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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
In acute anterior uveitis, the pupil is –
assistant
The correct answer is  There is a narrowing of the pupil (miosis) due to irritation of sphincter pupillae by toxins. Iris edema and engorged radial vessels of iris also contribute to making the pupil narrow.
The shape of the pupil becomes irregular due to segmental posterior synechiae.
The papillary reaction becomes sluggish or may even be absent due to edema and hyperemia of iris which hamper its movement.
There may be ectropion of pupil (eversion of papillary margin), owing to the contraction of organising exudates upon the iris. This causes the pigmented epithelium on the posterior surface of iris to be pulled around the papillary margin so that the patches of pigment may be seen on the anterior surface of the iris, i.e. ectropion of the uveal pigment.
The pupil is small, irregular and sluggish reacting.