Myopia is the most common ametropia. It presents with blurry distance vision.
Myopia usually has very characteristic signs and symptoms.
The classical symptoms of myopia include include the following:
- Blurred far vision
- 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:
Entire Body System
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]
It causes blurred vision when viewing objects at a distance. As the most common cause of blurred vision symptoms in teens, about one in five 12-year-olds in the United States has myopia. [chp.edu]
Prevalence and causes of visual impairment in an elderly Chinese population in Taiwan: the Shihpai Eye Study. Ophthalmology 2004; 111 : 62–69. 22. Van Newkirj MR. The Hong Kong vision study: a pilot assessment of visual impairment in adults. [doi.org]
The Visual Impairment Project is a population-based prevalence study of eye disease in which both urban and rural adult populations were examined. [ncbi.nlm.nih.gov]
Mechanical stretching and thinning of the choroids may lead to the development of irreversible degenerative changes in the eyeball and visual impairment. [web.archive.org]
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]
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]
The diagnostic interventions include:
- Patient’s history
- Eye examination for visual acuity by Snellen’s test chart
- A-scan ultrasonography
- Use of glasses
- Contact lenses
- Concave lenses
- Pinhole glasses for low level myopia
- 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  .
- 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 . 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  .
- 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  .
- 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 .
Myopia can be congenital or acquired. The anatomical changes contributing in the etiology of myopia include the following :
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.
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.
The lens may be displaced anteriorly, resulting in abnormal focusing of the light rays.
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.
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:
- 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 . It is important to control and treat the underlying cause.
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”.
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.
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