Surgeons differ as to whether zero astigmatism is a feasible—or even uniformly desirable—goal of cataract surgery. Here, experienced surgeons discuss whether, when and how to pursue zero astigmatism in the setting of cataract surgery.

Arun Gulani, MD, founding director and chief surgeon of the Gulani Vision Institute in Jacksonville, Florida, thinks that although astigmatism can be useful in select cases, surgeons should strive to eradicate it most of the time.“The attitude of the surgeon should be intolerant to astigmatism at any level. There’s no such thing as a tolerable factor over zero,” he states. “Not reaching that zero point is human, and could be an honest mistake or just arise from natural variations in healing between patients. But to not aim for it is unacceptable in this day and age.”

Dr. Gulani, who teaches about astigmatism elimination in cataract surgery in the United States and abroad, adds that a substantial part of his practice involves correction of complications and providing second opinions for patients who’ve already undergone laser vision correction or premium cataract surgeries. “Astigmatism has been the most common residual refractive error that I’ve seen that could have been corrected by the surgeon,” he says. “In recent studies, it’s been documented to be the biggest reason for dissatisfaction following successful premium cataract surgery. It’s also an element that can easily be corrected, but results in unhappy patients and disturbs patient/doctor relationships.”

“Can we approach zero? Sure, but we can’t guarantee zero,” opines Natalie A. Afshari, MD, FACS, professor of ophthalmology and chief of the division of cornea and refractive surgery at the Shiley Eye Institute, University of California, San Diego, who thinks that promising zeroastigmatism gives rise to unrealistic patient expectations.

Corneal topography (top) shows approximately 1.6 D of astigmatism. Scheimpflug imaging (bottom) shows that the simK (blue circle) agrees with the topography, but that the total corneal refractive power (red circle) measures 2.2 D of astigmatism, having accounted for the posterior corneal surface. Considering only the anterior corneal surface’s contribution to astigmatism would have resulted in at least 0.6 D of astigmatism left uncorrected. (Image courtesy Jeremy Kieval, MD.)

Like Dr. Afshari, Jeremy Kieval, MD, a partner and director of cornea, cataract and refractive surgery at Lexington Eye Associates in Massachusetts, who also serves as an instructor of ophthalmology at Harvard Medical School, says that minimizing astigmatism as much as possible is important; but he also thinks we’re too far from understanding all the potential contributing factors to completely eliminate it every time. “I think there are many factors, like dry-eye disease and age-related changes in the cornea, as well as postoperative changes and capsule contraction. Additionally, the implanted lens creates some element of tilt. All of those things will contribute just minimally—a quarter- or a half-diopter—to astigmatism. I think that to really get down to zero, there will need to be a lot more understanding in terms of corneal biomechanics, dry-eye disease treatments, basement membrane dystrophy management and lens stabilization after cataract surgery. But, all those things being said, I think that the drive towards minimal astigmatism is absolutely reasonable and achievable,” he says.

Is Astigmatism Always Bad?

Dr. Kieval adds, however, that the drive towards zero astigmatism may have a downside: forgetting those cataract patients who have successfully adapted to their astigmatism. “I’ve read articles over the years saying that zero astigmatism should be the standard of care,” he says, “but I think that’s a dangerously slippery slope when there are some elements of astigmatism that can be beneficial for patients.

“For example, you might have a patient with essentially zero sphericalequivalent and 0.75 to maybe 1.25 D of astigmatism,” Dr. Kieval continues. “Sometimes patients who have a zero spherical equivalent, but also a small amount of defocus from astigmatism, really love the effect that they get from their astigmatism, without understanding what it’s doing and why. Many of these patients are able to read reasonably comfortably at a computer or even at nearer distances because of the depth of focus that they’re getting from their astigmatism. Obviously, there are benefits to correcting it, but there are sometimes benefits to leaving it alone.”

