Refractive Errors

Refractive error is a type of vision problem that makes it hard to see clearly. This is because images you see are not focused sharply on the retina. This is quite common and can be easily addressed by provision of spectacles (glasses).

What are the types of refractive errors?

There are 4 common types of refractive errors:

• Myopia

(close objects are clear, and distant objects are blurry). For instance, you can read a map clearly but have trouble seeing well enough to drive a car. Myopia is mostly inherited and discovered in childhood. Myopia often progresses throughout the teenage years when the body is growing rapidly.

• Hyperopia

(close objects are more blurry than distant objects). Hyperopia can also be inherited. Children often have hyperopia, which may lessen as they grow older. In mild hyperopia, distance vision is clear while near vision is blurry. In more advanced hyperopia, vision can be blurred at all distances.

• Astigmatism

This usually occurs when the front surface of the eye, the cornea, has an irregular curvature. Normally the cornea is smooth and equally curved in all directions, and light entering the cornea is focused equally on all planes, or in all directions.

In astigmatism, the front surface of the cornea is curved more in one direction than in another. This abnormality may result in vision that is much like looking into a distorted, wavy mirror. Usually, astigmatism causes blurred vision at all distances.

• Presbyopia

(gradual aging of the crystalline lens in the eye)-After age 40, the lens of the eye becomes more rigid and loses its flexibility. As a result, the eye loses its focusing ability and it becomes more difficult to read at close range. This normal aging process of the lens can also be combined with myopia, hyperopia or astigmatism. 

Causes 

– Changes in the shape of your cornea, your lens or your whole eye can cause refractive errors. 

Symptoms

 – Blurry vision. You may experience this symptom when looking at things that are either far away or up close, or sometimes both. 

– Double vision 

– Hazy vision 

– Squinting 

– Difficulty reading or seeing up close 

– Crossing of the eyes in children (esotropia) 

– Headaches or Eye aches especially when reading or using a computer for long periods of time 

– Eye strain (soreness or tiredness in your eyes) 

– Seeing halos or glare around bright lights, especially at night 

Tests and Diagnosis 

A Refractive error can be diagnosed by an eye care professional during a routine eye examination. 

Treatment and Drugs

Refractive disorders are commonly managed using corrective lenses, such as eyeglasses or contact lenses. Refractive surgery (such as LASIK) can also be used to correct some refractive disorders. 

Presbyopia, in the absence of any other refractive error, can sometimes be managed with reading glasses. There is no way to slow down or reverse presbyopia.