ESCRS
EUROTIMES
™
Supplement September 2011
Advancing Technology
in Cataract & Refractive Surgery
Supported by an unrestricted educational grant from
INCLUDING THE LATEST IN
LASER CATARACT SURGERY
See pages 1-2
Cataract Surgery
Advancing Technology in Cataract & Refractive Surgery
Femtosecond Laser Arcuate Incisions Using a femtosecond laser to perform customised arcuate incisions at the time of cataract surgery holds promise — especially if the same laser can be used for LASIK by Gunther Grabner MD
“The ability to perform both refractive and cataract surgery applications with the same laser system is highly desirable”
About 25 per cent of cataract patients have significant astigmatism, so there is a substantial market for the correction of astigmatism at the time of cataract surgery. Many eye surgeons already are buying femtosecond lasers, which means these devices probably will be part of standard treatment in cataract surgery in two or three years. Our early experiences with femtosecond laser incisions demonstrate that the ability to perform both refractive and cataract surgery applications with the same laser system is highly desirable. The advantages include more frequent use of the machine, more efficient use of space and reduced maintenance costs. Toward that end, we have been studying intrastromal arcuate incisions for astigmatism correction using our current femtosecond laser (AMO IntraLase). To date, we have treated about 25 eyes with up to one year of follow-up. Subjects have included both cataract patients and those patients who simply require a refractive astigmatism correction. At this time, we limit treatment to patients with astigmatism of 0.75 D to 2.50 D. Planning the incisions To determine the depth of the incision and appropriate treatment pattern, we obtain central pachymetry measurements in all four quadrants at the time of surgery. The thinnest quadrant – often the lower temporal quadrant – is selected. We identify an optical zone that is large enough for the procedure, approximately 6.0mm, and then set the laser for the appropriate depth. We use a surgical topography system (Keratron Scout, Optikon) to precisely determine the axis of astigmatism at the time of surgery. The arcuate cuts are made on the steep axis, with the procedure lasting nine to 12 seconds. Treatment is confined strictly within the stroma, eliminating danger of infection, wound gape or epithelial ingrowth because one doesn’t cut through Bowman’s. We can customise results for each patient by producing different treatment patterns based on optical zone diameter, incision depth and the angle of the cuts (Figure 1). Four angled incision patterns between 30° and 150° were identified for study. We selected patterns for individual patients based on factors such as amount of astigmatism, corneal thickness, age and pupil diameter. The larger the optical zone diameter and inclination angle with a given anterior diameter, the smaller the correcting effect.
Figure 1: Treatment zone diameter and angle of the incisions are among the features that can be customised in femtosecond laser astigmatic corrections
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Figure 2: Double-angle plot of the reduction of astigmatism and change in axis in eyes undergoing Intrastromal Arcuate Keratotomy (ISAK). The centre of the grid represents a ‘perfect’ result
Study results So far, our femtosecond laser arcuate incisions for correction of low astigmatism have produced very safe, precise and predictable results. During initial treatments, we identified an optimal treatment pattern with a constant arc length, inclination angle and changes in incision depth that were based on corneal thickness. This pattern was applied to 10 eyes, followed for three to six months (mean of 4.9 months), upon which we base our early results: n
Mean UCVA improved from 20/50 pre-op to 20/32 post-op;
n
81.8 per cent of subjects gained at least one line of UCVA, 19.2 per cent were stable, and no one lost a Snellen line of UCVA;
n
Average reduction of keratometric astigmatism was 58.7 per cent (Figure 2).
In the study, all incisions were on target and no perforations occurred. In one case, suction was lost during surgery, but the procedure was completed successfully. Patient satisfaction also has been high because the procedure can be done quickly and with minimal discomfort. Compared to bladed incisions, intrastromal laser incisions appear to be safer, enabling us to preserve the corneal surface, including Bowman’s membrane and the epithelium. We look forward to acquiring more data with the recent initiation of a larger trial involving about 125 eyes at our centre and three others in Europe. As the numbers of patients undergoing these treatments increase, we anticipate development of more accurate nomograms that incorporate new incision patterns and additional factors such as age and gender to improve results. We would also like to explore the addition of concentric incisions to increase effect for higher degrees of astigmatism. Prof Grabner is professor of ophthalmology and chairman of the University Eye Clinic at Paracelsus Medical University in Salzburg, Austria. Contact him at: G.Grabner@salk.at.
Cataract Surgery
Advancing Technology in Cataract & Refractive Surgery
Femtosecond Laser Clear Corneal Incisions Multiplanar incisions are repeatable and demonstrate excellent wound apposition and tight sealing immediately post-op and up to three months after surgery by James Loden MD
This is certainly an exciting time in the development of laser applications for cataract surgery. Surgeons have a great deal to consider, though, in deciding which technologies might benefit our patients and our practices. So far, I remain somewhat skeptical about the potential return on investment from adding a second, cataract-only femtosecond laser to my practice. However, I am interested in the clinical benefits of laser-assisted cataract surgery and the practice advantages of being able to market bladeless surgery. I think we may get the biggest “bang for the buck” in both areas from corneal applications of femtosecond technology, including clear corneal incisions and arcuate intrastromal incisions for the correction of astigmatism. We already have extensive experience with corneal femtosecond lasers, with more than five million femtosecond LASIK procedures globally to date. Eliminating bladed incisions is the part of laser cataract surgery that I believe will be most appealing and easiest for patients to understand, while at the same time potentially reducing risk and improving outcomes. And, of course, laser cataract surgery is a much more reasonable proposition financially for surgeon and patient if we can utilise the lasers we already have. For all these reasons, I have been investigating cataract surgery applications for my current femtosecond lasers (FS60 and iFS, Abbott Medical Optics).
