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EW San Diego 2015 2 astigmatism. If the goal is clear distance vision only, I use a toric IOL when addressing most cases of against-the-rule astigmatism with the goal of shifting to a slight degree of with-the-rule astigmatism. For low degrees of with-the-rule astig- matism, I will do laser astigmatic keratotomy in combination with the cataract surgery and toric lenses for larger degrees of astigmatism. Dr. Vukich: I consider LRIs for up to 1.00 D of astigmatism. For higher amounts of astigmatism, the visual quality from a toric lens is hard to beat. They don't require a healing response or biomechanical coupling. Regardless of the astigmatism level, the implantation technique is the same. In this regard, toric IOLs are not dose dependent. You do not need larger incisions or a more aggressive procedure to treat higher amounts of astigmatism. Dr. Donnenfeld: It's also the safest procedure and doesn't induce dry eye the way astigmatic keratotomy does. What is your threshold for implanting a toric IOL? Dr. Hovanesian: LRIs can be precise, but this accuracy drops off after 1 D of astigmatism (Figure 2). Therefore, I begin considering a toric IOL at 1.25 D of astigmatism. Dr. Garg: My threshold for consider- ing a toric lens is 1 D or 1.25 D, de- pending on the axis of astigmatism. For against-the-rule astigmatism, I try to overcorrect it a bit. For with- the-rule, I undercorrect a little. Dr. Mah: If a patient has 0.75 D against-the-rule astigmatism, I consider a toric IOL versus 1.25 D if the patient has with-the-rule astigmatism. Dr. Donnenfeld: I predict LRIs will become less important. I perform more and more intrastromal abla- tions using the Catalys femtosecond laser (Abbott Medical Optics, Abbott Park, Ill.), which result in less dry eye, less wound gape, and greater predictability. However, they only treat very small amounts of cylinder. I use them increasingly for 0.75 D and less cylinder, and I use more toric lenses for higher cylinder. I rely on toric IOLs almost uniformly after a cutoff of 1.25 D. Are there any patients who are not candidates for toric IOLs who have cylinder? Dr. Mah: Topography and tomogra- phy are critical preoperative tests. In patients with a moderate or high de- gree of cylinder, you want to make sure the corneas have regular astig- matism. Even patients with small amounts of irregular astigmatism that can be corrected with a refrac- tion of 20/20 may be candidates. Dr. Garg: Many patients have forme fruste or very subtle ectasias. If astig- matism is very symmetric you can consider toric IOLs in those patients with the proper informed consent. Dr. Donnenfeld: What if the patient wears a gas permeable contact lens? Dr. Garg: In patients with possible ectasia or who wear contact lenses, make sure their ocular surface and cornea are stable without contact lenses for a while. It may take some time, depending on how long they've been in contact lenses. You may have to check their measurements several times to verify stability. Dr. Donnenfeld: How would you manage a patient with irregular corneas and epithelial basement membrane dystrophy? Dr. Hovanesian: For unusual cor- neas, consider consulting a cornea specialist. If the epithelial basement membrane dystrophy affects the vi- sual axis, removal with debridement of the epithelium and often a light lamellar keratectomy with excimer laser phototherapeutic keratectomy will be curative. A couple of months later we usually can obtain stable " When you correct to less than 0.5 D of astigmatism, patients are more likely to recommend the procedure to their friends. " John Hovanesian, MD Figure 2. Accuracy of limbal relaxing incisions (N=69 eyes); 51% of patients have ≤0.25 D of cylinder, and 70% have ≤0.50 D. Data in press, John Hovanesian, MD, 2014.

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