Integrating computer-assisted toric IOL implantation
Surgeon finds image registration technology helps eliminate need for axis marking
A typical toric case
We do not make any ink marks now. The patient is brought to the operating room, the eye is prepped and draped, and the lid speculum inserted. On the screen, an assistant selects the correct patient and eye to pull up the reference images. As soon as the surgeon has centered and focused the microscope, the assistant starts the registration process.
Through the scope, I will see the 0 to 180 degree axis and the planned toric axis. I then turn on the intraoperative aberrometer (ORA, Alcon Laboratories) and orient the ORA reticle with the reference axis on the system.
I turn everything off to remove the cataract, then pressurize the eye, perform the aphakic ORA reading, and adjust the spherical power if necessary (I rarely change the cylinder based on ORA). I select the IOL and inject it as usual, aligning it with the steep axis on the system overlay.
Three parallel lines mark the intended axis of correction, so the surgeon can be very precise in aligning the IOL identification marks in one of the two “lanes” created by the axis overlay (Figure 1).
Next, I re-pressurize the eye and do a pseudophakic ORA reading to check the residual cylinder. With the clear acrylic Tecnis Toric (Abbott), I can make microadjustments in either direction (clockwise or counterclockwise). ORA is often immediately “no rotation recommended” because the system has the IOL on the planned axis. When an axis refinement is needed—to shift from an axis of 160 to 165 degrees, for example—the system quickly adjusts the overlay to the new axis.
Finally, as I remove the viscoelastic at the end of the case, the computer-aided system helps to ensure that the lens stays where I want it. Because the axis can be seen in real time, I can easily prevent the lens from moving off-axis as viscoelastic is removed and the eye is refilled with balanced salt solution, which reduces the need to make positional adjustments.
The real-time, continuous overlay is helpful in challenging cases where there is a small pupil or floppy iris. In such a case, the toric IOL marks may not be clearly visible through a large pupil, but I can still push the iris back and have the advantage of the overlay as the alignment on each side of the IOL is checked.