61022, Riyadh 11565
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Editor-in-Chief, The clinical review article on myopia by Dr Fredrick DR (Myopia: does reading damage your eyes? Fredrick DR. BMJ 2002;324:1195-9) is extremely valuable for physicians in all specialties as it identified myopia with its current epidemic proportions, and touched at its theories of pathogenesis, and possible modes of prevention. What caught the eye of most readers, including mine, was the striking cover page photo of a family with high degrees of refractive error. To the non-ophthalmologist, probably the next step would be to flip through the journal and read the article. From an ophthalmologist’s perspective what caught my eye as well, was the fact that the photo on your cover page for this article on myopia was for non-myopic individuals! Lenses for correction of myopia (divergent lenses) minify images, and thus the eyes of a person wearing myopic spectacles typically appear smaller than they actually are. On the contrary the photo on the cover page is for individuals wearing hyperopic correction spectacles with hyperopic lenses (converging lenses that magnify images) making their eyes appear larger through those lenses. This most likely would not have passed unnoticed through an ophthalmology journal, and I felt it should not do so as well at your esteemed journal. Albert S. Khouri, MD
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Huseyin Bayramlar, Associate professor in ophthalmology, Medical Doctor Ýnonü University; Turgut Özal Medical Centre, 44300, Malatya, Turkey.
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Convergence: a possible cause for the development of myopia Dear Editor; I would like to comment on the clinical review article of Fredrick entitled “myopia” appearing on the issue of 18 May 2002 in BMJ.1 The author stated that “most research into myopia has been limited by its retrospective nature; lack of control group and follow up”. We, however, performed a prospective, controlled, three-year follow-up study on myopia. 2 In this study, we showed a direct evidence of myopic shift in students reading and doing intensive near work compared with the children who not attending the school, not reading much as schoolchildren and working as skilled laborers. The author also mentioned three possible causes for the development of myopia: retinal blur, accommodation and familial factors. I think there is a fourth possible hypothetical explanation for that: convergence. It has been suggested that convergence, rather than accommodation, could be an important factor in myopic progression.3-5 Parssinen et al, in their 3 year-follow-up study, showed that neither the use of bifocals nor avoiding the use of myopic spectacles in reading has slowed down the myopic progression.3 Again, Parssinen and Lyyra found more myopic progression in subjects needing less accommodation stimulus than the subjects needing more accommodation.4 They concluded that if accommodation played a significant role in myopic progression, the feedback mechanism would probably halt the process when reading with undercorrected glasses or without glasses.4 In our different study, we observed a significant axial length elongation during near fixation both with and without cycloplegia, that is, with and without accommodation.5 Those reports and our results do not support the hypothesis of accommodation as a significant cause of myopia. Rather, axial elongation during near focusing in our study could support the hypothesis that convergence may be one factor inducing myopia. Parssinen and Hemminki3 and Parssinen and Lyyra4 have supposed that constant saccadic back-and-fourth eye movements during reading could cause repeated pressure and stretch pulses on the eye during reading. Based upon above-mentioned studies, we suggest that the axial elongation which is a main cause of myopic progression, seems to be due to the effect of accomodative convergence rather than accommodation itself. Much use of convergence may be one of the contributing factors in adult onset and adult progression of myopia. Hüseyin Bayramlar, M.D.
References: 1. Fredrick DR. Myopia. BMJ 2002;324:1195-9. 2. Hepsen IF, Evereklioglu C, Bayramlar H. The effect of reading and near- work on the development of myopia in emmetropic boys: a prospective, controlled, three-year follow-up study. Vision Res 2001;41:2511-20. 3. Parssinen O, Hemminki E, Klemetti A. Effect of spectacle use and accommodation on myopic progression: final results of a three-year randomized clinical trial among schoolchildren. Br J Ophthalmol 1989;73:547-51. 4. Parssinen O, Lyyra AL. Myopia and myopic progression among schoolchildren: a three-year follow-up study. Invest Ophthalmol Vis Sci 1993;34:2794-2802. 5. Bayramlar H, Cekic O, Hepsen IF. Does convergence, not accommodation, cause axial-length elongation at near? A biometric study in teens. Ophthalmic Res 1999;31:304-8. |
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