Femtosecond laser refractive surgery first entered the clinic in 2001 with the FDA approval of the IntraLase system. That system is now in its fifth iteration, and has since been joined by three other femtosecond laser platforms. EuroTimes got an update on the features, performance, and applications of the individual lasers at a refractive surgery session at the WOC.
Comparing and contrasting
Holger Lubatschowski PhD, Germany, began the session by providing an overview of basic principles of femtosecond laser performance and a side-by-side comparison of the technical features of each of the four commercial platforms. All of the femtosecond lasers use photodisruption to cut through corneal tissue, and they all operate at a wavelength of about 1040 nm, but they differ in a number of technical respects.
The Femtec (20/10 Perfect Vision) and IntraLase have a high pulse energy, the LDV (Ziemer) has a very low pulse energy, and the VisuMax (Zeiss) lies somewhere in between. With the IntraLase, Femtec, and VisuMax, the cutting process is directly visible to the operator, whereas it is seen only on the monitor using the LDV. The Femtec and VisuMax have a spherical contact interface to the cornea, while the VisuMax has a contact glass for corneal fixation.
The LDV delivers its laser beam through a mirror arm that fits under all excimer lasers and consists of just an oscillator without an amplifier. Therefore, the LDV can be used without moving patients during the surgical process, and it is also the smallest of the devices.
The four femtosecond lasers also differ in pulse width, which ranges from 250 femtoseconds for the LDV to 500 femtoseconds for the IntraLase and Femtec. The repetition rate is in the MHz range for the Femtec and in the kHz range for the other platforms, while pulse energy is in the nanoJ range for the LDV and in the milliJ range for the others.
IntraLase
Perry Binder, MD, US, presented worldwide clinical experience with the IntraLase femtosecond laser. Since the introduction of the first generation system, the IntraLase platform has been used to perform more than two million procedures, including over 500 IntraLase-enabled keratoplasties. Other uses have included astigmatic keratotomy, wedge resection, lamellar keratoplasty, penetrating keratoplasty, creation of INTACS channels, and corneal biopsy.
The recently introduced 5th generation device provides a number of important features and benefits. This 150 KHz femtosecond laser allows reductions in time for flap creation and total energy delivery. It also permits unique methods of flap customisation, including a bevel-in sidecut angle, which has been shown in various studies to result in stronger flap healing.
The newest IntraLase laser also offers a high-resolution video microscope for increased depth of focus during surgery, a touchscreen user interface, and digital video output.
“We think the fifth-generation IntraLase laser enables most of the idealised goals of LASIK surgery better than any currently existing femtosecond laser while placing all the tools necessary for customising the flap within the hands of the surgeon,” Dr Binder said.
Femtec
The Femtec is a highly capable workstation that is also able to perform roles beyond LASIK flap creation, said Julian Stevens, MD, UK.
A key feature of this platform is that it has a curved patient interface that is important because it translates into less distortion of the cornea and less compression of the eye. Therefore, IOP is minimally increased.
The Femtec also features excellent diagnostic graphics on the video screen that are particularly useful for monitoring shape when cutting corneal grafts, a torque feature that detects patient head movement, and a direct diagnostic link with customised treatments.
In addition to having proven itself as a capable flapmaker, the Femtec laser has been used for astigmatic keratotomy, intrastromal astigmatic keratotomy, and cutting corneal grafts.
However, the capability that most distinguishes it from other existing platforms is its potential to be used to perform intrastromal refractive surgery with no flap.
“The Femtec laser is a very capable workstation with excellent software. It is one of the most sophisticated and advanced systems available today and may bring us to the Holy Grail of femtosecond lasers, which is to use this technology to put energy into the cornea in order to achieve a shape change without cutting a flap,” Dr Stevens said.
LDV
Theo Seiler MD, PhD, Switzerland, discussed the Ziemer LDV based on his experience over the last two years. His presentation delivered three messages relating to precision, safety, and platform dependability.