Dr. Kieval looks at the spectacle wear of patients with zero spherical equivalent and a little astigmatism to determine which ones might appreciate more aggressive astigmatism treatment. “Sometimes the way I determine which ones will do better with the correction and which ones won’t is to ask, ‘Do you wear glasses?’ If they say, ‘I never really wore glasses, but sometimes I’ll put on a pair of reading glasses.’ That tells me they’re utilizing their astigmatism to get some depth of focus. If you correct that patient’s astigmatism to zero, they may say, ‘My distance vision is better, but I can’t read anymore or see things up close like I used to,’ and they might really be upset about that. The drive to zero astigmatism may not be the best thing for that particular patient,” he explains. “The patient who has the same refractive error but says, ‘I always wear glasses because my vision is blurry,’ is the patient for whom I’ll correct that astigmatism. They’re going to do great, and they’ll love it.”

Daniel H. Chang, MD, of Empire Eye & Laser Center in Bakersfield, California, isn’t convinced that patients benefit from any amount of astigmatism. “Although it’s commonly suggested that uncorrected astigmatism can help with near vision, I do not use this as a viable clinical strategy for improving depth of focus,” he says. “Nevertheless, I’m not afraid to leave a little with- or against-the-rule astigmatism. I find that patients who are unhappy with their uncorrected visual acuity generally have a diopter or more of astigmatism at any axis: It is not a matter of whether 0.25 or 0.5 D of astigmatism lies in the original axis. Therefore, I generally shoot for zero astigmatism, whether it’s with or against the rule; and I’m okay with flipping the axis for less than 0.5 D of astigmatic power. After all, the refractive variability of manifest refractions is around 0.4 D.”

Dr. Kieval always strives for zero astigmatism for one segment of his patients. “Patients who are seeking correction with toric lenses, premium IOLs like presbyopia-correcting lenses and EDOF lenses are the patients we should all absolutely be striving to correct to zero astigmatism—or as close as possible, considering the limitations that exist,” he stresses. “Obviously, those patients are paying a premium and they expect a premium level of vision. Presbyopia-correcting lenses can cause some loss of modulation transfer function and a loss of contrast sensitivity that can be worsened by any residual astigmatism. If their residual astigmatism is zero, they’re going to get better contrast than if their residual astigmatism is 0.5 D. Is that going to be perceptible? Maybe not. But you want to give patients receiving those types of implants every benefit by striving for the best visual acuity they can have,” he says.

Preop Workup

Just as a thorough preoperative workup is necessary to choose an IOL with the proper spherical power, it’s also critical in order to treat astigmatism successfully. Many surgeons turn to corneal topography. “First we do refraction. Then we also do a corneal topography with Scheimpflug imaging using the Pentacam (Oculus),” explains Dr. Afshari. “That lets us see how much corneal astigmatism is there: Is it the regular bow-tie pattern, or is it irregular? The third step we do is an astigmatism check. We do an axial-length measurement and get the keratometry values during the preoperative visit.”

Scheimpflug imaging is also crucial to Dr. Kieval’s astigmatism treatment planning. “I rely heavily on Scheimpflug imaging for both magnitude and axis of astigmatism. I use the Pentacam, and I like the true net corneal power feature because it looks at the whole cornea by incorporating the posterior aspect ofthe astigmatism,” he says. “But I obviously don’t want to take measurements in a vacuum, and I want to see consistency between measurements. I look at topography primarily for the axis, to ascertain that there is a pattern of astigmatism. Our technicians do biometry, including manual keratometry. I just look for consistency, and as long as I see consistency, I tend to rely on the Scheimpflug imaging for magnitude and axis. The true net power is really the data point that I use to calculate the magnitude and axis, provided that it’s consistent with my other measurements.”

Dr. Gulani thinks that surgeons should use all of the modalities at their disposal to assess astigmatism as part of a comprehensive workup. “Before surgery, it’s important to measure the astigmatism by refraction, keratometry, topography, wavefront, ray tracing, OPD or whatever technology is available to the doctor—even all of them if they’re available—to ensure that the power and axis of astigmatism are as accurate as they can be,” he says.

