The first postoperative clinic visit on the day after cataract surgery is typically a pleasure; patients are so amazed to have great visual acuity, improved contrast and vivid colors that they beam with joy. Even after tens of thousands of such procedures, I never tire of seeing it. But, rarely, we are confronted with a surprise at the postoperative visit: a retained lens fragment in the anterior chamber.
When we break up the cataract during phaco surgery, we create many tiny pieces that are then aspirated from the eye. The move to small incisions has made cataract surgery less invasive, but it has also necessitated breaking the nucleus into smaller fragments to easily phaco-aspirate. Occasionally, even if the surgery goes well and there are no intraoperative complications, there can be a retained cataract piece, either cortex or nucleus, that is not discovered until the postoperative period.
In many cases, the retained lens fragments are easily spotted. Sometimes, however, the fragment is hidden behind the iris and does not present until weeks or months after surgery. In some cases, a lens fragment can be hidden in plain sight and just obscured by focal corneal edema. When we change the lighting at the slit-lamp microscope and adjust our viewing angle, we can see that there is a retained cataract fragment at the inferior angle (Figure 1).
This small piece of the cataract can cause inflammation and focal corneal edema.
A light-colored iris along with corneal arcus senilis makes cataract fragments difficult to see if they are pushed into the angle. Filling the eye with viscoelastic can entrap small cataract pieces in the angle. Novice surgeons seem to have a higher risk of retained lens fragments — each photo in this article is from our resident clinic over the past few years.
Patients with small pupils are also at a higher risk for retained lens material, which can hide behind the iris. Nuclear chips can become stuck between the anterior lens capsule and the back of the iris, whereas cortex can be inadvertently left attached to the capsule due to poor visibility. Within a day or two, these cortical remnants swell due to exposure to the aqueous and then become dislodged and drift into the visual axis. Using a second instrument, such as a chopper, at the time of surgery can reveal these hidden lens pieces (Figure 2).
PREVENTING LENS FRAGMENTS
Besides lifting the iris in a smaller pupil, we can also use the fluidics of our phaco machine to help wash out any retained lens material. For the final setting on your machine, often labeled as “viscoelastic removal,” using a high flow rate of at least 40 cc to 60 cc per minute to create fluidic currents can help bring any pieces to the center of the anterior chamber. Another preventive measure is to remove viscoelastic from under the IOL optic, from under the iris and from the angle of the eye. Sometimes, you will be surprised by a hidden cataract fragment that had become dislodged and then revealed itself.
At the end of the case, after hydrating and sealing the incisions, the balanced salt solution on a 27-g cannula can be used to sweep the angle of the eye to remove any retained viscoelastic or cataract pieces. The amount of retained viscoelastic can be surprising, and it accounts for the elevated IOPs that are sometimes seen right after surgery. Occasionally, this procedure reveals hidden viscoelastic as well as cataract pieces.
DETERMINING A PLAN
For a retained cataract fragment, we need to first determine if it is a piece of nucleus or a tuft of cortex. Nuclear pieces are denser and may not dissolve in the inflammatory cascade, whereas cortical fragments tend to be wispy and cotton-like. In addition, the cortex will swell to double or triple the size when exposed to the aqueous.
We should also assess the size of the retained lens fragment and note any sequelae that are causing conditions, such as persistent inflammation, corneal edema, corneal endothelial cell loss, increased IOP and blockage of the visual axis.
Our treatment options are the following:
- Return to the OR. The quickest and most definitive treatment is a return to the OR where, under sterile conditions, we can go back inside the eye and remove the piece. We can use the original incision for this procedure, which takes just a minute or two, but it is associated with additional costs due to use of the operating room. While it is possible to flush out a piece of lens material in a clinic’s procedure room, this may not have the same level of sterility as a proper OR. During the procedure to flush out the retained lens fragment, the opening of the main incision can cause flattening of the anterior chamber and a shift in IOL position, both of which we would need to address. If the retained lens fragment is a nuclear chip or a larger piece of cortex, this is likely the best approach.
- YAG laser disruption. If the retained lens fragment is a minor piece of cortex, we can use the YAG laser to break it into smaller pieces (if, though, the retained piece is nuclear, it is better to return to the OR). This increases the surface area-to-volume ratio and allows the lens material to dissolve faster — the same principle behind crushed ice melting faster than a large ice cube. Keep in mind that this will temporarily cause a high IOP because small pieces of cortex are pushed into the trabecular meshwork, so topical IOP-lowering medications and oral acetazolamide may be required for a few days. This technique works surprisingly well and can give resolution in a week or two.
- Observation. For a small piece of retained lens cortex, observation with treatment of the inflammation and monitoring of the IOP may be a reasonable approach. Retained lens fragments cause inflammation, which slowly dissolves the lens material over the course of weeks to months. If there is a nuclear piece or a large cortical fragment that obstructs the vision, observation is not the best option. With observation, the lens fragment may cause focal corneal endothelial cell loss, corneal edema, iris synechiae and an elevated IOP.
With these techniques, we can do a good job of preventing and treating most cases of retained lens fragments. For experienced surgeons, the rate is much less than 1% of cases, and even in these rare cases in which we have retained cortical or nuclear cataract pieces (Figure 3), we can resolve the issue and the patients will still achieve excellent visual results. OM
For lens fragment videos, visit CataractCoach.com .