7/2/2023 0 Comments Blown pupil![]() ![]() Not until the early 20th century was the importance of a fixed dilated pupil recognised as an ominous physical sign. Compression or stretching of the oculomotor nerve were considered possible causes, but the related mechanisms of coning and the importance of lateral shift were only more recently realised.įEW investigations of late years have excited more interest than those which have been made into the connection of certain changes in the eye with diseases of the central nervous system, and into the additional means of diagnosis which such changes may afford. The observation of the ominous fixed, dilated pupils in those with expanding brain lesions dates to Richard Bright and Jonathan Hutchinson in the 19th century, but its significance and mechanisms were only debated in the early years of the 20th century. Once these are systematically excluded, benign episodic unilateral mydriasis should be considered a possibility.This paper recalls the descriptions and early ideas about the dilated pupil accompanying raised intracranial pressure resulting from head injuries and space-occupying lesions. 1 Adies pupil and trauma are other common causes. These pupils can be identified by their refusal to constrict with 1% Pilocarpine. 4 Pharmacological blockade is the most common cause of such a presentation. 1 We found only one report of an intracranial aneurysm causing internal ophthalmoplegia without extraocular muscle involvement. 3 In the absence of any other ocular abnormality, unilateral mydriasis is rarely due to an intracranial cause. A systematic approach is required to examine and investigate this condition. The cataracts in our patient were an incidental finding.Īnisocoria is often viewed as a worrying sign. 2 The dilated pupil is the only ocular finding. ![]() 2 The episodes may be accompanied by blurred vision, orbital pain, headache, or photosensitivity. The features of our patient were consistent with a rare but innocuous condition termed ‘benign episodic unilateral mydriasis.’ 2 The affected individuals, usually women, often have a history of migraine. ![]() Each time there were no other significant findings and pharmacological tests were negative. Three of these episodes were accompanied by headache and two by ocular pain. Over the next 2 years, this patient presented four times with similar episodes of unilateral mydriasis, twice affecting the left eye ( Figure 1b). The anisocoria spontaneously disappeared in 3 days. It was observed that 0.125% Pilocarpine did not constrict the pupil, whereas 1% Pilocarpine constricted both pupils well. There was no other ocular abnormality, except for the previously noted cataracts. There was no ptosis and full ocular motility. Her vision was unchanged from her last visit to the department. A detailed history revealed no trauma and no possibility of pharmacological dilation. Six months later, she was referred to us with a dilated left pupil. This was interpreted as an abnormally prolonged response to tropicamide drops. The right pupil, however, remained dilated ( Figure 1a). The abrasion healed in 2 days with vision improving to 6/18. Examination revealed bilateral congenital cataracts. Vision was 6/12 in the right eye and 6/36 in the left. She was systemically well, except the occasional classical migraine. A 39-year-old lady presented to the casualty with a traumatic corneal abrasion to the left eye. ![]()
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