After proposing that a femtosecond laser has a role in refractive surgery for procedures where flap dimension precision truly matters, Dr Seiler reported that in a series of 92 eyes undergoing creation of flaps with an attempted thickness of 110 microns, the mean ± SD thickness was 109 ± 3.7 microns with a range from 101 to 116 microns. Flap diameter outcomes also showed sufficient precision and reproducibility, although Dr Seiler noted that the desired flap diameter is obtained only if the suction is complete.
Safety has been excellent. Complications encountered in the last 200 patients consisted of strong adhesion necessitating manual cut in two eyes, failure of the scan in one eye, too small flap diameter in one eye, and inability to perform two treatments because of a small eye and deep orbit. There were no air bubbles in the anterior chamber or eyes with transient light sensitivity, and eyes with Sands of Sahara have been very infrequent.
The LDV has also proven itself to be an easy-to-use and dependable workhorse, he noted.
“We have had to cancel only one surgery session over the last two years and consider this platform a Volkswagen, not a Ferrari. There is no need for a technician, no calibration, and no extra temperature and humidity controls. We know that with the LDV, we can just turn it on, and it goes,” Dr Seiler said.
VisuMax
As described by Marcus Blum MD, the VisuMax platform (Zeiss) is an integrated solution combining a femtosecond laser and excimer laser. It uses a spherical contact interface system to the cornea with low suction pressure so there is no vision loss during suction, and treatment positioning is precise as the patient fixates on a blinking light within the system.
A study using high-frequency digital ultrasound to measure flap thickness showed it performs reliably and precisely for flap creation. In a series of eyes with an attempted thickness of 110 microns, the mean achieved was 112 microns, 25 per cent of eyes were within two microns of intended, and 88 per cent were within 10 microns.
However, ongoing research using the VisuMax femtosecond laser for femtosecond lenticule extraction (FLEx) as a new method of refractive surgery is what is distinguishing this platform, said Dr Blum.
He presented data from six months of follow-up of more than 100 eyes showing good safety, refractive stability, and reasonable accuracy but with slight overcorrections in lower myopes.
“We have been very grateful to use this system because it works perfectly for LASIK flap creation. However, we have tried to take the VisuMax beyond the point where it is only a flap maker. Obviously there is a learning curve, but we expect the outcomes with FLEx will become more precise as the technique is refined, and this approach would have the advantage of eliminating the need for two lasers,” said Dr Blum.
Novel application
The various femtosecond lasers are being used for a number of different indications in corneal surgery. Diverging from that path, Ronald Krueger, MD, US, described research he has been conducting using a femtosecond laser to cause intralenticular photodisruption as a method for restoring accommodation.
The basic concept is to use an ultrashort pulse laser to cause photo-phaco-modulation in order to alter lens elasticity.
“The idea for this procedure is that creating small laser microperforations within the hardened lens nucleus would enhance the sliding of fibres within the lens and thereby increase lens flexure,” he explained.
An early study in cadaver eyes showed that treatment of a lens from a 54-year-old donor with 100 suprathreshold pulses in an annular pattern was associated with increased deformation when submitted to strain. Subsequent studies have focused on identifying the mechanism for that change, identifying the best pattern for the laser treatment, evaluating the potential to induce cataract, and determining what happens to the bubbles created.
So far, animal studies showed the treatment did not cause cataract, alter light scattering, or result in thermal damage into the peripheral lens tissue. Using a finite element model, it was determined that the procedure works because of sliding fibres within the lens and that layered shells are the best potential pattern so far. With the use of lens tissue cultures, it was seen that the bubbles disappear, and using an instrument to evaluate relative lens resistance to displacement with gradient steps of applied compression force, the results achieved were seen to be repeatable. These data are now being used to determine the parameters for achieving an accommodative effect.
“So far, our studies show accommodation restoration with intralenticular femtosecond lens treatment is theoretically possible and experimentally feasible. With sufficient clinical efficacy, laser lens modulation could become a new strategy in the quest for presbyopic correction,” Dr Krueger said.
More Info-----
For more information on femtosecond lasers in the clinic, listen to a EuroTimes podcast with Michael Knorz MD.
