Refractive error check up (Spectacle check up):
In normal eyes, rays of light entering into the eye are focused on the retina by cornea and lens. In
patient with any type of refractive error the ray of light are not focused on retina which leads to blurring
- Blurring of vision
- Eyeache (more after work in the evening)
- Shadowing of letters
Types of refractive error:
There are mainly four types of refractive error: Myopia, Hypermetropia, Astigmatism and Presbyopia
Myopia, also known as short sightedness, is a common refractive error in which eye ball is too long and
because of which rays of light are focused infront of retina which is corrected by putting concave
(minus) spectacle lenses infront of the eye.
Hypermetropia, also known as Far sightedness, is a refractive error in which rays of light are focused
behind the retina which is corrected by putting convex (plus) spectacle lenses in front of the eye.
Astigmatism is a type of refractive error in which rays of light in one particular axis are focused either in
front or behind the retina instead of the surface of retina which leads to blurring of lines in one
particular axis. This type of error is corrected by cylindrical lenses.
Presbyopia is a type of refractive error which occurs because of ageing. In young people with age less
than 42-43, lights coming from near object are focused on the retina because of flexibility of lens inside
the eye. With aging, this flexibility of eye is reduced which leads to blurring of near objects which is
known as presbyopia. This error is corrected by age appropriate convex glasses in front of the eye.
Treatment for refractive error
- pectacle correction
- Contact lens
- Surgery for removal of error : Lasik surgery