a
Clear corneal incisions We have now performed laser CCIs in 16 eyes, with three-month data available for 10 eyes. In the first few eyes, I made a straight, 30° entry angle into the anterior chamber. Although the wounds looked good and all these eyes achieved good results, two had Seidel wound leaks on day one, so we refined the technique to achieve better wound sealing. My current approach relies on the IntraLase-enabled keratoplasty (IEK) software along with a mask to control the incision size at 2.3 or 2.6mm. This represents an offlabel use of approved technology in the US. I create a three-step, multiplanar incision that is much stronger than my initial uniplanar incisions. There is very precise wound apposition and sealing, as can be seen on postoperative OCT images (Figures 1a-c). At three months post-op, all eyes had BCVA of 20/20 or better. There was no trauma to Descemet’s and no problems in either group with wound leak or incision gaping while the femtosecond laser suction was on. Similar to bladeless LASIK, femtosecond laser CCIs offer a theoretically lower risk of complications such as wound leaks and early or late ingress of tear fluid into the anterior chamber. It may even reduce the risk of endophthalmitis that has been associated with CCIs in the past.
c
Arcuate incisions We have also treated three eyes with intrastromal arcuate incisions using the iFS laser. Initial post-op day one results were very good. The hope and expectation is that the astigmatic correction will endure over time. Immediately post-op, there is a very interesting separation of the incision by the opaque bubble layer on OCT. To me, this is a good indication that, while the cornea anterior and posterior to the incision is intact, there is a distinct separation of the corneal lamellae in the desired location.
“Femtosecond laser CCIs offer a theoretically lower risk of complications such as wound leaks and early or late ingress of tear fluid into the anterior chamber”
b
Fig 1a-c: One can see precise wound apposition in OCT images of a 3-step clear corneal incision created with a femtosecond laser, 30 minutes post-op (a), 1 day post-op (b) and 1 week post-op (c)
If the procedure proves to be predictable and effective, I see a number of advantages in performing astigmatic corrections with a laser instead of a diamond blade. It will be much easier to make incisions at the exact optical zone, arc and depth desired and to achieve perfect symmetry between paired incisions – something that is nearly impossible by hand. Furthermore, by not opening the epithelium, we limit the risk of infection, corneal melt and epithelial ingrowth into the wound. Dr Loden is in private practice at Loden Vision Centers in Nashville, Tennessee, USA. Contact him at: lodenmd@ lodenvision.com.
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Cataract Surgery
Advancing Technology in Cataract & Refractive Surgery
Microincisional Cataract Surgery: Harmony Ensures Success Using the latest phaco technologies will help improve safety and efficacy
by Gerd U Auffarth MD
“Among the factors that will help make microincisional cataract surgery successful is the ability to use modern lenses and the most updated phaco systems in conjunction with small incisions”
a
b A Tecnis 1-piece IOL is implanted via a 2.2mm incision using a new micro-implantation suite that harmonises the latest phaco and lens technology with a small-incision injector system
Today’s phacoemulsification systems have made sub3.0mm incisions standard. Better fluidics control during smaller-incision surgery means we also have fewer collapsing chambers and fewer intraoperative problems. This is the main reason I use microincisional surgical techniques today. But it’s by far not the only one. Another reason to consider microincisional surgery is because it helps minimise induced astigmatism, a critical factor in an age when patients are demanding true emmetropia, not just the spherical equivalent. Consider that a good majority of patients present with 0.5 D - 1.0 D of astigmatism. Cataract surgery, with some degree of induced cylinder, may result in a final astigmatism of 1.5 D or even 2.0 D. That’s not good enough. Surgeons with a burgeoning presbyopia patient base must consistently achieve emmetropia. For our most demanding patients – those who want both their presbyopia and astigmatism corrected – we need to minimise the amount of induced astigmatism. With clear corneal incisions approaching 2.0mm or less, surgeons can reduce the amount of induced astigmatism to about 0.25 D. I believe patient demands will continue to drive our techniques to smaller and smaller incisions. But none of that will matter unless there is complete harmony between the machine and the type of surgery one performs. For me, it is crucial that all the components of cataract surgery – the handpiece, phacoemulsification system, lens injector and IOL – work together, regardless of incision size. For example, it makes little sense to perform surgery through a small incision only to enlarge the wound to insert a particular lens. Similarly, if surgeons try to squeeze a 2.2mm injector through a 2.0mm incision, they will either damage the wound construction or get a fishmouth configuration where the wound doesn’t close properly. This is problematic, because when the surgeon hydrates the paracentesis, the fluid just leaks out. This will result in a necessary suture and the astigmatic calculation will be off. In the end, I prefer enlarging the wound slightly over forcing an injector through.
