We want to ensure an appropriate intra-ocular pressure (IOP) at the end of surgery. This puts the eye in a physiologic state and also helps to keep the incision sealed. Our primary phaco incisions are created as valves where the IOP pushes outwards against the floor of the incision and keeps it well apposed and sealed tightly.
To measure the IOP we can use a tonometer such as a Schiotz device which gives a specific reading, or a Barraquer tonometer which tells more of a narrow range. We can also use electronic tonometers such as the Tono-Pen which gives a digital read-out. Though I do not routinely do it, the surgeon can use a gloved fingertip to palpate the globe to estimate IOP. My preferred method for routine cases is to lightly push on the central cornea using a 27g cannula. The degree of corneal indenting gives me a good idea of the IOP. I like to leave the IOP at about 20 mmHg at the end of the surgery, which is on the higher end of the normal physiologic range.
Click below to learn how I check the IOP at the end of cataract surgery: