Before the era of refractive cataract surgery, refractive misses weren’t much of a concern says Robert J. Weinstock, MD, of The Eye Institute of West Florida. “We didn’t promise spectacle independence, like we do today, so if there were refractive errors after cataract surgery we didn’t worry as much,” he explains. “Back then, if there was a significant refractive miss or if the IOL dislocated, requiring an IOL exchange, it felt like a huge failure. The idea of going back into the eye to remove an IOL was a daunting, almost unimaginable task. It was something we tried to avoid at all costs, given how high the stakes seemed. It’s remarkable how much the landscape has changed with the advent of refractive cataract surgery.

Figure 1. Several cuts are made in the IOL to facilitate removal during a lens exchange procedure.

“As we began to focus more on refractive outcomes and offered patients the possibility of being free from glasses, there was an increasing awareness that, despite improvements in technology, refractive misses would still occur,” he continues. “Over the last 20 years, we’ve seen significant advancements in IOL power formulas, optical biometry devices like the Lenstar and IOLMaster, and corneal topography tools such as the Pentacam, Cassini and Galilei, which help with accurate keratometry and total corneal power readings. Additionally, intraoperative devices like ORA have allowed us to make real-time adjustments during surgery, improving our ability to reach the target refraction. The Light Adjustable Lens is also an amazing technology. But with the promise of spectacle independence, patients have higher expectations, and every day surgeons deal with patients who are either slightly off target or dissatisfied with their outcome, requiring some form of refractive intervention. This is especially true with premium multifocal IOLs, where precision is paramount, as well as with monovision targeting.”

Certain patient subgroups are also at higher risk for experiencing a refractive miss. “The highest-risk group includes patients who have had previous corneal refractive surgery, such as LASIK, PRK or RK,” says Neda Shamie, MD, of Maloney-Shamie-Hura Vision Institute in Los Angeles. “Patients with very high myopia or hyperopia—those at the extremes of refractive error—also face an increased risk. Additionally, individuals with irregular corneas, keratoconus, or dry eyes are more likely to experience a refractive surprise. Essentially, any patient whose keratometry isn’t optimized during measurements could potentially have an unexpected refractive outcome.”

Here, veteran surgeons take us through the management decision process for residual refractive errors and discuss the factors that help them determine the most appropriate approach.

Investigate the Cause

Though most refractive surprises are mild, even small deviations from target can cause visual symptoms for patients. Experts say it’s important to take a step back and consider what led to the error. “The success of multifocal and extended range lenses is highly dependent on achieving the target refraction,” Dr. Shamie says. “The first step in addressing suboptimal postop vision is to rule out common problems such as ocular surface disease or residual refractive error. Less common concerns, which tend to occur after the acute postoperative period, could include cystoid macular edema, posterior capsular opacity and IOL malposition. In the event that the suboptimal uncorrected vision is due to a refractive miss, the manifest refraction should correct the patient’s vision to 20/20 or to the expected visual potential.

“Investigating the cause of the miss involves looking at the preoperative measurements such as topography, ocular surface health and biometry,” she continues. “One question is whether the data inputted for determining the IOL power was in error or not ideally captured. I also check the postoperative topography and corneal measurements to compare with what I obtained preoperatively. If the two aren’t consistent, I’d evaluate the discrepancy. Reasons for a shift in keratometry may include dry eye, epithelial basement dystrophy, corneal edema, a gaping limbal relaxing incision or incorrectly placed relaxing incision. The IOL position or orientation is also an important factor, especially in the case of toric IOLs. And of course, the IOL power needs to be checked to be sure an error didn’t occur in selecting the IOL. 

Figure 2. The IOL is explanted through the incision.

“The options at this point are: Do nothing (i.e., have the patient wear glasses or contact lenses), perform a refractive surgical procedure (such as a limbal relaxing incision, LASIK or PRK) or opt for a lens exchange,” explains Dr. Shamie. “A lens exchange may be necessary for more significant refractive misses, especially in cases where corneal-based procedures may be contraindicated, such as with keratoconus or other corneal diseases. In extreme cases, a piggyback lens may be required if the refractive miss is too large to correct with standard lens powers.”

Before deciding whether to perform an IOL exchange, laser correction or any other procedure, experts say it’s crucial to optimize the ocular surface since a refractive miss can sometimes be due to poor ocular surface conditions. “Dry-eye disease can alter biometry and lead to refractive errors,” explains Audrey Talley Rostov, MD, of Seattle. “If you don’t optimize the ocular surface preoperatively, you might end up off by a half diopter or even a full diopter. So, make sure the ocular surface is in good shape before proceeding. Once that’s addressed, you can decide on the best course of action. Generally speaking, if the residual error is greater than one diopter, I’ll do an IOL exchange; if it’s less, then I’ll perform LASIK or PRK. It also comes down to comfort with procedures like IOL exchange or whether you have access to an excimer laser for touch-ups.”

