EyeWorld Asia-Pacific March 2011 Issue

Ciliary continued from page 25 26 EW CATARACT/IOL March 2011 capsule to increase its curvature during accommodation, yet what is the first thing we do during cataract surgery? We remove the central anterior capsule, so it is possible we actually reduce the ability of the eye to accommodate by performing cataract surgery,” Dr. Harton said. Conversely, the scleral implants are compressive devices, possibly enhancing accommodation “by decreasing the ciliary muscle to lens equator space, relaxing the zonules slightly in the disaccommodated state, and increasing their range of motion during accommodation”, said Richard L. Lindstrom, MD, adjunct professor emeritus, Department of Ophthalmology, University of Minnesota, Minneapolis, Minn., USA, and founder, Minnesota Eye Consultants, Minneapolis, Minn., USA. He said these types of “Schachar implants” could work and continue to be consistent with Helmholtz’s theory. “Scleral relaxing incisions also work in many patients,” he said. “Incising the sclera over the ciliary body weakens the sclera, creating a ‘controlled ectasia’, but in this case as the circular muscle of the ciliary body contracts, it can pull in the weakened sclera, enhancing zonular loosening and range of motion. This accommodation can be enhanced, again consistent with Helmholtz’s theory.” Dr. Lindstrom believes “most of the action is on the anterior lens surface with the zonules inserting in about 2 mm onto the anterior capsule and sliding centripetally as the patient accommodates and the zonules move centrally, resulting in a steepening in the central anterior 3-4 mm.” Gary Wortz, MD, Louisville, Ky., USA, said he imagines the zonules, capsule, and lens complex “somewhat like a double-sided trampoline with a gelatinous material in the middle. If you cut a large circular hole in the anterior surface of the apparatus, you change the entire equilibrium of the opposing mechanisms.” Dr. Wortz said, “Whatever lens we implant in the case of pseudophakia must be the maximal ‘accommodated’ state at rest—i.e., ciliary muscle fully contracted, zonules fully relaxed.” The research being undertaken now will, with luck, lead to “a way to perform cataract surgery through a sub-1-mm incision in the peripheral bag and leave the anterior capsule intact”, Dr. Wortz said. “I think it will be difficult to achieve a real restoration of accommodation without dramatically changing the way we perform cataract surgery.” In addition to demonstrating a more complex anatomy of the zonule, “the Croft study demonstrates that stiffening of the vitreous zonule may contribute to age-related loss of accommodation. The implications of these findings, along with supporting evidence that lysis of the posterior zonule results in increased accommodation in phakic, pseudophakic, and aphakic Rhesus monkeys, suggests a therapeutic target for presbyopia correction and may help in the quest to design better accommodating IOLs,” Dr. Goldberg said. EW References 1. Lutjen-Drecoll E, Kaufman PL, Wasielewski R, Ting-Li L, Croft MA. Morphology and accommodative function of the vitreous zonule in human and monkey eyes. Invest Ophthalmol Vis Sci. 2010;51:1554-1564. 2. Hartridge H. Helmholtz’s theory of accommodation. Br J Ophthalmol.1925;9(10):521-523. 3. Schachar RA. Cause and treatment of presbyopia with a method for increasing the amplitude of accommodation. Ann Ophthalmol. 1992;24(12):445-7,452. Editors’ note: Dr. Harton has financial interests in the Accommodation and Ocular Imaging Council. Dr. Lindstrom is a consultant to industry. Drs. Goldberg, Novis, and Wortz did not report any financial interests related to their comments. Contact information Goldberg: 732-219-9220, goldbergeye@gmail.com Harton: 706-233-8502, pharton@harbinclinic.com Lindstrom: 952-888-5800, rllindstrom@mneye.com Novis: +27 11 815-1117, clivenovis@mweb.co.za Wortz: 270-692-0047, 2020md@gmail.com MORIA S.A. 15, rue Georges Besse 92160 Antony FRANCE Phone: +33 (0) 1 46 74 46 74 - Fax: +33 (0) 1 46 74 46 70 moria@moria-int.com - www.moria-surgical.com SBK without compromise Think Thin • Thin, 100-micron, planar flaps • Accuracy and predictability equivalent to Femto-SBK • Smoother stromal bed • No femto-complications • … At a fraction of the cost 6%. QHZVOHWWHUV QRZ RQOLQH 'RZQORDG ORQJ YHUVLRQ WHVWLPRQLDOV RQ ZZZ PRULD VXUJLFDO FRP 5RXQGWDEOH ZLWK LQWHUQDWLRQDO 6%. 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