Also known as nearsightedness, myopia is a term used for a condition where the individuals can see close objects clearly but the farther away ones become blurred. This condition occurs when the light entering the eye cannot be focused properly which can be the result of the eyeball that is too long or when the cornea of the eye is more curved than normal. Myopia mostly affects the school-aged children as the eyes continue to grow during their childhood years but can also affect the adults as the result of visual stress or health ailments such as diabetes.
Causes
It is not exactly understood why the eyes tend to grow too long which is not able to produce clear images of objects in the distance. Normally, the light passes through the cornea and into the lens which focuses it onto the retina that is sent to the brain. In order to produce a clear image of objects, the cornea of the eye should be evenly curved and the eyes length should be right. Among the affected individuals, the eyes tend to be grown a bit too long meaning the light is not focused directly onto the retina so the blurry images are sent to the brain. Myopia can develop because of various causes such as the excessive time spent on focusing on nearby objects or can develop as the result of other conditions such as diabetes or developing the cataract.
Symptoms
Individuals with myopia mostly find it difficulty seeing distant objects clearly but don’t have any problems with reading close-up objects. Additional signs can include eye strain, headaches and squinting.
Diagnosis
The diagnosis is based on measuring how the eyes focus light and to identify the power of optical lenses required by the individual. The visual acuity test uses a standard chart with rows of letters in decreasing size which the affected individual are required to read out loud by covering one eye and then the other. Following this, the optometrist will use an instrument called retinoscope which shines light into the eyes to determine their focusing power. Along with other tests, the diagnosis will be confirmed to determine the power of lens correction required by the individual.
Treatment
In order to have the clear distance vision, the treatment options for myopia can include eyeglasses which are the initial choice of treatment in most of the cases. Normally, a single-vision lens is prescribed but for individuals over the age of 40 or among those when the condition has developed as the result of near-vision work, a bifocal lens may be required. Ortho-K or CRT is another treatment option for myopia involving a procedure where the individual wears a series of rigid contact lenses to help reshape the curvature of the cornea which is worn for limited periods of time. Alternatively, laser procedure involves a laser beam of light that reshapes the cornea by removing the small part of eye tissue.
References
http://www.allaboutvision.com/conditions/myopia.htm
https://nei.nih.gov/health/errors/myopia
http://www.nhs.uk/Conditions/Short-sightedness/Pages/Introduction.aspx