Monday, June 30, 2008
Medical journals join the 21st Century at WOC
In a time of instant messaging, online interaction, and easy access to information online, medical journals often seem soooo last century. EuroTimes listened in on a session given at the World Forum of Ophthalmological Journal Editors in which editors discussed issues they face in the 21st century.
Open-access publishing
Cost issues, commercial influence scandals, and a call for public access to government-funded studies all helped create demand for new models of peer-reviewed medical information delivery. In particular Biomedcentral and the Public Library of Science have quickly gained support and have forced traditional journals to re-evaluate their methods.
However, the concept of what should be open access in the medical field is controversial because while it offers advantages, it can also result in a variety of threats, said Thomas J Liesegang MD, editor-in-chief, American Journal of Ophthalmology.
Quality of content and its interpretation are two major concerns about open access.
“Access to information is crucial to the health and economic wellness of people in all countries, but I maintain that health information is not the same as other information on the web. It needs to be vetted and I also maintain the average consumer does not have the skill to discern good from bad science,” Dr Liesegang said.
There is also the concern that historical scientific literature may be lost as there may not be enough resources to support both traditional and open-access systems simultaneously and continuously. Some journals may not be able to afford to appear in open access and the result could be the termination of small non-profit scientific journals or societies, Dr Liesegang explained.
Open access can be supported by a pay-to-publish model. However, some authors, especially in developing countries, cannot afford the fees, and institutions will have to decide which researchers to support. The result may be that journals become filled with articles supported by commercial interests.
Quality of research published is another issue as some start-up journals in need of material may be willing to accept any manuscript.
“The old subscription-based model has worked well and should not be abandoned until another form of communication is vetted and proven successful,” Dr Liesegang said.
EuroTimes looked at these issues in an earlier article,
Click to read article.
Evidence-based medicine
Randomised clinical trials are considered the gold standard of medical knowledge, and yet the high costs of developing this evidence-based medicine are making it affordable only to multinational drug and device company sponsors, said Francesco Bandello MD, Chinese Journal of Ophthalmology.
The result is a potential for publication of biased and misleading information. And even when the study is high quality, questions remain about how far and to which populations the results can be generalised.
Dr Bandello acknowledged he has no answers to the existing issues. He proposed it may be useful to have trials conceived, designed, and planned by physicians and sponsored by public, independent bodies. Importantly, it is also critical that trials with negative results be published.
“Perhaps we need to pay greater attention to small, smart, independent studies and to focus more on the substance of the research and not just the methods,” he said.
Citation analysis
Citation analysis methods assume more influential articles are cited more often, and these data are being widely used in research environments and by institutions. However, the information can be misleading, said Charles McGhee MD, PhD, editor, Clinical & Experimental Ophthalmology.
Dr McGhee discussed how the perception created by such statistics as citation counts and journal impact factor can differ from reality, and he also reviewed a new parameter – the H factor and provided an example to show it can be misconstrued when comparing two authors.
“The sole reliance on citation data provides at best an incomplete and often shallow understanding of research, an understanding that is only valid when reinforced by other judgments. Numbers are not superior to sound judgment,” said Dr McGhee.
Clinical trial registration
Andrew Schachat MD, editor-in-chief, Ophthalmology, discussed registration of clinical trials, noting that this issue gained attention due to concerns about publication bias favouring clinical trials with positive results. The idea behind registration is to get all trials out into the public record and it is required by all International Committee of Medical Journal Editors' member journals.
While three years ago registration was the exception; it is now becoming the rule. This is a change for the better. However, there is still room for improvement, said Dr Schachat.
“Registration facilitates the dissemination of information among clinicians, researchers, and patients. It also helps to assure trial participants that the information accrued as a result of their altruism will become part of the public record. However, key challenges remain, including problems with duplicate registrations and a need for better search engines,” he noted.
Reviewer issues
For peer-reviewed journals, the present system an editor uses to decide whether a submitted manuscript should be accepted, revised, or rejected depends on his or her review of comments provided by two or three reviewers who are “experts” in the field and anonymous to the author(s). However, problems plaguing this system have driven interest in an open system of review where the reviewers’ identity is made known to the author(s).
