What is Refractive Error?

 What is refractive error?

By Muhammad Jamiu Omeiza

According to the world health organization, refractive error is a very common eye disorder, which occurs when the eye cannot focus on the images from the outside world. The result of refractive errors is blurred vision, which is sometimes so severe that it causes visual impairment.

Worldwide, it is recorded that uncorrected refractive error is the main cause of moderate and severe visual impairment and it's the second leading cause of blindness accounting for an estimated 153 million and 8 million affected persons, respectively. (Christian Ezelu et, al).

What are the causes of refractive error?

Normally, rays of light entering the eye are supposed to focus their image on the central portion of the retina, the fovea for clear vision.

Any deviation from this normal physiological process will result in errors in vision and visual processes.

An increase or decrease in the length of the eyeball, a change in the shape of the cornea (the clear outer layer of the eye), and aging changes in the crystalline lens are the leading causes the refractive error.

Risk Factors

-People who use their smartphones or personal computers often. Studies have shown that harmful blue rays are among the contributing factors to the development of most refractive errors.

-Genetic vs hereditary: People who have a family history of refractive error are also at risk of developing this disorder. This is the reason why eye screening and examination are necessary.

What are the types of refractive errors?

Myopia, hyperopia, Astigmatism, and presbyopia are the most common types of refractive error.

Myopia

In Nigeria, it is reported that myopia also known as short-sightedness has the highest occurrence compared to other refractive errors.

Myopia is the refractive condition of the eye in which light rays entering the eye are focused in front of the retina in a relaxed accommodative state.

People having this type of condition usually have symptoms of blurry vision at a distance.

In children, It is mostly observed with the following sign and symptoms:

-Children sitting closer to the television set at home while watching movies.

-Sitting in the front row of the class during lectures.

-They always prefer close work like drawing or art designs.

Hyperopia

Hyperopia also known as hypermetropia or long-sightedness is a refractive condition of the eye in which images focus on the eye and fall behind the retina.

People with this condition complain of the Inability to see near objects. And in some situations distance images also appear to be blurry.

Common noticeable signs in children:

-They prefer sitting in the back row of the class.

-They are relatively lazy with doing homework and other close work that demands their near vision.

Astigmatism

Astigmatism is a refractive condition of the eye causing vision too blurry and distorted.

It occurs as a result of the imperfect curvature nature of the surface of the eye causing rays of light entering the eye to focus on different points on the retina.

Common symptoms are:

1. Blurry vision.

2. Distorted vision.

3. Double vision and discomfort.

Can a refractive error be treated?

If you notice any of the symptoms or signs above, it is best to visit your Optometrist for a complete eye examination.

Your Optometrist will provide you with corrective lenses which can come in the form of spectacles or contact lenses.

However, in some situations, refractive surgery can be performed by steepening or flattening the surface of the cornea, your clear outer layer of the eye.