REFRACTIVE ERROR

What is a Refractive Error?

Refractive Error is a common vision problem in which your eyes are not able to focus clearly on an object. It occurs when light rays from an object do not focus correctly on the retina (light-sensitive inner back layer of the eye).

Symptoms of Refractive Error

Blurred vision is the most common symptom of refractive error, while impairment of vision may occur in severe cases.

You may also experience other symptoms such as

headaches,
squinting,
double vision, or
eye strain.

Causes of Refractive Error

Refractive Error can be primary, where it occurs on it's own, or secondary, where it is caused by an underlying condition. These may include:

Infections of the cornea due to bacteria, virus, fungus, or parasites
Trauma to the cornea such as abrasion or exposure to harmful chemicals
Genetic factors
Nutritional deficiencies such as vitamin A deficiency
Degenerative Eye Diseases
Growths on the cornea
Ectasia (Thinning of the cornea)
Corneal damage due to eye conditions such as dry eye or Glaucoma

What are Types of Refractive Error?

Refractive Error can be classified as follows:

Myopia or Near-Sightedness - Light rays are focused in front of the retina, thereby causing distant objects to appear blurred.
Hyperopia or Farsightedness - Light rays are focused behind the retina and causes nearby objects to appear blurred.
Astigmatism - Irregularly curved cornea (dome-shaped clear front part of the eye) causes light rays to get distorted, affecting distant and near vision.
Presbyopia - Age-related difficulty in focusing on objects at near.