EyeWorld Asia-Pacific September 2014 Issue

September 2014 9 EWAP FEAturE Views from Asia-Pacific CHEE Soon Phaik, MD Senior Consultant, Head of Department Singapore National Eye Centre 11 Third Hospital Avenue, Singapore 168751 Tel. no. +65-6227-7255 Fax no. +65-6227-7290 chee.soon.phaik@snec.com.sg T oday’s cataract patients demand a perfect refractive outcome and are intolerant of anything less. Indeed, we are in the era of refractive cataract surgery. With the advent of optical biometry, our refractive predictability has improved significantly. However, our abilities are limited when faced with a significant posterior subcapsular cataract or mature cataract when we would still need to rely on immersion biometry. Even with fourth generation formulas, we still encounter many high myopes with a hyperopic outcome. Eyes with extreme keratometric readings that did not have prior refractive surgery also face IOL calculation inaccuracies. Even with the numerous techniques and online calculators available for calculating the IOL power for post- refractive patients, they still need to be counseled regarding the possibility of an IOL exchange in the event of a refractive surprise. Astigmatism correction is even more challenging. Most importantly, the acquisition of readings must be accurate. Eye drops instilled during a consultation, dry eyes and head tilt are some of the factors that can affect the keratometry results. Which keratometry instrument is the most accurate is unclear. Few instruments are able to measure the posterior corneal astigmatism. Furthermore, the toric calculator among the various IOL manufacturers varies in its accuracy. There are now devices in the market that guide the surgeon in the placement of the toric IOL axis. Such devices are able to recognize and track the eye during surgery and do not require marking of the axis prior to surgery. After careful surgery and accurate positioning of the IOL, in-the-bag rotation may still occur postoperatively especially in big bags. Yet with all this sophisticated equipment, astigmatism may still not be abolished completely. Indeed, a recent publication found that the source of residual astigmatism after toric IOL placement was in the acquisition of preoperative astigmatism. Apart from toric IOLs, astigmatic keratotomy (AK) or intrastromal AK using the femtosecond laser has gained renewed interest because of reimbursement issues. However, regression is always of concern with any incisional technique. Whether femtosecond laser-assisted cataract surgery achieves better visual outcomes and refractive predictability than manual cataract surgery is still debatable. There is no doubt that multifocal IOLs are extremely sensitive to refractive errors. The closer to plano, the better the outcome. I agree that 0.75 cylinder and above must be corrected to have a happy patient. Despite all the efforts, refractive inaccuracies still occur. The intraoperative wavefront aberrometer was thus designed to minimize these inaccuracies. However, its accuracy is questioned even though conceptually the idea is attractive, because of the numerous variables that exist during the intraoperative scenario. To be successful, any premium cataract service should offer a package to correct any residual refractive errors in an unhappy patient. A touch up using LASIK or a supplementary IOL may be necessary when all else has failed. I certainly think that the Light Adjusted IOL will have a definite role in eyes the surgeon identifies as being at risk of inaccurate refractive outcome. Editors’ note: Prof. Chee is a consultant for Abbott Medical Optics and Bausch + Lomb and receives travel support and an honorarium. Ramamurthy DANDAPANI, MD Chairman, The Eye Foundation D.B. Road, Coimbatore 641002 Tel. no. +91-422-4242000 Fax no. +91-422-4242099 info@theeyefoundation.com A chieving the targeted refractive outcome with premium IOL surgery has become as important as in laser vision correction. Since patients expectations are also partly determined by the expenses incurred by them for a particular procedure, it becomes even more imperative to hit the target, when they have paid a price for their IOLs and maybe LRCS. Management As always, prevention is better than cure, and it is not just the IOL which is premium but it is the entire surgical process which has to be premium. Toward this, proper counseling, understanding patient’s visual requirements, perfect biometry, optimizing the A-constant, performing quality surgery, and perfecting toric markings are all important. In the event of a suboptimal refractive outcome, I consider a stepwise approach: A) If the patient does not have any complaint, nothing needs to be done just because there is a residual error. B) Especially with multifocal IOLs, consider second eye surgery with titration of the IOL power, so that bilaterally implanted they have good functional vision for all distances. C) LASIK after 3 months once the wound as well as the refractive error is stable and take care of both the sphere and cylinder. I prefer LASIK over PRK (unless a flap is contraindicated due to ocular surface or corneal issues) since these patients are less tolerant to the pain and the prolonged recovery that sometimes follows a PRK. D) Rotate the toric IOL to the appropriate position. It will work if the spherical equivalent of the residual refractive error is near zero. E) Consider a laser arcuate keratotomy, if it is purely a residual cylinder. Even though it is better than manual arcuate keratotomy, still the results are not as predictable as with LASIK. F) Consider IOL exchange if it is a large surprise which can sometime occur in cataract surgery following laser vision correction. G) Consider piggyback IOL if the refractive error is large and LVC or IOL exchange is not feasible. With the multiple options available, the modern day cataract surgeon or the patient need not put up with a suboptimal refractive outcome. Editors’ note: Dr. Ramamurthy has no financial interests related to his comments.