Article

How and why to explant an IOL

Patient education and satisfaction are vital to the explant process.

Reentering the eye after cataract surgery is not ideal. Although most cataract and refractive surgeries are successful,1 explantation is the best option in some circumstances.

The decision to go back in the eye often depends largely on patient satisfaction. In some cases, removal or exchange of the lens is a medical need. Otherwise, a surgeon does not have to reenter the eye if the patient is happy with his or her results, even if the results are not ideal. Patient education sets proper expectations of possible outcomes preoperatively and fully informs patients of their circumstances postoperatively (see “Avoidance is always best,” page 62).

When a patient is still dissatisfied or there is an unusual circumstance, here is my approach to IOL explantation.

REASONS TO EXPLANT AN IOL

  1. The IOL was implanted in an unintended place. Rarely, one can find a single-piece hydrophobic IOL in the sulcus or just one haptic in the sulcus. This can induce uveitis-glaucoma-hyphema syndrome, causing chronic inflammation, glaucoma and refractive error.
  2. The lens shifts. In certain circumstances, as the capsule naturally contracts, it can induce some tilting of the IOL or anterior vaulting of the lens, which in turn can lead to refractive error issues. In some cases, early YAG capsulotomy can help reverse the tractional forces and realign the IOL. In some cases, even after YAG capsulotomy, the patient still has significant aberrations from tilting and may need a lens exchange.
  3. Multifocal lens patients with complaints of glare and halos or quality of vision. Optimize the surface of the eye before you assume the lens is the cause of the dysphotopsia. Often, aggressive ocular surface disease (OSD) treatments pre- and postoperatively can help decrease the symptoms. Also, patients can neuroadapt over time. We educate the patient and wait a few months before we decide if the lens should be removed.
  4. The IOL may opacify. Over time, opacifications within the lens can occur, depending on the material. In most of these cases, patients do not appreciate the impact in daily life, but an explant is needed in a small subset of patients.
  5. You miscalculated the IOL power. Research shows that incorrect corneal power determination is the most frequent reason for incorrect IOL power implantation, followed by error in axial length (AL) measurement and inserting the wrong IOL.2 Researchers concluded the pre-exchange refraction can be used theoretically to calculate the IOL power for exchange. Another common reason for miscalculations is previous refractive surgery. I use the Barrett True K Formula to adjust for the previous corneal work. OSD is another common reason for lack of consistency between various technologies as well as variations within a specific test.

WHAT ARE YOUR OPTIONS?

First, talk to patients and let them know the risks of a surgical solution. Often, once patients are educated and understand why they are experiencing their symptoms, they are fine with non-surgical options, such as contacts, glasses or even observation. Sometimes, patients just need you to listen to them. Once you give them a chance to express themselves, they are fine leaving things alone.

If one of those options is not acceptable to the patients, then you can consider these:

  1. Perform refractive surgery: In some cases, PRK, LASIK, or small incision lenticule extraction (SMILE) are options. If the cause of the dissatisfaction is a refractive error and the patient has a healthy cornea and is an otherwise good candidate, refractive surgery is a safe and ideal option.
  2. Piggy back IOL: If the original IOL was compatible with the patient’s expectations but the IOL power was off, then inserting an IOL anterior to the first IOL is an option, such as a piggy-back IOL. This avoids the need to remove an IOL and is usually a safer and quicker procedure than an IOL exchange.
  3. Replace the lens: When explanting due to a dislocated or malpositioned IOL, in the context of a broken capsule with vitreous loss, you may need to limit your IOL to a lens in the sulcus, anterior chamber or a sewn-in IOL depending on the anatomy. Often, you can still implant a multifocal lens in the bag if the IOL is being exchanged due to IOL calculation issues. A sulcus lens is preferred if the patient is post-YAG capsulotomy or has a weak posterior capsule. I prefer to exchange the lens as soon as possible, before significant capsular fibrosis has occurred. YAG capsulotomy can help glare and halos and can potentially reverse an IOL malposition in the setting of an accommodating lens. I recommend holding off on a YAG capsulotomy since an exchange is harder to perform without an intact posterior capsule.

CASE STUDY

A 64-year-old woman with a history of cataracts underwent surgery with an implantation of a Tecnis Multifocal IOL (Johnson & Johnson Vision) in her left eye. She was very happy with the first eye and therefore underwent surgery two weeks later in the right eye with the same type of IOL. The patient stated she was hit in the right eye many years ago, but no observable evidence of zonular instability or weakness was identified. She underwent uneventful cataract extraction in the right eye. Postoperative day one vision was 20/25 J2. One week later, her vision dropped to 20/60 with evidence of a nasal decentered lens. There was evidence of a small posterior capsular tear on the postoperative exam. She was informed the lens had shifted, causing the vision changes. A decision was made to pursue the IOL to reposition or, if need be, exchange the lens with a three-piece multifocal in the sulcus if possible. As a last resort, a standard monofocal lens would be implanted depending on intraoperative stability. Due to the posterior capsular tear, the patient underwent a lens exchange with a three-piece multifocal IOL replacement. The optical biometer was used to help ensure centration of the IOL. Postoperative day one visual acuity was 20/20 J1, and the patient was very happy.

