EyeWorld India June 2015 Issue

56 EWAP DEVICES June 2015 lid speculum off the eye and out of the measurements. Those are things that can give you false readings from aberrometry,” he said. Even if every step was performed perfectly, the intraoperative readings may at times differ significantly from the preop readings, especially if there is more edema, a prominent vitreous detachment, or prominent vitreous floaters. In those instances, Dr. Solomon will use his original preop measurements to guide IOL choice and alignment. Similarly, if the cornea is healthy and has never undergone surgery and there is still a large discrepancy between pre- and intraoperative readings, Dr. Lane will err on the side of caution and use his preop measurements to guide IOL choice. “But it’s an extremely rare occurrence for the two to be drastically different,” he said. During the initial learning curve, Dr. Lane said if there are discrepancies in the readings, “you can’t go wrong by going with your preoperative measurements because that’s what you’ve done your whole career. That’s what we’ve all done our whole career.” But there are always exceptions to the rule, Dr. Lane said, including the post-LASIK patient, where the preop and intraoperative measurements can vary by as much as 1.5 D. “Those are the patients that I use my intraoperative aberrometry measurement for, regardless of how far off the preoperative one might be, simply because of the inaccuracy of trying to use preoperative values and the changes that take place in terms of the cornea during LASIK,” he said. For all others, if the readings do not concur, repeat the aberrometry readings, Dr. Lane suggested. Ensure the eye is properly pressurized, and “make sure that the speculum isn’t pushing on the eye in a certain way that can induce astigmatism or change astigmatism. You want to make sure that the ocular surface is well moistened,” he said. If the axis of astigmatism agrees pre- and intraoperatively but the lens power differs, Dr. Solomon typically uses the intraoperative assessment. If, however, preop indicates with-the-rule and intraoperative suggests against- the-rule, Dr. Solomon is likely to use the preop measurements instead. That noted, “I throw out the intraoperative aberrometry measurement maybe 2% [to] 5% of the time. So 95% [to] 98% of the time, I find intraoperative aberrometry to be accurate and helpful.” Dr. Lane estimated that he changes his IOL powers about 50% of the time, “however, 90% of the time it changes by only 0.5 D or so,” he said. “Intraoperative aberrometry has improved the percentage of patients that I’m able to achieve within ±0.5 D of target to about 94% of the time.” EWAP Editors’ note: Drs. Lane and Solomon have financial interests with Alcon. Contact information Lane: sslane@associatedeyecare.com Solomon: kerry.solomon@carolinaeyecare.com Views from Asia-Paci c Cesar Ramon G. ESPIRITU, MD Chairman, Department of Ophthalmology, Manila Doctors Hospital United Nations Avenue, Ermita, Manila, Philippines Tel. no. +63-2-525-2260 Fax no. +63-2-524-3011 loc. 4080 espiritueyemd@me.com T he arguments presented favoring the use of intraoperative aberrometry in choosing the correct toric IOL power and position are with merit. The inability to accurately measure posterior corneal surface curvature and, therefore, total corneal astigmatism is the main contributor to unexpected postop residuals. My personal take on the primary use of this technology, however, is for achieving refractive goals in post-refractive surgery patients. Even with the latest formulas, my accuracy rate (within 0.5 diopters of target) has been 60% at best. If intraoperative aberrometry brings this to a level near 85%, then that would be a remarkable achievement. A very important point was brought up in the article and that is that one should not abandon one’s preoperative measurements all together but rather use these as comparative data and even as “fall back” choices when issues regarding ocular surface problems, intraoperative pressures, corneal edema, and eye positions cast a palpable amount of doubt as to the accuracy of the aberrometry. The decision to adopt a new technology or technique depends on several factors. First is its contribution to achieving one’s treatment goal—in this case, the additional accuracy in correcting pre-existing astigmatism versus currently used methods. Second is the ease of its use, including the learning curve needed to be able to achieve targets consistently. And third but not least is the cost. The overriding consideration here is the perception of the added value it brings to one’s practice or, simply put, the percentage of patients where using the technology will make a positive difference. It goes without saying that surgeons who are not particular about correcting astigmatism during cataract surgery will not place any value in this device. Hopefully, this sub-population will steadily decrease. Editors’ note: Dr. Espiritu is on the advisory board and speaker bureau of Alcon. Using - from page 55