Eye examination: acuity, fields, pupils and fundoscopy

• The eye examination is a bedside search for the single most useful piece of clinical information in neurology, endocrinology, vascular medicine and trauma: a direct look at the retina and its blood supply, plus a check of how the eyes and pupils behave.
• It runs in a fixed order so that nothing is missed and the patient is not disturbed more than necessary: acuity, colour vision, fields, pupils, eye movements, red reflex, anterior segment, intraocular pressure if measured, then fundoscopy.
• Most of the yield is in two tests done well: visual acuity measured properly, and direct ophthalmoscopy done at the right distance with a dilated pupil.
• Findings must be recorded as signs, not diagnoses: stony pale disc, absent cup, bilateral, not "papilloedema", until the summary line of the presentation.
• The examination is only finished when it has been presented aloud in the set order, with the negatives that change the differential stated and no diagnosis stated too early.
• Many of these skills are felt rather than read: start by examining normal eyes until the optic disc and macula are familiar.

By the end of this page you should be able to:

1. Set up and perform a complete eye examination safely, with consent and chaperone.
2. Measure and record visual acuity and colour vision, and explain why each is documented as it is.
3. Test the visual fields by confrontation in all four quadrants and name the defect you find.
4. Examine the pupils and perform the swinging light test, and say what a relative afferent pupillary defect means.
5. Perform a red reflex examination and a step-by-step direct ophthalmoscopy, naming the structures in the order in which they are seen.
6. Recognise normal, diabetic, hypertensive and papilloedematous fundi from their described appearances.
7. Present a normal and an abnormal eye examination aloud and in writing.

The eye examination is the bedside part of assessing anyone with lost or blurred vision, eye pain or redness, headache, a suspected neurological or endocrine problem, diabetes or hypertension, or trauma, and it is part of almost every general examination when the situation allows. Its aims are to find evidence of eye disease, to place that disease in the right anatomical pattern (anterior segment, optic nerve or retina), to spot the systemic signs that change management (hypertension, diabetes, raised intracranial pressure), and to catch the ophthalmic emergencies that need same-day treatment. Done properly it takes only a few minutes; the fundoscopy part of it is the part most often skipped, which is the part that changes outcomes.

The examination is best done in a dim room, with the patient sitting, facing you, at a height where you can look into both eyes without bending. Have to hand: a Snellen or logMAR (logarithm of the minimum angle of resolution) distance chart, a near vision card, a colour vision plate or test card, an occluder or a piece of card, a pen torch, dilating drops if they are to be used, and a direct ophthalmoscope. For each eye, position your eye at the same horizontal level as the patient's; the patient should be comfortable, warm, and able to lean forward.

For a first-time learner, remember that the eye is a window into both the central nervous system and the small vessels of the body. Optic disc swelling means raised intracranial pressure or optic nerve disease; flame-shaped haemorrhages and arteriovenous nicking mean hypertensive disease; microaneurysms mean diabetic disease. None of these can be detected by a glance at the fundus in a bright room through an undilated pupil.

Preparation is part of the examination, and an eye examination done badly here cannot be repaired later.

• Introduce yourself by name and role, and confirm the patient's identity and date of birth.
• Explain what you are about to do, in words the patient understands: "I am going to check how well you see, move a light in front of your eyes, and look at the back of the eye with this torch-like instrument."
• Obtain informed consent and invite questions, remembering that consent can be withdrawn at any time.
• Offer a chaperone. In the United Kingdom a chaperone is offered whenever the examination involves close personal contact or exposing the face and eyes in a vulnerable way, whatever the sex of the patient or the examiner, and the offer must be recorded.
• Clean your hands with alcohol gel or soap and water before and after the examination.
• Remove glasses for acuity testing as instructed by the chart, but test later with the patient's own correction in place when assessing the macula.
• Position the patient sitting, with the head supported, facing a light source you can dim. Warm the room: a cold patient tenses the orbicularis and keeps the eyes half-closed.
• If the patient cannot sit, support them upright as far as possible; note the limitation.
• Dilating drops blur vision for several hours: warn the patient before instilling them, and check that there is no narrow anterior chamber angle risk before dilating.

