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April 2011
 

CATARACT / IOL
 

Surgeons need to reduce power in cataract patients with soft lenses


by David Laber EyeWorld Contributing Editor
 


 

Ophthalmologists discuss different techniques to safely and effectively remove soft cataracts


In a new technique for soft cataract removal, an OVD (such as those pictured here) is gently injected into the eye, creating a small crack Source: Steve A. Arshinoff, M.D.

Although it sounds counterintuitive, cataract patients with a soft lens present trickier cases because most physicians spend about 95% of their time performing divide-and-conquer and other chopping techniques, said Thomas A. Oetting, M.D., professor of clinical ophthalmology, University 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 phacoemulsification more efficient aim to reduce the energy delivered to the eye, diminishing the damage to all intraocular structures. These techniques do not work well on soft lenses because the techniques 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 nucleus 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 capsulorhexis is created, cortical cleavage hydrodissection is performed. Hydrodelineation is carried out in the usual fashion, and complete mobility of the lens within the capsule is established, according to the study. A golden halo sign indicates that hydrodelineation has been performed successfully.
An OVD is introduced into the eye using a hydrodissection cannula and, with a small amount of pressure, into the nucleus. The OVD is gently injected, creating a small central crack.
The surgeon can explore this first crack, enlarging it in both directions to create a complete fracture of the nucleus. This maneuver can be repeated by rotating the nucleus 90 degrees, performing additional fractures 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 fragments and to further divide the previous fractures.



Benefits of the technique

"Good hydrodissection and hydrodelineation, with complete mobility of the lens, are sometimes sufficient to allow aspiration of a soft nucleus by an experienced surgeon 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 fracture occurs as the OVD is being injected. Phaco energy can be used exclusively to remove the lens fragments. Less energy is associated with less damage to intracameral structures.
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 associated 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 technique simple and reliable and the results 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 simple and safe technique.
The study's proposed technique is similar to one of Dr. Oetting's preferred 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 nucleus 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 setting.
Soft lens cataract patients are a rare occurrence—Dr. Oetting estimated about 5% of his patients fit the description, although that number probably varies depending on the practice. He noted, however, that younger patients seem more prone to soft lens cataracts, as are diabetic or trauma patients. This tends to be the cause of the development of cataracts in younger patients in the first place.



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







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