Eyeworld

38 | EYEWORLD | SEPTEMBER 2022 by Liz Hillman Editorial Co-Director About the physicians Steve Charles, MD Charles Retina Institute Germantown, Tennessee Dagny Zhu, MD NVISION Eye Centers Rowland Heights, California BACK TO BASICS ATARACT C membrane or signs of geographic atrophy, their vision might not be as good as you would expect after cataract surgery, and they might be disappointed. An OCT is also helpful in coun- seling the patient on whether they may need an additional intervention before or after surgery, for example, anti-VEGF injections prior to cat- aract surgery in an eye with diabetic macular edema or wet age-related macular degeneration to reduce the chances of postop inflammation," she said. Dr. Charles emphasized that he thinks OCT should be obtained for all cataract surgery candidates as well and said he also recommends OCT at every office after cataract surgery. OCT primer 1. Familiarize yourself with what a normal OCT of the macula looks like. "Refresh yourself on the different layers of the retina," Dr. Zhu said. "Oftentimes it's easy to miss pathology in the inner and outer layers of the retina. If it's mild atrophy, you might not pick up on the missing retinal layers if you aren't familiar with what a normal OCT looks like. Sometimes you'll see a subtle localized RPE defect, and that's a sign of long-standing atrophy." 2. Consider but don't necessarily rely on retinal mapping features. "If you're not good at inter- preting each layer, you can use the retinal map- ping features on OCT. It will pull up a picture for you and flag areas of atrophy as red. … The healthy areas are green," Dr. Zhu said, adding that she prefers to scroll through every slice of the OCT herself to better localize defects. Dr. Charles said he does not advise using thickness maps or pseudo-color. "Review all black and white B-scan slices," he said. "Do not import a technician-selected single image into EMR; use native imaging software." 3. Look at more than one area. Dr. Zhu has her technicians print out the sheet with multiple slices for her review, so she doesn't miss rele- vant pathology. "I think it's important to capture as many slices as possible. Sometimes the sur- geon doesn't have time to sit there and scroll, so A primer on interpreting OCT for cataract surgery continued on page 40 C ontinuing with the "Back to basics" theme of this issue, EyeWorld spoke to Dagny Zhu, MD, and Steve Charles, MD, for a primer on interpreting OCT of the macula and optic nerve in preparation for cataract surgery. The cataract surgeon is primarily using OCT to detect retinal or glaucoma pathology that could affect whether a patient is a candidate for a premium, presbyopia-correcting IOL. If pathol- ogy is detected for the first time that potentially requires treatment, they refer the patient to a retina specialist. "If you diagnose an issue that you think will be limiting vision, you refer to a retina special- ist for their intervention. I think the cataract surgeon should be good at some of those basic diagnoses," Dr. Zhu said. "With glaucoma, it can be tricky whether the patient truly has glaucoma or not, so I might refer to a glaucoma specialist for clearance on whether they are a glaucoma suspect rather than an actual glauco- ma patient." Dr. Zhu said she uses the Optovue Avanti OCT device. This device does the basics that she needs—OCT of the macula and optic nerve head—in addition to anterior segment OCT, which can be helpful when there's a need to look at the angle and/or cornea. Epithelial thickness mapping is another useful feature that can help diagnose subclinical keratoconus or epithelial basement membrane dystrophy, both of which can affect final visual outcomes. Dr. Zhu said she does OCT on all cataract and refractive lens exchange patients. She thinks that because it's an out-of-pocket ex- pense, not all cataract surgeons do it. "I treat everyone as a potential premium IOL candidate when they walk through the door, so I get an OCT on everyone even before I see the patient to confirm that a multifocal or trifocal IOL is an option for them. If an abnor- mality is detected, depending on the extent of posterior pathology, we may limit the options to an extended depth of focus IOL or monofocal IOL instead. Even if we end up using a monofo- cal IOL, the OCT gives you an idea of the visual potential of the patient. You can counsel them on what their vision might be after cataract surgery because if you find a thick epiretinal

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