“The open system seems to make more sense because it would level the playing field and result in a review that is fair, just and constructive. However, it may be more difficult to find reviewers, and those who accept may tend to be less critical, resulting in higher acceptance rates for already overburdened journals,” said Arun Singh MD, editor, British Journal of Ophthalmology.
Studies evaluating open systems show these fears are well founded, and Dr Singh noted that while reviewers for papers submitted to the British Journal of Ophthalmology are offered the option for open review, only 15 per cent accept.
“We must move towards an open system of review, and newer technology, like Internet blogs, may make this easier. While we are not there yet, I think we may get there sooner than some think,” he said.
Continuing with the topic of reviewers, Alexander Brucker MD, editor-in-chief, Retina, discussed the challenges and opportunities for their selection that have emerged in the computer age. While the number of manuscripts being submitted to journals has increased thanks to the ease of online submission and recent growth in the number of journals, the number of reviewers has not kept pace with the demand, Dr Brucker said.
On the positive side, the Internet has made it easier to identify and contact potential reviewers, and it has also facilitated the reviewing task itself. However, potential reviewers receiving an email message soliciting their cooperation are also finding it easier to refuse by simply selecting the “decline” button, noted Dr Brucker.
“These are exciting times for medical journal editors. We face a number of challenges, but also have opportunities to seize that can result in an improved final product that is better for our consumers,” he said.
Open-access publishing
Cost issues, commercial influence scandals, and a call for public access to government-funded studies all helped create demand for new models of peer-reviewed medical information delivery. In particular Biomedcentral and the Public Library of Science have quickly gained support and have forced traditional journals to re-evaluate their methods.
However, the concept of what should be open access in the medical field is controversial because while it offers advantages, it can also result in a variety of threats, said Thomas J Liesegang MD, editor-in-chief, American Journal of Ophthalmology.
Quality of content and its interpretation are two major concerns about open access.
“Access to information is crucial to the health and economic wellness of people in all countries, but I maintain that health information is not the same as other information on the web. It needs to be vetted and I also maintain the average consumer does not have the skill to discern good from bad science,” Dr Liesegang said.
There is also the concern that historical scientific literature may be lost as there may not be enough resources to support both traditional and open-access systems simultaneously and continuously. Some journals may not be able to afford to appear in open access and the result could be the termination of small non-profit scientific journals or societies, Dr Liesegang explained.
Open access can be supported by a pay-to-publish model. However, some authors, especially in developing countries, cannot afford the fees, and institutions will have to decide which researchers to support. The result may be that journals become filled with articles supported by commercial interests.
Quality of research published is another issue as some start-up journals in need of material may be willing to accept any manuscript.
“The old subscription-based model has worked well and should not be abandoned until another form of communication is vetted and proven successful,” Dr Liesegang said.
EuroTimes looked at these issues in an earlier article,
Click to read article.
Evidence-based medicine
Randomised clinical trials are considered the gold standard of medical knowledge, and yet the high costs of developing this evidence-based medicine are making it affordable only to multinational drug and device company sponsors, said Francesco Bandello MD, Chinese Journal of Ophthalmology.
The result is a potential for publication of biased and misleading information. And even when the study is high quality, questions remain about how far and to which populations the results can be generalised.
Dr Bandello acknowledged he has no answers to the existing issues. He proposed it may be useful to have trials conceived, designed, and planned by physicians and sponsored by public, independent bodies. Importantly, it is also critical that trials with negative results be published.
“Perhaps we need to pay greater attention to small, smart, independent studies and to focus more on the substance of the research and not just the methods,” he said.
Citation analysis
Citation analysis methods assume more influential articles are cited more often, and these data are being widely used in research environments and by institutions. However, the information can be misleading, said Charles McGhee MD, PhD, editor, Clinical & Experimental Ophthalmology.
Dr McGhee discussed how the perception created by such statistics as citation counts and journal impact factor can differ from reality, and he also reviewed a new parameter – the H factor and provided an example to show it can be misconstrued when comparing two authors.
“The sole reliance on citation data provides at best an incomplete and often shallow understanding of research, an understanding that is only valid when reinforced by other judgments. Numbers are not superior to sound judgment,” said Dr McGhee.
