EyeWorld India September 2018 Issue

42 EWAP REFRACTIVE September 2018 Diagnostics in refractive cataract surgery: Corneal topography by Michelle Stephenson EyeWorld Contributing Writer F ew surgeons perform cataract surgery without first performing cor- neal topography, and it is critical for refractive cataract surgery. “Every patient who comes into our clinic receives corneal to- pography,” said Steven Dell, MD, Austin, Texas. “It surprises me that there are surgeons who perform cataract surgery without the benefit of corneal topography, but I do see that occasionally. I would not be comfortable proceeding with cataract surgery without the benefit of the information that we get from a topographer.” Douglas Koch, MD, Houston, agreed and said there are at least six reasons for performing corneal topography on every refractive cataract surgery patient: 1. It is imperative for evalu- ating the health of the cornea. “Placido disc topog- raphy is critical because you can look at the regularity or irregularity of the mires, and this is an excellent way to detect the optical impact of surface disorders such as epithelial basement mem- brane disease,” Dr. Koch said. 2. It is used to evaluate and confirm the meridian and magnitude of the astigma- tism that the biometers provide. Ultimately, as devices improve in their ability to measure the pos- terior cornea, it will also calculate true total corneal astigmatism. 3. Combined with tomography, it is used to determine whether the cornea is suf- ficiently thick and sufficient ly healthy or normal. “In other words, it is used to confirm that the patient doesn’t have keratoconus, that there is no irregular astigmatism or other pathol- ogy that would rule out certain IOLs, and that the patient’s cornea would toler- ate a postoperative excimer laser adjustment,” Dr. Koch explained. 4. It should be used, espe cially for patients wearing rigid gas permeable lenses, for at least two sequential measurements to determine that patients’ corneas are stable after discontinuation of the contact lenses. 5. “In patients who have un- dergone corneal refrac- tive surgery, I can assess corneal asphericity to select an IOL whose asphericity is an optimal match,” Dr. Koch said. 6. Postoperatively, it can be helpful to detect unusual changes. “You can look at the cornea to see if there are unusual topographic fea- tures that were ostensibly introduced from the sur- gery,” Dr. Koch said. Ocular surface Dr. Dell explained that one of the main reasons for performing corneal topography is to ascertain Galilei Placido mires that show irregularity from EBMD Greatly improved but not perfect mires after healing following epithelial debride- ment Source: Douglas Koch, MD, and Ildamaris Montes de Oca, MD