Our most important sensory organ works like an ultra sensitive camera.

The eye is a complex optical system made up of the cornea, crystalline lens and vitreous body, which deflects or refracts incoming light. The total power of refraction from all these optical components is expressed in dioptres (dpt). In a normal-sighted eye the rays of light are refracted so that they land at the exact centre of the retina – at the point of best vision. Images are thus perceived in focus.

Defective vision

If the focal point does not fall exactly on the retina, but instead in front of or behind it, the object viewed is represented in a blurred manner: This is known as defective vision. Distinctions are made between near-sightedness, far-sightedness, astigmatism and age-induced far-sightedness.