Deciding Among Strategies

In cataract and refractive surgery, managing refractive misses requires a range of techniques. “Every cataract and refractive surgeon needs to be proficient in offering solutions such as IOL exchanges, PRK, LASIK and piggyback IOLs,” Dr. Weinstock says. “These strategies are essential for managing patients whose results aren’t exactly what was intended during their initial surgery. There’s no one-size-fits-all solution, and the approach is evolving. For example, four to five years ago, if a patient was off target, the common strategy was to let the eye heal for two to three months, perform a YAG capsulotomy and then wait for stability before considering PRK. Over time, LASIK has become a more popular option instead of PRK because of its faster recovery. These days, however, many surgeons are more comfortable with performing an IOL exchange even for small refractive errors, such as a half-diopter or one-diopter error.” 

Experts say the choice of strategy depends on several factors: 

• Patient preferences. Patient preferences play a crucial role in deciding the management approach. Some patients prefer to avoid a second surgery and would rather wait for a few months and opt for a surface ablation. Others, however, might want a more immediate fix and are open to an IOL exchange. “It’s important to discuss these options with patients, as well as the possibility that some may adapt well to a bit of residual refractive error, particularly in cases where one eye is a little myopic or slightly undercorrected, creating a ‘mini-monovision’ effect,” says Dr. Weinstock. “Explaining this to patients upfront can sometimes make them more comfortable with a less-than-perfect result and prevent unnecessary second surgeries.”

• Amount of residual refractive error. “In general, I prefer an IOL exchange if a patient is post-cataract surgery and there’s a refractive miss greater than one diopter,” Dr. Rostov says. “If the miss is less than a diopter, I’d typically go for a laser vision correction procedure like LASIK or PRK.” 

Dr. Weinstock agrees. He adds, “If the patient’s prescription is close to plano but with residual astigmatism, a corneal arcuate incision performed manually or with a femtosecond laser can be an effective way to correct lower levels of astigmatism without going back into the eye or performing PRK/LASIK. This is especially useful for patients with multifocal IOLs who have only mild refractive errors, primarily astigmatism, and need a bit of refinement for better vision.

“When the spheroequivalent deviates significantly from plano, that’s when we need to carefully weigh our options: Should we wait and do a YAG capsulotomy and then proceed with PRK/LASIK, or should we opt for an IOL exchange? Several factors play a role here: how far out from surgery the patient is; whether they’ve already undergone a YAG capsulotomy; and whether they have myopia or hyperopia. For example, myopic eyes tend to respond better to PRK/LASIK, whereas hyperopic eyes are trickier to treat with excimer lasers, often leading us to consider IOL exchange or piggyback IOLs.”

• State of the posterior capsule. “If the posterior capsule is intact—usually within a year or so post-surgery—I would go for an IOL exchange for a larger refractive miss,” says Dr. Rostov. “If it’s been a bit longer, say a few years, and there’s an open capsule, I may lean more toward LASIK or PRK instead.” 

• Time since surgery. While IOL exchanges can generally be performed up to six months or even longer post-surgery, the timing is critical. “The degree of capsule contraction and scarring affects the difficulty of removing the IOL,” Dr. Weinstock points out. “You want to avoid performing a posterior capsulotomy with a YAG laser if there’s a chance you’ll need to perform an IOL exchange later, as this can make the process of removing the IOL more complicated. Once a YAG capsulotomy is performed, an IOL exchange would likely require an anterior vitrectomy, which can increase complication rates and is a more complex procedure.

“There are cases where, even after a year or more, you can safely remove an IOL if the capsule is still relatively clear and there’s minimal traction or haze,” he continues. “But in other cases, particularly with recently placed IOLs or if there’s significant capsule contraction, removing the IOL might be more challenging. In such cases, a piggyback IOL, PRK or LASIK might be a better option.”

John Vukich, MD, of Summit Eye Care of Wisconsin in Wauwatosa, says that when it comes to addressing a refractive miss, it’s also a good idea to consider the type of implant initially used. “In general, we’re dealing with premium lenses,” he says. “Patients have paid out of pocket for a specific refractive outcome, and they expect us to do our best to meet that. Now, nothing is perfect, and it’s not uncommon to have a refractive miss. But usually, it comes down to patient satisfaction. You can be off by as little as half a diopter or three-quarters of a diopter, especially with an astigmatic miss, and that can leave a patient with a multifocal lens dissatisfied. The fix can be relatively straightforward—if you’re comfortable with limbal relaxing incisions, that’s the quick way to go, assuming you’ve got an acceptable spherical equivalent, ideally plano.

