Eye and Vision OSCE Examination Quiz

See Colour Vision. Option B is correct. Colour vision is tested with Ishihara plates, which are circles of coloured dots that hide a number for people with normal colour vision. Each eye must be tested separately, because the healthy eye would otherwise cover for the weaker one. Ishihara plates mainly test red-green discrimination. Reduced performance in a symptomatic eye can support an acquired colour defect from optic nerve disease, such as optic neuritis (inflammation of the optic nerve), even when acuity is still relatively good. Red desaturation, where a red object looks washed out or less vivid in one eye, is assessed separately by comparing the same red target between the two eyes. The two checks look at different aspects of colour perception, and neither on its own proves optic neuritis. The first plate is a demonstration plate that everyone should see, so it checks that the patient has understood and can see the dots. A memory aid: reds go pale first, so compare red between the eyes, one eye at a time.

• Test: Ishihara plates, with each eye tested separately.
• Coverage: mainly red-green discrimination, so reduced performance can support an acquired colour defect from optic nerve disease.
• Red desaturation: assessed separately by comparing a red target between the two eyes.
• First plate: a demonstration plate that everyone should see.