Cystitome is a small knife that is used in cataract operation to cut the lens capsule. This knife has a small curved or hooked blade. One special Cystitome is Rotating Stylus Cystitome, which was invented by David S. C. Pao and is a Patented Products. It includes a lengthened rigid shaft, and a cutting member. A cystotome is used to cut into the capsule of a lens, during cataract surgery. Various Cystitome manufacturers offer these in disposable and sterile type, as these are required for single use only.