A refractive error means that the eye does not focus or refract light properly to a single point so as to see images clearly. There are three basic types of refractive errors than can occur in the eye.
Myopia – Nearsightedness
Nearsightedness (myopia) is a common visual condition, where one can see objects clearly when close by and objects further away appear blurry. The degree of your nearsightedness affects your ability to focus on distant objects. People with severe nearsightedness can see clearly when objects are just a few centimeters away, while those with mild nearsightedness, their vision may be clear up to several meters away.
Myopia may develop gradually or rapidly, often worsening during childhood and adolescence. Myopia tends to be hereditary and a basic eye exam can confirm Myopia or nearsightedness. You can easily correct the condition with spectacles and contact lenses. Alternatively, another treatment option is surgery for myopia using excimer laser or lens implants.
Hyperopia – Farsightedness
This vision condition is when distant objects are usually seen clearly, but up close you may struggle to see images in the proper focus. Farsightedness (Hyperopia) occurs if your eyeball is too short or the cornea has too little curvature, so light entering your eye is not focused correctly. Often patients with farsightedness will notice that even their distance vision starts to deteriorate later in life.
Astigmatism
Another focus error is astigmatism. This is due to an abnormal curvature of the cornea or the lens. The shape of the cornea is slightly oval instead of being spherical. This mean that the vision for both near and far objects appears blurry or distorted. This condition can be corrected with spectacles or contact lenses. Surgery can also be used to correct or improve astigmatism. Again this can be done with the excimer laser or by lens implants.
Presbyopia
This is a natural age related change in vision. Presbyopia is the gradual loss of your eye’s ability to focus on nearby objects. It is a natural, often annoying part of aging. Presbyopia usually becomes noticeable in your early to mid-40s’ and continues to worsen until around the age of 65 years.
This error is corrected with simple reading glasses. Numerous surgical procedures have been attempted to correct this error but the success is variable at best.