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System dynamics Hydrophilic IOLs (in Germany, most are from Acri.Tec and Zeiss) can be rolled and implanted through the smallest, 1.8mm or 1.5mm incisions. In Germany, the two companies with the greatest market share in both phaco systems and IOLs (Abbott Medical Optics and Alcon) both have systems where the phaco handpieces can go through a 2.0mm incision, through which one can then implant hydrophobic IOLs. AMO’s new MicroImplantation Cataract Suite includes an injector that is compatible with all dioptre versions of the Tecnis IOL (including the multifocal and toric). An added advantage for the surgical staff is that there is only one cartridge size, which makes IOL preparation much easier. The smaller the incision, the more careful the surgeon must be in removing viscoelastic. Viscoelastics are easily flushed out of a 4.0mm incision, but with a tight, small incision, every little molecule must be removed by irrigation and aspiration (I/A). Especially in cases where Healon 5 or DuoVisc are used, one should be very thorough in removing it. In my opinion, there are two factors that will help make microincisional cataract surgery successful. The first is creating small incisions, with careful attention to wound architecture in order to minimise induced astigmatism; the second, the ability to use modern lenses and the most updated phaco systems in conjunction with those small incisions. Prof Auffarth is professor and chairman of the Department of Ophthalmology at the University of Heidelberg in Germany. He receives research support from AMO, Carl Zeiss Meditec, Rayner and Schwind EyeTech Solutions. Contact him at: Gerd.Auffarth@med. uni-heidelberg.de.
Cataract Surgery
Advancing Technology in Cataract & Refractive Surgery
Improved Stability in Toric IOLs
Today’s premium lens patients will accept nothing less than perfection — and today’s toric lenses deliver
by Sunil Shah FRCS(E), FRCOphth, FBCLA
Surgeons have two methods for correcting pre-existing corneal astigmatism during cataract surgery: We can perform arcuate incisions (typically limbal relaxing incisions or some modification of LRIs) or we can implant a toric IOL. In the UK, there are numerous toric IOLs available to us from Acri.Tec, Alcon, Abbott Medical Optics (AMO), Oculentis and Rayner; some are also available in a toric multifocal platform. My personal threshold for implanting a toric lens over LRIs is fairly high, at about 2.0 D of astigmatism, as I have confidence in my corneal astigmatic surgery. It is slightly lower for implanting a toric multifocal lens, however, at about 1.5 D. From among the many options, one should look for toric IOLs that offer good optical performance, excellent visual quality, with good alignment and excellent rotational stability. Ease of use for the surgeon is also a factor. Toric IOL outcomes We recently took part in a multi-centre study to evaluate visual acuity and patient satisfaction following implantation of one of the newer toric lenses, the Tecnis Toric (AMO), an open-loop hydrophobic acrylic IOL (Figure 1). The lens was implanted in 65 eyes with >0.75D of preoperative astigmatism, all undergoing routine cataract surgery. Postoperative assessments were performed four to eight weeks after surgery. The mean cylinder was reduced from -1.96 ± 1.04 D pre-op to -0.66 ± 0.53 D post-op. Best-corrected visual acuity went from a mean of 20/40 pre-op to 20/25 postop. Mean postoperative uncorrected visual acuity was 20/30. Perhaps most importantly, we have seen very high rates of overall patient satisfaction (Figure 2), with hardly any photic phenomena. The length of this lens (13mm) provides good contact between the capsular bag and IOL during the early postoperative period. This, in turn, means there is increased friction to help keep the lens stable. Acrylic lenses have also been reported as being rotationally more stable than silicone; C-loop lens designs do have the potential to rotate clockwise under capsular compression, but I think rotation here is minimal, as evidenced by the patient satisfaction and visual acuity. Pearls for success In my experience, achieving excellent visual outcomes with a toric lens is dependent on two things: Precise axis placement initially, followed by rotational stability postoperatively. For precise placement, we are limited by the inherent errors in corneal power measurements and reference marker placement. For example, the width of the corneal mark can easily introduce 5° of error. Keep in mind that for every 10° the lens is off-axis, there is a 33 per cent loss of efficacy. My preference is to obtain corneal topography on all patients and rely on this, more than the biometry, for the magnitude and axis of astigmatism. I am convinced surgeons have to be obsessive about ensuring correct lens alignment with the visual axis. Once aligned, watch out for sudden decompressions of the globe that may cause the lens to rotate.
“One should look for toric IOLs that offer good optical performance, excellent visual quality, with good alignment and excellent rotational stability”
Figure 1: Tecnis Toric IOL
Figure 2: 94 per cent of the Tecnis Toric subjects said they were “happy” or “very happy” with their postoperative vision
Today’s toric IOLs offer much greater stability than earlier versions, increasing patient satisfaction and helping us set the bar for outcomes higher. I believe we should be able to get at least 80 per cent of our patients within 0.5 D of the intended cylinder correction. Of the numerous toric lenses available in the UK, patients are best served by IOLs that offer excellent spherical and cylindrical results. Prof Shah is a consultant ophthalmic surgeon at the Midland Eye Institute, Solihull, and the Birmingham & Midland Eye Centre in the UK. He is also an honorary professor at the University of Ulster and a visiting professor at Aston University, Birmingham. He is an investigator for AMO, Alcon, Rayner, PhysIOL, Bausch + Lomb, and a consultant to Lenstec and Topcon. Contact him at: sunilshah@doctors.net.uk.
