Central scotoma

Published on 05/05/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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43 Central scotoma

Instruction

Examine this patient’s visual fields.

Salient features

History

• Sudden onset usually

• Patient notices a ‘hole’ in the vision while reading a poster or looking at a clock

• Difficulty performing in reading, driving, walking and recognizing faces.

Examination

• Central scotoma (allow the patient to find the defect by moving the white hat pin in his or her own visual field). Then determine:

• the size and shape of the defect by moving the pin in and out of the blind area
• whether the defect crosses the horizontal midline (vascular defects of retina do not do so)
• whether the defect crosses the vertical midline (defects caused by pathway damage have a sharp vertical edge at the midline)
• whether the defect extends to the blind spot: so-called caecocentral scotoma (seen in glaucoma, vitamin B12 deficiency) (Fig. 43.1)
• whether there is a similar defect in the other eye (to exclude homonymous hemianopic scotomas).

• Examine the fundus; remember that the optic discs may be:

• pale (optic atrophy)
• normal (retrobulbar neuritis)
• swollen and pink (papillitis).
image

Fig. 43.1 Compressive optic neuropathy causing contraction of left visual field and cecocentral scotoma. Right visual field is normal.

Diagnosis

This patient has a central scotoma (lesion) caused by optic atrophy (aetiology).

Advanced-level questions

What do you understand by the term scotoma?

It is a small patch of visual loss within the visual field.

Mention a few underlying causes for central scotoma

• Demyelinating disorders (multiple sclerosis)

• Optic nerve compression by tumour, aneurysm

• Glaucoma

• Toxins: methanol, tobacco, lead, arsenical poisoning

• Ischaemia, including central retinal artery occlusion caused by thromboembolism, temporal arteritis, syphilis, idiopathic acute ischaemic neuropathy

• Hereditary disorders: Friedreich’s ataxia, Leber’s optic atrophy

• Paget’s disease

• Vitamin B deficiency

• Secondary to retinitis pigmentosa

• Late age-related macular degeneration: the patient usually has enough vision to be ambulatory because the peripheral visual field around a central scotoma is intact

• Valsalva retinopathy, which is characterized by a painless, sudden loss of vision in an otherwise healthy patient with no ocular history after activities such as vomiting, coughing and weight lifting. (The sudden rise in intrathoracic pressure increased the intraocular venous pressure, causing the rupture of perifoveal capillaries.) Visual loss can be marked but spontaneous recovery usually occurs (N Engl J Med 2005;352:e16)

• Bungee jumping.

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