YOU NEED TO EXPLANT AN IOL. NOW WHAT?

  1. Be prepared for unforeseen circumstances. Know your comfort level before you go in. If you don’t feel comfortable when you look at the eye and suspect that the case may be complex, you may need to refer the patient out. For example, a patient may need a concomitant vitrectomy with an anterior chamber (AC) maintainer in the context of a broken capsule with no capsular support and vitreous prolapse; this patient might be better off with a sewn-in IOL rather than an AC IOL. As we get closer to the day of the exchange, I repeat many of the same tests as the primary surgery including another optical biometry scan, specular microscope scan and ray-tracing aberrometer/topographer scan to determine if the IOL needs to be rotated or exchanged.
  2. Keep extra tools on hand. Have various tools available in the OR just in case the surgery becomes more complicated. For instance, I will make sure I have microscissors and microforceps, lens cutters, various viscoelastics (including dispersives and cohesives), capsular tension rings of varying sizes and a vitrectomy set up and ready to go.
  3. My surgical protocol.
    A. Depending on how complicated I think the case may be, I consider topical, retrobulbar block or even a general anesthetic. General anesthesia can help to reduce posterior pressure and therefore decrease chances of further vitreous prolapse.
    B. A technique, which I learned from my father, Kanwar Singh, MD, is to place two 6-0 silk sutures superiorly and inferiorly, through the episclera around 3-4 mm behind the limbus, to clamp them to the drape. This allows me to keep the eye immobilized and centered throughout, even in a topical case.
    C. Depending on the previous incision placement and time from surgery, I may go through the previous corneal wound or adjacent to it. I also recommend considering two paracenteses on each side to allow for access to the haptics of the IOL.
    D. If I use topical anesthesia, I then inject intracameral 1% PF lidocaine. I then fill the AC with dispersive viscoelastic and use the viscoelastic for viscodissection of the IOL at the haptic-optic junction, since there is usually an open area between the capsule and IOL. I use the cannula to lift the IOL and determine the amount of fibrosis and tension on the IOL.
    E. If needed, I use a 30-gauge needle to further dissect the anterior capsule edge from the IOL. I am careful not to overinflate the bag, which can cause the iris to prolapse out of the wound and also further open a previously opened posterior capsule.
    F. Once I free the IOL, I use a cannula to move the IOL side to side to make sure there is no tension on the capsule. If I see it move within the bag, then I feel comfortable prolapsing it into the anterior chamber. I try to lift the IOL rather than rotate it, since rotating can cause additional stress on the zonules. I may use a lens cutter and cut the haptics from the optic as close to the peripheral side of the haptic as possible rather than ripping the zonules from continuously pulling the haptics.
    G. Once the optic is in the AC, I can cut the IOL in half, or fold it, then remove it. More commonly, surgeons choose to cut the implant 90% of the way using a microscissors. I use a second instrument to stabilize the IOL while trying to grasp it, then I keep that second instrument in place while cutting the IOL to keep it stable. I often inject some more viscoelastic over the IOL to further deepen the AC and provide more room to work.
    H. I place the new IOL in the sulcus or the bag (if there is enough support) before I cut the IOL. This provides a platform to protect vitreous from coming forward or the IOL from falling back into the vitreous. Anterior vitrectomy is commonly performed during IOL exchanges, especially in the context of an opened posterior capsule or trauma. If you have a retina colleague close by, consider having him or her scrub in and perform a core vitrectomy first.
    I. When centering the IOL, I use a digital markerless system. The system takes the images from the optical biometer and matches the scleral vessels with the live scope feed of the surgical microscope. Since the optical biometer can determine the center of the visual axis, the digital markerless system displays a “plus” sign to indicate the center of the visual axis. This can be helpful for implanting a multifocal lens or to confirm centration of a monofocal lens in the context of an irregular pupil. The optical biometer is also essential for aligning toric IOLs and helps significantly to align the new IOL. Also, intraoperative aberrometry can help confirm the IOL power when the patient is aphakic or when there is a clean bag-to-bag exchange of a posterior chamber IOL.
    J. If the posterior capsule is not sufficient to place an IOL, I often place a three-piece IOL in the sulcus with a reverse capture technique. If there is more than 270° of capsule support and there are poor zonules not amenable to a capsular tension ring or optic capture, a lens could be put in the sulcus and haptics sutured to the iris using 10-0 polypropylene in a McCannel- or Siepser-type fashion.
    K. Finally, if there is no capsule support, consider an anterior vitrectomy with a peripheral iridotomy and AC IOL, or a pars plana anterior vitrectomy and intrascleral haptic fixation, using either the Yamane or glued IOL technique. Use of triamcinolone in vitrectomy cases can help with visualizing retained vitreous in the AC.

