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10 | EYEWORLD DAILY NEWS | JULY 24, 2021 ASCRS ANNUAL MEETING DAILY NEWS pachymetry pattern, Dr. Don- aldson said that less than 470 microns indicates an abnormally thin cornea. You also need to look at where the thinnest point is located. It needs to be closer to the center, and if it's more than 0.5 mm from the center, this is an indicator that there's an issue. Topography and tomography can help look for any underlying pathology. The quality of the scan is important. Inability to accurate- ly image is a sign. When considering potential outcomes, Dr. Donaldson said it's important to consider how the surgery will affect the topography. Sumit "Sam" Garg, MD, dis- cussed what to do differently in cataract surgery if the cornea is not normal. He first noted some of the "classic" compromised corneas to be on the lookout for, including patients with ocular sur- face disease, ABMD/Salzmann's, refractive surgery, and irregular astigmatism. These can be challenging cases, so it's important to plan accordingly and manage patient expectations. Dr. Garg emphasized the importance of visualization. A modern microscope with excellent optics/illumination can help with this, as can trypan blue. He went on to highlight a number of conditions to consider carefully. With corneal ectasia and keratoconus, it's important to check for regularity. Make sure these patients have a contact lens holiday. If you're able to get good correction in spectacles, a toric IOL can be considered, he added. For patients with Fuchs, Dr. Garg noted that it's important to minimize phaco energy and to check the endothelial cell count and pachymetry. It's not just the number of cells, but the quali- ty as well. He said to use extra OVD, aim a little myopic, and avoid light splitting IOLs in these patients. For post-PKP patients, these would be handled similarly to Fuchs. It's important to use a lot of OVD/trypan, consider FLACS, check the endothelial cell count/ pachymetry, and suture the wounds. A toric may be OK if there is regular cylinder and a healthy endothelium. Dr. Garg also mentioned post- RK patients. In these, he said to avoid light splitting lenses, avoid RK incisions (consider a scler- al tunnel), aim myopic (these patients will drift hyperopic over time), and suture wounds. Editors' note: Dr. Donaldson and Dr. Garg have financial interests with various ophthalmic companies. Refractive Day kicks off with focus on the preoperative evaluation T he first section on the Refractive Day program covered the preoperative evaluation. Kendall Donaldson, MD, presented "Everything You Need to Know About Corneal Topogra- phy But Were Afraid to Ask." She noted some uses for topography in preoperative screening and planning. First, she said it helps with safety because it's important to screen out bad candidates with pathology that can affect the out- come. It also helps to set patient expectations preoperatively. Preoperative treatment allows physicians to handle certain conditions, like ocular surface disease, before surgery. Identify- ing and treating astigmatism is also important, she said. Topogra- phy dictates the most appropriate procedure and/or IOL choice. Dr. Donaldson stressed five key elements of topography/to- mography: keratometry mapping; anterior and posterior elevation mapping; pachymetry; underlying pathology; and the potential out- come (how the surgery will affect the topography). When considering keratom- etry, Dr. Donaldson said it's important to look at the astig- matism value and shape of the cornea. A normal cornea should not be more than 47 D, and it's important to ensure that the topography matches the manifest refraction. Anterior and posterior ele- vation mapping is a comparison to a perfect sphere, Dr. Don- aldson said. When looking at a Dr. Garg discusses what to do differently in cataract surgery if the cornea is not normal. Source: ASCRS

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