Dr. Chang uses his topographer to help assess the quality of his keratometry. “I use the IOLMaster 700 (Zeiss) to provide the mean K’s, as well as astigmatic power and axis. I then use the Atlas topographer (Zeiss) to verify visually that what I’m getting on the IOLMaster 700 makes sense. The topography also gives me an overall map of the cornea, which is important because biometers will not show when there is irregular astigmatism. In essence, the topographer verifies whether the Ks from my biometer are any good,” he says.

“I’ll do at least two different measurements with the same device if I’m going to correct astigmatism—ideally on separate days,” Dr. Chang continues. “I do this to look for fluctuations of the ocular surface, so I like to measure it on two separate days with the same device. If I have two devices and two different readings, I don’t know if the K changed, or if it’s just the different devices giving me different readings. After obtaining multiple measurements, I look at all of the readings to determine the power and axis that I plan to treat— for example, ‘1.25 D at 180 degrees’— which lets me determine my desired surgical approach.”

Dr. Chang has devised a unique way to take his preop data into the OR once he’s verified it. “After using my topography to guide my axis selection, I will use the pupil image taken by the topographer. I visualize the iris structures to translate my figures onto the eye at the time of surgery. It’s a way to directly correlate my preoperative measurements with what I do intraoperatively. The IOLMaster 700 now prints an iris image as well, but my current workflow still involves the images from my topographer. I export it as a JPEG,” he explains. “Then I mark a crosshair vertically and horizontally over the corneal vertex, or the light reflex, which George Waring and I have described as the subject-fixated coaxial corneal light reflex. It’s basically the fixation light that’s reflected off the cornea. I place a line vertically and horizontally, and I take the image and digitally enhance it with Photoshop to maximize the contrast of the iris structures. At the surgery center, I put the patient in the slit lamp at the YAG laser. Using the preoperatively marked and enhanced pupil image, I then put a laser spot at 0° and 180° to reference the cardinal meridians. When I get the patient on the table, I then take a compass and mark the steep axis of astigmatism,” he says.

Douglas D. Koch, MD, professor and the Allen, Mosbacher, and Law chair in ophthalmology at The Cullen Eye Institute, Baylor College of Medicine in Houston, combines topography and readings from two different biometers. “My standard workup is to use the Galilei (Ziemer) for topography, and both the IOLMaster 700 and the Lenstar (Haag-Streit). I’m also currently using the Cassini (Cassini), because it seems to be giving some interesting data about the posterior cornea that may prove to be quite accurate.”

Overcorrect? Undercorrect?

Some surgeons believe certain patients benefit from a small amount of astigmatism, and that they may be dissatisfied if it’s corrected to zero. A related issue is the question of whether to over- or undercorrect astigmatism to account for posterior astigmatism and/or a drift from with the rule to against the rule over time.

Daniel H. Chang, MD, creates a JPEG of an image from his topographer, enhancing it in Photoshop to optimize his view of the unique iris structures, and adding crosshairs over the subject-fixated coaxial corneal light reflex. He references this enhanced image when marking the cardinal meridians and the steep axis of astigmatism on the day of surgery. (Image courtesy Daniel Chang, MD.)

Dr. Kieval bases his decisions about adjusting for anticipated changes in astigmatism on the preop Scheimpflug imaging. “In terms of over- or undercorrecting, I don’t feel like I need to use nomogram-like adjustments because I think that net-power data point on the Scheimpflug imaging is giving me the true power of the cornea. The only thing I will consider with regard to variance is the shift from with-the-rule to against-the-rule astigmatism with time and age. I’ll account for that more in my younger patients, such as the early-onset cataract cases—the 40- and 50-year-olds. But it’s not a dramatic accounting. If it’s a pediatric case, like a teenager with a congenital cataract or posterior polar cataract, I tend to treatthe astigmatism but try to leave about a half-diopter of with the rule to account for the drift that may occur over time. With the 30-year-olds and middle-aged patients, I try to leave about a quarter-diopter of with the rule to account for that drift. I think the drift can be variable, and it can be further managed later if it does occur,” he says. “I think that astigmatism is dynamic. I would guess that 90 percent of our patients’ astigmatism is static, and we can strive to treat that. But there’s some element of astigmatism that appears to be dynamic, whether it’s due to age, environment or other factors that can’t be accounted for at this time.”

