EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/111385
58 EW FEATURE February 2011 Refractive/astigmatism February 2013 Managing corneal astigmatism in cataract surgery patients by Ellen Stodola EyeWorld Staff Writer AT A GLANCE ��� Patient input and interaction is very important in the initial discussion about astigmatism management because patients need to know the options, while doctors need to know the patient���s desires for management. ��� Slit lamp examinations are important to determine whether a patient is a good candidate for an LRI. ��� Proceeding with corneal astigmatism management often works on a case-by-case basis because of the differences that can occur in degree and severity of astigmatism. W hen it comes to cataract surgery, a concern doctors must sometimes take into account is managing corneal astigmatism. Corneal astigmatism can often affect the outcome of cataract surgery and can especially impact whether or not a patient is able to achieve freedom from glasses. Not only would a physician have to decide whether a patient is a candidate for astigmatism management, but the physician also has to look at indicators of other ocular surface diseases that may be present, as well as evidence of asymmetric or irregular astigmatism. Michael Lawless, M.D., Vision Eye Institute, Chatswood, New South Wales, Australia, and John Doane, M.D., Discover Vision Centers, Kansas City, Mo., commented on the topic. Determining who is a candidate Dr. Lawless said anyone with corneal astigmatism could qualify for astigmatism management. ���There is no advantage in having residual astigmatism following cataract surgery, so anybody with treatable corneal astigmatism is a good candidate,��� Dr. Lawless said. He said the options would need to be discussed with the patient but that ���there is no clinical downside to dealing with astigmatism effectively and accurately.��� Dr. Doane also highlighted the importance of a discussion with the patient about how to manage astigmatism. He said he uses multiple means to determine whether a patient is a candidate for astigmatism management at the time of cataract surgery. ���The IOLMaster [Carl Zeiss Meditec, Jena, Germany] and topography are two tools to determine this,��� he said. To begin, Dr. Lawless said a surgeon must first figure out what he or she is going to induce. ���If you are like me, you will find that it is slightly different for left and right eyes and that, for example, the average might be 0.4 D of surgically induced astigmatism, but the range Monthly Pulse Figure 1. Topographic (Orbscan) image of irregular astigmatism. can vary from zero to 1.25 D,��� he said. He said that others may have different opinions, but he believes that the incision can cause some flattening in the axis of the primary incision; however, it���s hard to tell just how much flattening the incision will induce. Important variables can include quality of the ocular surface, the keratometry and biometry used, and even variations in the technicians performing the measurements. ���As best as you can, you need to have control of these variables,��� he said. Although Dr. Lawless said there are a number of patients who are candidates for astigmatism treatment, it���s important to exclude certain patients, such as those with slit lamp signs of keratoconus. ���They do not do well with toric intraocular lenses because the optics of the eye become quite complex with an irregular toric surface within the cornea and a toric lens inside the eye.��� He said in this case, the astigmatism is irregular and part of the patient���s cornea, and although it can be treated, it���s best not treated with cataract surgery. ���It is important to know whether a patient will be able to receive corneal laser treatment post-cataract and lens surgery in Keeping a Pulse on Ophthalmology T his survey shows that a majority of surgeons do treat corneal astigmatism less than 1 D and greater than .5 D in their cataract patients. The preferred technique for the majority of these surgeons is limbal relaxing incisions. About 7.1% of surgeons are using femtosecond arcuate incisions. At the time of surgery, nearly half of surgeons are using a combination of methods to con���rm astigmatism, with a majority incorporating the IOLMaster or Lenstar keratometry. The ideal refractive target was to reduce astigmatism to zero. About half of surgeons treat both with-therule and against-the-rule astigmatism similarly. Overall, I think this survey shows that surgeons are recognizing the importance of treating even small amounts of astigmatism and utilizing all available technologies to help maximize the refractive outcomes for patients. I think this will become more important as laser refractive cataract surgery increases in acceptance and usage. Y. Ralph Chu, M.D., refractive editorial board member