[Verse 1]
When the brain maps vision, there's a pathway to trace
From retina to cortex, each fiber finds its place
But when damage strikes along this neural highway
The pattern of your blindness tells us where things went astray
One optic nerve gets severed, that eye goes completely dark
While the other keeps on seeing, like a candle in the park
[Chorus]
Cut before the crossing, lose one eye alone
Cut right at the junction, outer fields are gone
Cut behind the meeting, same side disappears
The pattern tells the story that the doctor's trained to hear
Routing matters deeply when the visual system breaks
Every lesion's signature shows the path that vision takes
[Verse 2]
At the chiasm crossing, nasal fibers interweave
Like dancers switching partners in a neurologic weave
When pituitary tumors press from underneath this spot
They crush the crossing fibers but the straight-through ones they're not
Bitemporal hemianopia means both outer fields have fled
While the center and the inside keep the visual pathway fed
[Chorus]
Cut before the crossing, lose one eye alone
Cut right at the junction, outer fields are gone
Cut behind the meeting, same side disappears
The pattern tells the story that the doctor's trained to hear
Routing matters deeply when the visual system breaks
Every lesion's signature shows the path that vision takes
[Verse 3]
Past the chiasm junction, in the tract and LGN
When damage strikes these regions, there's a pattern once again
Homonymous hemianopia takes the same side from both eyes
Contralateral blindness where the damaged pathway lies
But retinotopy's preservation keeps the map intact and clear
From the eyeball to cortex, every point is stationed here
[Bridge]
In the radiations spreading to the primary visual zone
The fovea gets protection from its blood supply alone
Macular sparing happens when the center stays alive
While peripheral vision fades, the detail zone will thrive
This clinical neuroanatomy tells us something profound
The orderly arrangement can be traced and can be found
[Chorus]
Cut before the crossing, lose one eye alone
Cut right at the junction, outer fields are gone
Cut behind the meeting, same side disappears
The pattern tells the story that the doctor's trained to hear
Routing matters deeply when the visual system breaks
Every lesion's signature shows the path that vision takes
[Outro]
From optic nerve to cortex, through chiasm, tract and more
Each lesion writes its story on the visual field's door
The routing tells us everything about where damage lies
In the wondrous neural highway that connects our brain to eyes