Eyeworld

SEPTEMBER 2022 | EYEWORLD | 69 C Dr. Koch said to look for consistency (and inconsistency). "If you see inconsistency be- tween two devices with regard to overall corne- al power or astigmatic values, that's a red flag that requires further investigation, and further measurements are needed, perhaps after more intensive treatment of the ocular surface to make the best recommendation and best choice for the patient," he said. Dr. Koch said technicians at his practices are trained to look at the ease with which measure- ments can be obtained and any warning signals coming from the devices, for example, distor- tions in the mires produced from the Galilei. 3. Know when reimaging won't improve results. Dr. Miller added that some corneas are irregular—those with Salzmann's nodules or map-dot-fingerprint, for example—and will not improve with repeat imaging. The surgeon needs to know when repeat imaging won't make a difference unless prior intervention is taken. 4. Get multiple measurements. Dr. Koch reiterated that his practice gets multiple mea- surements on different occasions, which allows him to look for consistency and inconsistencies. While he said that most surgeons aren't getting two different measurements on two different occasions, he thinks it's a best practice. "Surgeons who are doing refractive cataract surgery by and large are doing two different measurements, but I think it's not common to do two different measurements and different measurements on different days," he said. 5. Look at the total cornea. If you have ac- cess to a device that looks at both anterior and posterior surfaces, Dr. Miller thinks you should consider the total cornea in your IOL planning and not just the anterior surface. "I think a lot of people still use a biometer, an IOLMaster or Lenstar, to do their astigmatism planning," Dr. Miller said. "The problem with those devices is they only see a small portion of the anterior surface of the cornea; they don't see the total cornea. You have to make assumptions about the back surface of the cornea if you're only measuring the anterior surface of the cornea. You can use the Barrett formula for that, for instance." Dr. Miller noted that some, like Warren Hill, MD, have put forth the idea that the posterior surface measurements might not be all that accurate and measuring the anterior surface and making assumptions might produce an equally adequate result. Dr. Miller said he doesn't share this perspective but some physicians do. 6. Look for LASIK and PRK. Dr. Miller said that 10–15% of his cataract practice includes patients who have had prior PRK or LASIK. "On any given day, there is a good chance that I am operating on someone who has had prior laser vision correction surgery," he said. The catch is some of them don't include these procedures in their medical history. Even continued on page 70 This patient underwent LASIK almost 20 years earlier. The edge of the flap could not be seen on slit lamp biomicroscopy. The patient reported prior "eye surgery," and the cornea was mapped with tomography. This patient had LASIK in the days of the broad-beam laser. A central steep island of partially ablated cornea can be seen in the center of the map. This patient has a multifocal cornea and would not be a good candidate for a multifocal lens.

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