Tuesday, January 31, 2012

How Does the Retina Work?

The Retina, located at the back of the eye, contains specialized cells called photoreceptors which are sensitive to light of different colors. These allow us to see in both the light and the dark. There are two mail types of photoreceptors: rods, which operate in dim light and provide low acuity vision in scales of grey; and cones, which operate in bright light and provide high acuity, color vision.

The eye has adapted through evolution to be extremely sensitive to light. However, the bulk of the eye tissue in not responsive to light; rather, the muscles which surround the eyeball, as well as the iris, cornea and lens, all act to focus light on to the retina, a relatively small area at the back of the eyeball which contains photoreceptors.

At its simple level, the Retina consists of four layers of cells:
  • at the back of the retina is the outer, pigmented layer-these epithelial cells absorb light
  • next are aligned a layer of photoreceptors which are able to convert light energy into electrical energy
  • the electrical potentials the photoreceptors generate are transmitted to the bipolar cells
  • the bipolar cells in turn communicate with ganglion cells; these nerve cells receive information from photoreceptors which they pass on to ganglion cells
Thus light has first to travel through the ganglion and bipolar cells before it reaches the light-sensitive photoreceptors at the back of the Retina. The, all of this information is transmitted to the Optic Nerve and finally makes its way to the brain so that we can see.

If you have any questions about your Retina, please do not hesitate to call Doctor & Associates at 203-227-4113 with any questions.