Eyeworld

EW CATARACT/IOL 30 April 2011 by David Laber EyeWorld Contributing Editor Surgeons need to reduce power in cataract patients with soft lenses Ophthalmologists discuss different techniques to safely and effectively remove soft cataracts A lthough it sounds coun- terintuitive, cataract pa- tients with a soft lens present trickier cases be- cause most physicians spend about 95% of their time per- forming divide-and-conquer and other chopping techniques, said Thomas A. Oetting, M.D., professor of clinical ophthalmology, Univer- sity of Iowa, Iowa City, chief, Eye Service, and deputy director, Surgery Service, VA Medical Center, Iowa City. Furthermore, Gustavo Ricci Malavazzi, M.D., and Rachel Gomes Nery, M.D., both of the Santa Casa de Misericordia, Sao Paulo, Brazil, said in a study in the January 2011 issue of the Journal of Cataract & Refractive Surgery that variations to make phacoemulsifica- tion more efficient aim to reduce the energy delivered to the eye, dimin- ishing the damage to all intraocular structures. These techniques do not work well on soft lenses because the tech- niques use higher vacuum power than would be recommended in a soft lens patient, Dr. Oetting said. To get around this problem, Drs. Malavazzi and Nery proposed a visco-fracture technique for soft nu- cleus removal that is performed in a slow and controlled fashion without the use of special surgical devices. New technique for soft cataract removal After a continuous curvilinear capsu- lorhexis is created, cortical cleavage hydrodissection is performed. Hy- drodelineation is carried out in the usual fashion, and complete mobil- ity of the lens within the capsule is established, according to the study. A golden halo sign indicates that hy- drodelineation has been performed successfully. An OVD is introduced into the eye using a hydrodissection cannula and, with a small amount of pres- sure, into the nucleus. The OVD is gently injected, creating a small cen- tral crack. The surgeon can explore this first crack, enlarging it in both direc- tions to create a complete fracture of the nucleus. This maneuver can be repeated by rotating the nucleus 90 degrees, performing additional frac- tures in the same way. The machine settings recommended for managing soft lens removal are 55 cc/min of aspiration flow rate, 360 mm Hg of vacuum, and continuous torsional ultrasound energy. Phaco of the quadrants can be continued using an auxiliary second instrument, according to the study. This is inserted through a side-port incision to chop the remaining frag- ments and to further divide the pre- vious fractures. Benefits of the technique "Good hydrodissection and hy- drodelineation, with complete mo- bility of the lens, are sometimes sufficient to allow aspiration of a soft nucleus by an experienced sur- geon but can be a challenge for the novice," the study authors said. "The technique we describe provides a safe and reliable way of chopping a soft lens within the capsular bag." According to the study, the frac- ture occurs as the OVD is being in- jected. Phaco energy can be used exclusively to remove the lens frag- ments. Less energy is associated with less damage to intracameral struc- tures. This approach can be used with different OVDs and cannulas, and the study authors said they have used it with several OVDs and have achieved the same effects. Traumatic endothelial contact with nuclear fragments and surgical instruments is reported to be associ- ated with an increased risk of cell loss. "Viscofracture has few steps and requires minimal manipulation of intraocular structures," the study authors said. "We consider the tech- nique simple and reliable and the re- sults efficient and predictable. This technique is ideal for teaching the beginning surgeon when soft nuclei are difficult to fracture using other techniques." Alternative techniques for soft cataracts Dr. Oetting, although he has not tried this approach, said it does make sense and appears to be a sim- ple and safe technique. The study's proposed technique is similar to one of Dr. Oetting's pre- ferred techniques; he said he has found success prolapsing the lens with balanced salt solution. With this method, first he hydrodissects, careful to keep the cannula over the lens to avoid prolapse, followed by spinning the lens. Then he performs hydrodelineation and allows the nu- cleus to prolapse into the anterior chamber. "In a perfect world, you can just prolapse the nucleus and leave the epi-nuclear material in the bag," Dr. Oetting said. Then he removes the nucleus with the phaco needle with epi-nuclear settings and removes the epi-nuclear material with the phaco needle and a shizzle manuever or with the irrigation/ aspiration tip. Another technique Dr. Oetting said he has had success with is to soft chop with no vacuum. Using too much vacuum power will likely cause the lens to jump into the tip and create a hole in the lens, "Swiss cheesing" the lens. In this method, the idea is to use the phaco needle to hold and support the soft lens while slicing through the lens with the chopper. Then the phaco needle simply supports the lens and the chopper goes deep and moves in a horizontal fashion just to the left of the phaco needle, moving to the left when reaching the needle to split the lens. If the lens does not break into pieces, Dr. Oetting said he will slice it, usually into six pieces, so that the lens will come into the anterior chamber with the epi-nuclear set- ting. Soft lens cataract patients are a rare occurrence—Dr. Oetting esti- mated about 5% of his patients fit the description, although that num- ber probably varies depending on the practice. He noted, however, that younger patients seem more prone to soft lens cataracts, as are di- abetic or trauma patients. This tends to be the cause of the development of cataracts in younger patients in the first place. EW Editors' note: Drs. Malavazzi and Nery have no financial interests related to their study. Dr. Oetting has no financial interests related to his comments. Contact information Nery: rachelgnery@gmail.com Oetting: 319-384-9958, thomas-oetting@uiowa.edu I n a n e w t e c h n iq u e f o r s o f t c a t a r a c t r e m o v a l, a n O V D ( s u c h a s t h o s e p ic t u r e d h e r e ) is g e n t ly in je c t e d in t o t h e e y e , c r e a t in g a s m a ll c r a c k Source: Steve A. Arshinoff, M.D.

• Cover