Pupilla eye exam simulator: frequently asked questions
Short, direct answers about what Pupilla is, what you can practice on it and how students and educators use it.
About Pupilla
What is Pupilla?
Pupilla is a free, browser-based eye exam simulator for optometry and ophthalmology education. It gives you a virtual patient with 54 simulated conditions and real clinical tools — penlight, occluder, prisms, retinoscope and trial lenses — so you can perform the exam and watch the eyes respond. It also includes a streak retinoscopy simulator, a refraction simulator, a visual pathway lesion simulator, 3D extraocular muscle anatomy, a case quiz and learning guides in English and Arabic.
Is Pupilla free? Do I need an account?
Yes, Pupilla is completely free and needs no account, sign-up or installation. Open pupillalab.com in a modern browser and start examining.
Who is Pupilla for?
Pupilla is built for optometry students, medical students, ophthalmology residents, orthoptists, optometrists and ophthalmologists who want to practice or revise the eye exam, and for educators who teach it. It is useful for self-study, lectures, small-group teaching and practical (OSCE-style) exam preparation.
What is the best simulator for optometry students?
The best choice depends on the skill you are practising. Pupilla is a free simulator platform built for optometry and ophthalmology students: a virtual patient with 54 conditions (esotropia and exotropia subtypes, phorias, cranial nerve palsies, INO, Duane, Brown, nystagmus and pupil disorders) whose eyes respond physiologically to the penlight, occluder and prisms; cover tests, Hirschberg and Krimsky; streak retinoscopy with trial-lens neutralization; refraction, lensometry, OCT, the visual pathway and 3D anatomy; and an Arabic voice lesson that walks through a full strabismus case on the simulator. It runs in the browser with no account, in English and Arabic. See how it compares with other simulators.
What is a good free eye exam simulator for optometry and ophthalmology students?
Pupilla is a free eye exam simulator that covers the core bedside eye exam in one place: pupils and RAPD, anisocoria, cover and alternate cover tests, Hirschberg and Krimsky, ocular motility and cranial nerve palsies, streak retinoscopy, refraction and visual field defects from visual pathway lesions. The eyes respond to the tools you use — a swinging penlight, an occluder or a prism — instead of showing a static picture, and the interface is available in English and Arabic.
What can I practice on Pupilla?
You can practice: the swinging flashlight test and RAPD grading; anisocoria (Horner syndrome, Adie tonic pupil, Argyll Robertson pupil); the cover–uncover and alternate cover tests; Hirschberg and Krimsky; ductions, versions and the H-test; third, fourth and sixth nerve palsies; INO, one-and-a-half syndrome and gaze palsies; nystagmus; streak retinoscopy; refractive errors and astigmatism; visual field defects; and extraocular muscle anatomy.
How realistic is the simulation?
Pupilla models the physiology behind each sign rather than playing fixed animations. Pupils constrict and redilate with light and near effort, a relative afferent pupillary defect is graded on a continuous scale, covered eyes drift and refixate with saccades, prisms shift the corneal light reflex by the amount you place, and the retinoscopic reflex changes speed, brightness and direction with the refractive error. It is still a teaching model: real patients vary, and supervised clinical practice remains essential.
Is Pupilla available in Arabic?
Yes. The whole simulator interface can be switched between English and Arabic from the language button, and the learning guides and this FAQ are published in both languages. Arabic pages start at pupillalab.com/ar/.
Does Pupilla work on phones and tablets?
Yes, Pupilla runs in current versions of Chrome, Safari, Edge and Firefox on computers, tablets and phones. A larger screen is more comfortable for the full exam simulator and the visual pathway simulator.
What is hand tracking and is my camera video uploaded?
Hand tracking is an optional mode that lets you hold the penlight or occluder with your real hand in front of your webcam. The hand-tracking model runs inside your browser, so the camera video is processed on your device and is not uploaded. The camera turns on only when you enable hand tracking.
Can Pupilla be used to diagnose patients?
No. Pupilla is an educational simulator, not a medical device. It is meant for learning and revision and does not replace clinical examination, supervised training or professional judgement.
Learning with Pupilla
How can I practice the swinging flashlight test for RAPD online?
Open the exam simulator with an RAPD in the right eye, pick up the penlight and swing it between the eyes, spending two to three seconds on each. Both pupils dilate when the light reaches the affected eye. The RAPD guide explains the technique, grading and causes.
Is there a free online streak retinoscopy simulator?
Yes. Pupilla's streak retinoscopy simulator lets you sweep the streak, read with and against motion, and neutralize the reflex with lenses for myopia, hyperopia and astigmatism. The retinoscopy guide covers working distance and the principal meridians.
How do I learn to tell a tropia from a phoria with the cover test?
Use the cover–uncover test first: if the uncovered eye moves to take up fixation when you cover the other eye, there is a tropia; if the covered eye moves back when it is uncovered and no tropia was seen, there is a phoria. In Pupilla you can compare esotropia with esophoria side by side, and the cover test guide walks through each step.
Can Pupilla help me prepare for an OSCE or practical eye exam?
Yes. You can rehearse the sequence of a pupil, motility and cover test station on a patient whose signs match a real condition, check your interpretation in the clinical explanation under the eyes, and test yourself with the visual pathway case quiz. Practicing the words you would say to an examiner alongside the simulator works well.
Can educators use Pupilla in lectures and teaching?
Yes. Pupilla is free to use in lectures, tutorials and skills labs, and it works well on a projector. Links can open a specific condition directly, for example pupillalab.com/#exam?condition=cn3-od for a right third nerve palsy, and adding ?lang=ar opens the simulator in Arabic.
How can I learn visual field defects from visual pathway lesions?
Open the visual pathway simulator, place a lesion on the optic nerve, chiasm, optic tract, optic radiations or occipital cortex, and watch the matching field defect appear on both eyes' charts. The visual field defects guide lists each lesion site and its classic pattern.
How do I cite Pupilla?
Cite Pupilla as a website: Pupilla. Ophthalmology & Optometry Simulation Platform. https://pupillalab.com (accessed day month year). To cite a specific guide, use its title and URL; every guide shows a ready-made citation at the end.
Eye anatomy
What are the main parts of the eye?
The main parts of the eye are the cornea, iris and pupil, lens, ciliary body, vitreous, retina with the macula and fovea, choroid, sclera and optic nerve. Light passes through the cornea, aqueous, pupil, lens and vitreous before it is focused on the retina, which sends the signal along the optic nerve. Rotate and label each part in the 3D eye anatomy simulator.
What are the three layers of the eye wall?
The eye wall has three coats: the outer fibrous layer (cornea and sclera), the middle vascular layer or uvea (iris, ciliary body and choroid) and the inner neural layer (retina). The 3D eye model lets you slice the globe to see each coat.
What are the layers of the cornea?
The cornea has five classic layers, from front to back: epithelium, Bowman's layer, stroma, Descemet's membrane and endothelium; the stroma makes up about 90% of its thickness. A pre-Descemet layer (Dua's layer) has also been described. Pupilla's 3D anatomy simulator shows the tear film plus the five layers at true thickness.
What are the 10 layers of the retina?
From the vitreous outward, the 10 retinal layers are: internal limiting membrane, nerve fibre layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, external limiting membrane, photoreceptor (rod and cone) layer and retinal pigment epithelium. You can see them in cross-section on the OCT simulator and the 3D eye model.
What is the difference between the macula and the fovea?
The macula is the central area of the retina, about 5.5 mm across, responsible for detailed central vision; the fovea is the small pit at its centre where cones are most densely packed and visual acuity is highest. On OCT the fovea is the central dip in the retinal profile — explore it in the OCT simulator.
Where is aqueous humour made and how does it drain?
Aqueous humour is secreted by the ciliary body into the posterior chamber, flows through the pupil into the anterior chamber and drains mainly through the trabecular meshwork into Schlemm's canal, with a smaller uveoscleral outflow. Blocking this outflow raises intraocular pressure, as in glaucoma.
Which seven bones form the orbit?
The orbit is formed by seven bones: frontal, zygomatic, maxilla, ethmoid, sphenoid, lacrimal and palatine. The thin medial wall (ethmoid) and orbital floor (maxilla) are the most common sites of blowout fractures. See them in the orbit view of the 3D anatomy simulator.
Eye muscles and cranial nerves
How many muscles move the eye?
Six extraocular muscles move each eye: four recti (superior, inferior, medial and lateral) and two obliques (superior and inferior). A seventh orbital muscle, levator palpebrae superioris, lifts the upper eyelid. Watch each one work in the 3D extraocular muscle simulator.