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Cataract Surgery
Advancing Technology in Cataract & Refractive Surgery
Dual-optic Accommodating IOLs New generation of accommodating IOLs offers objective forward movement and significant pseudoaccommodative effect by Eduardo F Marques MD
“In patients who want good spectacle independence at all distances and the highest possible quality of vision, or those who spend all day at the computer, my preference is a dual-optic accommodating IOL”
Many of our patients desire spectacle independence following cataract surgery. Ideally, we could provide them with perfect vision at all distances, in all lighting conditions, without dysphotopsia or any impact on quality of vision. Although no lens available today can do all that, we are getting closer to the ideal with newer accommodative designs. The original single-optic accommodating IOLs, while successful in many eyes, provide limited or inconsistent near vision. Our research measuring movement of these older accommodating IOLs with Scheimpflug photography demonstrated axial movement of less than 0.5 D1. The theory behind dual-optic lenses is that the combination of a high-plus anterior optic with a negatively powered posterior optic should be able to produce a significant amount of pseudo-accommodation with relatively small lens movements. We have been studying the first of these dual-optic lenses, the Synchrony Accommodating IOL (Abbott Medical Optics Inc., Figure 1). Movement of the lens has been objectively demonstrated with both aberrometry and ultrasound biomicroscopy. Study results In the first 48 eyes of 24 patients implanted bilaterally with the Synchrony lens, visual acuity results have been excellent (Figure 2). Many of our patients are completely spectacle-independent or only use spectacles for prolonged reading of fine print. The average spherical equivalent is plano ± 0.70 D. And since light is not divided into multiple zones, contrast sensitivity with Synchrony is comparable to that of monofocal IOLs. 10 per cent of the eyes had very mild posterior capsular opacification (PCO). Surgical pearls The lens is designed to be implanted through a 3.8mm incision. Although I prefer smaller incisions, there is one major advantage to having such a large optic. Like the crystalline lens, it fills the capsular bag completely, which may help to prevent PCO. I make the incision on the steep axis to reduce minor amounts of astigmatism and will occasionally place a temporary suture to reduce the chance of inducing cylinder. As with all accommodating IOLs, it is very important for the capsulorhexis to be round, perfectly centred, intact and free of notches. In order to allow the lens to move correctly, the capsulorhexis should be 5.0 to 5.5mm in diameter. I mark the cornea or use a forceps with a ruler for accurate sizing. One needs to have pristine cortical cleanup. Polishing the underside of the anterior lens capsule with low flow/ low vacuum settings helps prevent capsular contraction and fibrosis. The goal with any accommodative IOL is to ensure that the capsule remains crystal clear and flexible. Before implanting the IOL, I fill the bag with cohesive viscoelastic. Synchrony comes pre-loaded in a disposable injector that ensures the lens unfolds in a slow, controlled fashion inside the bag. OVD removal is best achieved with bimanual I/A to access the space between the two optics.
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Figure 1: The Synchrony Accommodating IOL is a dual optic lens. With accommodative effort, the plus-powered anterior optic moves, increasing near power
Figure 2: At six months post-op, binocular vision is very good at all distances. Intermediate vision is a particular strength of this lens
Patient selection Although dual-optic accommodating IOLs are an important addition to our armamentarium, we continue to implant a full range of presbyopia-correcting IOLs to meet patients’ needs. For the patient who is most concerned about superb near vision and doesn’t mind the potential for nighttime glare and halo, I might opt for a multifocal IOL. In patients who want good spectacle independence at all distances and the highest possible quality of vision, or those who spend all day at the computer, my preference is a dual-optic accommodating IOL. Because the dual optics are monofocal optics, these lenses may also provide some security to surgeons or patients who are concerned about future macular or retinal developments. I have implanted a Synchrony lens in a healthy eye that later went on to develop an epiretinal membrane. Following macular surgery, the patient is back to 20/20 UCVA and continues to enjoy the benefits of the dual-optic lens without any loss of contrast or light transmission. Dr Marques is head of the Department of Ophthalmology at the Portuguese Red Cross Hospital in Lisbon, Portugal. Contact him at: em.lx@netcabo.pt. References: 1. Marques EF. Objective measurement of anterior movement of an accommodating IOL, paper presentation, ASCRS, March 18 2006.
Advancing Technology in Cataract & Refractive Surgery
Cataract Surgery
Meeting Expectations with Multifocals Preoperative steps ultimately determine postoperative visual outcomes with multifocal IOLs
by Nikica Gabric MD, PhD
Figure 1: Uncorrected near visual acuity on six-year follow-up in patients who had refractive lens exchange with multifocal intraocular lens implantation
Figure 2: Portion of time patients spend wearing spectacles six years after refractive lens exchange with multifocal intraocular lens implantation
Surgeons can find success with multifocal intraocular lens (IOL) implantation by laying the groundwork with meticulous patient selection, intraocular lens power calculation and surgical skills. Approximately 20 per cent to 30 per cent of all IOLs we implant are multifocal lenses. In Croatia, multifocal IOLs are too expensive for public hospitals, so patients who want multifocals must pay for them at private clinics, but these patients are willing to invest in their health. Since 2004 we have implanted more than 2,000 multifocal IOLs. We began implanting multifocal IOLs in 2004 in patients with cataracts, beginning with the AcrySof ReSTOR +4 (Alcon) and then adding the Tecnis multifocal IOL (Abbott Medical Optics) and ReZoom multifocal IOL (AMO) to our repertoire, as well as others, such as the AT LISA and AT LISA TORIC IOL (Carl Zeiss), AT TORBI IOL (Carl Zeiss), M-flex (Rayner), and AcrySof ReSTOR +3 IOL (Alcon). Achieving excellent results, we began performing refractive lens exchange in presbyopic patients.
