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Myopia

Shortsighted

Myopia is the most common ametropia. It presents with blurry distance vision.


Presentation

Myopia usually has very characteristic signs and symptoms.

The classical symptoms of myopia include include the following:

  • Blurred far vision
  • Headache
  • Strain on the eyes
  • Intermittent divergent squint (exodeviation of the eyes)
  • Constant divergent squint
  • Fatigue upon trying to focus on a nearby object for long
  • Normal near vision

The signs of myopia include the following:

  • Prominent eyeballs
  • Increased depth of the anterior chamber of eye upon fundoscopy, normal in simple myopia
  • Degenerative changes seen in case of pathological myopia
  • Increased axial length
Turkish
  • Similarly, Hepsen et al studied 117 Turkish boys with a mean age of 12.9 years old and found that 48.8% of the children with a mean of 6 hrs/day of reading and near work activities had a myopic shift over 3 years compared with only 18.9% boys who displayed[doi.org]
Blurred Vision
  • If no glasses was a cure, there should be no blurred vision to begin with. But people do develop blurred vision due to myopia.[myopiaprevention.org]
  • A 21-year-old woman with bilateral blurred vision 1 day after the use of Cefalium. The main outcomes measures were BCVA, ocular fundus, ocular coherence tomography, and angiography findings.[ncbi.nlm.nih.gov]
  • Cataract When your child has a cataract, the clouding of the lens in the eye leads to blurred vision. This can make reading difficult for your child. Fight myopia Excessive near work may lead to or worsen myopia.[healthhub.sg]
Vision Disorder
  • Myopia is the most common vision disorder and the leading cause of visual impairment worldwide.[ncbi.nlm.nih.gov]
  • Disorders--diagnosis a schema:Intangible ; schema:name " Vision Disorders--diagnosis "@ en ;. # Vision Disorders--therapy a schema:Intangible ; schema:name " Vision Disorders--therapy "@ en ;. # Vision Tests a schema:Intangible ; schema:name " Vision[worldcat.org]
  • The impact of pediatric vision disorders in adulthood. Pediatrics 2011 ; 127: 334 – 9. Google Scholar Medline ISI 8. Pinquart, M, Pfeiffer, JP. Body image in adolescents with and without visual impairment.[doi.org]
Eye Pain
  • A common use for atropine these days is to reduce eye pain associated with certain types of uveitis.[allaboutvision.com]
  • Many of these patients present to the ophthalmologist relating episodes of blurry vision, and sometimes eye pain, after exercise.[web.archive.org]
Chemosis
  • A complete ophthalmologic examination revealed bilateral myopic shift, intraocular pressure elevation, shallowing of the anterior chambers, choroidal effusions, radiating retinal folds, and conjunctival chemosis.[ncbi.nlm.nih.gov]
Corneal Infiltrate
  • However, potential complications of contact lens use include allergic conjunctivitis, corneal infiltrates, and infective keratitis, and contact lens hygiene compliance may be a problem in less responsible children.[doi.org]
Rabies
  • Storey JK, Rabie EP. Ultrasound- a research tool in the study of accommodation. Ophthal Physiol Opt 1983; 3: 315–20. Google Scholar 43. Beauchamp R, Mitchell B. Ultrasound measures of vitreous chamber depth during ocular accommodation.[doi.org]

Workup

The diagnostic interventions include:

  • Patient’s history
  • Eye examination for visual acuity by Snellen’s test chart
  • A-scan ultrasonography
  • Retinoscopy
  • Fundoscopy

Treatment

Conservative treatment

  • Use of glasses
  • Contact lenses
  • Concave lenses
  • Pinhole glasses for low level myopia

Surgical interventions

  • Photorefractive Keratectomy (PRK): This is the refractive surgery in which a layer of corneal epithelium in the center of cornea is removed with the help of excimer laser so as to flatten the curvature of cornea to reduce its refractive power [2] [3].
  • Radial keratotomy (RK): In this procedure, the curvature of the cornea is reduced by giving incisions in the peripheral part of cornea with the help of a diamond knife [4]. This results in decrease in the refractive power of cornea.
  • Laser-assisted in situ Keratomileusis (LASIK): It is currently the most commonly applied procedure. An epithelial flap is reflected with the help of keratotome; laser is applied and the flap is repositioned [5] [6].
  • Laser epithelial Keratomileusis (LASEK): In LASEK, the epithelium is detached at the level of basement membrane in this procedure. After the application of laser, the flap is re-positioned. It is a relatively painless method and causes rapid recovery [7] [8].
  • Clear lens extraction: This is done to correct the error of more than 20 diopters.
  • Phakic posterior chamber lens implant: This consists of insertion of crystalline lens behind the iris [9].

Prognosis

Low or even moderate level myopia can be corrected with the use of glasses and corrective lenses. The prognosis is usually very good and the patients have a very good quality of life. Degenerative changes in pathological myopia can lead to blindness in the long term.

Etiology

Myopia can be congenital or acquired. The anatomical changes contributing in the etiology of myopia include the following [1]:

Increase in axial length of the eye

The myopic eyeball is enlarged. The axial length of the eyeball, therefore, enhances. The light rays entering the eye fall short and the image fails to form on the retina and forms, instead, at some point proximal to the retina, resulting in blurring of vision.

