If you can see perfectly well at both near and far distances, you’re lucky enough to enjoy normal vision. However, many people have trouble seeing either up close or far away, and it’s usually as a result of a refractive error due to the shape of the cornea at the front of the eye.
These people can get by using corrective eyewear, but the moment they take off their glasses they are vulnerable and have blurred vision. Glasses can be an added inconvenience for those who have a high refractive error, especially in cases of myopia or short sightedness.
Because myopia affects distance vision, it is virtually impossible to carry out simple daily tasks without wearing glasses.
Hyperopia or long sightedness affects near vision so it normally becomes a problem when it comes to reading or deciphering small text at close range. With hyperopia, glasses need only be worn in certain instances.
Understanding your prescription is important to evaluate how advanced your refractive error is and whether it has stabilized.
The refractive power of each eye is measured in diopters (D) and if you are short sighted, your prescription will begin with a minus, e.g. -1.50D, while long sightedness prescriptions begin with a plus, e.g. +1.50D.
In cases of astigmatism, the error is measured in cylinders because the amount of distance is not the same in all directions since astigmatism is caused by an irregular shaped cornea.
A person who is short sighted and needs a -1.00D lens has low or mild myopia and may not need to wear glasses constantly, while a prescription above -1.50 is considered moderate myopia and a person would rely heavily on glasses.
A diopter represents the inverse of a person’s focal length in metres, so that if a short sightedness person with a -2.00D prescription was to experience their “normal vision”, he/she would only be able to see objects up to ½ metre in front of them.
Oppositely, a long sighted person who needs +1.00D reading glasses can see objects at 1metre in focus, but anything closer is blurred.
Laser Eye Surgery can correct a person’s refractive error by using a cool beam of laser energy to remove a precise amount of tissue from the cornea to match their prescription so that clear vision can be experienced from any distance.
To find out more about correcting your refractive error with Laser Eye Surgery, book your free consultation at Optilase Northern Ireland today on 08000 121 565.