Types of refractive errors of the eye
The words ‘refractive error’ sounds more like a computer error message than a description of the eye but what do we mean by this phrase?
Refractive Errors
What are refractive errors?
Refractive errors refer to the eye’s inability to bend light correctly. The result of this condition is a blurred image.
The main forms of refractive errors are:
- Presbyopia (the loss of near vision)
- Myopia (classed as nearsightedness)
- Hyperopia (farsightedness)
- Astigmatism.
What are the symptoms of refractive errors?
The symptoms of refractive errors can include difficulty reading, the crossing of eyes (particularly in children) and blurred vision.
What are the causes of refractive errors?
Refractive errors are not caused by overuse of the eyes. Refractive errors stem from the conditions detailed below:
1. Myopia
Myopia is typically diagnosed in childhood and is commonly an inherited condition. It is known to progress during adolescence when the body undergoes rapid growth.
2. Hyperopia
Hyperopia is inherited and a condition that is typically present in children. The condition may be less pronounced in adulthood.
3. Presbyopia
Presbyopia typically occurs in adults over the age of 40, when the ability of the eye lens to flex diminishes. This causes the eye to lose its focusing ability and it, therefore, becomes harder to read. Presbyopia can be combined with other forms of refractive errors such as hyperopia, myopia and astigmatism.
4. Astigmatism
Astigmatism refers to the asymmetric curvature on the eye’s front surface, which can happen over time, or as the result of an injury. Another cause is keratoconus, a rare condition in which the cornea becomes cone-shaped and thinner. It typically occurs in adulthood and can precede natural cataracts development. The symptoms of astigmatism have been compared to looking into a ‘bendy mirror’.
How are refractive errors diagnosed?
The conditions associated with refractive errors can usually be diagnosed in a routine eye examination.
If you experience any of the symptoms related to the conditions above, it is best to visit your doctor.
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