Dr. Koch says that research suggests that this dynamic component of astigmatism that shifts from with the rule to against the rule appears to be slight and related to age.

Dr. Chang credits Dr. Koch’s research regarding the posterior cornea with informing some of his decisions about treating astigmatism. “Primarily based on the work of Doug Koch at Baylor, we have become aware of the posterior-corneal component of astigmatism,” he notes. “Depending on the axis, we should make a correction for total corneal astigmatism. As a rule of thumb, if the anterior corneal astigmatism is with the rule, I’ll subtract 0.5 D; if it’s against the rule, I’ll add 0.5 D. Then, I’ll use LRIs or a toric lens with the appropriate astigmatic power.”

With regard to the against-the-rule drift over time, however, Dr. Chang prioritizes immediate patient satisfaction over accommodating a gradual shift. “It’s tough to account for a decade of drift,” he says. “I really try to make the patient happy in the early postoperative period. If it drifts by 0.5 D over 10 years, they’ll probably forgive me. I may leave a little with-the-rule astigmatism, but I definitely try to get close to zero on the day of surgery.”

Dr. Gulani says that skilled surgeons may be able to use a patient’s astigmatism to create a customized visual outcome. “In many cases, we can use astigmatism to our advantage by leaving natural astigmatism to help monofocal patients read with that refractive error,” he says. “In some cases I have used astigmatism by flipping the axis using a toric lens implant, and then coming back to treat the corneal scar along that new flat axis using laser corneoplastique¹ and vice versa. Astigmatism should not only be corrected to zero levels for emmetropia; it can also be used to our advantage as an art. Understanding of astigmatism (both anterior- and posterior-corneal) and additionally, the mutual impact of coma and spherical aberration, is a must to successfully tread on the terrain of sure and happy patient endpoints.”

The Role of LRIs

With the availability of toricIOLs for astigmatism correction, what’s the role of limbal relaxing incisions in cataract surgery? Dr. Koch says they’re alive and well in the United States. “In my practice, I use them in patients who have up to 1.4 to 1.5 D of with-the-rule astigmatism and in patients who have less than a half-diopter of against-the-rule astigmatism. The reason I have such a disparity between those two groups is because of the posterior-corneal effect. And there’s also a little contribution from lens tilt; we know that lens tilt creates a little against-the-rule effect, along with the posterior cornea. Since our toric lenses correct a minimum of 1 D, if you take a patient with 1.5 D of astigmatism, they may easily have a quarter-diopter on the cornea, plus lens tilt,” he explains. “If you put a toric lens in, you might flip the axis of their astigmatism, which would not be desirable because we know that eyes tend to drift against the rule. Therefore, I like to leave patients with a little bit of with the rule. For patients with against-the-rule astigmatism, again factoring in a little tilt and certainly the posterior cornea, a half-diopter or less on the cornea could easily add up to 0.7 or 0.8; and then if you put a 1-D toric in, you’ve just flipped their axis by about 0.2 D, which would be ideal for them in the long term.”

Dr. Gulani creates incisions using a femtosecond laser intraoperatively to treat astigmatism. “During surgery, the femtosecond laser can create accurate limbal relaxing—or astigmatic keratotomy—incisions, which can be created during, but opened during or after, cataract surgery,” he says. “Of course, the modality of laser vision surgery is always available after premium cataract surgery to address and correct any residual astigmatism, right down to the zero-tolerance level. Not as accurate as laser vision surgery, but surely feasible and cost-effective, is an LRI at the slit lamp itself after cataract surgery for any residual astigmatism.”

Dr. Kieval describes manual LRIs at the slit lamp as his own version of “postop enhancement” for small amounts of astigmatism. “I think that’s different from what many people do,” he says. “I treat that astigmatism with an LRI at the slit lamp even if it’s 0.75D, because I want to drive to zero. This is my preference because the incision in cataract surgery can be so variable in terms of inducing astigmatism that I really think it’s better to wait for it to heal after cataract surgery before going after a small amount of astigmatism, just to ensure that it’s residual. For higher amounts—1 D or more—it’s much better to drive that astigmatism to zero with a toric lens.”

