Pupilla learning lab
Hirschberg & Krimsky Simulator
Study corneal light reflex displacement, compare simulated strabismus and angle kappa, and explore prism-based Krimsky testing in the eye exam simulator.
- Free in your browser
- English & Arabic
- Education & training
This workflow uses the shared Eye Exam Simulator. The button opens the existing examination tools.
Your first practice session
- Illuminate both eyes and compare reflex positions.
- Choose graded deviations and observe displacement.
- Compare an angle-kappa case before using prisms.
Common mistakes to avoid
- Assuming a displaced reflex always indicates strabismus.
- Mixing degrees of rotation with prism dioptres.
For education and training only. Pupilla is not a medical device and must not be used for diagnosis or treatment decisions.
Understand the principles
Hirschberg and Krimsky tests: measuring strabismus with the corneal light reflex
The Hirschberg test estimates strabismus from where a penlight's reflection sits on each cornea: a reflex displaced temporally means esotropia, nasally means exotropia, downward means hypertropia and upward means hypotropia. Each millimeter of decentration is traditionally counted as about 7 degrees, or 15 prism dioptres, although photographic studies suggest closer to 21 prism dioptres per millimeter. The Krimsky test measures the angle more precisely by placing prisms in front of an eye until the corneal reflexes are symmetric in both eyes.
The cover test: cover–uncover, alternate cover and prism cover test
The cover test detects and measures strabismus. In the cover–uncover test you cover one eye and watch the other: if the uncovered eye moves to take up fixation, there is a manifest deviation (a tropia). If no tropia is seen but the covered eye moves back into line when the cover is removed, there is a latent deviation (a phoria). The alternate cover test breaks fusion to reveal the total deviation, and adding prisms until the movement stops (the prism cover test) measures it in prism dioptres.
Try a virtual patient
Teaching examples in the exam simulator. Observe and explain the signs before comparing cases.
Questions about this simulator
What can I practise with the Hirschberg & Krimsky Simulator?
Study corneal light reflex displacement, compare simulated strabismus and angle kappa, and explore prism-based Krimsky testing in the eye exam simulator.
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.