Common vision problems involve myopia, hypermetropia, presbyopsia, and astigmatism.  These are also called ‘refractive errors’ which means shape of eye is so altered that it hinders light rays to focus on retina. These errors can be acquired at any age. Their treatment is based on use of spectacles and lenses. Some fundamental preventive measures can avoid these vision defects. These errors may not cause havoc to vision as it does not develop into blindness or cancer but it is definitely a problem to wear glasses throughout the day.

Myopia (short or near sightedness)

Myopia take place when the eyeball is too long compared to the focal force of the cornea and lens of the eye. This allows light rays to concentrate at a point in front of the retina, rather than directly on the surface of the retina. A person suffering from myopia can see close objects evidently but objects at a specific distance will appear to be blurred. It is the most common cause of impaired vision in people under the age of 40. Its prevalence has increased dramatically in recent years.

Types of Myopia:

High Myopia: It is a dangerous condition in which the size of the eyeball increases significantly more than average, leading to a severe disorder of the eye, such as retinal detachment, cataract and glaucoma.

Degenerative Myopia: Often known as pathological or malignant myopia, it is a rare type that you typically inherit from your parents. Your eyeball is getting longer very quickly and induces serious myopia, typically in teenage years or early adult life. This form of myopia can get much worse in adulthood.

Hypermetropia (long or far sightedness)                                             

Hypermetropia (hyperopia) often referred to as far-sightedness or long-sightedness, is a vision disorder caused by an inaccuracies in the eye (often when the eyeball is too short or the lens can not be circular enough), which causes the eye not to get enough power to see close or nearby objects. Instead of being image formed on the retina, is formed behind the retinal layers as the light rays converge beyond fovea centralis.

Types of hypermetropia :

Pathological Hypermetropia: Hypermetropia due to maldevelopment of eye , choroidal inflammation or neoplasm .

Congenital Hypermetropia : It is related to any genetic abnormality involving the eye.

Functional Hypermetropia: It can be due to 3rd nerve palsy or internal opthalmoplegia .

Myopia VS Hypermetropia

Basic defect:

  • Myopia refers to the condition in which image is formed in front of retina due to changes in cornea( the protective outer layer of your eye ) or lens for being too curved for the size of eyeball.There’s increased power crystalline lens to unite light rays.
  • Hypermetropia is a condition in which image is formed beyond retina.It may be because the eye is too short, or the cornea or crystalline lens does not absorb enough light.

Cause:

  • In myopia,you have to blame the structure of your eye. Whether your eyeball is too long or your cornea is too rounded, the light that reaches your eye does not focus correctly.

Myopia typically starts in infancy, so you could be at greater risk if your parents are short-sighted. For most cases, early adulthood is stabilised, but often it tends to grow with age.

  • In hypermetropia, eye is shortened or lens power is decreased. It is usually seen after 40 years, but could be seen at an early age due to any inherited problem.

 Risk factors:

  • Myopia may be caused aging, chromosomal abnormalities or drugs.
  • Hypermetropia can be caused by cataract, trauma of infective diseases.

Symptoms:

  • Symptoms seen in myopia are headache, eye strain, squinting and eye fatigue when you try to see distant objects.
  • Symptoms seen in hypermetropia double vision, lack of clarity, glower or halos around intense lights and headaches or eye pull.

Diagnosis:

Tests can be carried out for all of the above listed refractive errors, visual acuity, extra ocular muscle eye movement, slit lamp examination and, ultimately, fundoscopy.

Treatment:

  • Myopia may be corrected by use of concave Other techniques include refractive surgery procedure or a Lasik procedure. This laser surgery modifies the outline of the cornea to give the patient a clear vision again. Phakic intraocular lens implantation (between the cornea and the crystalline lens) is the safest treatment for high myopia patients.
  • Hypermetropia is corrected through convex lens. Eye procedure, such as LASIK, is accessible for adults including those with mild to moderate far-sightedness. The most suitable treatment for you depends on your eyes and lifestyle.

Complications:

  • Myopia is associated with cataract, glaucoma ,detached retina and choroidal or vitreous hemorrhage
  • Hypermetropia may develop into strabismus (abnormality of eye in which patient cannot use both eyes with co-ordination) and amblyopia (childhood disease in which vision of one eye is effected).

Conclusion:

Refractive errors are the vision defects which hamper normal convergence of light on retina resulting in blurred vision. Myopia could lead to some serious eye condition as compare to hypermetropia. They both can be corrected with spectacles, contact lenses or laser surgery.

https://www.urbanpro.com/bsc-tuition/what-is-hypermetropia

https://www.imo.es/en/high-myopia

https://www.allaboutvision.com/conditions/myopia.htm

https://www.oftalica.com/en/myopia