There are times when you will need to make a surgical iridotomy either during cataract surgery or as a stand-alone procedure. This is most easily done with the small gauge bimanual vitrectomy instrumentation. With the appropriate settings on your phaco machine, we can make precise, full-thickness iridotomies in a minimally traumatic manner.
The key is to have appropriate settings for the phaco machine:
- mode must be “I/A Cut” so that foot pedal position 1 is irrigation, 2 is aspiration, and 3 is activating the cutting action of the vitrector
- the infusion pressure (or bottle height) can start at 50 mmHg in order to give a sufficiently deep anterior chamber. You can go higher if needed.
- the vacuum level should be at least 300 mmHg with a quick rise
- the cut rate for the vitrector should be very low. You want just 1 or 2 cut actions per second which is a cut rate of 120 cuts/minute or less. On the phaco machine used in this video the lowest cut rate is 100 cuts/minute, which is good.
Make two paracentesis incisions in the eye. Simply place the infusion cannula in the eye to inflate the anterior chamber with one hand, while the other hand inserts the vitrector with the port facing down. Place this open port over the peripheral iris and step down to position 2 to aspirate some of the iris into the port. Now step down more to position 3 to activate the cutter for just a bite or two of the iris. This will result in a clean and effective peripheral iridotomy and the size can be expanded as needed by repeating the steps.
Click below to learn how to make a surgical peripheral iridotomy: