EyeWorld Asia-Pacific June 2012 Issue

30 EWAP CATARACT/IOL June 2012 Presbyopia-correcting IOLs on the horizon by Faith A. Hayden EyeWorld Staff Writer Will they ever reach U.S. soil? C ataract surgeons around the world have a common goal: implant patients with a presbyopia-correcting IOL that mimics Mother Nature’s mechanism of accommodation. A handful of developers, including PowerVision (Belmont, Calif., USA), Oculentis (Berlin, Germany), and PhysIOL (Liège, Belgium), believe they’ve created a lens that comes close to achieving that ideal target. Regretfully, these lenses are not approved in the U.S., although PowerVision and PhysIOL hope their devices reach U.S. soil. “A lot of the product development has come to a halt with the new climate at the FDA,” said Steven Dell, MD , Austin, Texas, USA. “The translation for that ultimately is products never reach the U.S.” Despite the issues with the U.S. market, ophthalmologists and developers worldwide are making strides in solving the accommodation problem. These companies have widely varying approaches, but all are innovative, unique, and potentially beneficial to the presbyopia patient population. PowerVision’s FluidVision FluidVision from PowerVision is a dynamic accommodating IOL in clinical development that changes the shape of the capsular bag by shifting fluid through the structure of the lens. “The mechanism of action takes advantage of extremely small volumes of fluid, which are present in the outer haptics, that is forced in the center of the lens as accommodation occurs through the natural ciliary body and zonular apparatus,” said Louis D. “Skip” Nichamin, MD, Laurel Arup CHAKRABARTI, MD Senior Consultant, Cataract and Glaucoma Services Chakrabarti Eye Care Centre No. 102, Kochulloor, Trivandrum 695011, Kerala, India Tel. no. +914712555530 Fax no. +914712558530 arupeye@gmail.com T he ultimate goal of the cataract surgeon today is to provide his patient uncorrected normal high quality vision at all distances. To achieve this end the industry has come out with a wide array of presbyopia-correcting IOLs which belong to two categories: multifocal and accommodative. The fact that such a wide variety is available points to the fact that we still don’t have the single best IOL meeting all our requirements. Hence the need to choose an IOL that best suits a given patient’s requirements. This article discusses three lenses in the horizon: an accommodative lens (FluidVision), and two multifocal IOLs of differing optic designs. The current FDA-approved accommodative IOL (Crystalens) has perhaps not lived up to its initial promise both in terms of degree of accommodation as well as its undesirable interaction with the capsular bag resulting in Z deformity, etc. The FluidVision IOL which claims to offer 5 D of accommodation looks like an interesting IOL with a lot of possibilities. But we need to know how the IOL performs in the long run with respect to PCO and capsular bag contraction. The durability of the IOL and the potential degradation of silicone oil inside it are also a few issues to watch out for. The Lentis MPlus IOL is a refractive non-rotation symmetric IOL which seems to have done well in the hands of its users. It is interesting that a refractive MFIOL is making waves due to an innovative design (with a sector shaped near segment) since as of today diffractive design MFIOLs have relegated the refractive MFIOLs to the background. The loss of light is only 5-7% which is much less than the 14-15% seen with diffractive MFIOLs and this definitely contributes to the HD vision. The fact that one of the surgeons has felt the need for an inverted orientation of the IOL (against the manufacturer’s instructions) indicates that the IOL may be associated with troublesome side effects. It would be interesting to know the performance of this lens in small pupils and also the long-term centration issues. PhysIOL’s FineVision IOL is the first trifocal apodized diffractive IOL and seems to be an interesting concept with a combination of two diffractive structures. It is made of a hydrophilic acrylic blue blocking biomaterial and is a multifocal IOL with far vision dominance. Energy loss is 14% which is less than the other bifocal diffractive MFIOLs. Patient selection as well as selection of presbyopia-correcting IOL should be meticulously performed to optimize outcomes. It is advisable to avoid MFIOLs in patients with corneal opacity, poor ocular surface, tear film and meibomian gland disease, astigmatism, advanced glaucoma, maculopathy etc. An inaccurate biometry resulting in a residual refractive error will negate the good results expected with a presbyopia correcting IOL. The surgeon should pay attention to surgical details with respect to astigmatically neutral incision, round central appropriately sized capsulorhexis and adequate cleaning up of the capsular bag perhaps including the LECs. CME prophylaxis is of paramount importance. Failure to pay attention to these details will result in suboptimal outcomes even if the best IOL is chosen in a given case. Editors’ note: Dr. Chakrabarti has no financial interests related to his comments. Views from Asia-Pacific Eye Clinic, Brookville, Pa., USA. “Those forces are transferred to the implant, and the fluid is then hydraulically pushed into the center of the lens.” Once in the central optic, the fluid expands, changing the optics’ shape by increasing its thickness and therefore its power, explained Samuel Masket, MD , Advanced Vision Care, Los Angeles, Calif., USA. The lens creates myopia while patients are accommodating so they can see well at near. “To achieve this physically has been no small feat,” said Dr. Nichamin. “Theoretically, it blows the mind to think one could do this and then not only do it but show through bench testing, proof of theory, and sighted eyes that this concept works.” The lens has been implanted in man, first in blind eyes in South Africa, then in sighted eyes with reduced vision. PowerVision demonstrated upward of 5 diopters or more of true accommodation in these patients, Dr. Masket said. Most developmental obstacles have been overcome, although there’s always a long, continuing pathway of improvements necessary. One lingering question during the IOL’s infancy was if energy could be transferred through the zonular apparatus and fibrotic capsule to the pseudophakic lens. “Fortunately, despite considerable variability from patient to patient in regard to zonular capsule, most have the ability to transfer those vector forces to the still-working ciliary body to this man-made, accommodative, shape-changing lens,” said Dr. Nichamin. Three primary hurdles remain: sizing, leakage, and long-term complications. Both Drs. Masket and Nichamin were quick to point out that the fluid used in the lens is ophthalmic-grade silicone oil, a