Related Experiment Video
Updated: Aug 16, 2026
Echocardiographic Evaluation of Atrial Communications before Transcatheter Closure
Published on: February 8, 2022
Use of ultrasound biomicroscopy to diagnose Ahmed valve obstruction by iris
Monica M Carrillo1, Graham E Trope, Charles Pavlin
1Department of Ophthalmology, Toronto Western Hospital, Ont.
Background:
We report 2 cases in which ultrasound biomicroscopy (UBM) was used to diagnose Ahmed valve obstruction by the iris.
Methods:
Two patients underwent unilateral placement of Ahmed implants, one into the anterior chamber and the other into the ciliary sulcus.
Results:
Intraocular pressures increased in the early postoperative period. In each case, a clear view of the aqueous drainage tube was precluded. Occlusion of the end of the tube by iris tissue was demonstrated by UBM. An iridectomy over the tip of the tube instituted filtration in each case.
Interpretation:
UBM was instrumental in diagnosing the presence and cause of occlusion of aqueous drainage tubes.
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