Techniques and tips for tackling cortex removal

March 15, 2014

Complete removal of lens substance is critical in pediatric cataract surgery. M. Edward Wilson, MD, offers helpful strategies.

 

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Complete removal of lens substance is critical in pediatric cataract surgery. M. Edward Wilson, MD, offers helpful strategies.

Dr. Wilson

By Cheryl Guttman Krader; Reviewed by M. Edward Wilson, MD

Charleston, SC-Use of a bimanual approach and a sequence that removes subincisional cortex first and the entire peripheral cortex before aspirating the central nucleus will enable safe and thorough removal of the cortex during pediatric cataract surgery, according to M. Edward Wilson, MD.

Dr. Wilson discussed instrument selection and a host of standard and advanced maneuvers for successfully removing difficult cortex.

“I consider using a bimanual technique a big advantage, because it allows the surgeon to switch hands as needed to better reach cortex while maintaining chamber stability,” said Dr. Wilson, professor of ophthalmology and pediatrics, and the N. Edgar Miles Endowed Chair, Albert Florens Storm Eye Institute, Medical University of South Carolina, Charleston.

“Removing the peripheral cortex before the nucleus is the reverse of what is done in adult eyes, but is helpful in pediatric cataract surgery for preventing a convex posterior capsulethat can occur because of posterior vitreous pressure,” Dr. Wilson said. “This is a uniquely pediatric phenomenon.”

 

 

Instrument choice and entry

Use of tapered and curved bimanual irrigation and aspiration handpieces is another consideration for optimizing full accessibility to cortex. Placing the instruments through peripheral corneal tunneled paracentesis openings created with a matching gauge microvitreoretinal blade optimizes safety, as well as maneuverability.

“There can be a lot of chamber bounce and collapse in pediatric eyes during cataract surgery,” Dr. Wilson said. “Therefore, we want the instruments to fit tightly through their entry sites to maintain the chamber stability needed to get the often ‘gummy’ cortex out.”

He added that avoiding an excessively long tunnel is important when creating the paracenteses as that architecture will lead to oar-locking with restricted instrument movement. Distancing the paracenteses farther apart from each other is also helpful for enabling instrument maneuverability.

Cortex can also be removed using a vitrector handpiece, but it is a less efficient choice because the vitrector handpiece is not tapered and has a larger aspiration port opening, he noted.

If a vitrector is used, Dr. Wilson recommended applying short bursts of cutting to move thick cortex into the aspiration port while remaining vigilant not to inadvertently cut iris or capsule.

 

 

Instrument maneuvers

In using the aspiration handpiece for cortex removal, Dr. Wilson advised placing it just under the edge of the capsulorhexis with the aspiration port turned toward the capsular equator.

Then, the surgeon should build suction and wait for cortex to come to the instrument opening. He noted a Venturi-pump machine is preferred for this maneuver.

“In pediatric eyes we try to avoid early stripping and tearing of the cortex,” Dr. Wilson said. “While that technique is used in adults, in pediatric eyes it tends to leave small pieces of residual cortex in the equator that will be difficult to remove.

“Keeping the instrument under the edge of the capsulorhexis promotes full evacuation of equatorial cortex,” he said.

To enhance efficiency and safety, the irrigation cannula can be used to hold the iris back and to feed cortex into the aspiration opening.

“Using the irrigation handpiece to loosen cortex and bring it out of the capsular equator represents a form of precise and safe hydro-dissection,” Dr. Wilson said.

Conventional hydro-dissection and hydro-delineation have a more limited role in pediatric procedures than in adult eyes due to the absence of a firm solid nucleus and the frequency of posterior capsule pathology, he noted.

“Many times in pediatric cases we are dealing with posterior polar cataracts, lentiglobus, or fetal nuclear cataract with posterior capsule plaques where the posterior capsule is adherent to cortex and often is incompetent,” Dr. Wilson said. “Hydro-dissection or hydro-delineation in eyes with these types of cataract may cause posterior capsule tears, and the payoff achieved by performing these maneuvers in an effort to speed cortex removal is relatively modest in pediatric cataract cases in general compared to adults.

“Therefore, it may not be worth the risk,” he said.

 

 

Surgical aids

Dr. Wilson advocated expanding the pupil as needed with iris hooks or rings to improve visualization and therefore the ability to remove difficult cortex safely.

“Getting the cortex out completely without traumatizing the iris can be a struggle if the pupil is not opened widely,” he said. “I believe devices for enlarging the pupil are underutilized in pediatric cataract surgery.”

Surgeons may also find it helpful to use an ophthalmic viscosurgical device (OVD) to viscodissect residual cortex into the center of the capsular space where it can be removed “dry” with a cannula or the aspiration handpiece.

“Sometimes, however, difficult cortex is best brought out with viscodissection at the end of the procedure,” Dr. Wilson said. “After IOL insertion, the viscodissected material can be removed along with the OVD using the bimanual handpieces.”

 

M. Edward Wilson, MD

E: wilsonme@musc.edu

Dr. Wilson has no relevant financial interests to disclose.

 

 

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