Abnormal curvature of lens or cornea or both

The curvature is increased which causes abnormal refraction of the light rays entering the eye and hence, the image fails to form on retina.

Abnormal refractive index of the lens

Change in the refractive index of the lens, as in nuclear sclerosis, can lead to myopia.

Positional error

The lens may be displaced anteriorly, resulting in abnormal focusing of the light rays.

Epidemiology

Children and old people are affected more. A familial tendency to myopia has been found. A lot of factors affect the prevalence of myopia including, age, sex, race and occupation.

Sex distribution
Age distribution

Pathophysiology

As the light rays enter the eye of myopic person, they undergo abnormal refraction due to changes in the refractive power of various refractive media in the eye, i.e. the cornea or lens. The axial length of eye is also increased. Due to the combination of these factors, the light rays focus at a point proximal to retina and hence, image forms before the retina. The resultant image of the distant objects, is therefore, blurred.

Degenerative changes in the sclera also contribute in the development of myopia. Due to these changes, the sclera fails to withstand the normal intraocular pressure. Further changes in the retina and choroid include the following:

Prevention

  • Regular eye checkup must be ensured.
  • Avoid exposure to sunlight. Use protective sunglasses.
  • Foods with plenty of vitamin A and beta carotenes like carrots should be incorporated in diet.
  • While reading and writing, ensure good light exposure.
  • Don’t watch TV at a close range. Proper distance should be maintained while watching TV.
  • Dim the brightness of the computers and mobile phones’ display.
  • Avoid reading while lying down and in a moving vehicle.
  • Symptoms of blurry vision must be recognized at once and eye physician should be consulted promptly.
  • Avoid smoking.
  • Use correction lenses and glasses regularly for improvement of vision.
  • Visual disturbances can be associated with other diseases such as diabetes [10]. It is important to control and treat the underlying cause.

Summary

Myopia, also commonly known as short sightedness or near sightedness, refers to the inability of eye to focus the incoming light of rays on the retina when the accommodative power of the eye is at rest. Hence a myopic person faces difficulty seeing the far objects. The near objects, however, can be clearly visualized.

Myopia is a common refractive error that is prevalent in people beyond 40 years of age. Mild degree of myopia is called “low myopia” whereas a higher degree of myopia is commonly called ‘high myopia”.

Patient Information

Myopia is he condition in which the individual is unable to visualize the far objects properly. He can see near objects perfectly. Various changes in the structure of the eyeball lead to this condition. If myopia is of low level, it can be corrected by regular use of glasses and contact lenses. If myopia is too high, surgical methods can be used for the correction of this condition. With proper care, myopia can be prevented in the early age.

References

Article

  1. Wilson A, Woo G. A review of the prevalence and causes of myopia. Singapore medical journal. Oct 1989;30(5):479-484.
  2. Eggink CA, Deutman AF, Meurs PJ, Schilt PD, de Boo TM, Lemmens WA. [Results of photorefractive keratectomy using the excimer laser in the treatment of myopia; 1-year follow-up]. Nederlands tijdschrift voor geneeskunde. Nov 18 1995;139(46):2369-2375.
  3. Van Gelder RN, Steger-May K, Yang SH, Rattanatam T, Pepose JS. Comparison of photorefractive keratectomy, astigmatic PRK, laser in situ keratomileusis, and astigmatic LASIK in the treatment of myopia. Journal of cataract and refractive surgery. Mar 2002;28(3):462-476.
  4. Binder PS. Radial keratotomy and excimer laser photorefractive keratectomy for the correction of myopia. Journal of refractive and corneal surgery. Jul-Aug 1994;10(4):443-464.
  5. Vukosavljevic M, Milivojevic M, Resan M, Cerovic V. [Laser in situ keratomyleusis (LASIK) for correction of myopia and hypermetropia--our one year experience]. Vojnosanitetski pregled. Military-medical and pharmaceutical review. Dec 2009;66(12):979-984.
  6. Teus MA, de Benito-Llopis L, Sanchez-Pina JM. LASEK versus LASIK for the correction of moderate myopia. Optometry and vision science : official publication of the American Academy of Optometry. Jul 2007;84(7):605-610.
  7. Li Y, Li JH, Zhou F. [LASEK for the correction of residual myopia and astigmatism after LASIK]. [Zhonghua yan ke za zhi] Chinese journal of ophthalmology. Nov 2005;41(11):981-985.
  8. Lohmann CP, Winkler Von Mohrenfels C, Gabler B, Hermann W, Muller M. [Excimer laser subepithelial ablation (ELSA) or laser epithelial keratomileusis (LASEK) - a new kerato-refractive procedure for myopia. Surgical technique and first clinical results on 24 eyes and 3 months follow-up]. Klinische Monatsblatter fur Augenheilkunde. Jan-Feb 2002;219(1-2):26-32.
  9. Zaldivar R, Ricur G, Oscherow S. The phakic intraocular lens implant: in-depth focus on posterior chamber phakic IOLs. Current opinion in ophthalmology. Feb 2000;11(1):22-34.
  10. Mantyjarvi M. Myopia and diabetes. A review. Acta ophthalmologica. Supplement. 1988;185:82-85.

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Last updated: 2019-07-11 22:54