The eyes and visual system

Published on 09/04/2015 by admin

Last modified 09/04/2015

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The eyes and visual system

An examination of the eyes and the visual system can prove helpful in patients with no visual or ocular symptoms. This section will first describe examination of the eye generally, then examination of the pupils, visual function, acuity, visual fields and fundoscopy. Eye movements are discussed on pages 18–19.

General examination of the eye

Ptosis is common and is often missed (Table 1). Partial ptosis is usually associated with unilateral overactivity of the frontalis. Ptosis is not a feature of facial nerve palsy (with a facial nerve palsy the eye does not close).

Table 1 Ptosis

Ptosis	Causes	Features
Neurogenic	Horner’s syndrome, sympathetic lesion Oculomotor palsy (3rd nerve)

Partial ptosis, small pupil, enophthalmos, may be altered sweating

May be complete ptosis, associated reduced adduction and elevation, pupil may be large

Neuromuscular junction Myasthenia gravis Variable ptosis that fatigues, may be associated diplopia and facial weakness Myopathic Myopathies, especially myotonic dystrophy Usually symmetrical. Features of associated muscle disease Mechanical Aponeurotic dehiscence (common in the elderly) The tarsal plate is separated from the levator muscle

Exophthalmos is usually a feature of hyperthyroidism but may indicate orbital disease. Enophthalmos is a feature of Horner’s syndrome. Lid retraction is seen in hyperthyroidism and in rare upper brain stem lesions.

Remember false eyes can be cosmetically effective – a pitfall in exams.