Which nerves supply the eye muscles? (LR6 SO4)
The lateral rectus is supplied by the sixth cranial nerve (abducens), the superior oblique by the fourth (trochlear), and all the others — superior, inferior and medial rectus, inferior oblique and levator — by the third (oculomotor); remember it as LR6 SO4, the rest 3. The extraocular muscle guide covers origins, insertions and actions.
What does the superior oblique muscle do?
The superior oblique's primary action is intorsion, its secondary action depression and its tertiary action abduction; it depresses the eye most when the eye is adducted, which is why it is tested by looking down and in. A fourth nerve palsy causes vertical double vision that is worse looking down, such as on stairs or when reading — see the cranial nerve palsy guide.
What are the actions of the superior rectus?
The superior rectus elevates the eye (primary action), intorts it (secondary) and adducts it (tertiary); it is a pure elevator when the eye is abducted about 23°, so it is tested by looking up and out. Compare it with the inferior oblique, which elevates best in adduction, in the 3D eye movements simulator.
Why is the eye "down and out" in a third nerve palsy?
In a complete third nerve palsy only the lateral rectus (sixth nerve) and superior oblique (fourth nerve) still work, so the eye is pulled out and down; the lid droops because the levator is paralysed, and the pupil may be dilated. A painful palsy with a dilated pupil needs urgent imaging for an aneurysm. Examine one on the virtual patient.
What is the H-test in an eye exam?
The H-test checks eye movements by having the patient follow a target in an H pattern into the six cardinal positions of gaze, each of which isolates one muscle of each eye. It reveals a weak muscle or nerve palsy as under-action in one direction. Learn it in the ocular motility and H-test guide.
What is the difference between ductions and versions?
A duction is the movement of one eye with the other covered; a version is a movement of both eyes together in the same direction. Versions follow Hering's law of equal innervation to yoke muscles, which explains why the deviation is larger when the paretic eye fixates. Practise both in the motility guide.
Optics and refraction
What is the difference between myopia, hyperopia and astigmatism?
In myopia (short-sightedness) light focuses in front of the retina and is corrected with minus lenses; in hyperopia (long-sightedness) it focuses behind the retina and is corrected with plus lenses; in astigmatism the eye has two different powers in two meridians, so there are two focal lines, corrected with a cylinder. See all three in the refraction simulator and the refractive errors guide.
What is a diopter?
A diopter (D) is the unit of lens power, equal to the reciprocal of the focal length in metres: a +2.00 D lens focuses parallel light at 0.5 m. Plus lenses converge light and minus lenses diverge it.
How do I read a glasses prescription (sphere, cylinder, axis)?
A glasses prescription gives sphere (SPH, the overall plus or minus power), cylinder (CYL, the extra power for astigmatism) and axis (the orientation of the cylinder, 1–180°), with ADD for extra reading power. For example −2.00 / −1.00 × 180 is a myope with astigmatism. Read finished lenses yourself on the lensometer simulator and see how a prescription blurs vision in the vision simulator.
What is presbyopia?
Presbyopia is the age-related loss of accommodation, usually noticed in the mid-40s, as the lens stiffens and can no longer focus on near objects. It is corrected with a reading addition (ADD) in reading, bifocal or progressive glasses.
What is retinoscopy and what is it used for?
Retinoscopy is an objective way to measure the eye's refractive error by watching the light reflex in the pupil while lenses are placed in front of the eye, so it works even in children and patients who cannot answer. It is the starting point for a glasses prescription. Learn it in the streak retinoscopy guide and practise on the retinoscopy simulator.
What do "with" and "against" motion mean in retinoscopy?
With motion means the reflex moves the same way as the streak, so you add plus power; against motion means it moves the opposite way, so you add minus power; at neutrality the pupil fills with light. Subtract the working-distance lens (+1.50 D at 67 cm) from the neutralizing lens to get the prescription. Try it on the retinoscopy simulator.
What does a lensometer measure?
A lensometer (focimeter or lensmeter) measures the sphere, cylinder, axis and prism of a spectacle lens and locates its optical centre. It is used to check new glasses and to read an old prescription. Practise reading lenses on the lensometer simulator.
What is Prentice's rule?
Prentice's rule states that the prism induced by looking through a lens away from its optical centre equals the decentration in centimetres times the lens power in diopters (Δ = c × D). For example, 5 mm of decentration in a 4 D lens gives 2Δ. The lensometer simulator shows induced prism on the reticle.
