The examination should take place in a suitably darkened room. The patient's right eye should be examined with the examiner's right eye, and vice versa. The patient is asked to focus on an object in the distance, and the examiner's head is kept vertical to permit this.
First use the ophthalmoscope at +12 dioptres - the red numbers of most ophthalmoscopes - and at arm's length with the patient gazing into the distance - starting the examination in this manner prevents reflex pupil contraction which occurs if the patient attempts to accommodate. Rack the ophthalmoscope towards zero.
Sequentially, with racking down, examine the:
- cornea for ulcers
- lens for opacities - cataracts may cause and prevent full examination of the fundus
- this is found by following a large retinal vein back towards the disc as all veins radiate from the disc
- look for:
- optic atrophy; a pale disc as opposed to the normal yellow
- papilloedema; a pink disc with blurred edges and swelling
- examine blood vessels - these radiate away from the optic disc; there is a normal arterial/venous width ratio of 2:3 - venous engorgement occurs in retinal vein thrombosis
- examine the cup of the optic disc - a physiological cup occurs centrally and occupies approximately 1/3 of the disc diameter. Deepening and widening of the cup occurs in glaucoma
- veins - look for AV nipping
- look for exudates, haemorrhages, choroiditis