Visual Field Localizer
Localize the lesion before you name the disease
This module bridges retina, visual cortex, and neuroanatomy by turning field geometry into localization logic. The question is not just what the patient cannot see. The question is whether the pattern is monocular, chiasmal, retrochiasmal, posterior, or attentional.
Lesion presets
Read the pattern, then rank the pathway
Consult-level visual localization
Syndrome frame
Left optic nerve
Complete monocular visual loss in the left eye with preserved right-eye vision is a prechiasmal syndrome until proven otherwise.
Strongest localization
Left optic nerve or severe left retinal input failure
Only one eye is affected. Once the fibers have crossed or merged, defects stop respecting one eye so cleanly.
Decisive next data
- • Pupil exam for a left relative afferent defect
- • Fundus and optic-disc correlation to separate retinal from optic nerve disease
Teaching pearls
- • Monocular means prechiasmal until proven otherwise.
- • Do not jump to cortex when one eye alone is blind.
Left optic nerve
Each eye is shown separately so monocular, chiasmal, retrochiasmal, and attentional patterns stay visually distinct.
Compare mode
Best fit versus attractive wrong turn
Best fit: Left optic nerve
Left optic nerve or severe left retinal input failure
Only one eye is affected. Once the fibers have crossed or merged, defects stop respecting one eye so cleanly.
Compare to: Optic chiasm
Optic chiasm
Crossing nasal retinal fibers carry temporal visual fields. A midline lesion there strips temporal fields from both eyes at once.
Why the selected preset beats this alternative
Compared with Optic chiasm, the selected pattern is stronger because only one eye is affected. once the fibers have crossed or merged, defects stop respecting one eye so cleanly.
Case Mode
Practice field localization before the reveal
Treat these like consult questions. Decide whether the complaint is monocular, chiasmal, retrochiasmal, posterior, or attentional, then pick the best field pattern before you reveal the answer.
Training stage
Consult-level visual localization
Post-clinical objectives
- • Separate true field loss from neglect and extinction using bedside logic rather than labels.
- • Use congruity, quadrant pattern, and macular sparing to rank retrochiasmal lesions by posterior depth.
Clinical vignette
Sudden monocular loss
A patient loses vision in the left eye, while the right eye sees normally.
Chief complaint
The left eye suddenly went dark, but the right eye is unchanged.
History
The deficit respects one eye completely rather than one side of space. Reading with the right eye remains possible.
Syndrome frame
This is a monocular visual syndrome, which localizes before the chiasm until proven otherwise.
Exam findings
- • Left-eye visual loss with intact right-eye field
- • No homonymous pattern on bedside testing
- • No clear cortical visual behavior change
Prompt
Which lesion pattern is the best fit, and why is a cortical explanation much weaker?
Localization cues
- • The deficit respects one eye, not one hemifield of shared space.
- • Later visual pathway lesions stop behaving monocularly.
Differential traps
- • Do not call monocular blindness an occipital problem.
- • Do not confuse a single-eye complaint with a homonymous field cut that the patient describes poorly.
Next data to request
- • Pupil exam for an afferent defect
- • Retinal and optic nerve correlation before chasing retrochiasmal lesions
Working pattern selection
Current pick: Right optic tract
Reading rules
Four rules that prevent most localization errors
Rule 1
Monocular loss localizes before the chiasm until proven otherwise.
Rule 2
Bitemporal patterns are chiasmal wiring problems before they are tumor labels.
Rule 3
Homonymous defects are retrochiasmal, and congruity usually pushes the lesion posteriorly.
Rule 4
Neglect is an attention disorder that can mimic field loss without being a true visual field cut.
Module handoff
Where to go next
Retinal Receptive Field Lab
Post-clinical neuro-ophthalmic triage
Visual Cortex
Consult-level cortical vision reasoning
Brain Atlas
Post-clinical anatomical convergence
Neuro Tutor
Cross-module consult reasoning rubric