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 7 of 11 |
Clinical Correlation - Visual Deficits & Damage to the Retina
Visual Deficits
Armed with knowledge of the anatomy of the visual system, one can predict the deficits associated with a lesion at a particular point in the central visual pathway.
Damage to the retina
Results in a loss of input from the affected portion of the retina leading to a monocular field deficit.
Since axons of the ganglion cells converge toward the optic disc, damage to a portion of the retina closer to the optic disc will affect a greater number of neurons than would the same amount of damage in the peripheral retina leading to a larger visual field defect in that eye.
Since the cones are concentrated in the fovea, damage to the fovea results in a greater visual handicap than damage to peripheral regions of the retina.
Damage to the optic nerve will also result in a monocular visual defect due to loss of input from the ipsilateral eye. The patient will complain of blindness in that eye.
Figure 2-7. Visual deficits - damage to the retina.
