Eyeworld

57 EW REFRACTIVE by Michelle Stephenson EyeWorld Contributing Writer 5. "In patients who have undergone corneal refractive 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 features that were ostensibly intro- duced from the surgery," Dr. Koch said. Ocular surface Dr. Dell explained that one of the main reasons for performing corneal topography is to ascertain the status of the patient's tear film and ante- rior corneal surface. "The Placido image from a corneal topographer is valuable in assessing the quality of the anterior refracting surface of the eye. The first thing we're using topography for is to determine Diagnostics in refractive cataract surgery: Corneal topography July 2018 T o remove someone's cataract and have his or her vision not improve because of undiagnosed keratoconus should not happen in modern day cataract surgery. The same can be said for macular pathology. A thorough exam is critical before any surgical procedure, but our exam does not rule out all pre-existing issues such as keratoconus and an epiretinal membrane. As Steven Dell, MD, and Douglas Koch, MD, teach us, corneal topography should be a part of every cataract evaluation for set- ting up pre-cataract surgery expectations, understanding if the ocular surface/tear film is affecting image quality (both can be optimized before any cataract surgery), and improving lens implant calculations. Cor- neal topography has become mainstream technology in anterior segment surgery and can make us better cataract surgeons and diagnosticians. Corneal topography is also a reminder to us that cataract surgery is indeed refractive surgery. Thank you to Dr. Dell and Dr. Koch for sharing their wisdom in this month's "Refractive editor's corner of the world." Vance Thompson, MD, Refractive editor continued on page 58 Refractive editor's corner of the world F ew surgeons perform cat- aract surgery without first performing corneal topog- raphy, and it is critical for refractive cataract surgery. "Every patient who comes into our clinic receives corneal topography," said Steven Dell, MD, Austin, Texas. "It surprises me that there are surgeons who perform cata- ract surgery without the benefit of corneal topography, but I do see that occasionally. I would not be comfortable proceeding with cata- ract 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 cata- ract surgery patient: 1. It is imperative for evaluating the health of the cornea. "Placido disc topography is critical because you can look at the regularity or irreg- ularity of the mires, and this is an excellent way to detect the optical impact of surface disorders such as epithelial basement membrane dystrophy," Dr. Koch said. 2. It is used to evaluate and confirm the meridian and magnitude of the astigmatism that the biome- ters provide. Ultimately, as devices improve in their ability to mea- sure the posterior cornea, it will also calculate true total corneal astigmatism. 3. Combined with tomography, it is used to determine whether the cornea is sufficiently thick and sufficiently healthy or normal. "In other words, it is used to confirm that the patient doesn't have kera- toconus, that there is no irregular astigmatism or other pathology that would rule out certain IOLs, and that the patient's cornea would tolerate a postoperative ex- cimer laser adjustment," Dr. Koch explained. 4. It should be used, especially for patients wearing rigid gas per- meable lenses, for at least two sequential measurements to de- termine that patients' corneas are stable after discontinuation of the contact lenses. Galilei Placido mires that show irregularity from EBMD Greatly improved but not perfect mires after healing following epithelial debridement Source: Douglas Koch, MD, and Ildamaris Montes de Oca, MD

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