Final answer:
A lesion after the optic chiasm on the left side would result in compromised vision in the right visual field of both eyes, a condition known as right homonymous hemianopia.
Step-by-step explanation:
If there is a lesion after the optic chiasm on the left side, the vision would be affected in such a way that all information from the right visual field would be compromised. This is because the optic chiasm is where fibers from the retina of each eye cross to the opposite side of the brain. The axons from the lateral retina do not decussate; thus, the right visual field information transmits to the left side of the brain, while information from the left visual field transmits to the right side of the brain. A lesion on the left side after the optic chiasm disrupts the pathways coming from the right halves of both eyes, resulting in a loss of vision in the right visual field, a condition known as right homonymous hemianopia.
A clinical example of vision being compromised due to a lesion in the optic pathway is bilateral hemianopia, where the outermost areas of the visual field are lost, typically caused by something like a pituitary tumor pressing against the optic chiasm. In the case of a lesion on just one side after the optic chiasm, the vision loss would be restricted only to one side of the visual field, corresponding to the opposite visual field of the affected side of the brain.