Key Points:
- Visual Fields: We have two visual fields, left and right. The information from each half of the visual field goes to the opposite side of the brain.
- Optic Chiasm: This is the point where the fibers from the nasal retina (which sees the opposite visual field) cross to the other side.
- Lesions: Damage at different points in the visual pathway can cause specific visual field loss.
- Damage to the optic nerve of one eye: blindness in the corresponding visual field (e.g., damage to the right optic nerve causes blindness in the right visual field of the right eye and the left visual field of the left eye).
- Damage behind the optic chiasm (optic tract, optic radiation, or primary visual cortex): homonymous hemianopsia (loss of vision in the same half of the visual field in both eyes).
- Damage to the optic chiasm (e.g., by a pituitary tumor): bitemporal hemianopsia (loss of vision in the outer halves of both visual fields).
- Blurry Vision: Blurry vision can be caused by problems in the visual pathway or misaligned eyes. Closing one eye can help differentiate between the two causes. If vision is normal in each eye individually but blurry with both eyes open, the cause is likely misaligned eyes.
Additional Notes:
- The lecture mentions the importance of the thalamus, which relays visual information to the cortex.
- The lecture uses the example of an anhinga to illustrate how misaligned eyes can cause blurry vision. Importance of Edges Visual Perception