EyeWorld Asia-Pacific June 2015 Issue

39 EWAP CATARACT/IOL June 2015 Views from Asia-Paci c Vaishali VASAVADA, MS Raghudeep Eye Hospital, Ahmedabad and Jaipur, Gurukul Road, Memnagar, Ahmedabad, Gujarat-380052, Ahmedabad-380054, India Tel. no. +91 79 40400900, 40400909, 27490909 Brij Vihar, A-16, Shanti Path, Tilak Nagar, Jaipur-302004, India Tel. no. +0141 4043900, +91 702 375 4444 vaishali@raghudeepeyeclinic.com T his is a very interesting debate on whether toric IOLs or incisional approaches are the way to go for astigmatism correction. In general, for regular astigmatism in conjunction with cataracts, toric IOLs are becoming more and more popular. The advantages with toric IOLs are their predictability, stability of the correction, and, in case of a judgement error, the possibility of repositioning the IOL. Two major issues that still remain a matter of discussion with toric IOLs are: 1. How to estimate the exact corneal astigmatism, and what is the contribution of the posterior cornea? Fortunately, with newer automated imaging technologies, it is now no longer necessary to rely only on manual keratometry for measuring the magnitude and axis of corneal astigmatism. However, we must all keep in mind that the posterior cornea does contribute to the total corneal astigmatism, and should be taken into account wherever possible to improve predictability of outcomes. 2. How to exactly align the toric IOL to its desired axis? Until very recently, surgeons relied on various marking devices to estimate the 0- and 180-degree meridians and then intraoperatively align the IOL using those marks as a reference. With the advent of newer imaging and aberrometry devices, as has been discussed, the future for precise toric IOL alignment without relying on the surgeon’s subjective judgement is bright. Overall, in spite of these problems, the best thing about toric IOLs is their effectivity and forgiving nature. They de nitely add to the wow factor in today’s refractive cataract surgery without many side effects. LRIs, on the other hand, were widely practiced before the advent of toric IOLs, and the possibility to create desired depth, length, and design of incisions for astigmatic correction with femtosecond lasers (FS) has revived the interest in astigmatic keratotomies. Drawbacks of incision approaches still remain an inability to precisely predict the amount of correction, regression over time, induction of surface irregularities which are often a major source of patient dissatisfaction, and the potential to induce irregular astigmatism. Another less reported aspect of incisional modalities is the induction of aberrations on the corneal surface, which may cause deterioration in visual quality. I foresee their role more and more, especially with FS laser-assisted cataract surgery, and for small to moderate amounts of astigmatism, but long-term data will be required. References: 1. Koch DD, Jenkins RB, Weikert MP, Yeu E, Wang L. Correcting astigmatism with toric intraocular lenses: effect of posterior corneal astigmatism. J Cataract Refract Surg. 2013 Dec;39(12):1803-9. 2. Abula a A, Barrett GD, Kleinmann G, O r S, Levy A, Marcovich AL, Michaeli A, Koch DD, Wang L, Assia EI. Prediction of refractive outcomes with toric intraocular lens implantation. J Cataract Refract Surg. 2015 Apr 30 [Epub ahead of print]. 3. Goggin M, Zamora-Alejo K, Esterman A, van Zyl L. Adjustment of anterior corneal astigmatism values to incorporate the likely effect of posterior corneal curvature for toric intraocular lens calculation. J Refract Surg. 2015 Feb;31(2):98-102. 4. Hayashi K, Masumoto M, Takimoto M. Comparison of visual and refractive outcomes after bilateral implantation of toric intraocular lenses with or without a multifocal component. J Cataract Refract Surg. 2015 Jan;41(1):73-83. Editors’ note: Dr. Vasavada declared no relevant nancial interests. the “third piece of the puzzle,” Dr. Koch said. This is helpful if there is any question or variability in measurements. He obtains at least three measurements preoperatively. These include the LENSTAR (Haag-Streit, Koniz, Switzerland) or IOLMaster (Carl Zeiss Meditec, Jena, Germany), the Cassini, and a GALILEI image (Ziemer, Port, Switzerland). The GALILEI and Cassini give posterior corneal measurements that are evaluated for further accuracy as well, he said. “Refraction is a fourth piece of important preoperative data (something I learned from Robert Cionni, MD): It can give clues to posterior corneal astigmatism. “With those four, if there’s some disparity among them, then certainly the ORA [Alcon, Fort Worth, Texas] can play a helpful role.” Other systems in the space include the Holos IntraOp Wavefront Aberrometer (Clarity Medical, Pleasanton, Calif.) and imaging modalities including Callisto Eye with Z-Align (Carl Zeiss Meditec), the iTrace with Zaldivar Toric Caliper (Tracey Technologies, Houston), TrueGuide software (TrueVision), and the VERION Digital Marker (Alcon). If there is any question about lens selection, use the ORA at the time of surgery for IOL magnitude of toricity and actual alignment, he said. “We find it helpful,” Dr. Koch said. “It’s not perfect, but it’s certainly helpful.” EWAP Editors’ note: Dr. Koch has financial interests with Abbott Medical Optics (Abbott Park, Ill.), Alcon, i-Optics, TrueVision, and Ziemer. Dr. Hardten has financial interests with Abbott Medical Optics. Contact information Hardten: drhardten@mneye.com Koch: dkoch@bcm.edu especially if they have higher visual potential. “If the vision drops significantly less than that, they could develop corneal scarring in the anterior layers of the cornea that may not be cleared as quickly by an endothelial keratoplasty,” she said. “The more the cornea remains edematous, the more anterior stromal scarring can occur, which can impact the visual outcome long term,” she said. In addition, for those who have Fuchs’ dystrophy, even if Snellen acuity is good, Dr. Shamie finds that if they complain of glare from light’s reflection off of guttata or thickened Descemet’s, it may be time to make the referral. Going forward, Dr. Shamie is confident that DSAEK will remain a viable transplant option for many. “I don’t think that DMEK will ever replace DSAEK 100%,” she said. “I think that an excellent endothelial keratoplasty surgeon needs to be comfortable and proficient at performing both DSAEK and DMEK to offer patients the appropriate procedure.” A patient with Fuchs’ dystrophy who has otherwise normal corneal stroma would be best managed with DMEK with its better visual potential. However, those with pseudophakic bullous keratopathy and a disorganized anterior chamber (tube, iris loss, etc.) tend to be more complicated, with more limited visual potential. “In a lot of those patients, DSAEK is the gold standard and will remain the standard,” Dr. Shamie said. EWAP Editors’ note: Dr. Busin has financial interests with Moria (Antony, France). Drs. Neff and Shamie have no financial interests related to their comments. Contact information Busin: mbusin@yahoo.com Neff: drneff@carolinacataract.com Shamie: nshamie@yahoo.com DSAEK - from page 31