EyeWorld India March 2021 Issue

FEATURE EWAP MAR C H 2021 33 REFRACTIVE you can correct the lens itself and you don’t have to fine tune the cornea, it gives me more confidence that we can hit the refractive target despite lens positioning, corneal healing, and preoperative measurement variations,” she said. Dr. Wiley emphasized the importance of taking the patient’s perception of their current astigmatism into account and setting appropriate postop expectations. He said it’s important to diagnose all areas of astigmatism preop and relate to the patient. Intraoperative aberrometry can be helpful as well. “I tell patients even though you might not be showing astigmatism now, you don’t know what the final astigmatism is going to be until after the cataract is removed, after I make my incisions for cataract surgery and the eye is in a new state. If you want to see well without glasses, we need to manage your astigmatism, and it may be something that appears during surgery or even after surgery, but we should be prepared for that,” he said. In terms of the different options for astigmatic correction in cataract surgery, Dr. Wiley talks to his patients in percentages. “I’ll tell them that with basic technology we can often reduce the prescription somewhere between 50–100%; even with basic we can get lucky and hit 100%, and that’s great. Advanced technologies, like a toric lens, can reduce it to 90–100%, better than basic and quite good but even that means some margin of error. If you want 98–100%, I’ll say the Light Adjustable Lens,” Dr. Wiley said. Considering irregular astigmatism Ocular surface conditions causing irregular astigmatism, such as ABMD, Salzmann’s nodular degeneration, and pterygium, are very treatable. Dr. Swan said he’ll treat these conditions and wait 3 months before retaking measurements for cataract surgery. Causes of irregular astigmatism that are untreatable are keratoconus, post-refractive ectasia, and pellucid marginal degeneration. Dr. Swan said some stable keratoconus or pellucid marginal degeneration that has non-skewed astigmatism in the central 6-mm zone could still respond well to a toric lens. It goes without saying that a limbal relaxing incision would not be appropriate for these patients, he added. “The defining questions to ask are 1) is it stable and 2) have they gotten good vision in glasses, historically, or did they need to be in a scleral lens or a rigid gas permeable lens. If they had to be in a hard contact lens, your likelihood of success with a toric is very low,” Dr. Swan said. He added that while the IC-8 pinhole IOL (AcuFocus) is not yet FDA approved, there is hope for its use in patients with irregular astigmatism. If there is significant irregularity, Dr. Lee said he mentions the possibility of wearing a rigid gas permeable contact lens during the preop consultation. “I explain that no IOL can correct an irregular cornea perfectly and that choosing a Gary Wortz, MD, et al. recently published a paper in Clinical Ophthalmology that shared real-world outcomes of treating low corneal astigmatism of less than 1 D with a novel formula for femtosecond laser arcuate incisions. The outcomes of this were compared to basic cataract surgery without surgical management for low levels of astigmatism. According to the paper, the Wortz-Gupta Formula calculated arcuate parameters for 224 patients with less than 1 D of astigmatism; the Barrett Universal II formula was used for IOL calculations. Average preoperative cylinder was similar in the femtosecond group vs. the conventional cataract surgery group (0.61 D [n=124] and 0.57 D [n=100], respectively). More patients had more than 0.5 D of astigmatism in the femtosecond group compared to the conventional group. The investigators found that the mean postop refractive astigmatism was significantly higher in the conventional cataract surgery group. More patients achieved UCDVA 20/20 or better in the femtosecond group (62%) vs. the conventional group (48%). The study authors concluded that “[u] sing femtosecond laser for arcuate incisions in combination with a novel nomogram can provide excellent anatomic and refractive outcomes in patients with lower levels of preoperative astigmatism at the time of cataract surgery.” Treating low corneal astigmatism with femto toric or adjustable lens means closing the door on a rigid gas permeable lens, practically speaking,” he said. EWAP Editors’ note: Dr. Berdahl is in practice with Vance Thompson Vision, Sioux Falls, South Dakota, and has interests with Alcon, Bausch + Lomb, Johnson & Johnson Vision, and RxSight. Dr. Lee is in practice with Altos Eye Physicians, Los Altos, California, and has interests with Carl Zeiss Meditec. Dr. Ristvedt is in practice with Vance Thompson Vision Alexandria, Minnesota, and declared no relevant financial interests. Dr. Swan is in practice with Vance Thompson Vision Bozeman, Montana, and declared no relevant financial interests. Dr. Wiley is in practice at Cleveland Eye Clinic, Division of Midwest Vision Partners Cleveland, Ohio, and has interests with Alcon, Johnson & Johnson Vision, RxSight, and Carl Zeiss Meditec. Reference Wortz G, et al. Outcomes of femtosecond laser arcuate incisions in the treatment of low corneal astigmatism. Clin Ophthalmol. 2020;14:2229–2236.