|Stabilize the eye (with Thornton ring, cotton tip, .12 forceps, or other)|
|Create paracentesis wound (with supersharp, superblade, MVR blade, or other)|
|Paracentesis with a Supersharp blade, and the eye stabilized with a Thornton fixation ring|
While seemingly straightforward, there are a few key points to keep in mind during paracentesis creation.
Instrumentation, as in most of cataract surgery, varies slightly depending upon surgeon preference. Blade styles vary, such as a Supersharp, Superblade, MVR, etc. Likewise, the dominant hand, which provides stabilization, has a selection of instruments to aid in its task. A Thornton fixation ring, or a modification thereof, provides tractional feet with which the globe can be stabilized. Appropriate downwards pressure must be applied to maintain traction. Other surgeons prefer a cotton tip applicator, applied at the limbus with the dominant hand, 180 degrees away from the site of paracentesis entry. Still others use a .12 forceps, either to grasp the sclera for stability, or straddling the site of entry to prevent eye rotation.
The incision needs to be placed to provide access for cataract instruments held in the non-dominant hand. So, a location that provides comfortable access and mobility for these instruments is necessary. Thought must also be given to the proximity between the paracentesis and main wound. Closely spaced wounds creates “oar locking”, which makes manipulating instruments in the eye difficult. We typically space the paracentesis about 90 degrees away from the eventual main wound.
In general, beginning surgeons often hold phaco instruments, including the paracentesis blade, too far up the handle. This can result in less control, by translating small hand movements into larger displacements at the instrument tip. For many surgeons, grasping instruments closer to the tip, or “choking up”, can help achieve better control.
While the blades for creating a paracentesis vary, the goal of all is a 1 mm wide incision. The technique for creating a paracentesis is typically a “stab” incision, with the blade maneuvered by the non-dominant hand at an angle of entry that is maintained for the duration of the creation process. This angle of entry is typically flat, such that the blade enters the eye close to parallel to the iris plane as to avoid inadvertent injury to the iris. A paracentesis should be long enough to allow self-sealing, but not so long as to make instrument manipulation through the paracentesis difficult. It is likewise important to keep the incision close to the 1 mm target, as a small wound will not allow instruments through the opening, and a wide wound will contribute to wound gape and fluid escape both during surgery and potentially after as well. Be careful to maintain blade positioning until the blade is completely removed from the eye, to avoid undesirable widening of the wound from a misguided blade edge while exiting. An MVR blade is advantageous in that blade design may limit wound extension on exit.