Neuro-Ophthalmology Eye Exam Simulator

A virtual patient whose two eyes are driven by one binocular alignment model. Pick a condition and examine it the way you would at the bedside: every movement, measurement and corneal reflex comes out of the same engine, so the cover test, the prism that neutralises it, the motility and the head-tilt result always agree.

The examiner's tools sit together in one tray: a penlight for the pupils and the corneal reflexes (Hirschberg and Krimsky), a near/distance target, follow-my-finger motility, an opaque or translucent occluder for cover–uncover and alternate cover, a prism box for prism cover measurement, the Bielschowsky head tilt, the near point of convergence and the Maddox rod. Explore mode names the condition; Assessment mode is a scored virtual OSCE.

What the simulator models

  • Ocular motility from muscle and nerve physiology, obeying Hering's law, with restrictive and paretic patterns
  • Eyelids that follow the eyes, including ptosis, lid retraction and lid lag in thyroid eye disease
  • Pupils with separate afferent and efferent pathways: relative afferent pupillary defect, amaurotic pupil, Horner, Adie and Argyll Robertson pupils
  • Tropias and phorias revealed by cover–uncover and alternate cover, measured with loose prisms
  • Internuclear ophthalmoplegia, the one-and-a-half syndrome, gaze palsies and nystagmus
  • Head tilt (three-step test), near point of convergence and Maddox rod findings

Conditions you can examine (43)

Cranial Nerve Palsies

  • Right third nerve (oculomotor) palsy
    Weakness of the right medial, superior and inferior recti and inferior oblique, with ptosis and (in the complete, pupil-involving form) a dilated unreactive pupil. The eye rests “down and out”; only abduction (LR) and intorsion (SO) remain.
  • Right fourth nerve (trochlear) palsy
    Weakness of the right superior oblique: right hypertropia that increases in left gaze (especially down-and-left) and on right head tilt, with right excyclotorsion.
  • Right sixth nerve (abducens) palsy
    Weakness of the right lateral rectus: an esotropia that increases in right gaze and almost disappears in left gaze, larger at distance than near, and larger when the paretic right eye fixes (secondary deviation).
  • Right cavernous sinus syndrome (combined CN III, IV and VI palsy)
    A right cavernous sinus lesion involving the oculomotor, trochlear and abducens nerves (and V1–V2): an almost immobile right eye with ptosis — a total external ophthalmoplegia — resting slightly out and down.
  • Complete right optic nerve lesion (amaurotic pupil)
    No light perception in the right eye. Light shone into it reaches neither pupil; light in the left eye constricts both, because the efferent (CN III) pathway of the right pupil is intact. The pupils are equal in size and both constrict to near.
  • Right relative afferent pupillary defect
    Reduced (but not absent) conduction in the right optic nerve. The right eye still sees, so the pupils react to light in either eye, but less to light in the right eye: on the swinging flashlight test both pupils dilate as the light swings onto the right eye.

Internuclear & Gaze Disorders

  • Right internuclear ophthalmoplegia
    A lesion of the right medial longitudinal fasciculus: the right eye fails to adduct (or adducts slowly) on gaze to the left, the abducting left eye shows nystagmus, and convergence is spared.
  • Bilateral internuclear ophthalmoplegia
    Both medial longitudinal fasciculi are involved: adduction fails in each eye on lateral gaze with abducting nystagmus in the other; convergence may be spared.
  • One-and-a-half syndrome (right)
    A right pontine lesion of the abducens nucleus/PPRF and MLF: no horizontal gaze to the right (the “one”) and no right adduction on gaze to the left (the “half”). The only horizontal movement left is abduction of the left eye, with nystagmus. Convergence is spared.
  • Right horizontal gaze palsy (abducens nucleus / PPRF)
    Neither eye can move to the right beyond the midline: a conjugate palsy, so the eyes stay aligned and there is no diplopia. Convergence is spared (the left medial rectus still adducts to near).
  • Right frontal eye field lesion (acute gaze deviation)
    An acute lesion of the right frontal eye field (e.g. a right hemispheric stroke): both eyes deviate toward the side of the lesion and the patient cannot look voluntarily to the left. Brainstem gaze centres are intact, so the doll’s-head manoeuvre moves the eyes across.
  • Dorsal midbrain (Parinaud) syndrome
    A lesion at the posterior commissure (pineal tumour, hydrocephalus, midbrain stroke): upgaze palsy, mid-dilated pupils with light–near dissociation, eyelid retraction (Collier sign) and convergence–retraction nystagmus on attempted upgaze.
  • Skew deviation (right hypertropia)
    A supranuclear vertical misalignment from damage to the otolith–ocular pathways: right hypertropia with the hypertropic eye INtorted (the opposite of a fourth nerve palsy), little change with head tilt, and ≥ 50 % reduction lying supine.
  • Hypermetric saccades (cerebellar dysmetria)
    Saccades overshoot the target and are followed by a corrective saccade back — saccadic dysmetria from cerebellar (dorsal vermis / fastigial) disease.
  • Slow vertical saccades (supranuclear gaze palsy pattern)
    Vertical saccades are markedly slowed while horizontal ones are near-normal, with limited vertical range on versions — the pattern of progressive supranuclear palsy.
  • Saccadic (impaired) smooth pursuit
    Low pursuit gain: the eyes fall behind a moving target and catch up with a staircase of small saccades. Common and non-specific (age, fatigue, drugs, many cerebral and cerebellar lesions).

Pupillary & Sympathetic

  • Right Horner syndrome
    Interruption of the oculosympathetic pathway to the right eye: a small right pupil that reacts normally to light and near, a mild right ptosis (Müller muscle) and, if pre-ganglionic, facial anhidrosis.
  • Argyll Robertson pupils
    Small, often irregular pupils that do not react to light but constrict normally to near (light–near dissociation), from a lesion in the rostral midbrain affecting the light-reflex fibres to the Edinger–Westphal nuclei. Both eyes, often asymmetrically.
  • Right Adie tonic pupil
    A ciliary ganglion lesion: the right pupil is dilated and reacts little or not at all to light, but constricts slowly and strongly to a sustained near target and redilates slowly (tonic). Often a young woman, sometimes with reduced tendon reflexes.

Nystagmus

  • Gaze-evoked nystagmus
    Absent in primary position, appearing on eccentric gaze with the fast phase beating toward the direction of gaze — a failure of the neural integrator to hold the eyes eccentric (cerebellar disease, anticonvulsants, alcohol).
  • Downbeat nystagmus
    Vertical nystagmus with the fast phase beating down, increasing in downgaze and lateral gaze — classically from cervicomedullary junction or cerebellar (flocculus) disease.
  • Upbeat nystagmus
    Vertical jerk nystagmus with the fast phase beating up, present in primary position and increasing in upgaze — from lesions of the medulla or the cerebellar vermis.
  • See-saw nystagmus
    A pendular disconjugate oscillation: one eye rises and intorts while the other falls and extorts, then they reverse — from parasellar / chiasmal lesions or congenital achiasma.
  • Acquired pendular nystagmus
    A sinusoidal oscillation with no fast phase — both phases equal speed — present in primary position. Acquired in adults with multiple sclerosis or oculopalatal tremor; causes oscillopsia.
  • Infantile nystagmus (with a null zone)
    Conjugate horizontal nystagmus present since infancy. Intensity is least in a “null zone” (here about 12° to the patient’s left) and it damps on convergence.

Strabismus

  • Right esotropia (constant, comitant)
    A manifest inward deviation of the right eye with a strong left-eye fixation preference. The angle is the same in every direction of gaze.
  • Alternating esotropia
    A large constant esotropia with free alternation: whichever eye has just taken up fixation keeps it after the cover is removed.
  • Refractive accommodative esotropia
    A hyperopic child whose esotropia is driven by accommodation: without glasses there is a large left esotropia; with the full hyperopic correction the eyes are straight (small esophoria).
  • Convergence excess (high AC/A esotropia at near)
    Straight (esophoric) at distance but esotropic at near, because accommodation drives excessive convergence. A bifocal add relaxes the near deviation.
  • Right exotropia (constant, comitant)
    A manifest outward deviation of the right eye with left-eye fixation.
  • Alternating exotropia
    A constant exotropia with free alternation of fixation.
  • Intermittent exotropia
    A large exodeviation, greater at distance than near, that is controlled most of the time but breaks down after dissociation — recovering only after a blink.
  • Right hypertropia (comitant)
    A manifest upward deviation of the right eye that is the same in all positions of gaze and with either head tilt.
  • Right hypotropia (comitant)
    A manifest downward deviation of the right eye, the same in all positions of gaze, with the left eye fixing.
  • Dissociated vertical deviation (bilateral, asymmetric)
    Each eye floats up and extorts slowly when it is covered, and comes back down with incycloduction when uncovered — without the fellow eye moving. That violation of Hering’s law distinguishes DVD from a true hypertropia.

Heterophorias & Vergence

  • Exophoria
    A latent outward deviation held straight by fusional convergence. It appears only when fusion is broken: the covered eye drifts out and, once uncovered, makes a slow inward fusional movement.
  • Esophoria
    A latent inward deviation controlled by fusional divergence. Under cover the eye drifts in; when uncovered it moves out to re-fuse.
  • Right hyperphoria
    A small latent vertical deviation held by vertical fusional vergence. Under cover the right eye drifts up; it comes back down to re-fuse.
  • Convergence insufficiency
    An exophoria much larger at near than at distance, with a remote near point of convergence and reduced base-out reserve at near.

Special Forms of Strabismus

  • Duane retraction syndrome type 1 (right)
    Congenital miswiring of the right lateral rectus (innervated by a branch of CN III instead of CN VI): almost no right abduction, near-normal adduction with retraction of the globe and narrowing of the eyelid fissure, and little or no deviation in primary position.
  • Brown syndrome (right)
    Restricted movement of the right superior oblique tendon through the trochlea: the right eye cannot elevate in adduction, with milder limitation straight up and nearly normal elevation in abduction. Usually straight in primary position.
  • Thyroid eye disease — restrictive strabismus
    Enlarged, stiff extraocular muscles (inferior rectus most often, then medial rectus) tether the globe: the right eye is hypotropic and cannot elevate; the left eye cannot fully abduct. Both upper lids are retracted.
  • Ocular myasthenia gravis
    Fatigable weakness at the neuromuscular junction: ptosis and ocular misalignment that change during the examination. Sustained upgaze worsens the left ptosis; sustained gaze makes the right medial rectus fail (a pseudo-INO).

Related tools

  • Visual Pathway Simulator — retina to occipital cortex localisation, with the field defect each lesion produces
  • QBank — image-based clinical cases, including neuro-ophthalmology cases with the same bedside tools
  • Condition library — symptoms, findings, investigations and treatment for 158 ophthalmic conditions