A false-positive Seidel test after Ahmed valve insertion

An 80-year-old monocular man with long-standing primary open angle glaucoma underwent successful filtering surgery in his sighted right eye in 1980. He subsequently developed a cataract and had an uncomplicated clear cornea phacoemulsification with posterior chamber intraocular lens in 1996. Post-operatively, the filtration bleb remained very avascular but shallowed; the intraocular pressure increased and remained uncontrolled despite maximally tolerated medical therapy. His vision improved to 6/7.5 and automated perimetry revealed a less than 5 degrees small central island of vision. His left eye was phthisical with no light perception.