Dr. Afshari says she finds herself using LRIs less frequently in recent years. “Now I do far fewer of them because of toric implants,” she says. “That’s one factor; another factor is if the patient’s astigmatism is low enough that I can help it by the placement of my wound superiorly vs. temporally: I’ll adjust my wound based on the steep axis to decrease the astigmatism, and get a little help from that wound.”

Another surgeon who prefers a toric-IOL astigmatism solution is Dr. Chang. “The problem with LRIs is that you’re never too sure of what you’re going to get,” he says. “I have found that while femtosecond-based LRIs provide far more precise cuts than manual incisions, variable corneal biomechanics can still can result in unexpected outcomes that will leave you scratching your head. Because I see a lot of variability with LRIs, I tend not to use them.”

Dr. Gulani generally avoids manual LRIs for patients seeking premium results. “One cannot implant a premium lens implant and do an inaccurate manual LRI to complement it—though some cases of low-level astigmatism and high predictability, like a normal cornea, could justify this—but in most cases there are multiple astigmatic factors at work that will surprise the surgeon who thinks they were diligent enough,” he says.

The Femto Factor

Astigmatic keratotomy by femtosecond laser gets mixed reviews. “I don’t use femtosecond, but many colleagues like creating AKs with it, says Dr. Afshari. “It used to be that we’d do it more often, but now there are other options such as toric lenses and adjustment of the wound placement to help small amounts of astigmatism.”

“I find myself doing a lot less femtosecond laser cataract surgery over the years, because I’m finding that the benefits have not outweighed the time and cost issues,” says Dr. Kieval. “I currently feel that best management of astigmatism is achieved with a toric lens.”

“The evidence does not clearly support that you get a better overall result or that you have improved safety,” says Dr. Koch of FLACS. “The safety is comparable, but the evidence doesn’t suggest that it’s better. There are a couple of studies that suggest you may be a bit more accurate with femto with regard to the controlled capsulorhexis, but for astigmatism there are two issues: One is the toric IOL and its position. FLACS doesn’t seem to improve the accuracy of the toric alignment. The other concern would be whether the incisions made by the femtosecond laser are better than those made with a diamond knife.

“What I really like are intrastromal relaxing incisions, which I can use to correct about a half-diopter,” Dr. Koch continues. “What’s nice about them is that they don’t cause any discomfort or dryness, and they can just give you a little, tiny correction that is sometimes just what you need with a premium IOL. From that standpoint, I do like laser procedures, but the data are not in to support them, aside from than the fact that they do seem to work.”

Wavefront Aberrometry

Dr. Chang says that he doesn’t use the ORA VerifEye (Alcon) for intraoperative aberrometry. Dr. Koch only uses it for a limited number of cases. “I don’t find it particularly helpful in most of my patients,” he says. “The measurements we obtain in our office are so good that I don’t feel the need to use wavefront very often in toric-IOL situations. There are cases in which I’ll use it if my preoperative data are conflicting, and I also use it in post-LASIK eyes to help me with astigmatism correction sometimes, but I’m just not a strong advocate of the ORA, only because the cornea has been so modified by the time you get to that point in the operation that I don’t think it can match the precision and the accuracy of the measurements that you get preoperatively in the clinic.”

Dr. Afshari finds it helpful to compare wavefront aberrometry’s readings with her preoperative data. “We do intraoperative aberrometry with the ORA,” she says. “But beforehand, obviously, we determine how much of the astigmatism is corneal and how much is lenticular. Then, we see if all of the numbers match or are at least similar, and if the axes are similar. Sometimes you’ll get a lot of astigmatism during the surgery, but when you check the topography from the Pentacam, you see very little astigmatism. In that case, you assume the astigmatism you’re seeing intraoperatively is mainly lenticular. So we know that when we take that lens out, things should match more closely to the topography again.”

The Toric Threshold

When should you use a toric lens for optimum astigmatism management? It depends on whom you ask. “For me the level of astigmatism at which I’ll consider using a toric is around 1.25 or 1.5 diopters,” says Dr. Afshari. “Before that, I’ll often evaluate to see if I can do a little bit of wound adjustment to treat astigmatism. The posterior cornea contributing a little bit of against the rule is also a consideration.”