The order below is the standard sequence taught in bedside clinical skills. Keep it fixed. Each item states what to do and what to look for.

1. General appearance. From the moment you meet the patient, note whether they are comfortable, the head posture, whether they are photophobic, and whether there is facial asymmetry. Note glasses, contact lenses, a prosthetic eye, and any obvious ptosis.
2. Visual acuity. Measure the patient's best corrected vision at distance with a standardised chart, then near vision if the page is read in ordinary life. Test each eye separately, with and without the patient's own correction. ^[1]
3. Colour vision. Test with pseudoisochromatic plates or an equivalent colour arrangement, if available and appropriate, one eye at a time, in good daylight or equivalent conditions.
4. Visual fields. Test by confrontation, one eye at a time, in all four quadrants. ^[5]
5. Pupils. Inspect size, shape and symmetry; test the direct and consensual light reflexes; test accommodation; then perform the swinging light test for a relative afferent pupillary defect. ^[1]
6. Eye movements. Follow the H pattern in each cardinal position of gaze; look for limitation, diplopia, nystagmus and any head turn.
7. Red reflex. Inspect the red reflex in both eyes together from about arm's length, looking for symmetry, loss of reflex or a white reflex.
8. Anterior segment and pen torch. Inspect the lids, conjunctiva, sclera, cornea, anterior chamber, iris, pupil and lens in good light.
9. Intraocular pressure. Estimate or measure if equipment is available, and record the method used.
10. Fundoscopy. Inspect the red reflex; examine the optic disc, the retinal vessels, the macula and finally the peripheral retina, in both eyes.

The table collects the signs produced by the steps above, with the way to elicit each and a short interpretation. It is not exhaustive: ophthalmology has far more signs than any one page can carry. The patterns that follow the table are the ones a medical student must know.

A few numerical points follow directly from the sources, and every one of them is recorded in the accompanying claims ledger:

• Confrontation visual fields. Test each eye at approximately an arm's length; in one validated protocol the examiner and patient were separated by about 65 centimetres. Test the peripheral monocular field in all four quadrants: upper left and right, and lower left and right. ^[5]
• Relative afferent pupillary defect. An afferent defect is present when the pupil either fails to constrict or does not constrict as briskly as expected on direct illumination; a relative afferent pupillary defect is present when the pupil paradoxically dilates as the light swings from the normal to the affected eye. ^[1]
• Amsler chart. A 10 cm by 10 cm square grid of 5 mm squares, with a central fixation spot; distortion of the grid suggests macular disease. ^[1]
• Direct ophthalmoscope. A direct ophthalmoscope has about 15 times magnification but a field of view of only about 10 to 15 degrees, which is why the pupil should be dilated first. ^[1]
• Hypertensive retinopathy. Look for arteriolar narrowing, arteriovenous nicking, flame-shaped haemorrhages and, in severe cases, disc oedema. ^[6]
• Diabetic retinopathy stages. Mild non-proliferative disease shows isolated microaneurysms; moderate disease shows microaneurysms, dot and blot haemorrhages, hard exudates or cotton-wool spots; severe non-proliferative disease shows 20 or more intraretinal haemorrhages in each of four quadrants, definite venous beading in 2 or more quadrants or intraretinal microvascular abnormalities in 1 or more quadrant; proliferative disease shows neovascularisation, vitreous or preretinal haemorrhage, or fibrovascular membranes. ^[3]
• Direct ophthalmoscopy optical limits. A direct ophthalmoscope offers a restricted view of the retina, which is a barrier to non-ophthalmic use; dilating the pupil and using the smallest possible working distance at the correct angle makes the difference. ^[6]

Direct ophthalmoscopy needs a darkened room and a dilated pupil; without both, failure is certain.

