A refractive error is a very common eye disorder. It occurs when the eye cannot clearly focus the images from the outside world. The result of refractive errors is blurred vision, which is sometimes so severe that it causes visual impairment.
The four most common refractive errors are:
- myopia (nearsightedness): difficulty in seeing distant objects clearly;
- hyperopia (farsightedness): difficulty in seeing close objects clearly;
- astigmatism: distorted vision resulting from an irregularly curved cornea, the clear covering of the eyeball.
- presbyopia: which leads to difficulty in reading or seeing at arm’s length, it is linked to ageing and occurs almost universally.