What are Refractive Errors
The normal vision is when the light passes through the cornea and the crystalline lens to help focus the light rays onto the retina for a clear vision. But if the refractive power of your eyes does not match the length of your eyeball causing refractive errors which can be classified as followed:
1) Near – Sightedness or Myopia
Near – Sightedness is caused by an excessive amount of focusing power in the eye relative to the axial length. This is when the cornea is too curved or the eyeball is too long. So, it is difficult the see an object far away, but better when is closer.
Treatment: Use curvy lens to reduce excessive refractive power to ensure that the light focusses on the retina.
2) Far – Sightedness or Hyperopia
Far-sightedness at birth occurs when light does not refract properly when compared to the length of the eyeball. This is when the lens is too flat or the eyeball is too short, causing the light ray to fall behind the retina, resulting in blurry vision both near and far.
Treatment: Use convex lenses to increase refractive power to focus on the retina.
3) Astigmatism
Astigmatism happens when the light bend differently as it enters your eye. This is when your cornea is not round compared to the curve of an egg or rugby ball. It can affect both short-sighted and congenial far-sighted vision, causing blurry vision.
Treatment: Use cylindrical lens which is a special lens which can form the lights into one direction.
4) Presbyopia
Presbyopia occurs when extraocular muscle degeneration and the intraocular lens cannot focus on close vision. This condition is common in people 40 years old and up. It will progress as you age. The difference between presbyopia and congenial far-sightedness is that people with farsightedness will have problems seeing nearby object.
Treatment: Use convex lenses for reading.