We prefer IOLs that provide satisfying vision at all distances with minimal side effects and favour hydrophobic acrylic IOLs, with a lower rate of posterior capsular opacification (PCO). The lens should ensure capsular stability, centration, and a small corneal incision without inducing astigmatism. Diffractive multifocal IOLs offer excellent near and distance vision, whereas refractive lenses enable intermediate and far vision with a higher rate of night vision disturbances. Although 95 per cent of multifocal patients experience haloes and glare, diffractive IOLs produce milder glare. The Tecnis, with its full diffractive design, prolate anterior surface and OptiEdge design, minimises dysphotopsia. We studied 620 eyes implanted with Tecnis Multifocal IOLs and 460 eyes implanted with ReZoom Multifocal IOLs after clear lens extraction within the last five years. In the Tecnis group, the mean binocular uncorrected distance visual acuity (UCDVA) was 0.9 (logMAR 0.05 or 20/22) and 90.3 per cent of patients achieved binocular UCDVA better than 0.8 (logMAR 0.1 or 20/25). At various contrast levels (100 per cent, 25 per cent, 10 per cent) under photopic and mesopic conditions, the Tecnis showed very good results. Mean binocular uncorrected intermediate visual acuity was 0.76 (logMAR 0.12 or 20/26) and mean binocular uncorrected near visual acuity was J1.13 at preferred distance. Questionnaire data showed that 94.5 per cent of patients never wear glasses. The major complaints were associated with computer use. After one year, only 7.7 per cent of patients reported mild haloes.
Patient selection The first step to success is a thorough preoperative assessment, which includes informing patients about potential adverse effects. Patients who expect guarantees and refuse the possibility that they may need glasses for certain tasks are not good candidates. The standard medical exclusion criteria apply (eg, retinal diseases, amblyopia, glaucoma, eye inflammation, pupil irregularities), and astigmatism should not exceed 1.0 D. Preoperative corneal topography is important, enabling the surgeon to place the corneal incision at the steepest meridian, reducing postoperative astigmatism. If the surgeon achieves emmetropia and the IOL is centred properly, vision will be good at all distances and visual disturbances will decrease shortly after surgery as the brain adjusts. Patients adapt more quickly if bilateral IOLs are implanted at the same time. Lens choices When selecting an IOL, it’s important to consider the patient’s age, profession, and expectations, as well as his or her preferences and lifestyle. Refractive lens exchange patients are highly motivated to be spectacle independent. Younger patients often work at computers and depend on their intermediate vision. They are usually very satisfied if they achieve spectacle independence, despite dysphotopsia or dry eye. Although we cannot promise spectacle independence, we work hard to achieve this goal.
“We prefer IOLs that provide satisfying vision at all distances with minimal side effects and favour hydrophobic acrylic IOLs, with a lower rate of posterior capsular opacification (PCO)”
Looking ahead Because refractive lens exchange patients are very demanding, further improvements in lens optics and design are necessary, especially to reduce haloes and glare. As this technology advances, careful patient selection, IOL calculation and surgical skills are keys to success. Nikica Gabric MD, PhD, is founder and head of the Eye Clinic Svjetlost in Zagreb, Croatia. Contact him at: tajnica@svjetlost.hr.