AVOIDANCE IS ALWAYS BEST

The key to avoiding IOL explantation is conducting a thorough assessment of the patient preoperatively to ensure that IOL selection is appropriate.

  1. Educate and listen to the patient. Explain the potential adverse events and side effects related to the procedures and technologies, then let patients decide if they can live with them or not. For instance, if a patient selects a multifocal lens, ensure that he or she understands the risks of glare or halos in certain conditions. Patients should be aware of the small chance they may not be able to adapt to these technologies and that lens exchange is a small but real possibility. Also, if a patient has a history of trauma, zonular weakness or other anatomical variants, educate the patient on the condition and set proper expectations.
  2. Know your patients. For instance, if a patient suffers from dry eye, cornea aberrations, history of eye trauma or even a pterygium — conditions that may prevent an ocular surface from being pristine or predictable — this patient may not be ideal for a premium lens, such as a multifocal IOL. Conditions like dry eye that disrupt the ocular surface (including tear film) can lead to fluctuating or inaccurate measurements, so these patients are not ideal candidates for a multifocal IOL. In addition, very short or very long eyes may not be the best candidates for accommodating lenses because the lens position may not be as predictable as a normal AL eye. Create a protocol in your practice that allows you to identify deficiencies that affect certain IOLs.
  3. Make use of technology that optimizes IOL calculations. One common cause of refractive misses is the accuracy of our pre-operative IOL measurements. It is important to use optimized technology to verify the anatomy of the eye and achieve the most predictable and most accurate preoperative measurements. For instance, I use a Zeiss IOLMaster 700, the only biometer featuring both swept-source OCT and telecentric keratometry. Swept-source OCT allows for a cross-section B-scan view of the entire eye from the cornea to the retina. This ensures a correct and reproducible AL measurement, minimizing IOL miscalculations; it also helps detect out-of-the ordinary anatomical variants and macular pathologies overlooked at consultation. Telecentric keratometry allows for consistent measurement regardless of distance from the eye. Using a topographer also allows you to verify the biometer reading and identify anterior and posterior cornea, magnitude and axis of corneal astigmatism. Wavefront topography is also useful for measuring angle kappa — if the angle kappa is high, you may avoid a multifocal IOL. I use a MacuLogix AdaptDx, for its dark adaptation technology, to help evaluate the function of the retina rather than rely only on structural testing from the OCT. A decrease in function of the retina would potentially limit options for IOL selection.
  4. Use the right formula. Newer generation formulas are designed to help minimize refractive surprises. SRK/T formula, a previous gold standard, is recommended for normal to rather long eyes, whereas the Hoffer Q formula is recommended for rather short eyes. The Holladay 1 and Hoffer Q formulas are equally good for eyes with an AL between 21.00 mm and 21.49 mm, and the Holladay 1 formula seems more optimized for eyes between 23.50 mm and 25.99 mm. Fourth-generation formulas, like the Barrett, Haggis or Holladay 2, are also able to include the non-proportional relationship between the anterior chamber depth and AL and therefore seem to provide the highest accuracy over the full range of ALs. If a patient needs an IOL exchange, try to obtain the records of the first surgery. The power of the original IOL and the resultant postoperative refraction will help you better select the new IOL.

A three-piece multifocal IOL is placed in the sulcus of an irregular pupil, with the Zeiss Callisto eye system indicating the center of the visual axis.

A photo taken just prior to an IOL exchange, displaying a one-piece multifocal lens that has decentered nasally. The IOL was originally properly centered but shifted postoperatively.

CONCLUSION

Even though rates of an IOL exchange are very low — a recent study of Minnesota residents found a rate of 1.5% over 30 years3 — cataract surgeons should prepare for them.

Managing expectations is the key to a successful IOL explanation and the subsequent procedure of choice. Explain to your patients that an explant is not be the same as the primary cataract surgery noting that, because you are re-entering the eye, the anatomy has changed from removing the cataract and the outcome may not be the same.

There are many options available, but your comfort level will ultimately guide your decision. At the end of the day, there is no right or wrong way to approach these cases. Use all the tools to guide you, and do what it takes to help optimize patient satisfaction. OM

REFERENCES

  1. Serious Adverse Events After Cataract Surgery. Curr Opin Ophthalmol. 2012;23:219-225.
  2. Jin GJ, Crandall AS, Jones JJ. Intraocular lens exchange due to incorrect lens power. Ophthalmology. 2007 Mar;114:417-424.
  3. Bothun ED, Cavalcente LCB, Hodge DO, Patel SV. Population-based incidence of intraocular lens exchange in Olmsted County, Minnesota. Am J Ophthalmol. 2018;187:80-86.

About the Author