But beyond a threshold amount of astigmatism, “It is a discussion with the patient,” she says of the decision to use a toric IOL. “When I look at patients with around 1 D of astigmatism, many are fine with wearing glasses. They’re used to them, or they like the eye protection, for example. Of course, the cost is another issue. When the astigmatism is a little higher, I really try to make sure that they know that a toric could be very helpful. I’ll repeat that to them a couple of times.”

“I prefer a toric IOL solution for astigmatism,” says Dr. Chang, who estimates that when treating presbyopia he implants about 55 percent toric vs. 45 percent nontoric IOLs. “I think they’re more reliable than incisional techniques,” he says. Regarding his astigmatism threshold for toric implantation, he says, “I use IOLs to correct as little as 1 D of corneal astigmatism, so if patient has 1 D or more of estimated total corneal astigmatism (1.5 D or more of WTR or 0.5 D or more of ATR), I’ll use a toric IOL. But if there is less than a diopter of total corneal astigmatism, I’ll likely leave it uncorrected.”

Dr. Koch’s threshold for toric-IOL use also takes the posterior-corneal effect into account: “It would be around 1.5 diopters for with-the-rule, and about 0.5 against-the-rule,” he says.

“Intraoperatively, I’m geared towards a toric-lens solution for astigmatism,” says Dr. Kieval. “The most typical protocol if the patient has 1 D or more is to treat with a toric lens intraoperatively. If it’s anything less than a diopter, I tend to try to operate on axis, and then treat any residual astigmatism with an LRI postoperatively in the office. If there’s residual astigmatism, I’ll manage it with a limbal relaxing incision afterward. The literature soundly supports the use of toric lenses over the intraoperative limbal relaxing incision. But I also think that I can treat low enough that if there’s 0.75 D preoperatively, I can hope that an on-axis incision will be enough. If it’s not enough because the patient really needs zero astigmatism, then I can enhance it with a limbal relaxing incision at the slit lamp, rather than doing that LRI at the time of surgery for somebody who has maybe 0.75 or 0.5 diopters of astigmatism.”

Arun C. Gulani, MD, believes that some surgeons may avoid toric IOLs due to concerns about lens selection, alignment and staying power once placed. He says they can deliver great visual outcomes in skilled hands, however, even in complex eyes like the post-RK one shown here.  (Image courtesy Arun Gulani, MD.)

Dr. Gulani decides to recommend toric lenses on a case-by-case basis. “As I always teach, there should be no mathematical cutoff point, but a clinical judgment about when to use a toric lens or when to use an LRI, either manual or femtosecond-laser-assisted. Given the accuracy and stability of toric lenses, I have a low threshold to use them in patients with astigmatism and associated cataracts, with inclusion of surgically induced astigmatism, which can vary between surgeons. In my mind, if the patient has more than even 0.6 D of astigmatism, a toric lens should surely be the first choice. With less than 0.65 D, I would still aim for a toric lens implant, calculating for any incisional astigmatism. Alternatively, one can certainly use a femtosecond laser. If monetary issues come up for the patient, a manual astigmatic keratotomy is also suitable, but the drive still has to be to relentlessly pursue zero astigmatism.

“Toric lenses are extremely accurate,” Dr. Gulani continues. “I have used toric lenses not only in virgin eyes with astigmatism, but also in eyes with keratoconus, status post-RK, penetrating keratoplasty, corneal scarring and irregular cornea cases very successfully, to 20/20 outcomes. Given the accuracy of toric lens implants, I believe their utilization is low mainly because surgeons may not be confident in predicting the power or aligning the axis during and/or after surgery. Surgeons may be intimidated at three levels: accurate preoperative measurement; accurate placement during surgery; and concerns about persistent staying power of that ‘accurately’ placed lens implant on that axis,” he says.