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Cornea & Refractive Surgery
Advancing Technology in Cataract & Refractive Surgery
Expanding Therapeutic Horizons
High dynamic range aberrometry makes it possible for surgeons to capture wavefronts and create treatment plans for highly aberrated eyes by Julian D Stevens FRCS, FRCOphth
“I anticipate that a major indication for high dynamic range aberrometry will be in analysing and treating patients with loss of corneal tissue due to contact lens infections”
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The limiting factor currently in treating highly aberrated corneas is the ability to obtain good wavefront data. Without a good wavefront, a topography-guided treatment may be the only option. But by definition, this fails to address aberrations on the posterior surface of the cornea, which commonly occur in concert with anterior surface injuries, or elsewhere in the eye. Registration of topography-guided or complex conventional treatments is another challenge. A precise correction is of limited value if it cannot be delivered by the treatment laser to the exact x-y and rotational coordinates on the cornea. My preference, therefore, is always to take the whole-eye optics into account and perform a wavefront-guided correction whenever possible. In complex eyes, this can be accomplished only with a high dynamic range wavefront sensor (see figure). Although several such prototypes or custom systems have been tested, including one in my clinic, developing a robust new aberrometer that can perform at a very high dynamic range has been challenging. What we demand from such a device is the accuracy and reliability of Hartmann-Shack technology, but at higher resolution than is currently possible today. It must prove to have low interscan and intrascan variability and high levels of precision in both normal and aberrated eyes. We want the capture rate and the number of eligible scans to be higher than with current technology – but without sacrificing the robustness of the rejection algorithms. Finally, a new aberrometer must also satisfy workflow concerns such as efficiency, ease-of-use and ergonomics. The first clinical units of a new aberrometry platform developed to meet all these parameters, the iDesign aberrometer (Abbott Medical Optics), are scheduled to arrive in the UK and Europe later this year. This device also integrates a new, spot-based corneal topographer. Essentially, similar spots can be used to reconstruct the corneal shape as well as the whole-eye wavefront, providing great insight for diagnosis of complex problems. Although we have other systems that integrate topography with wavefront (Topcon) or OPD-Scan (Nidek) for diagnostic purposes, only the Nidek is linked to a treatment laser and this OPD system employs a different technology and does not have the spatial resolution and Fourier wavefront reconstruction of the iDesign system. We anticipate a real-world dynamic range of about 8 D from the iDesign aberrometer, along with resolution of 210 µm. Much remains to be proven with this new platform, but even if laboratory projections aren’t fully met in clinical practice, it should be able to capture most eyes, including those with high cylinder, fairly significant distortions from corneal transplants or injuries, and diffractive lens implants.
A high-dynamic range aberrometer can be used to capture highly aberrated eyes, such as this case in which a toric IOL implant was misaligned, leaving the patient with an RMS error of 0.58 and severe visual symptoms. Because he could capture this eye, Dr Stevens was able to perform wavefront-guided LASIK with iris registration to successfully correct the coma and cylinder without a lens exchange.
I anticipate that a major indication for high dynamic range aberrometry will be in analysing and treating patients with loss of corneal tissue due to contact lens infections. 15 per cent of contact lens-related infectious keratitis results in reduced quality of vision, which can be devastating for the patient. There is often a small divot that is too small to justify a lamellar corneal transplant, but can be highly aberrating and impossible to capture and accurately reconstruct with conventional scanners and wavefront technology. Of course, imaging is not the only challenge in highly aberrated eyes. Some of these patients have lost such significant tissue from infection or injury that there may not be enough left to recreate the correct corneal curvature. Nevertheless, having the wavefront data opens the door to creative, staged solutions that greatly expand the therapeutic horizon for these patients. Based on my past experience with earlier platforms, what I expect surgeons to notice most immediately from a high dynamic range system is the remarkable clarity of the Hartmann-Shack spots. Even before the system constructs a wavefront map, one can subjectively see obvious problems just from the spot distortions. My guess is that we will also find the high resolution very helpful in tear film assessment, an entirely new application for wavefront sensing. From both a diagnostic and treatment perspective, I am very enthusiastic about high dynamic range technology. Dr Stevens is a consultant ophthalmic surgeon at Moorfields Eye Hospital in London. He is also a consultant to Abbott Medical Optics.
Advancing Technology in Cataract & Refractive Surgery
Cornea & Refractive Surgery
High Resolution Wavefront Treatments in Normal Eyes As aberrometer technology continues to evolve, there is growing optimism about the potential for improving treatments in both normal and complicated eyes by W Bruce Jackson MD
The University of Ottawa Eye Institute is one of four Canadian centres evaluating the effectiveness of a highresolution aberrometer (iDesign, Abbott Medical Optics) for wavefront-guided laser vision correction. Although several investigators have used the device diagnostically and/or in unusual cases, this study represents the first standardised use of it to drive clinical treatments. Initially, we are evaluating the aberrometer in normal eyes. To be enrolled in the study, subjects must have bestcorrected preoperative acuity of 20/20, no prior surgery and no ocular disease or conditions other than refractive error. The myopia trial is complete. From the clinician’s perspective, the aberrometer works exactly like its predecessor, the WaveScan. However, its capabilities are expected to go well beyond the current technology. For one thing, the resolution is up to five times higher, allowing the aberrometer to capture 6001200+ data points, depending on pupil size, rather than the current maximum of 240 data points. The dynamic range of the device is expected to be much broader, as well. Although I have not yet had the opportunity to test its range in highly aberrated eyes, it is theoretically able to image wavefronts from eyes with spherical error of -16.0 D to +12.0, more than 8.0 D of cylinder, and more than 8 µm of RMS error. One of the very interesting questions to be determined in this study is whether high-resolution aberrometry can provide automated refractions on which surgeons can rely without referring back to the subjective, manifest refraction. We have always been impressed with the accuracy of wavefront-derived cylinder refractions and have found that the wavefront refraction is the ideal starting point for quickly obtaining the best manifest. Nevertheless, we often make nomogram or physician adjustments to ensure that the treatment more closely matches the manifest. Better aberrometry could eliminate that step. Benefits in practice In addition to wavefront aberrometry, iDesign also incorporates new-technology topography, autorefractometry, pupillometry and keratometry. The immediate benefits of this are the ability to get more precise K readings across the entire cornea and to register topographical maps with the wavefront in order to isolate the source of aberrations. The potential to some day perform treatments that are both wavefront- and topography-guided is very exciting. We already achieve excellent results with wavefrontguided surgery in normal eyes, of course, but one would expect that capturing higher-resolution data from more points on the cornea would at least incrementally improve the precision of visual results in all eyes. The combined myopic data from the trial are currently being analysed and will be reported at the ESCRS meeting. Anecdotally, we are delighted thus far with the clinical results at our centre.
