EyeWorld Asia-Pacific December 2011 Issue

8 December 2011 EW NEWS & OPINION is available, and there are many different methods,” Prof. Barrett said. To deal with LASIK patients, Prof. Barrett has developed his own method to more accurately predict lens power, which he’s dubbed the “True-K Formula.” This formula allows physicians to calculate the true K value from the measured K post-LASIK and the change in refraction produced by the refractive procedure. It also provides a double K solution in that the formula derives a modified formula constant for use with different lens calculation formulae, he said. For the myopia issue, Dr. Barrett concluded that the primary culprit was the formulae itself and how they deal with negative-powered IOLs. “Most third-generation formulae are thin lens formulae that do not allow for the change in shape factor to the necessary adjustment in optical formulae required in the presence of a negative IOL,” he said. The solution, he said, is to use the Universal Formula, which acknowledges “that in the presence of a negative-powered IOL, the lens factor has a negative vergence that has to be accounted for in calculating the effective lens position.” He continued, “As long as you use the correct formula, patients with extreme myopia are no longer an obstacle.” EW floppy iris syndrome, surgeons may consider using pupil expansion devices such as iris hooks. The problem with iris hooks, said Dr. Malyugin, is that four is about the optimal number to use intraoperatively—any more would be cumbersome; this creates a square pupillary opening that overextends the iris and may lead to more damage and trauma. Dr. Malyugin thus developed the Malyugin ring, a foldable, injectable device that creates eight expansion points, while doing away with the iris hook’s potentially damaging sharp edges. Even in the face of such challenges, modern cataract surgery is generally thought of as nearly perfect, but is it really? Philippe Sourdille, MD, representing Jose Güell, MD, president, European Society of Cataract and Refractive Surgeons, said that, clinically speaking, the answer is probably yes. However, he said, using a laser flare meter, fluorescein angiography, and OCT post-operatively reveals iatrogenic changes to the blood-aqueous barrier that indicate otherwise. These tests, said Dr. Sourdille, reveal changes in the blood-aqueous barrier that typically resolve after a few months, but may on the other hand lead to the development of complications like cystoid macular edema. These changes can be caused by various factors inherent to standard phaco surgery: ciliary stress caused by zonular stretching during capsulorhexis, nuclear rotation, and IOL implantation; anterior chamber volume and pressure changes due to the insertion and withdrawal of instruments; and intraocular temperature changes. Dr. Sourdille concluded that, despite the standard phaco procedure’s apparent perfection, it is possible for the femtosecond laser to improve upon it, in part by providing an alternative technique that may eliminate or minimize these factors. However, he added, the burden of proof lies on the newer development, and femtosecond laser-assisted cataract surgery needs to be assessed objectively, probably using a flare meter, fluorescein angiography, and OCT, before making any conclusions about the device’s future role in cataract surgery. D. Ramamurthy, MD, chairman, Scientific Committee of the All India Ophthalmological Society, focused on the different types of toric IOLs while Prof. Bissen-Miyajima suggested that ophthalmologists may be able to move beyond traditional patient indications for multifocal IOLs. Prof. Bissen-Miyajima pointed to her own successful cases, a glaucoma patient, a small pupil case, a patient with high myopia, and a 97-year- old patient who insisted on being given multifocals, to prove that these types of cases shouldn’t immediately be ruled out. “We should be cautious when we expand the indications for the multifocal IOL,” she cautioned. “However, these challenging cases can enjoy the benefits of multifocal lenses in their daily lives.” Ke Yao, MD, president, Chinese Cataract Society, concluded in his talk that coaxial microincision cataract surgery (MICS) is an innovative way to perform cataract surgery because there is a smaller incision. “The ongoing coaxial mi- croincision phacotrab- eculectomy can reduce tissue dam- age and the chances of surgically induced astigmatism and offers enhanced postoperative visual rehabilitation,” he said. The simple operation also means minimized injury and a watertight incision, he said. The final lecture given during the Presidents’ Symposium was from Prof. Barrett, with his talk on “Perfect IOL Power Prediction.” Prof. Barrett admitted to struggling with the issue of refractive predictability due to several hurdles such as formulae inaccuracy, extreme myopia, and patients who have had previous radial keratotomy or LASIK. Three categories of patients exist: those with a full clinical history, those with no clinical date, and patients with a partial history, where the change in refractive status before and after LASIK is known. “You can see that the approach to biometry needs to be adjusted depending on how much data APACRS-KSCRS - from page 7