How the eye sees

The process of vision begins when light rays that reflect off objects and travel through the eye’s optical system are refracted and focused into a point of sharp focus.

For good vision, this focus point must be on the retina. The retina is the tissue that covers the inside of the back of the eye, where light-sensitive photoreceptor

cells capture images in much the same way that film in a camera does when exposed to light. These images are then transmitted through the eye’s optic nerve to the brain for interpretation.

Just as a camera’s aperture is used to adjust the amount of light needed to expose film in the right way, the eye’s pupil widens or constricts to control the amount of light that reaches the retina.

In dark conditions, the pupil widens. In bright conditions, the pupil constricts.

More on the eye and ‘refractive errors’ next week.

Very important: Always make sure you discuss and make decisions about your eye care based upon a formal appointment with your optician or doctor.

For more information please call us or visit


Tel: 011 884 8413  |