The informed cataract surgeon approaches the removal of lens cortex with the familiar adage in mind, last but not least. Successfully removing the lens requires meticulous surgical handling of even the last cortical fiber. Complications during this portion of the cataract procedure result in significant associated comorbidities. Most excellent surgeons constantly remind themselves of the basic elements of their refined procedure, which are outlined in this article.
The complexity of the human eye commands the utmost respect, especially when it is being surgically altered. During the cortical-removal phase of lens extraction, this level of respect must be maintained. For example, your initial attention is always directed toward an analysis of the characteristics of the eye tissues you are manipulating that identify potential complications, as well as human factors that may affect your choices and behavior.
Despite the imminent danger in the sharp tip of the phaco needle, remind yourself not to let your guard down the moment you remove the instrument from the eye. The work is certainly not yet finished. Even at the outset, prudent surgeons constantly work to focus their attention on the issues at hand. Cortical removal is greatly enhanced by the perfection of the preceding steps. An intact capsulorhexis and protection of the entire zonulocapsular support apparatus are perhaps the most important issues in long-term success for the patient.
During each step, remain focused on factors that could make or break a successful procedure. Give immediate consideration to the quality of visualization, which is profoundly important in removing lens cortex. When visualization is poor, the implications for the entire procedure are grave. Cortical whitening may be associated with weak zonules, fragile capsules, an expanded capsular bag, and poor visibility, which can negatively affect all phases of surgery (so be ready to use a capsular dye). Polar subcapsular cataracts are a harbinger of a weak or open posterior capsule. Small pupils equal restricted visualization and, likely, weak zonulocapsular support, with all of its attendant challenges.
Several factors during nuclear extraction affect the cortical-removal phase. Mature, dense nuclei—especially in the presence of a thin, fragile anterior capsule—have implications for zonulocapsular stability, visualization, and, ultimately, the behavior of the lens cortex during its attempted removal. One useful technique for cortical removal is to use the phaco handpiece to carve the anterior cortex and epicortex into a circular opening, just inside the edge of the capsulorhexis. This maneuver enhances the visibility of the capsulorhexis' edge when the phaco needle is in the eye and thus prevents the inadvertent disruption of the anterior capsule. The technique also clears cortex from the central path so that the phaco tip is less likely to pull cortex (and capsule) during nuclear and epinuclear removal. As always, the early recognition of and response to a damaged capsulorhexis or posterior capsule are key.
EARLY CORTICAL MANAGEMENT
You are managing cortex even before the I/A instrument enters the eye. This phase of the procedure depends on hydrodissection and hydration. Hydrate the cortex as completely as possible. Avoid high fluid volumes and velocities but persist with smaller volumes at a controlled, constant rate or in pulsations. Laminar and intralaminar cleavage facilitate nuclear mobility, improve visualization, loosen cortex for clean stripping, and spare the lens capsule and zonules. When in doubt, repeat these steps.
During nuclear removal, reassess the condition of the cortex and epicortex. If thorough hydrodissection and cleavage techniques have failed to prepare the cortex appropriately for safe removal, do not despair! While the final heminuclear fragment remains in the eye during phacoemulsification, you can use it as a third instrument to separate epinucleus. Rotating a heminuclear fragment around the bag's equator can free unwanted epinucleus and friable, pasty, adherent cortex, thereby promoting cleaner, safer, and less stressful cortical stripping. The nucleus also supports the bag and facilitates the distribution of BSS during hydrodissection. Proceed with care and use slow hydrodissection. Your aim is to hydrate cortex and lift epinuclear and epicortical planes, without fragmenting the cortex into fine shards. Do not attempt to power-spray large cortical segments out of the bag with BSS, or you may fragment the cortex into strings that are difficult to remove.
MANAGE THE I/A INSTRUMENT CAREFULLY
Reinflate the anterior chamber and capsular bag with BSS through the sideport incision before initially inserting the I/A instrument. The IOP and anatomic configuration of the anterior segment will return to a more physiologic state. The capsule will remain back, away from the I/A tip during its insertion, and visualization will be enhanced for better safety. If the epicortex needs to be lifted or hydrated further, the BSS cannula can help, as mentioned earlier.
Inspect the I/A tip immediately after its insertion, before beginning cortical cleanup. The 0.3-mm aspiration aperture should be smooth and free of burrs or other threats to the capsule. A silicone-tipped I/A cannula may be even more gentle than other designs and spare an incarcerated posterior capsule. The equipment's function is the surgeon's responsibility, so do not forget to check it!
Focus your microscope just posterior to the capsulorhexis for maximum visualization of the capsule anteriorly and posteriorly. The better the depth of field of the microscope, the better your visualization. A spray of faint radial lines interrupting the red reflex may be the earliest indication of an inadvertently grasped posterior capsule. In such a case, immediately release aspiration and vacuum and kick the reflux button on the foot pedal.
CORTICAL I/A SPECIFICS
Gently strip cortex in an anterior-to-posterior direction while avoiding aspiration until after the segment is clear. Large numbers of persistent, fine cortical fibers often remain when cortex is not properly stripped. Purchase and hold a generous amount of the anterior cortical leaflet near the capsulorhexis by means of carefully controlled aspiration and vacuum, then strip the largest possible sheet of cortex to reduce fragmentation. A straight I/A tip may offer the greatest freedom of rotation for grasping cortex.
Whenever possible, remove subincisional cortex early. The remaining cortex will provide some support for the capsular bag while you enlarge the incision and reach downward into the subincisional zone.
A compromised capsule or zonules require a different cortical cleanup strategy. Avoid traction near the area of compromise. Never strip cortex radially from weak zonules or a capsular rent. Instead, start away from and move toward the defect. If you note that the zonules are compromised, move the I/A instrument toward and tangential to the area of zonular weakness. Support the inside of the equatorial bag with a curved instrument in your opposite hand or consider using capsular/iris hooks, a capsular tension ring, or the lens implant's haptics for additional support. When required, manual I/A with a 27-gauge cannula (on a 3-mL syringe with no filter) under viscoelastic may be safest.
Consider polishing the capsule directly. Sweep the 0.3-mm aspiration port across the posterior capsule, face down, on low aspiration and vacuum to thoroughly clean residual lens material and free cortical wisps. Fine cortical threads will release the posterior capsule and extend from the equatorial bag, where you may grasp them against the anterior capsule's lip for removal.
Occasionally, you may wish to place the IOL in the capsular bag despite the presence of residual cortical fragments. The IOL's optic serves as a barrier between the I/A tip and a dangerously undulating posterior capsule. Also, the lens' haptics can provide some zonular support, but you can rotate them away from the cortex being removed so as not to bind it. The presence of the IOL and the viscoelastic used to support the bag during the lens' implantation will aid in the manual aspiration of tenacious subincisional cortex with a J-shaped, 27-gauge cannula.
Brief, pulsating jets of BSS through a 30-gauge cannula identify and free lingering, wispy cortical fibers. A jet directed behind the IOL's optic and into the bag's fornix will displace viscoelastic, hydropolish remaining lens cortical cells, and free wispy cortical segments from the fornix for removal. The small aperture of the 30-gauge cannula may enable you to grasp the smallest remaining cortical threads more effectively.
The long-term health of the eye depends on the complete, careful extraction of lens cortex. Mind the hints that the eye gives to you during all phases of the cataract procedure. The surgeon who maintains a back-to-the-basics approach will likely go home happy.
Gerald J. Roper, MD, is in private practice in Batesville, Indiana. Dr. Roper may be reached at (812) 934-9400; email@example.com.