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Surgeon: crack-and-stack supracapsular method is safe
Procedure saves time, allows for a better patient safety profile and increases surgeon confidence.
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A note from the editors:
In 1997 I published an article in the Journal of Cataract and Refractive Surgery describing a new supracapsular approach to phacoemulsification. Taking advantage of the trend to a slightly larger (5.5 mm) capsulorrhexis, this approach removes the cataract from the confines of the capsular bag before emulsification either with or without nuclear disassembly.
Supracapsular phaco offers many alternatives, most famously David Brown’s “phaco flip,” which was the original. The “flip” maneuver in this technique is understandably daunting for surgeons whose entire phaco experience has been during the endocapsular era since 1989.
Other “non-flip” supracapsular techniques, which simply tilt the lens out of the capsule, have been described. These include Richard Lindstrom’s “tilt and tumble phaco,” which is a variation of Richard Kratz’s technique, one of the standard methods widely used before the advent of capsulorrhexis forced phaco into the relatively hostile confines of the capsular bag. This article by Kenneth Anthone describes another non-flip supracapsular technique.
If you have been reluctant to transition to supracapsular phaco because of concern with the flip maneuver, I encourage you to consider one of these non-flip alternatives. The advantages of greater efficiency and, more importantly, greater safety (capsular rupture is exceedingly rare) will almost surely be immediately evident.
William F. Maloney, MD
Cataract/IOL Section Editor
by Kenneth D. Anthone, MD
The new Anthone crack-and-stack method (ACASM) is a highly adaptable cataract surgical procedure that allows the surgeon to perform phacoemulsification in less time than more traditional procedures, with a better safety profile for the patient.
The procedure is ideal for most cataracts, ranging from the softest posterior subcapsular cataract (PSC) found in the younger patient to a hard brunescent cataract. The high degree of predictability of the ACASM allows the surgeon to approach more challenging cases with a greater degree of optimism and confidence in the final outcome.
The ACASM is a variation of the supracapsular approach that has been advocated by other surgeons. Recent articles suggest that it is more efficient to remove the nucleus from the capsular bag prior to phacoemulsification.
In the popular intracapsular “divide-and-conquer” method, the first challenge is positioning the initial quadrant for emulsification. Dense cataracts often prove quite difficult to disengage because of significant resistance by the remaining three quadrants, which remain interlocked even though they have been cracked. The surgeon must move one-quarter of the entire nuclear mass against the other 75% — a series of maneuvers that require significant force to be directed against the resistance, particularly if residual epinuclear adhesions remain. Four discrete triangular-shaped quadrants translate into 12 pointed areas that clearly increase the potential of a capsular rent if excessive manipulation is required to engage and position each quadrant for emulsification.
The crack
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The ACASM begins with a single deep groove in the central nucleus (figure 1), which facilitates the cracking of the nucleus, thus resulting in two discrete halves (figure 2).
Only four pointed areas remain potential threats to the posterior capsule, as opposed to 12.
The stack
Next, the entire nucleus is rotated 90°, orienting the crack horizontally (figure 3). With the phaco tip placed against the middle of the proximal half of the nucleus (figure 4), I am able to remove my foot from the pedal, causing irrigation to cease, thus softening the eye. Gentle downward and forward force is applied, subducting the proximal half beneath the distal half. The distal half then rotates into an inverted superior position by folding over the proximal half. The halves are now stacked (figures 5, 6 and 7).
The capsule remains intact with this method because no pressure is exerted against the capsule by the sharper edges of the nucleus. In more traditional nucleus-flip techniques, the phaco tip must be pushed much further into the eye to achieve inversion than with the ACASM. Nucleus-flip techniques may also lead to greater incidences of corneal edema and striae immediately postoperatively.
In the ACASM, the short phaco tip only needs to be pushed half as far into the eye (figure 6), since the relatively blunt half of the cracked nucleus displaces the other half. Since only the distal half is inverted, the amount of force and manipulation required is minimized.
Pupil size
When first learning this method, the procedure should be performed with a well-dilated pupil and wide capsulorrhexis (approximately 6 mm), since the halved nucleus is a relatively large mass to manipulate into a stacked position and ultimately out through the capsulorrhexis opening. The large pupil and wide capsulorrhexis are also helpful in that they allow adequate space to properly position the phaco tip on the proximal half of the nucleus and subsequently push it forward. A smaller capsulorrhexis does not leave much room between its border and the cracked edge of the nucleus.
The use of a second instrument, such as a Bechert spatula or the new Anthone Enabler, which is not yet available for distribution and sale, is essential not only in the initial cracking stage but also as an aid to nucleus inversion.
In the stacked position, the distal half of the nucleus is now tumbled or folded forward over the proximal half (figure 7). This leaves adequate room for manipulation and excellent visibility, as the phaco tip may now engage the entire nucleus in the central area of the pupil. Since no epinuclear adhesions remain, the surgeon also enjoys complete freedom of movement of both halves of the nucleus; thus, phacoemulsification becomes faster, safer and easier.
At this point, the linear vacuum level is raised from 50 mm Hg to 110 mm Hg, or whatever level the surgeon desires. The top half of the nucleus is emulsified in the center (figure 8), which leaves two smaller pieces that are easily emulsified using low phaco power and higher vacuum levels (figure 9). Also, each cataract may present in a slightly different manner. As the golfers among us might say, “play it the way it lays” — whichever way the nucleus turns is the way to go.
Following this step, the inferior half, which is still in the bag but free from epinuclear adhesions, is easily emulsified since it usually remains centered after removal of the superior piece. If, however, it does not easily move to the center of the pupil, slightly increase the vacuum power and after insertion of the phaco tip into the middle of it, pull the piece toward the center, or just manually move it with your second instrument (figure 10).
When first using this method, manual movement of the inferior half of the nucleus may be easier by rotating it 90°. Then take your foot off the pedal and when the tip of the nucleus tilts upward, the phaco tip can easily engage it. This second half of the nucleus is then easily emulsified longitudinally, or through its strongest central part where the surgeon has the option of cracking it while emulsifying (figures 11 and 12).
Once you become proficient at this method, it is also a safe and effective way to phaco a cataract with a small pupil and narrow capsulorrhexis. It is satisfying to see how efficiently a cataract may be removed through a 3.5-mm pupil using the ACASM.
The flap-and-stack
If you are dealing with a relatively soft cataract, as might be found in a younger patient, cracking may not be necessary; after creating a deep groove, the surgeon may simply fold the nucleus upon itself, in a position resembling a taco. I call this variant of the procedure the flap-and-stack.
When pushing the proximal half of the nucleus into the distal half, the latter will fold on top of the former in the same manner as previously described for the crack-and-stack. For cataracts 2+ nuclear sclerotic or less, or with soft PSC cataracts, this method often proves simple and is extremely time efficient.
For Your Information:Reference:
- Kenneth D. Anthone, MD, may be reached at 170 Maple Road, Williamsville, NY 14221; e-mail: K_Anthone@yahoo.com. Dr. Anthone has a direct financial interest in the products mentioned.
- Maloney WF, Dillman DM. Supracapsular phacoemulsification: a capsule-free posterior chamber approach. J Cataract Refract Surg. 1997;23(3):323-328.