Chapter 13 The eyes, ears, nose and throat
The eyes
Examination anatomy (Figure 13.1)
The structure of the eye is shown in Figure 13.1. Many of these structures can be examined as outlined below.
Examination method
The uveal tract consists of the anterior uvea (iris) and posterior uvea (ciliary body and choroid). |
Figure 13.3 (a) Normal sclera (b) Conjunctival pallor in an anaemic patient
Note contrast between anterior and posterior parts in the normal eye.
Figure 13.4 The cranial nerves III, IV & VI: voluntary eye movements
(a) ‘Look to the left.’ (b) ‘Look to the right.’ (c) ‘Look up.’ (d) ‘Look down.’
Examine the retinas (Figure 13.5; see also Figure 11.8, page 336). Focus on one of the retinal arteries and follow it into the optic disc. The normal disc is round and paler than the surrounding retina. The margin of the disc is usually sharply outlined but will appear blurred if there is papilloedema or papillitis, or pale if there is optic atrophy. Look at the rest of the retina, especially for the retinal changes of diabetes mellitus or hypertension.
There are two main types of retinal change in diabetes mellitus: non-proliferative and proliferative. Non-proliferative changes include: (1) two types of haemorrhages—dot haemorrhages, which occur in the inner retinal layers, and blot haemorrhages, which are larger and occur more superficially in the nerve fibre layer; (2) microaneurysms (tiny bulges in the vessel wall), which are due to vessel wall damage; and (3) two types of exudates—hard exudates, which have straight edges and are due to leakage of protein from damaged arteriolar walls, and soft exudates (cottonwool spots), which have a fluffy appearance and are due to microinfarcts. Proliferative changes include new vessel formation, which can lead to retinal detachment or vitreous haemorrhage.
Hypertensive changes can be classified from grades 1 to 4:
It is important to describe the changes present rather than just give a grade.
The causes of common eye abnormalities are summarised in Table 13.3.
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