This week we will continue with the second part of visual field deficits. ⏺️The image on the left illustrates the visual pathway and indicates the location of various lesions. The right panel illustrate the visual field defects associated with each lesion. ⏺️As it was explained previously, pathologies such as trauma, tumors, stroke, or glaucoma involving the visual pathway can cause visual defects. Depending on which area of the visual pathway is affected this cause to loss of vision in particular regions of the visual field. ⏺️Damage to the optic chiasm, optic tract, optic radiations or visual cortex is rarely complete. ⏺️As a result, the deficits associated with damage to these structures are typically more limited to specific regions of the visual fields. ⏺️This is especially true for damage along the optic radiations, which fans out under the temporal and parietal lobes in its course from the lateral geniculate nucleus (LGN) to the visual cortex. Different parts of the optic radiations carry information from different areas of the visual field. Therefore, lesions at the optic radiations can generate different patterns of partial loss of vision in both eyes (4 and 5). ⏺️Injury to certain visual structures can lead to loss of vision throughout wide areas of the visual field. This is commonly found when the occipital visual cortex is damaged (6). .
📸Used materials: #cauliflower
(brain), cherrybelle #radish
(eyes), orange #carrots
(LGN and visual fields), violet carrots (visual fields), green beans (optic nerves and tracts), #lemon
peel (optic radiations) and red bell pepper (visual cortex). .
Kandel ER, Schwartz JH and Jessell TM (2000). Principles of Neural Science, Fourth Edition. Chapter 27 - Central Visual Pathways.
Purves D, Augustine GJ, Fitzpatrick D, et al. (2004). Neuroscience, Third Edition. Chapter 11 - Central Visual Pathways.