The precision and accuracy of the femtosecond laser in cataract surgery simplifies the creation of the capsulotomy. The laser’s imaging system allows surgeons to manage the location and size of the capsulotomy reliably with each case. Free-floating capsulotomies have been reported in 97% of cases.1 Despite these advantages, caution should be exercised to avoid potential pitfalls that could ruin your day. You don’t want to get stuck missing an uncut capsule bridge because you were unable to see it. Perhaps even worse is not realizing the capsule is scrolled up and trapped in the angle by viscoelastic … until the next day.
BENEFITS OF THE FEMTOSECOND LASER
Using a femtosecond laser to cut the capsule has many advantages that contribute to the precision and accuracy of laser cataract surgery. Imaging can allow the surgeon to center the capsulotomy on the undilated pupil, the visual axis, or the geometric pupil center. In addition to positioning, the size of the capsulotomy can be varied to facilitate nucleus removal, depending on the surgeon’s preferred technique.
Refractive goals are more likely to be achieved if capsulotomy creation is consistent. Many surgeons believe that a consistently sized and shaped capsulotomy will yield lower risk during nucleus removal. When the capsulotomy is always the same size and shape, the surgeon can grow accustomed to knowing the exact location of the anterior capsule edge during nucleus removal. This consistency can help to avoid causing a rent with the phaco tip. The surgeon can also pull quadrants of nucleus out of the bag with potentially less chance of tearing the anterior capsule. Even if the pupil comes down, it can be easier to work “behind the iris curtain” once the surgeon is comfortable with the capsule size and the impact the laser cuts have on nucleus removal.
Of course, all of these upsides need a few potential downsides to keep us surgeons in check.
KEEPING THE CAPSULE FREE
When surgeons learn that 97% of capsulotomies are free-floating, often what we absorb is that 3% are not. We worry about how to identify and handle the small percentage that can become problematic. With some simple techniques and attention to detail, the surgeon’s concerns can be put at ease.
I have found that it is better to change the vector forces on the capsule from horizontal to vertical traction in laser-cut capsules. After the eye is filled with viscoelastic, the cannula tip can be used to tap down on the capsule to identify tags, adhesions of less than 1 mm, bridges, and adhesions of more than 1 mm. For example, I tap down on the cut anterior capsule 1 mm central toward the visual axis. The capsule will move centrally; however, if there is an adhesion, striae will be seen extending across the assumed cut capsule to the peripheral anterior capsule. If the adhesion is a tag, I push down with the cannula to break the tag. I have found that applying downward force 1 mm central to the tag but just superior to its location allows ease of separation.
When striae expose an adhesion of more than 1 mm, I proceed around the capsule, applying downward pressure to confirm that the other quadrants are free. I then use Utrata capsular forceps to rip across the bridge. I always attempt to tear the capsule larger than the intended laser cut to avoid a partially cut capsule remaining as part of the capsular opening.
TAKING CARE OF THE CUT CAPSULE
Unfortunately, I have been humbled by not keeping watch on the cut piece of capsule. I’ve been on guard ever since having to explain to a patient the day after surgery that I needed to go back into the OR to remove a 5-mm scrolled-up capsule piece left in the inferior angle. I haven’t had to have that conversation again, but I think about it with each subsequent case.
In creating the capsulotomy, the laser travels through the aqueous, through the capsule, and into the cortex. The cortex often becomes white, which can mask visualization of the capsule. The surgeon can easily visualize the cut cortex and mistake this as cut capsule. Just recognizing the concept that these two layers are cut by the laser brings you 95% closer to avoiding this problem. Three more considerations for avoiding a retained cut capsule are below.
No. 1 Fill the anterior chamber
First, carefully inject viscoelastic to fill the anterior chamber. I always first position the cannula distal to the cut capsule and then fill the eye by moving toward the entrance incision, taking care to keep the capsule flat in its native position and not blow it into the angle.
No. 2 Move the cannula under the capsule
After tapping to confirm that the capsule is free, I move the cannula under the capsule and lift it up toward the cornea. This maneuver allows me to observe the exact location of the cut capsular button in the anterior chamber. Next, I burp the wound and watch the capsular button exit the eye or immediately aspirate it with my phaco tip.
No. 3 Sweep the angle
Near the end of the surgery, carefully sweep the angle after IOL insertion while aspirating viscoelastic, especially if a dispersive agent was used. During this step, I hunt for any possible retained capsular remnants. Just recently, I unexpectedly caught a retained cut capsule during this step. I took the time to fish for the capsule, and, to this day, I am happy to report that I have not had another “capsule conversation” with a patient.
A laser-cut capsule is an advantage of laser cataract surgery. Becoming mindful of minor pitfalls related to the cut capsule can have a big impact on the surgeon’s comfort with the procedure. Be familiar with techniques to manage adhesions, and do not let a capsule be “the one that got away.” These are easy starting points to build confidence.
1. Nagy ZZ, Takács AI, Filkorn T, et al. Complications of femtosecond laser-assisted cataract surgery. J Cataract Refract Surg. 2014;40:20-28.