REFRACTIVE ERROR - Blog By Dr. Rajesh Khanna

Refraction in the eye is the bending of light rays as they pass through the cornea and lens. The light is then focused on the retina which converts the rays into messages. These messages are then interpreted by the brain into the images.
Definition - Refractive error occurs when shape of cornea prevents light from focusing directly on the retina. Length of the eyeball (longer or shorter), changes in the shape of cornea, or aging lens can cause refractive error.
Children form one of the main age groups requiring attention to refractive errors. Common types of refractive errors are myopia (nearsightedness), hypermetropia (farsightedness) and astigmatism. They are the important causes of visual impairment and blindness.

Myopia is a common cause of visual impairment which is usually acquired and nearly always progressive. It rarely occurs before the age of 5 years and new cases appear throughout childhood and adolescence, particularly between the ages of 6-15 years.
Moreover, if refractive error is detected late the child can suffer from lazy eye (Amblyopia) – A condition where vision remains low even after wearing glasses. This condition can be treated only till 7-8 years of age, hence the importance of early detection.

Types of refractive errors –

Myopia (nearsightedness) is a condition, where near objects appear clear but far objects appear blurred.
Hypermetropia (farsightedness) is a common type of refractive error where distant objects appear clearer than the near objects. Young people may not notice any problem with their vision. However, for people with significant hypermetropia, vision can be blurred at any distance.

Astigmatism (distorted vision) is a condition where the eye does not focus light evenly onto the retina. This causes images to appear blurry and stretched out. 
Risk factors – children whose parents are having refractive errors may be more likely to get one or more refractive errors.

Symptoms and detection
Blurred vision is the most common symptom. Others are double vision, haziness, squinting, headache, eyestrain, frequent rubbing of eyes.
They can be detected by an eye care professional.

Treatment – refractive errors can be corrected with eyeglasses, contact lenses or surgery.
Eyeglasses are the simplest and safest way to correct refractive errors especially in young children.
Contact lenses provide clearer vision, a wider field of vision, and greater comfort. But they need a certain amount of extra eye care in order to prevent infection and injury to cornea. This option must be discussed in detail with your eye specialist.

Refractive surgery aims to change the shape of cornea permanently in order to allow light rays to focus precisely on retina for improved vision. The pros and cons must be discussed with the eye specialist.

Article Topic : Refractive Error
Article Compiled By : Dr. Rajesh Khanna

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