Pupils, visual pathway and eye alignment
What is a relative afferent pupillary defect (RAPD)?
An RAPD, or Marcus Gunn pupil, is a sign that one optic nerve or retina transmits less light than the other: in the swinging flashlight test both pupils dilate when the light moves to the affected eye. It points to optic nerve disease such as optic neuritis, or extensive retinal damage. Learn the test in the RAPD guide.
What causes unequal pupils (anisocoria)?
Anisocoria can be physiological, or caused by Horner syndrome (small pupil and mild ptosis), Adie tonic pupil (large, slowly reacting pupil), third nerve palsy, drugs or iris damage; comparing the difference in dim and bright light shows which pupil is abnormal. See the anisocoria guide.
Which visual field defect does a pituitary tumour cause?
A pituitary tumour compressing the optic chiasm from below typically causes bitemporal hemianopia — loss of the outer half of the field in both eyes, often starting in the upper temporal quadrants — because it damages the crossing nasal retinal fibres. Place the lesion yourself in the visual pathway simulator.
Where is the lesion in a homonymous hemianopia?
A homonymous hemianopia — loss of the same half of the field in both eyes — means a lesion behind the chiasm on the opposite side: the optic tract, lateral geniculate body, optic radiations or occipital cortex. Occipital lesions often spare the macula. See every lesion site in the visual field defects guide.
What is the Hirschberg test?
The Hirschberg test estimates a squint from the corneal light reflex: a reflex displaced 1 mm from its normal position corresponds to roughly 7°, about 15 prism dioptres, by the classic ratio (some studies suggest closer to 21Δ per mm). The Krimsky test then measures it with prisms. Learn both in the Hirschberg and Krimsky guide.
What is nystagmus?
Nystagmus is an involuntary, rhythmic oscillation of the eyes; jerk nystagmus has a slow drift and a fast corrective phase that names its direction, while pendular nystagmus moves at equal speed both ways. It can be congenital or acquired from vestibular, brainstem or cerebellar disease. Compare the types in the nystagmus guide.
What is OCT of the eye?
Optical coherence tomography (OCT) is a non-invasive scan that uses light to make micrometre-resolution cross-sections of the retina and optic nerve head, showing each retinal layer, fluid and nerve fibre thickness. It is used to diagnose and monitor macular disease and glaucoma. Learn to read scans in the OCT simulator.
Learning guides
- RAPD and the swinging flashlight test Perform the swinging flashlight test, grade a Marcus Gunn pupil and know what causes it.
- Anisocoria: Horner syndrome, Adie tonic pupil and third nerve palsy Decide which pupil is abnormal and tell Horner, Adie, Argyll Robertson and third nerve palsy apart.
- The cover test: cover–uncover, alternate cover and prism cover test Tell a tropia from a phoria and measure the angle with prisms, step by step.
- Hirschberg and Krimsky tests: measuring strabismus with the corneal light reflex Read the corneal light reflex, convert millimeters to prism dioptres and neutralize with prisms.
- Ocular motility and the H-test: ductions, versions and the nine positions of gaze Trace the H, know which muscle each gaze position tests and interpret limited movements.
- Third, fourth and sixth cranial nerve palsies and the three-step test Recognize each ocular motor palsy, run the three-step test and spot the red flags.
- Internuclear ophthalmoplegia (INO), one-and-a-half syndrome and gaze palsies Localize INO, one-and-a-half syndrome, gaze palsies and Parinaud syndrome from eye movements.
- Types of nystagmus: gaze-evoked, downbeat, upbeat, see-saw and pendular Describe nystagmus properly and know what downbeat, upbeat, see-saw and pendular patterns suggest.
- Extraocular muscles: anatomy, actions and nerve supply Origins, insertions, actions and nerve supply of the six eye muscles — and why actions change with gaze.
- Streak retinoscopy: with motion, against motion and neutralization Read with and against motion, neutralize both meridians and correct for working distance.
- Refractive errors and astigmatism: myopia, hyperopia and Sturm's conoid Understand myopia, hyperopia and astigmatism, read a prescription and correct for vertex distance.
- Visual pathway lesions and the visual field defects they cause Localize a lesion from its field defect, from the optic nerve to the occipital cortex.