“If it’s a refractive miss with a routine single-vision lens—say, a patient who has a specific refractive goal in mind but elected not to use a premium methodology—the surgeon’s obligation to take further action is less clear,” he continues. “We need to make it clear to patients up front that while we’ll do our best to achieve the target outcome, there’s nothing better than being 20 years old and born with perfect vision. We can’t promise that with a standard lens. However, we do believe it’s very likely we’ll make things better, or we wouldn’t recommend surgery in the first place. But we also have to be realistic about the limitations.”

Dr. Vukich adds that it’s also key to consider the economics of a treatment. “You want to make sure your patient is happy, of course, and that they get the result they’re hoping for—your reputation as a refractive surgeon—since nearly all cataract surgeons are also refractive surgeons—depends on delivering good outcomes. But, a second procedure comes with its own costs: the facility fee; the new implant; any laser fees if you’re using an outside clinic.”

Figure 3. The new lens is inserted into the eye. (View the video below)

Corneal Treatments

Corneal treatments are good for small corrections, but they have limitations, says Dr. Vukich. “These patients are usually older—typically 50 or older—and may have dry-eye issues,” he notes. “Performing high-quality LASIK or PRK on a mature patient is possible, but it’s often more challenging. You also need access to an excimer laser, which not all cataract surgeons have in their own practices or readily available to them, or they may not have much experience with corneal refractive surgery. So, while corneal treatments are a viable option if you have access to a laser, a lot depends on the patient’s ocular surface health and your own comfort doing laser treatments.

Lens Exchange

“One often underutilized option is IOL exchange,” Dr. Vukich says. “You’ll usually know within a week if there’s been a refractive miss. At that point, you can determine if the patient can adapt to it or if an exchange is necessary. If it’s clear the patient won’t be satisfied, removing and exchanging the lens is an increasingly common and relatively straightforward procedure. The timing matters, though. If you do the exchange within six months to a year, ideally sooner, you can preserve the capsular bag, which makes the procedure technically easier. An exchange is never ‘easy,’ but doing it sooner helps. Then, knowing what you attempted versus what you achieved and the effective lens position, you can calculate the needed implant power and end up with a pretty good, predictable refractive outcome.”  

This option comes with a few caveats. “If the patient isn’t happy with their vision and you see some capsular opacity, think carefully before performing a YAG capsulotomy. While it might improve vision a little, it also complicates an IOL exchange. Once you do a YAG, the risk/benefit ratio for an exchange skews heavily against further intraocular surgery. So, I always explain to patients that if we go the YAG route, it’s a one-way decision. Afterward, an exchange is much more difficult.” 

It’s critical to understand why you’re exchanging the IOL, Dr. Rostov points out. “Is the patient unhappy with the quantity or quality of vision? For example, if it’s a large refractive miss, you need to look at why it happened in the first place,” she says. “Review the original biometry data to see if there was an incorrect K-reading or some other error in the initial calculations. It’s also important to ensure that you didn’t mistakenly use data from the wrong eye. If you have access to the preoperative biometry, compare it to your current measurements to look for discrepancies. If the preop data isn’t available, you can still try to figure out the original IOL model and use your current measurements to estimate what would have been expected.

“For patients who report quality issues with their vision—such as glare, halos, or dysphotopsia, especially with multifocal IOLs—have a candid discussion about expectations,” she continues. “In cases where they’re struggling with dysphotopsia, I might recommend an IOL exchange for an LAL. The LAL is a great option because you can place it either in the sulcus with optic capture or in the capsule bag. Even if the posterior capsule is open, you can still achieve a good range of vision with an EDOF lens.”

When deciding between a lens exchange and a corneal-based refractive procedure, the nature and size of the refractive miss plays a crucial role. “For smaller refractive errors, corneal-based procedures tend to be more precise—assuming the cornea is healthy and suitable for such interventions,” Dr. Shamie says. “This means the cornea isn’t affected by conditions like forme fruste keratoconus, severe dry eye or scarring.

“Lens exchange, on the other hand, can be less predictable for smaller corrections, as it’s influenced by the effective lens position and potential issues with toric alignment,” she continues. “This method also carries risks related to wound healing and overall predictability. Therefore, when the refractive error is minor, and the cornea is healthy, corneal-based procedures like LASIK or PRK tend to offer a more precise correction. For larger refractive misses, or if the cornea is compromised, a lens exchange may be the better option. This is especially true for hyperopic corrections, which are generally less predictable with corneal-based surgery compared to myopic corrections.”

