The incision is a very important part of the cataract surgery. It determines the access to the anterior segment and it allows us to maintain chamber stability since we match the incision width to the specific phaco tip that we are using. In this case, the resident inserts the keratome too far into the anterior chamber and then when withdrawing it, he allows the blade to drift to the side, thereby widening the incision. This causes a fluidic mismatch with too much outflow of fluid compared to the relative inflow level.
We have taught that we only want to insert the keratome until the widest part of the blade has hit Descemet’s layer.
There is one source of fluidic inflow: the balanced salt solution from the irrigation bottle or bag. But there are two sources of fluidic outflow: what you aspirate through the phaco tip and what leaks from the incisions. In this case, we have dramatically increased the leakage from the incision. To compensate, we can put a piece of a sponge in the incision or use a suture to one side of the incision to make the fit tighter. Or we can adjust the fluidic parameters: increase the bottle height/infusion pressure and decrease the aspiration flow rate.
The anterior chamber instability leads to iris prolapse which then causes pupillary miosis. And then the phaco probe inadvertently engages the iris and before you know it, there is a significant degree of iris damage. There is so much to be learned from this case — I hope you study it in detail.
Click to learn about how a bad incision can lead to more complications: