Examine / Visual fields

Confrontation, then perimetry

Confrontation takes a minute and finds the hemianopia the patient has not noticed. Your own field is the reference, so the technique is about lining up with the patient and keeping them fixed on you.

01
Sit opposite the patient at arm's length, eyes level. Cover one of the patient's eyes and close your own opposite eye, so your field is the reference.
02
Ask them to look at your nose or your open eye and keep looking there.
03
Bring a target (a wiggling finger, a red pin) in from beyond the edge of your own field in each quadrant, midway between you, and ask them to say when they first see it.
04
Test each quadrant of each eye. Compare with your own field: a defect is a place where you see the target and they do not.
05
Then a red target across the vertical midline, asking whether the red looks the same on both sides: desaturation is the earliest sign of a chiasmal or nerve problem.
06
Finish with the blind spot if you have time; then formal perimetry if anything is abnormal.

The patterns you are looking for

Localise them

Left eye
Right eye
Normal. Schematic fields, as the patient sees them; dark is lost.
Retina. Nothing is lost. Each eye's field extends about 60 degrees nasally and 90 degrees temporally, with the blind spot 15 degrees temporal to fixation where the disc has no photoreceptors.
Left eye
Right eye
Central scotoma, right eye. Schematic fields, as the patient sees them; dark is lost.
Optic nerve. One eye and the centre: the papillomacular bundle, the fibres from the macula, or the macula itself. In a young adult with pain on eye movement this is optic neuritis; in an older smoker, a toxic or nutritional neuropathy; with distortion, a macular disease.
Left eye
Right eye
Bitemporal hemianopia. Schematic fields, as the patient sees them; dark is lost.
Optic chiasm. The temporal field of each eye is seen by the nasal retina, and nasal fibres cross in the chiasm. A lesion there, classically a pituitary adenoma pressing from below, takes both temporal fields and respects the vertical midline in each eye.
Left eye
Right eye
Right homonymous hemianopia. Schematic fields, as the patient sees them; dark is lost.
Occipital cortex. The same side of both fields: behind the chiasm, on the opposite side of the brain (the left hemisphere sees the right world). When it is complete and congruous, the whole retrochiasmal pathway is possible; the occipital cortex is the most common site, from a posterior cerebral artery stroke.
Left eye
Right eye
Left homonymous hemianopia with macular sparing. Schematic fields, as the patient sees them; dark is lost.
Occipital cortex. Sparing of the central few degrees on the affected side points to the occipital pole, which has a dual supply from the posterior and middle cerebral arteries: a posterior cerebral artery occlusion leaves the pole alive.
Left eye
Right eye
Right superior quadrantanopia. Schematic fields, as the patient sees them; dark is lost.
Temporal lobe radiations. A pie in the sky: the fibres from the inferior retina, which sees the superior field, loop forward around the temporal horn as Meyer's loop before turning back. A left temporal lobe lesion takes the right upper quadrants of both eyes.
Left eye
Right eye
Left inferior quadrantanopia. Schematic fields, as the patient sees them; dark is lost.
Parietal lobe radiations. A pie on the floor: the superior retinal fibres run straight back through the parietal lobe. A right parietal lesion takes the left lower quadrants.
Left eye
Right eye
Inferior altitudinal defect, left eye. Schematic fields, as the patient sees them; dark is lost.
Optic nerve. One eye, and the horizontal midline respected: the optic nerve head, whose blood supply is divided into an upper and a lower half. This is the field of non-arteritic anterior ischaemic optic neuropathy, sudden and painless, with a swollen disc.
Left eye
Right eye
Superior arcuate scotoma with a nasal step, right eye. Schematic fields, as the patient sees them; dark is lost.
Optic nerve. The nerve fibres arch around the macula from the disc, and those from the inferior disc rim serve the superior field. Glaucoma damages the rim in bundles, so the loss is an arc that stops at the horizontal midline nasally: the nasal step.
Left eye
Right eye
Generalised constriction, both eyes. Schematic fields, as the patient sees them; dark is lost.
Retina. The periphery goes in from all sides. In the retina this is retinitis pigmentosa, with night blindness first; in the nerve, end-stage glaucoma or papilloedema of long standing. A field that stays the same size at two testing distances is functional (tunnel), a true one widens with distance (funnel).