Chapter contents
Overview
Sensory transduction
Central course
Primary visual cortex
Retinal deficits
Optic nerve damage
Chiasm damage
Damage posterior to chiasm
| Cranial Nerve II - Optic Nerve | Page 2 of 11 |
Sensory Transduction
Light passing through the cornea and aqueous humor and entering the pupil travels through the lens and vitreous body to reach the retina at the back of the eye.
The process of converting photons of light into electrical signals occurs in a deep layer of the retina which contains the photoreceptor cells - the rods and cones.
Rods and cones are specialized cells which have stacks of plasma membrane associated with visual pigments making them sensitive to light.
The differences between the rod system and the cone system are described in the table below:
|
|
|
| High sensitivity, specialized for night vision | Lower sensitivity, specialized for day vision |
| Saturate in daylight |
Saturate only in intense light |
| Achromatic | Chromatic, mediate color vision |
| Low acuity |
High acuity |
| Not present in central fovea | Concentrated in central fovea |
| Present in larger number than cones | Present in smaller number than rods |
Figure 2-2. Sensory transduction.