Keratoconus eye with 400mm resolution
“The potential to some day perform treatments that are both wavefrontand topographyguided is very exciting”
KC eye measured with 210mm resolution Figure 1: Higher resolution should improve spot quality and accuracy, leading to more accurate and more detailed wavefront images
After the conclusion of this trial, we hope to be able to treat high hyperopes and high myopes, who are not part of the current study. But the real potential for this technology is, of course, in treating highly aberrated eyes that are currently difficult or impossible to capture. High-resolution aberrometry offers a great opportunity for refractive surgery. In recent years, we have seen an improvement in outcomes from the move to femtosecond laser flaps, but the excimer laser hardware itself hasn’t changed much. Further gains in precision will likely come from more sophisticated wavefront analysis and treatment planning algorithms. Dr Jackson is professor of ophthalmology and director of the University of Ottawa Eye Institute in Ontario, Canada. Contact him at: bjackson@ohri.ca.
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Cornea & Refractive Surgery
Advancing Technology in Cataract & Refractive Surgery
Wavefront-guided Ablation for All
Even in low-risk eyes with minimal higher-order aberration, wavefront-guided surgery provides the best chance for ideal results by Jan A Venter MD and Steve Schallhorn MD
“Our business model is centred around achieving the best patient experience and highest level of patient satisfaction”
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We have previously reported on the excellent outcomes achieved by low to moderate myopes undergoing wavefront-guided ablation at our centres in Europe1. In routine refractive surgery cases – healthy, young patients with low to moderate myopia and low levels of higherorder aberration (HOA) – many surgeons are willing to consider a conventional or “optimised” ablation or to forgo femtosecond laser flaps. Our experience in our group of centres, however, demonstrates that patients overwhelmingly choose the most advanced technology available and that results with this combination of technologies in “routine” eyes are outstanding. We were recently asked how best to manage a hypothetical case: A 28-year-old male presenting for refractive surgery with best-corrected visual acuity (BCVA) of 20/16 and a refraction of -3.50 -0.75 x 173 OD and -3.75 -0.50 x 5 OS. HOAs were low (0.23 µm over a 6.0mm pupil) and the patient was a good candidate for LASIK. Consulting the data At least two studies suggest that wavefront-optimised (WFO) corrections induce more HOAs than wavefrontguided (WFG) ablations in patients with low preoperative aberrations2,3. However, other research indicates that both procedures induce about the same amount of HOAs4,5. In studies conducted by the US Navy, patients undergoing WFG treatments fared significantly better in terms of HOA induction than conventional LASIK or optimised ablations (Figure 1). We queried our common database to discover what our actual outcomes from WFG surgery have been in patients that fit the parameters of the hypothetical patient described above. From a 2009 dataset of more than 90,000 eyes treated, 28 eyes of 20 patients matched the criteria of a 28-yearold male with pre-op sphere between -3.50 and -4.00, with cylinder <1.0 D and at least one month of followup after wavefront-guided LASIK. All were treated with femtosecond laser flaps and Visx CustomVue (Abbott Medical Optics). At one month, the mean manifest sphere was +0.05 ±0.23 D (+0.75 to -0.25 D). Mean manifest cylinder was -0.12 ±0.17 D (0.00 to -0.50 D) and mean UCVA was -0.13 logMAR or 20/16+1. Most (57.1 per cent) had no change in BCVA or in post-op uncorrected visual acuity (UCVA) compared to pre-op BCVA. One-quarter had post-op UCVA that was better than their pre-op BCVA, while 18 per cent had post-op UCVA that was one line worse than their preop BCVA. Almost all these eyes (96.4 per cent) achieved better than 20/20 acuity (Figure 2), which we find to be the best predictor of satisfaction. And, not surprisingly, patient satisfaction was very high. All 20 patients said they would recommend the procedure to family and friends. All said the procedure had improved their normal daily activities and physical activities. Most (85 per cent) even said their night driving was improved, with the remainder saying night driving was unchanged after surgery. In short, patients meeting the exact description of this theoretical patient do extraordinarily well with wavefrontguided surgery. Because we track outcomes so closely, we can tell prospective patients exactly how similar patients have fared in the past, which greatly increases confidence in the procedure and in our surgeons.
