Final answer:
Blurred vision from slowed action potential propagation in the optic nerve occurs because the transmission of visual information to the brain is delayed. Continuous conduction is slower in unmyelinated neurons like the optic nerve, which leads to visual disturbances. Related conditions such as bilateral hemianopia can stem from compression of the optic chiasm but are distinct from general blurring.
Step-by-step explanation:
Slowed action potential propagation in the optic nerve can cause blurred vision because the rate at which visual information is transmitted to the brain is reduced. Action potentials are electrical signals that travel along neurons, and when these are impeded, it affects how quickly and efficiently visual signals reach the visual cortex for processing. Specifically, in the optic nerve, if there is continuous conduction along an unmyelinated optic nerve due to a pathological condition or damage, this can lead to slow propagation of action potentials. Continuous conduction is a slower process whereby voltage-gated Na+ channels need to be opened sequentially along the entire length of the axon, as opposed to the faster saltatory conduction seen in myelinated axons where the action potential jumps from node to node. This can result in visual disturbances like blurred vision.
Additionally, a related clinical issue is bilateral hemianopia, which involves the loss of lateral peripheral vision. This occurs when a growth, such as a pituitary gland tumor, compresses the optic chiasm where some of the optic nerve fibers cross. Interestingly, this does not affect the fibers that don't cross (projecting to the same side of the brain), resulting in a specific pattern of vision loss rather than general blurring. However, blurring could occur if there was an overall decrease in the ability of the optic nerves to transmit signals effectively due to some form of damage or pathology affecting action potential propagation.