The Piggyback IOL

The choice of piggyback IOL depends on the amount of residual refractive error. “I only use those in the most extreme cases,” says Dr. Vukich. “There are risks, including optic capture and iris chafing, as well as any number of other issues that could arise with a second implant in the eye. Though a second implant can improve optical outcomes, I reserve piggybacks for only the most extreme changes or rescues.”

“I don’t use a piggyback approach often, but for very large refractive misses, particularly with high myopia, it can be the best option,” Dr. Rostov says. “In such cases, I might opt for a piggyback ICL instead of a standard three-piece piggyback IOL. If choosing a standard three-piece IOL for piggyback in the sulcus, be sure that the piggyback IOL is available in low powers, as that’s usually what’s needed. I had a patient with a significant refractive error, something like -6 or -8 diopters, and for them, a piggyback ICL was the best solution.

“For piggyback IOLs, it’s crucial to consider all the same factors as a lens exchange—residual refractive error, timing and the status of the capsule,” Dr. Rostov says. “For piggyback IOLs placed in the sulcus, I often recommend a three-piece lens like the LI61AO, which is ideal for sulcus implantation. Make sure to choose an IOL specifically designed for the sulcus if you’re placing it there. For extremely high myopic refractive misses, another option to consider is an ICL. While the ICL is an excellent solution, it’s a more expensive option, and that cost will be passed on to the patient, so you’ll need to discuss that with them.”

Lens Rotation Tips

In some cases, fixing the refractive surprise is a simple matter of recentering the toric lens. “When a patient has a toric IOL, you must first ensure the spherical equivalent of the refractive error is aligned with your target,” says Dr. Shamie. “Any shift in the alignment of the toric IOL postoperatively will reduce the effectiveness of the toricity, leading to uncorrected astigmatism. You might still end up with a near-plano spherical equivalent, but the astigmatism won’t be fully addressed. This is often a clue that the toric lens has rotated.

“To assess this, dilate the pupil and examine the axis marks of the IOL,” she continues. “Compare them to your preoperative plan to check for misalignment. Using tools like AstigmatismFix.com, you can input the numbers and determine whether rotating the lens will bring the patient’s refraction back on target. Rotating the lens is a less invasive option compared to corneal-based procedures, and in many cases, it can correct the refractive error without additional surgery. However, if rotating the lens doesn’t yield the desired correction, or if there’s concern about compromising the capsule (e.g., after a YAG capsulotomy or prolonged IOL implantation), you may opt for a corneal-based enhancement such as a limbal relaxing incision or LASIK/PRK.”

Reducing Refractive Surprises

“One particularly promising tool in reducing refractive surprises is the LAL, which has revolutionized the way we manage patients at higher risk for refractive miss,” Dr. Shamie says. “In our practice, we rarely encounter refractive surprises anymore, largely because we offer the LAL to patients with a higher likelihood of postoperative refractive issues—such as those who’ve had corneal refractive surgery in the past. More than 98 percent of patients in our practice who undergo light adjustments achieve their target refraction within 0.5 diopters. This technology has proven particularly beneficial for post-RK, post-LASIK, post-PRK, keratoconus patients (with central bow-tie astigmatism) and even those with high myopia or hyperopia.

Figure 4. Using the light delivery device, the power of a Light Adjustable Lens can be fine-tuned postoperatively in a series of adjustment and lock-in visits.

“If you don’t have access to the LAL, the key to minimizing refractive surprises is ensuring you have the most accurate preoperative measurements,” she continues. “This means having a healthy ocular surface, a relatively normal corneal topography and using the best available nomograms and formulas to guide your lens selection. Additionally, intraoperative technologies like intraoperative aberrometry and image guidance systems can help verify the accuracy of the lens power and ensure the toric IOL is positioned correctly. With the wide range of tools now available, the risk of refractive surprises can be significantly reduced.”

Dr. Vukich notes that while the LAL is “a huge comfort for many patients since they can test out their vision and live with the result for a while before adjusting and deciding whether it meets their goals, there’s also extra effort involved on the patient’s part with return visits and appointments. It’s a great option but it also comes with added time and expense.”

Final Thoughts

“The field of cataract and refractive surgery is dynamic, and managing refractive misses requires both technical expertise and patient-centered decision-making,” Dr. Weinstock says. “Always assess the situation thoroughly, considering the timing, the patient’s goals and the specific nature of the refractive error. And never forget to factor in the patient’s preferences—sometimes, with the right communication and realistic expectations, you can avoid additional interventions and still achieve great results.”