Eyeworld

I INNOVATIONS IN LENSES APRIL 2019 | EYEWORLD | 103 by Ellen Stodola EyeWorld Senior Staff Writer/ Meetings Editor topography, and refraction as well as other modal- ities is often different. If you can't figure out the true axis, you can't put a toric IOL in, he said. Dr. Rubenstein noted that if the patient is a rigid contact lens wearer and needs those to have adequate vision, he or she will not do well with a toric IOL. "They will usually need the contact lens even after cataract surgery to correct or mask irregular astigmatism," he said. For these patients, you can put in a non-toric and correct any astig- matism by having them resume contact lens wear postoperatively. You can get a good sense of whether a pa- tient is a potential toric candidate if they come in and have relatively good spectacle corrected visual acuity, Dr. Rubenstein added. Dr. Waring said the regular component of the total astigmatism may be managed with toric IOLs in select cases of keratoconus. When treating irregular astigmatism in keratoconus patients, Dr. Waring recommends evaluating the smallest magnitude of astigmatism 90 degrees away from the steep meridian. A toric IOL is a radially symmetric treatment, but you're often treating a non-symmetric cornea. Therefore, you want to treat conservatively. Care should be taken not to destabilize a keratoconic cornea with limbal relaxing incisions that are penetrating, Dr. Waring said. Dr. Waring added that Intacs (Addition Tech- nology) are useful to debulk the irregular astig- matism associated with keratoconus. Crosslinking alone has some regularizing effect to the coma and higher order aberrations and when combined has a synergistic effect with intracorneal ring segments, he said. Eye with a corneal transplant Dr. Rubenstein said surgical management of astigmatism can be considered in patients with a prior corneal transplant. In some of these patients, it's a good solution for residual refrac- tive error, he said. Corneal transplant patients commonly have residual astigmatism and residual myopia or hyperopia. When you have a chance to do cataract surgery and implant a toric IOL, often you can correct them and potentially offer A ddressing astigmatism is an important issue, and surgeons may have to con- sider certain conditions and previous surgeries when choosing the appro- priate IOL option for a patient with a less-than-normal cornea. The management of astigmatism can be broadly defined by whether it is surgical or medical, said George Waring IV, MD, FACS. When physicians think about the different cate- gories of astigmatism, they should think of two primary categories: regular and irregular. Regular astigmatism is orthogonal and radially symmetric in nature and should be addressed sur- gically, Dr. Waring said. For low amounts, femto- second laser arcuate incisions can be used, and for large amounts, toric IOLs can be used. Irregular astigmatism is non-orthogonal and/ or radially asymmetric in nature and has a number of broad categories. This can be divided into the subcategories of asymmetric bowtie and skewed axes. These variations are often found in disease states such as keratoconus, Dr. Waring said. Keratoconus patients The only time you can adequately consider a toric IOL is if you know the true axis of astigmatism, said Jonathan Rubenstein, MD, and often that is very hard to determine in keratoconus because the patient usually has slightly irregular astigma- tism. The axis that shows up in glasses, corneal IOL options for less-than-normal corneas A patient with keratoconus and Intacs implantation who underwent cataract surgery with a toric IOL Source: Karolinne Rocha, MD continued on page 104 At a glance • Management of astigmatism can be broken down into medical and surgical. • Astigmatism can either be regular or irregular, with irregular often being found in certain disease states or after surgery. • When considering a toric IOL, it's important to know the true axis of astigmatism. • Using a variety of technologies can help determine astigma- tism, but this can often still be tricky following refractive and other surgeries. About the doctors Jonathan Rubenstein, MD Vice chairman and Deutsch Family Professor of Ophthalmology Rush University Medical Center Chicago George Waring IV, MD, FACS Waring Vision Institute Mount Pleasant, South Carolina

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