Pupilla learning lab
Visual Pathway Simulator
Place a lesion anywhere from the optic nerve to the occipital cortex and see the visual field defect, with lessons and a case quiz.
- Free in your browser
- English & Arabic
- Education & training
Your first practice session
- Trace the pathway from the eye to the occipital cortex.
- Place a lesion and predict the field defect before inspecting it.
- Compare nearby lesion sites, then attempt the case quiz.
Common mistakes to avoid
- Confusing retinal coordinates with visual field coordinates.
- Assuming every real lesion produces an ideal textbook defect.
For education and training only. Pupilla is not a medical device and must not be used for diagnosis or treatment decisions.
Understand the principles
Visual pathway lesions and the visual field defects they cause
The pattern of a visual field defect shows where the visual pathway is damaged. A lesion in front of the optic chiasm affects one eye; a lesion of the chiasm typically causes a bitemporal hemianopia; and any lesion behind the chiasm causes a homonymous defect on the opposite side in both eyes. The further back the lesion, the more congruous — alike in the two eyes — the defect becomes, so an occipital lesion gives a congruous homonymous hemianopia, often with macular sparing.
RAPD and the swinging flashlight test
A relative afferent pupillary defect (RAPD), or Marcus Gunn pupil, means one eye sends a weaker light signal to the brainstem than the other. It is found with the swinging flashlight test: when the light swings from the healthy eye to the affected eye, both pupils dilate instead of staying small. An RAPD points to asymmetric optic nerve disease or extensive retinal damage, and on its own it does not make the pupils unequal in size.
Questions about this simulator
What can I practise with the Visual Pathway Simulator?
Place a lesion anywhere from the optic nerve to the occipital cortex and see the visual field defect, with lessons and a case quiz.
Do I need to install software or create an account?
Open the simulator free in a modern browser without installation. An account enables supported saved progress and results; coverage varies by module.
Can I use a phone or tablet?
You can access it in modern phone and tablet browsers. A larger screen gives diagrams and controls more space; performance depends on the device and browser.
Does this replace clinical training or patient diagnosis?
For education and training only. Pupilla is not a medical device and must not be used for diagnosis or treatment decisions.
References & further learning
Sources for the teaching principles. Listing a source does not imply its institution endorses or validates this simulator.