1. Warm up and check. Turn the instrument on, set the light brightness, and check the lens wheel and the patient's distance correction.
2. Red reflex. From about an arm's length, with your eye on the side of the eye to be examined, lean back and 15 degrees towards the temple until you see the red reflex in both eyes, which assesses the clarity of the media. ^[1][2]
3. Approach. Follow the red reflex along this temporal flight path, slowly leaning towards the patient, until the optic disc appears. ^[1]
4. Disc. When found, move closer. Comment on the contour, colour and cup of the optic disc; if you cannot find it, look for the natural V-shape where vessels join and move in that direction. ^[1]
5. Vessels. Follow the arterioles and veins out from the disc in the four quadrants, commenting on calibre, crossing and any haemorrhage or exudate.
6. Macula. From the disc, move temporally until the darker macula and the central bright foveal reflex are seen; this is the last structure to be examined, because the light on it makes the pupil constrict. ^[1]
7. Periphery. Tilt the instrument and ask the patient to look in the direction you wish to see; a dilated pupil is essential here. ^[1]

Carry the lens in your ipsilateral hand so the freed hand can steady the lids if needed; hold the instrument with the light exit face towards the patient and rotate your head and the instrument together rather than the eye. ^[2]

Presentation is a separate skill from examination, and it is tested in every clinical examination. The aim is to give a listener the findings in an order they can follow, leading with what matters most, and ending with a summary and a differential that make sense.

Speak in this order, without apologising for steps you did not perform:

1. State the patient and the overall appearance: "She was comfortable, with no photophobia and no ptosis."
2. The most important positive finding first: "The important findings were on the fundus, with bilateral swollen optic discs and blurred margins."
3. The other positive findings, in the order of the examination: acuity, colour vision, fields, pupils, movements, red reflex, anterior segment, then fundus details.
4. The negatives that matter for the differential: "There was no relative afferent pupillary defect, no ophthalmoplegia and no arteriolar abnormality." Do not list every negative you looked for; a chosen negative is one that would change the differential.
5. Investigations you have to hand or are about to do: "Visual acuity was 6 over 9 in each eye, and intraocular pressure was normal to finger palpation."
6. End with one sentence and a differential: "In summary this is bilateral papilloedema, most likely secondary to raised intracranial pressure; the alternatives include optic neuritis and malignant hypertension."

• Speak in the past tense for findings you have completed: "The pupils were equal and reactive."
• Use numbers, not impressions: "6 over 9", "all plates read", and pupil sizes recorded in millimetres.
• Use the standard terms rather than private descriptions.
• State both sides when you have compared them: "the right disc margin was blurred nasally, the left was clear."
• Do not present a sign as if it is a diagnosis: say "bilateral swollen optic discs with blurred margins", not "papilloedema", until the summary line.
• Lead with what is abnormal and important, not with the first normal step the examiner already assumes.
• Finish with the patient: return the curtains or gown before you present.

A written entry mirrors the spoken entry, in short numbered or bulleted lines rather than prose:

• Comfortable, no photophobia or ptosis. Right-handed, wears glasses.
• Visual acuity: right 6 over 9, left 6 over 9, both with correction. Near vision normal. Colour vision intact.
• Fields: full to confrontation in all four quadrants, each eye.
• Pupils: equal and reactive with no relative afferent pupillary defect.
• Movements: full H pattern, no nystagmus.
• Red reflex: normal, symmetrical. Anterior segment: clear cornea, deep anterior chamber, clear lens.
• Fundi: discs pale pink with sharp margins and a small cup; vessels normal; macula normal with foveal reflex. No hypertensive or diabetic changes. No disc swelling.
• Summary: normal eye examination.

All patient details below are invented and illustrative. They are not real patient records.

Normal examination, spoken. "This 28-year-old woman was comfortable at rest with no photophobia. Her visual acuity was 6 over 6 in each eye with correction. Colour vision was intact in both eyes. The visual fields were full to confrontation in all four quadrants. The pupils were equal and reactive, with no relative afferent pupillary defect. Eye movements were full. The red reflexes were present and symmetrical. The anterior segments were clear, with deep anterior chambers and no lens opacity. On fundoscopy each optic disc was pink with sharp margins and a small central cup; the retinal vessels and maculae were normal, with a bright foveal reflex and no haemorrhage or exudate. In summary, this is a normal eye examination."

Hypertensive fundus, spoken. "The important findings were on the fundi of a 62-year-old man with a blood pressure that was elevated. Acuity was 6 over 9 in the right eye and 6 over 6 in the left. The pupils and movements were normal, and there was no relative afferent pupillary defect. On examination, both retinal arterioles were narrowed, with arteriovenous nicking at several crossings, and flame-shaped haemorrhages were present along the superior arcade. The discs were of normal colour with sharp margins and no swelling, and the maculae were clear. In summary: hypertensive retinopathy with arteriolar narrowing, arteriovenous nicking and flame-shaped haemorrhages, but no papilloedema."

Non-proliferative diabetic retinopathy, spoken. "This 54-year-old man with type 2 diabetes had acuity of 6 over 9 in both eyes. The significant findings were at the posterior pole of each eye: scattered microaneurysms, a few dot and blot haemorrhages, and a small cluster of hard exudates temporal to the macula in the right eye, with cotton-wool spots near the superior arcade. There was no neovascularisation on the disc or elsewhere, and no vitreous haemorrhage. The discs and vessels were otherwise normal. In summary: bilateral non-proliferative diabetic retinopathy, with macular exudates threatening central vision, requiring a retinal photograph and referral for specialist review."

Papilloedema, spoken. "The important findings were in a 24-year-old woman with a three-week history of headache and transient visual obscurations. Acuity was 6 over 6 in each eye. The fields showed enlargement of the blind spots to confrontation, and the pupils were equal and reactive with no relative afferent pupillary defect, and no ophthalmoplegia. Fundoscopy showed both optic discs to be hyperaemic and swollen, with blurred margins, loss of the physiological cup, splinter haemorrhages and a few cotton-wool spots. In summary: bilateral optic disc swelling consistent with papilloedema from raised intracranial pressure, requiring urgent neuroimaging and referral."

• Examining through glasses and recording the result as the uncorrected acuity.
• Testing acuity in a dim corner or with a chart at the wrong distance.
• Forgetting to test each eye separately, so a monocular loss is missed.
• Assuming normal fields because the patient can see a wiggling finger once; one unstructured confrontation is not a field test.
• Using a bright room or starting the light from in front, which constricts the pupils and hides the swinging light test.
• Forgetting the swinging light step once the direct reflex is brisk; the relative afferent pupillary defect is the most important sign in a painless monocular visual loss.
• Calling any nystagmus normal; congenital nystagmus has specific features and other nystagmus needs explanation.
• Leaving the lights on and never dilating, so a view of the disc and macula is not obtained at all.
• Starting fundoscopy at the disc when the red reflex has not been found at a distance.
• Confusing papilloedema with a congenitally crowded or tilted disc, or with drusen; refer when the margins are blurred and the cup is lost.
• Calling signs diagnoses in the middle of the examination, before the summary line.

• The eye examination is a fixed sequence: acuity, colour vision, fields, pupils, movements, red reflex, anterior segment, intraocular pressure, fundus.
• Document acuity as a fraction, with and without correction, each eye separately.
• The visual fields are tested by confrontation in all four quadrants; a monocular or altitudinal loss suggests retinal or optic nerve disease.
• A relative afferent pupillary defect is found by the swinging light test, not by the direct reflex alone.
• Eye movements are tested in the H pattern; diplopia and nystagmus localise.
• A normal red reflex is a warm glow from both pupils; absent, asymmetric or white reflexes are abnormal.
• Pen torch examination of the anterior segment includes cornea, anterior chamber depth, lens and iris, with fluorescein under cobalt blue light for the corneal surface.
• Direct ophthalmoscopy should follow the red reflex temporally from 15 degrees, then examine disc, vessels, macula and periphery, with a dilated pupil. ^[1]
• A direct ophthalmoscope has about 15 times magnification but only about a 10 to 15 degree field of view. ^[1]
• Papilloedema is bilateral disc swelling from raised intracranial pressure; hypertensive retinopathy produces arteriolar narrowing, arteriovenous nicking and flame-shaped haemorrhages; diabetic retinopathy progresses from microaneurysms to dot-blot haemorrhages and exudates and then to neovascularisation.
• Presentations lead with the most important abnormal finding and end with one summary sentence and a differential, after stating the chosen negatives.
• Numerical quantities belong in the examination record, not as vague impressions.