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Video Report

The Nuclear Slide: A Novel Approach for Unleashing the Potential of the Hydrodissection Wave

Mayo Clinic, Scottsdale, Arizona
Correspondence: Naseri.Ayman@mayo.edu

Date of acceptance: 24th January 2005

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Note: This video is best viewed in Quicktime

Background

Kenneth J. Faust published one of the earliest descriptions of the hydrodissection technique used in modern cataract surgery. In the American Intra-ocular Implant Society Journal, he wrote in 1984, "I describe a technique for freeing the nucleus in extracapsular cataract surgery that uses simple cannulas and balanced salt solution in a closed anterior chamber, produces no zonular stress, requires no assistant, needs no iris or capsule manipulation, and is compatible with all methods of nucleus removal including phacoemulsification."[1] Whereas there have been major changes in other aspects of cataract surgery including anesthesia, intraocular lenses and phaco techniques, hydrodissection is often performed the same today as he described it 20 years ago.

Despite the relative safety of hydrodissection, this technique is not without potential complications, particularly in the hands of a resident surgeon just learning the technique. Although a capsular block syndrome with early rupture of the posterior capsule may be the most feared complication of hydrodissection, [2,3] iris prolapse is a more common problem, as an inexperienced surgeon continues to push fluid through the eye, not realizing that the wave has already passed around the lens. To avoid this pitfall, many surgeons push downward on the lens after the initial hydrodissection wave so as to "decompress" the fluid that has passed behind the cataract.

Technique

In an effort to improve hydrodissection teaching, we introduce and describe a technique modification for this critical step in cataract surgery. The "nuclear slide" refers to a simple, sliding horizontal movement of the lens.
After passing the first hydrodissection wave under the lens, the fluid wave is halted. Then with a horizontal movement of the lens toward the initial fluid entry point ("nuclear slide"), we allow the sequestered fluid to be passively released around the opposite lens equator in a secondary wave. This horizontal movement of the lens is facilitated by a 90 degree bent cannula, in this case the cannula developed by Dr. David F. Chang of Los Altos, California, USA. The nuclear slide can be easily followed with hydrodelineation and lens rotation.

Sometimes the secondary wave that follows the nuclear slide occurs rather quickly. Other times, as in the case of a cortical-cleaving hydrodissection, the secondary wave is slower in velocity as it passes around the equator of the lens. In some cases the initial hydrodissection wave does not need to pass all the way across the diameter of the lens, and yet the nuclear slide can still release the secondary wave. This observation can be especially useful in teaching inexperienced surgeons. Once the primary wave is sequestered behind the lens, a delay in the nuclear slide maneuver can still release the potential energy stored between the cataract and the posterior capsule. The secondary wave is waiting to be released.

Comment

Video is certainly helpful in demonstrating this technique, but anatomical realities limit our ability to study this phenomenon further. Although the precise mechanism for this modification of hydrodissection is not known, animation may help elucidate one plausible explanation. We hypothesize that the primary fluid wave of hydrodissection contains a mechanical cleaving force that separates the lens from the posterior capsule. By distending the posterior capsule from the lens, the fluidic mechanical force is temporarily converted to potential energy, which is stored in the elasticity of the posterior capsule. With a simple sliding of the lens, the "nuclear slide," we create an outlet for the release of this sequestered potential energy. This release of potential energy is manifest in the visible passage of a secondary wave of hydrodissection.

Although this technique is most easily demonstrated in well-dilated eyes with bright red reflexes, the nuclear slide is useful for other situations as well. In a small-pupil case, the iris visually blocks most of the primary and secondary waves, and yet the nuclear slide is still effective. This technique can also be used in an eye with a dense cataract, although the wave is more difficult to identify due to the dimness of the red reflex.

Hydrodissection is one of the most underrated steps in cataract surgery. Mastery of the hydrodissection technique is essential to improve the efficiency and efficacy of phacoemulsification.[4,5] In teaching residents, we should place emphasis on the need to create a freely rotating, mobile lens prior to phacoemulsification. The "nuclear slide" can be a safe, useful modification to the standard hydrodissection that was described 20 years ago. The nuclear slide can be used as a teaching aid for beginning surgeons or it may become a powerful tool in any cataract surgery.

References

1. 1. Faust, KJ. Hydrodissection of soft nuclei. J Am Intraocul Implant Soc. 1984; 10:75-77.
   
2. Ota I, Miyake S, Miyake K. Dislocation of the lens nucleus into the vitreous cavity after standard hydrodissection. Am J Ophthalmol 1996; 121:706-708.
   
3. Yeo R. The ‘pupil snap’ sign of posterior capsule rupture with hydrodissection in phacoemulsification. Br J Ophthalmol 1996; 80:486.
   
4. Peng Q, Apple DJ, Visessook N, Werner L, Pandey SK, Escobar Gomez M, Schoderbek R, Guindi A. Surgical prevention of posterior capsule opacification. Part 2: Enhancement of cortical cleanup by focusing on hydrodissection. J Cataract Refract Surg 2000; 26:188-197.