Painless loss of vision
This may occur in one or both eyes, and the
visual loss may be transient or permanent. Possible causes are:
•
obstruction of the central retinal artery (Fig.
36.32);
•
obstruction of the central retinal vein (Fig.
36.33);
•
cranial arteritis;
•
ischaemic optic neuropathy;
•
migraine and other vascular causes;
•
retrobulbar neuritis and papillitis;
•
vitreous and retinal haemorrhages;
•
retinal detachment (Fig. 36.34);
•
macular hole, cyst or haemorrhage;
•
cystoid macular oedema often after surgery;
•
hysterical blindness.
Specialist help should be sought in any case
of loss of vision. The erythrocyte sedimentation rate and C-reactive protein
should be measured immediately if cranial arteritis is suspected, and the
carotid system should be examined for bruits and other signs of arteriosclerosis
in cases of ischaemic optic neuropathy and central retinal artery occlusion.
Glaucoma, hypertension, myeloma and diabetes should be looked for in cases of
central vein thrombosis.