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
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- We want to avoid a completely avascular incision since it will not heal as well
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- 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
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- This allows the best access to all parts of the anterior segment
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- 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
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- many steel keratomes have a marking on the blade to show the ideal tunnel length, which is about 2 mm
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- 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
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- The floor of the incision and the roof of the incision should have about the same overall thickness
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- Avoid the error of starting with too thin of a roof and then having to “dimple down” in order to enter the anterior chamber
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- The angle of the keratome will determine the tunnel length:
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- too flat of an angle will result in a short tunnel length
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- too steep of an angle will result in an excessively long tunnel length
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Click below for single-plane phaco incisions with a steel keratome:
All content is © 2018 by Uday Devgan MD. All rights reserved.
Which size blade do you like to use for your main incisions? Single or Dual bevel?
Either is fine. My favorite is a diamond keratome and this is what I use in Beverly Hills. At other locations I use a standard steel keratome, typically single bevel.
Any disadvantage using double bevel blade?
That is fine. It all depends on technique and architecture of the incision.
Doesn’t a double bevel blade give you a more square architecture rather than a chevron appearance? I actually didn’t know there was an option between the two types of knives until I was asked my preference.
the double bevel can help, but ultimately it is the surgeon’s technique that determines the wound architecture
I have had some poorer wound construction with non-BVI Beaver keratome blades. The blade tends to slide when making the entry incision and creates an uneven entry wound. Also, without the 2.0 mm depth line, my tunnel length tends to be more variable. Would you suggest creating an initial groove to create a consistent entry incision with these keratome blades? I prefer not to have these blades at all, but sometimes the surgery center doesn’t have the BVI-Beaver keratome blades available.
Try various types of incisions to see which you like best. Important for a surgeon to be able to use a variety of blades to create a good, consistent incision.