Refractive Errors

Normal Sight

Normal sight is achieved when light rays entering the eye through the cornea (the clear domed front surface of the eye) and the lens, are focused onto a single point on the retina.

Short Sight or Myopia

Short sight is due to the cornea being too steeply curved or the eye is longer than normal.

Therefore, light rays fall in front of the retina, resulting in blurred distance vision.

Long Sight or Hyperopia

Long sight occurs if the cornea is too flat or the eye too short.

Therefore light rays focus on a point behind the retina causing near vision to become blurred.

Astigmatism

Astigmatism is caused by the cornea being shaped rather like a rugby ball instead of being spherical.

This produces two different focal points which can blur images at all distances. Astigmatism can occur with both long and short-sight.

Presbyopia

On reaching mid to late forties, most people find they need reading glasses, this is due to the natural ageing process of the eye, Presbyopia. The crystalline lens inside the eye loses its flexibility, so it can’t change focus from distance to near vision. Laser treatment can correct an individual’s distance vision however they will continue to need reading glasses.

Cataract

A cataract is a clouding of the lens of the eye. The normal lens is clear and brings light into focus so we can see. A cataract can be compared to a window that is frosted or “fogged” with steam. Most commonly this cloudiness is age related, however occasionally it can be due to trauma to the eye, it may be secondary to diabetes or other medical conditions, and can be congenital.