When making your phaco incision, it is important to have the appropriate tunnel length as well as incision width. We have previously explained how the tunnel length can be adjusted by varying the entry angle of the keratome. The width of the phaco incision is determined by the width of the keratome and how far we insert it into the eye.
Ideally, we want a keratome that provides a specific incision width, such as 2.2, 2.4, or 2.75mm, in order to provide fluidics which are matched to the phaco tip / sleeve that we are using. This requires that we insert the keratome in a radial manner and then once we enter the anterior chamber, we reverse the blade out of the incision along the same path.
If we advance the blade in a straight path but then reverse the blade with a slight diagonal tilt, the incision will become wider than intended. This is why I recommend only advancing the keratome until the widest part has pierced Descemet’s layer and entered the anterior chamber. This will limit the risk of making too wide of an incision due to blade tilt. There is simply no benefit of advancing the keratome far into the anterior chamber.
Click below to learn from this video of making a phaco incision with the keratome: