This is such an important step of cataract surgery that we must review it again as our residents are beginning the academic year. A good incision makes the entire surgery safer and easier. A poor incision will lead to more complications and a compromised visual outcome.
Many of the more advanced cataract surgeons prefer a single-plane phaco incision because its consistent architecture makes for great sealing. In addition, the avoidance of an initial groove produces a smoother ocular surface at the incision site and perhaps there will be less accumulation of ocular surface contaminants in the absence of a groove. Typically, at our Beverly Hills surgery center, I make a single-plane phaco incision using a diamond keratome. These diamond instruments are many times sharper than steel and produce the smoothest possible tissue interface. But they are costly: $5000+ for a diamond keratome versus $10 (or less) for a steel keratome.
You can make an excellent single-plane phaco incision with a steel keratome. The video here features clips from two different surgeries to explain this technique.
The key points are:
- The incision should just barely nick the limbal blood vessels
- We want to avoid a completely avascular incision since it will not heal as well
- We want to be in the most peripheral cornea, farthest from the visual axis
- The incision should be radial, aimed toward the center of the cornea
- This allows the best access to all parts of the anterior segment
- Only advance the keratome until the widest part has entered the anterior chamber, then retract the blade
- The incision should have the correct tunnel length
- many steel keratomes have a marking on the blade to show the ideal tunnel length, which is about 2 mm
- the tip of the blade should pierce Descemet’s layer when the blade marking passes through the corneal epithelial edge
- The incision must have good architecture
- The floor of the incision and the roof of the incision should have about the same overall thickness
- Avoid the error of starting with too thin of a roof and then having to “dimple down” in order to enter the anterior chamber
- The angle of the keratome will determine the tunnel length:
- too flat of an angle will result in a short tunnel length
- too steep of an angle will result in an excessively long tunnel length
Click below for single-plane phaco incisions with a steel keratome: