Vitrectomy probe with adjustable cutter port size

A vitrectomy probe comprising:

• a housing;
• a cutter extending from a first end of the housing, the cutter comprising:
• a hollow outer cutting member coupled to the housing, the outer cutting member comprising an open end and a closed end;
• a hollow inner cutting member slideable within the outer cutting member, the inner cutting member comprising open opposing ends and a first cutting surface at a first end thereof;
• and
• an opening formed in the outer cutting member proximate an end thereof, the opening having a second cutting surface cooperative with the first cutting member to dissect materials that enter the opening, the opening and the first cutting surface defining a port, a size of the port defined by a location of the first cutting surface relative to the opening when the inner cutting member is in a fully retracted position;
• a first pneumatic chamber formed in the housing;
• a first diaphragm coupled to the inner cutting member and bisecting the first pneumatic chamber into a first chamber portion and a second chamber portion, the first chamber portion in fluid communication with a first passageway and the second chamber portion in fluid communication with a second passageway, the first passageway and the second passageway adapted to transmit a first pneumatic pressure to the first chamber portion and the second chamber portion, respectively, in an alternating sequence to oscillate the first diaphragm and the inner cutting member between the fully retracted position and a fully extended position;
• a second pneumatic chamber formed in the housing;
• a second diaphragm bisecting the second pneumatic chamber into a third chamber portion and a fourth chamber portion;
• a stroke limiter coupled to the second diaphragm and moveable therewith;
• a biasing element disposed in the third chamber portion;
• and
• a third passageway in communication with the fourth chamber portion, the third passageway adapted to transmit a second pneumatic pressure to the fourth chamber portion to displace the second diaphragm an amount proportional to the second pneumatic pressure.

A method of limiting a cutter port size of a vitrectomy probe, the method comprising:

• oscillating an inner cutting member between a fully extended position and a fully retracted position relative to an outer cutting member;
• altering a position of a stroke limiter relative to the inner cutting member;
• and
• contacting a portion of the inner cutting member with a portion of the stroke limiter to define the fully retracted position of the inner cutting member, the position of the inner cutting member at the fully retracted position relative to the outer cutting member defining the cutter port size.