In severe cases of anterior uveitis whole circle of pupil gets adhered to lens capsule resulting in:

Seclusio pupillae/ring synaechiae/annular synaechiae is seen in severe iritis or recurrent uveitis, in which whole circle of pupillary margin becomes tied down to the lens capsule. It can lead to secondary angle closure glaucoma. Note: Occlusio pupillae/blocked pupil occurs when exudation in uveitis is extensive. They organize across the entire pupillary area and opaque fibrous tissue fills the pupillary area. Festooned pupil: Pupil dilatation with atropine leads to failure of dilation of adhered segments resulting in irregularly shaped pupil. Pupil will be miotic and sluggishly reacting in uveitis. Ref: Parson's diseases of the eye, 21st edition, page no: 230