We know that the phaco incision will cause some degree of corneal flattening and this has the ability to alter the corneal astigmatism. We can also make limbal relaxing incisions (which are actually in the peripheral cornea and not at the limbus) to further treat pre-existing corneal astigmatism. We can also couple these two together to achieve even more corneal flattening at that steep axis.
In the case shown here, we want about 1.0 diopter of corneal flattening at the 30 degree axis of this right eye.
- Pre-op measurements:
- Refraction: +1.00 +1.00 x 030
- Keratometry: 44.00 x 120 / 45.00 x 30
- Intra-op treatment:
- Phaco incision 2.75 mm wide at 30 degrees
- Limbal relaxing incision 1 clock hour in length centered at 30 degrees (210 degrees if using 360 degree guide)
- Post-op measurements:
- Refraction: -0.25 spherical
- Keratometry: 44.50 / 44.50
For even more corneal flattening, some surgeons prefer to make a temporal LRI and then place the phaco incision within this LRI. This is a more challenging technique and I find that it is rarely needed. For about 1 diopter of corneal astigmatism, the LRIs tend to work quite well, but for 1.5 diopters or greater, a toric IOL is usually a better choice.
Click below to watch the video of the Phaco Incision and Paired LRI: