Eye exam: visual acuity, visual fields and eye movements !

Exam technique

Three simple tests of how much each eye sees, which part of the field it sees and whether the eyes move together.

Updated 2026-11-01

See it in 3D: Optic nerve · Oculomotor nerve (III) · Abducens nerve (VI) · Trochlear nerve (IV) · Optic chiasm · Lateral rectus · Medial rectus · Superior oblique · Eyelids

What it is

The basic eye exam measures visual acuity in each eye, tests visual fields by confrontation and checks eye movements, which depend on cranial nerves III, IV and VI. Together with the pupils and the fundus, it localises lesions from the cornea to the occipital cortex. It is quick, needs no special equipment and is part of every neurological exam.

Landmark anatomy

Optic nerve (II): carries vision; nasal fibres cross at the chiasm and continue to the occipital cortex.
Oculomotor (III): medial, superior and inferior rectus, inferior oblique, levator of the lid and pupil constrictor.
Trochlear (IV): superior oblique, which moves the eye down when it is adducted.
Abducens (VI): lateral rectus, which moves the eye outward.

Technique, step by step

Visual acuity: place the patient 6 metres from a Snellen chart, wearing their glasses, and cover one eye at a time.
Record the smallest line read as a fraction (for example 20/20 or 6/6); if none is read, test counting fingers, hand movement and light perception.
If acuity is low, repeat through a pinhole: if it improves, the problem is refractive.
Near vision is tested with a reading card at about 35 centimetres.
Confrontation fields: examiner and patient face each other at one metre; each covers the opposite eye and they look at each other's eye.
Bring a finger in from the periphery in each of the four quadrants and ask the patient to say when it appears; compare with the examiner's field.
Eye movements: ask the patient to follow a finger or penlight without moving the head, tracing a wide 'H'.
Watch whether the eyes move together, for limitation or nystagmus, and ask about double vision and the direction in which it worsens.
Inspect the lids (ptosis), eye alignment and the corneal light reflex, which should fall on the same spot in both pupils.

Abnormal findings

III palsy: eye down and out, ptosis; a dilated pupil points to compression (for example an aneurysm) and is urgent.
IV palsy: vertical double vision worse looking down (going downstairs); the patient tilts the head towards the healthy side.
VI palsy: the eye does not move outward and horizontal double vision worsens looking towards the affected side; it can signal raised intracranial pressure.
Loss of vision in one eye: lesion of the eye or optic nerve. Bitemporal hemianopia: lesion of the chiasm (pituitary adenoma).
Homonymous hemianopia: lesion behind the chiasm on the opposite side, as in a stroke.
Variable double vision with ptosis that worsens at the end of the day suggests myasthenia gravis.

Common errors

Testing acuity without the patient's glasses or with both eyes open.
Moving the hand too fast or in the centre of the field during confrontation; the test only finds large defects.
Asking for eye movements too fast or not holding gaze at the extremes, where mild limitation and nystagmus appear.
In children, not checking acuity and alignment in time: amblyopia responds better the earlier it is found.

Test yourself

Think of the answer, then tap the question to see it.

What does it mean when visual acuity improves through a pinhole?

The loss is due to a refractive error, correctable with lenses, not to retinal or optic nerve disease.

Which muscles do nerves IV and VI supply?

IV supplies the superior oblique and VI the lateral rectus; the other extraocular muscles depend on III.

Where is the lesion in bitemporal hemianopia?

At the optic chiasm, where the nasal fibres cross; the classic cause is a pituitary adenoma.

What does a complete third nerve palsy look like?

Eye turned down and out, ptosis and, if compressive, a dilated pupil that does not react to light.

Add to my cards (4)

See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Visual acuity test: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026); Visual field: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026); Evaluation of the Ophthalmologic Patient (Merck Manuals, 2026).

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Representative model, for educational purposes only.