Physical Examination - Eyes

Physical Examination

·        Trying to work out where is the problem: refractive, obstruction of light through the transparent tissues of the eye, or neural problem 

·        Measure Visual Acuity:

o   One at a time.  Wear glasses

o   Snellen‟s Chart: Distance of chart (normally 6 metres)/Distance they could read. Smaller fraction is worse

o   If can‟t see chart at all, then Count Fingers (CF) at X metres

o   If can‟t count fingers then Perceive Light (PL): flash torch on and off in eyes – can they see it

o  Check with pinhole, if clearer Þ refractive error or corneal scarring, refer to optometrist. If worse Þ retinal pathology 

o  Also check visual fields, colour, stereo vision

·        External inspection:

o  Be systematic: look for changes in shape, size, position, colour, transparency, is it focal or diffuse

o  Pupil reflexes: Should be simultaneous and equal. Swinging light test: Alternate light from one eye to the other, swapping it quickly. Both pupils should stay the same. Sensitive and complete test of neural pathways. If this shows a problem, test for an efferent pupillary defect with the near reflex test

·        Internal inspection with ophthalmoscope: 

o  Get patient to look at target a long way away: relaxes accommodation.  Dim the light ® dilation

o  Dilate pupil with Madriasil (not atropine, T½ too long)

o  Check for:

·        Red reflex defects: eg cataract, intra-ocular blood · Reduced transparency (compare two eyes)

o  Cup and disk: 

·        Disk is 15 degrees nasal to fixation. To examine macula, get patient to look directly at the light 

·        Check disk for distinct margins and symmetry  

·        Physiology cup is blood vessels in the centre of the nerve – not nerves

·        Normal cup to disc ratio < 1/3 (but lots of variation). Check it‟s the same in both eyes 

·        Large and/or deep cup sign of glaucoma (vessels „diving into‟ the cup) – especially if eyes different. Large ratio

o   Papilloedema: non-inflammatory nerve oedema due optic nerve axon flow obstruction or ­ICP ® red disk swelling towards you, blurred margins of disk but no early visual loss. Venous obstruction may ® haemorrhage. If bilateral then ­ICP

o   Papillitis: optic nerve head inflammation ® swollen disk with visual loss. If unilateral then optic neuritis (¯colour vision, orbital pain), sarcoidosis, Tb, Syphilis, etc

o   Pseudopapilloedema: occurs in hypermetropia, disc is smaller than normal and crowded

·        Fundus pathology: maculopathy, optic neuropathy, retinal detachment

·        Refractive errors: hard to focus on retina

·        Arteries: narrow, bright red, windy.  Veins: thicker, straight

·        Amount of melanin in choroid layer ® variation in pigmentation of retina. Deep green patch = coronial nevus (benign)

·        Clinical usefulness depends on good instrument, good technique, knowledge of normal anatomy and normal variations