Dr. Gulani adds that some of the surgeons who call and email him perseverate on having the latest “magic bullet” technology for toric alignment. “Additionally, surgery is an art, and there are nuances like how to not thoroughly clean the underside of the anterior capsule along the axis, or how to ovalize the capsulorhexis in deep-chamber cases like status post-RK or keratoconus, and then also how to align the lens during surgery without additional and laborious steps.” He uses the Gulani toric marker and alignment system (Bausch + Lomb).

“With nearly two decades of using toric lens implants in routine, complex and extreme cases, I have not had to rotate any implants post surgery to date,” says Dr. Gulani.

Dr. Koch notes the recent study showing that the Tecnistoric IOL (Johnson & Johnson Vision) tends to rotate in the eye more than AcrySof torics (Alcon),² but offers a pearl for stabilizing it. “I’ve found that when I’m using the J & J lens, it’s helpful to spin the lens at least 180 degrees before I put it in its final location. Then I hold it down against the posterior capsule with some pressure using a Sinskey hook for a good count of three or four seconds,” he explains. “That seems to stabilize it quite well. It doesn’t completely eliminate postoperative rotation, but the incidence is now minimal for me.”

Dr. Chang says that wound characteristics may influence whether or not toric IOLs rotate after cataract surgery. “When you’re using toric lenses, you’ve got to be really meticulous in implanting them,” he says. “Beyond marking the eye, unfolding the lens and aligning it in the eye, my biggest suggestion is to ensure that the wound is well sealed. A stable globe postoperatively provides a stable environment for the IOL, but if the eye becomes hypotonous, any force on the eye (squeezing, rubbing or pressure from an eye-drop bottle) can be transmitted through the eye wall, push on the lens and rotate it.” Although he notes that you can always rotate the lens back into position postoperatively and even do a laser enhancement if the patient remains unhappy, ensuring that the wound is sealed may help avoid that. “Sealing the wound at the end of the case is good surgical technique, and it can ensure stable lens position as well as protect against endophthalmitis,” he emphasizes.

Dr. Chang says that EDOFs are known to have refractive forgiveness for spherical error; but he says you can have that forgiveness for astigmatic error using these lenses, too. “However, you can’t just throw the lens in and expect it to magically take care of astigmatism. If you end up slightly hyperopic, and you left-shift the defocus curve, the extended focal range will provide some refractive forgiveness for distant vision, even for astigmatism,” he explains. “The tradeoff is that when you are slightly hyperopic, you lose a little bit of near vision in exchange. Therefore, it’s still best to correct all of the astigmatism and hit plano.”

“I encourage all eye surgeons to develop a zero tolerance for astigmatism,” says Dr. Gulani. Embracing as many pearls as possible will help surgeons gain more confidence withtorics and other astigmatism-management techniques, and get them “addicted to the beaming responses of their happy and gratified patients,” he states.

Dr. Kieval strives for zero astigmatism to the extent he believes possible within the scope of current knowledge. “I think it’s absolutely critical not to disrespect or disregard great cataract surgeons who aren’t so refractive-minded and may not treat astigmatism or use toric lenses or manage astigmatism with LRIs. I don’t think that’s unreasonable, but I do think its unreasonable for those surgeons not to let patients know that there are other options. As we all know, many patients are seeking their absolute best visual acuity after their cataract surgery, so treating that astigmatism and trying to reduce it is really critical for them.”  REVIEW


Dr. Gulani reports that he is a consultant/speaker for Oculus, Marco, Ocular Therapeutix, EyePoint and Bausch + Lomb. Dr. Afshari reports no relevant financial interests. Dr. Kieval is a consultant and speaker for Johnson & Johnson Vision/AMO. Dr. Chang is a consultant to Zeiss for the IOLMaster, and a consultant to Johnson & Johnson Vision for Symfony EDOF lenses and other products. Dr. Koch is a consultant for Alcon, Johnson & Johnson Vision and Zeiss. 



<sup>1. Gulani AC. Corneoplastique. Art of vision surgery. Indian J Ophthalmol 2014;62:1:3-11.
2. Lee BS, Chang DF. Comparison of the rotational stability of two toric intraocular lenses in 1273 consecutive eyes. Ophthalmology 2018;125:9:1325-31.</sup>