Figure 1: In a matched eye comparison, eyes undergoing WFG LASIK had statistically significantly lower post-op HOAs than eyes undergoing wavefront-optimised LASIK
Figure 2: Nearly one-third of patients matching the description of the hypothetical patient achieved 20/12.5 UCVA following wavefront-guided LASIK
Our business model is centred around achieving the best patient experience and highest level of patient satisfaction. A key element in that strategy is to provide the best possible unaided vision – and that means better than 20/20 vision. Our previous research would suggest that the greatest likelihood of achieving better than 20/20 results and lower induced HOAs comes from a WFG treatment with a femtosecond laser flap. Dr Venter is UK medical director for Optical Express and clinical director for the organisation’s International Medical Advisory Board (IMAB). Contact him at: janventer@opticalexpress.com. Dr Schallhorn is global medical director of Optical Express. Contact him at: scschallhorn@yahoo.com. References 1. Schallhorn SC, Venter JA. One-month outcomes of wavefront-guided LASIK for low to moderate myopia with the VISX STAR S4 laser in 32,569 eyes. J Refract Surg 2009;25 (Suppl):S634-41. 2. Padmanabhan P, Mrochen M, Basuthkar S, et al. Wavefront-guided versus wavefront-optimized laser in situ keratomileusis: contralateral comparative study. J Cataract Refract Surg. 2008;34(3):389-97. 3. Yu J, Chen H, Wang F. Patient satisfaction and visual symptoms after wavefront-guided and wavefront-optimized LASIK with the WaveLight platform. J Refract Surg. 2008;24(5):477-86. 4. Miraftab M, Seyedian MA, Hashemi H. Wavefront-guided vs wavefront-optimized LASIK: a randomized clinical trial comparing contralateral eyes. J Refract Surg. 2011;27(4):245-50. 5. Perez-Straziota CE, Randleman JB, Stulting RD. Visual acuity and higher-order aberrations with wavefront-guided and wavefrontoptimized laser in situ keratomileusis. J Cataract Refract Surg. 2010;36(3):437-41.
Cornea & Refractive Surgery
Advancing Technology in Cataract & Refractive Surgery
An Ounce of Prevention
Artificial tears are a critical tool in improving patient satisfaction and quality of vision after LASIK
by Jorge L Alió MD, PhD
“Lubricants containing hyaluronic acid especially have a role in preventing further aggravation of dry eye symptoms”
Aberrations before tear instillation
As we perform LASIK on middle-aged patients, we are encountering ocular surface syndrome more frequently after surgery, which delays the patient’s postoperative recovery, reduces quality of vision and leaves patients disappointed with their results. Often believed to be dry eye, ocular surface syndrome is not true “dry eye” but a condition caused by epithelial neuropathy of the operated cornea. Clinical examination In today’s refractive surgery environment, developing meticulous patient selection criteria and knowing whether to operate on a patient with dry eye are part of the art of being a good refractive surgeon. The preoperative examination should include a careful clinical history, noting dry eye symptoms. For patients older than 30 – particularly women and those over 40 – it’s important to evaluate the tear film volume using Schirmer’s, lissamine green or phenol red thread tests. To detect punctate keratitis, which evolves into a severe ocular surface syndrome after LASIK, the surgeon also should use fluorescein dye. If ocular surface inflammation or significant symptoms are present or patients do not respond to topical lubricant therapy, the surgeon should perform ocular surface cytology. Treatment options LASIK should not be performed until dry eye has resolved and the patient has no symptoms. Even after resolution, the patient must understand that LASIK is a risk in those with dry eye and ocular surface syndrome could develop after LASIK. Before and after refractive surgery, high-quality artificial tears can directly affect results. If the epitheliumtear film complex behaves optically better, patients should have less higher-order aberration (HOA) and better refractive results. Several studies have used wavefront analysis to demonstrate the reduction in HOAs after tear instillation. To prevent ocular surface syndrome, patients should be prepared for surgery with punctal occlusion, if necessary, and other treatments. For those with mild dry eye, I use lubricants containing hyaluronic acid as the main component, whereas for those with moderate dry eye I use these along with preservative-free topical steroids. Lubricants containing hyaluronic acid, such as Blink
Aberrations after tear instillation
Intensive, especially have a role in preventing further aggravation of dry eye symptoms. We use lubricants like this before LASIK to prevent ocular surface syndrome and treat symptoms that occur after LASIK. Our research has shown that artificial tears may reduce optical aberrations associated with an irregular tear film in patients with dry eye1. In an ongoing study, we are investigating Blink Intensive (Abbott Medical Optics) in patients undergoing myopic LASIK to determine whether it creates a better ocular surface with better optical quality of the operated cornea after refractive surgery, using anterior corneal aberrometry and total aberrometry to assess the ocular surface. During this study, we are studying the effect of Blink Intensive and other conventional artificial tears on higher-order aberrations before wavefront imaging and after LASIK. However, this study does not include patients with dry eye. In severe cases, my colleagues and I have found that autologous platelet-rich plasma eye drops treat dry eye effectively before and after LASIK, either alone or in combination with conventional treatments.2 Dry eye must be detected and treated effectively before LASIK. Lubricants used before LASIK help prevent ocular surface syndrome and can improve optical quality and treat symptoms that occur after LASIK. Prof Alió is professor and chairman of ophthalmology at Miguel Hernandez University and medical director of Vissum Corporation in Alicante, Spain. Contact him at jlalio@vissum.com. References 1. Montes-Mico R, Caliz A, Alio JL. Changes in ocular aberrations after instillation of artificial tears in dry-eye patients. J Cataract Refract Surg 2004;30:1649-52. 2. Alio JL, Pastor S, Ruiz-Colecha J, Rodriguez A, Artola A. Treatment of ocular surface syndrome after LASIK with autologous platelet-rich plasma. J Refract Surg 2007;23:617-9.
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