Clinical trial registration
Andrew Schachat MD, editor-in-chief, Ophthalmology, discussed registration of clinical trials, noting that this issue gained attention due to concerns about publication bias favouring clinical trials with positive results. The idea behind registration is to get all trials out into the public record and it is required by all International Committee of Medical Journal Editors' member journals.
While three years ago registration was the exception; it is now becoming the rule. This is a change for the better. However, there is still room for improvement, said Dr Schachat.
“Registration facilitates the dissemination of information among clinicians, researchers, and patients. It also helps to assure trial participants that the information accrued as a result of their altruism will become part of the public record. However, key challenges remain, including problems with duplicate registrations and a need for better search engines,” he noted.
Reviewer issues
For peer-reviewed journals, the present system an editor uses to decide whether a submitted manuscript should be accepted, revised, or rejected depends on his or her review of comments provided by two or three reviewers who are “experts” in the field and anonymous to the author(s). However, problems plaguing this system have driven interest in an open system of review where the reviewers’ identity is made known to the author(s).
“The open system seems to make more sense because it would level the playing field and result in a review that is fair, just and constructive. However, it may be more difficult to find reviewers, and those who accept may tend to be less critical, resulting in higher acceptance rates for already overburdened journals,” said Arun Singh MD, editor, British Journal of Ophthalmology.
Studies evaluating open systems show these fears are well founded, and Dr Singh noted that while reviewers for papers submitted to the British Journal of Ophthalmology are offered the option for open review, only 15 per cent accept.
“We must move towards an open system of review, and newer technology, like Internet blogs, may make this easier. While we are not there yet, I think we may get there sooner than some think,” he said.
Continuing with the topic of reviewers, Alexander Brucker MD, editor-in-chief, Retina, discussed the challenges and opportunities for their selection that have emerged in the computer age. While the number of manuscripts being submitted to journals has increased thanks to the ease of online submission and recent growth in the number of journals, the number of reviewers has not kept pace with the demand, Dr Brucker said.
On the positive side, the Internet has made it easier to identify and contact potential reviewers, and it has also facilitated the reviewing task itself. However, potential reviewers receiving an email message soliciting their cooperation are also finding it easier to refuse by simply selecting the “decline” button, noted Dr Brucker.
“These are exciting times for medical journal editors. We face a number of challenges, but also have opportunities to seize that can result in an improved final product that is better for our consumers,” he said.
Sunday, June 29, 2008
WOC debates the future of refractive surgery
The World Ophthalmology Congress (WOC) got rolling in earnest with a number of sub-specialty sessions. We report from the Cataract and Refractive Surgery programme.
Seven well-known researchers offered their prognostications for what refractive surgery might look like in 2020.
Luis Ruiz MD, a true LASIK pioneer, described a new procedure he has developed which promised to dramatically alter the treatment of presbyopia. The technique, which he calls intraCOR, provides flapless intrastromal ablation using the Femtec femtosecond laser (20/10 Perfect Vision) to achieve reshaping of the cornea without touching epithelium, endothelium, Bowman’s membrane, or Descemet’s membrane.
Compared with existing refractive surgery techniques, intraCOR has multiple advantages that include simplicity, speed and safety. The procedure would avoid complications related to flap ablation and surface ablation, can be performed in thin corneas, does not weaken corneal biomechanics nor induce dry eye, and has a reduced risk of infection.
Dr Ruiz has experience with intraCOR in more than 700 patients who have been treated for presbyopia, myopia, hyperopia and astigmatism using customised patterns. Although this new procedure is still being refined, he presented results from a study of presbyopia treatment that included 45 eyes treated with an identical ablation protocol. All had at least one month of follow-up with a range up to six months. Simultaneous UCVA distance and near results showed 100 per cent of eyes achieved 20/25 or better and J2 or better. At three months no patient had lost even one line of distance best corrected visual acuity. Contrast sensitivity was improved in both photopic and mesopic conditions.
Safety data are encouraging – hysteresis was increased, the corneal resistance factor was unchanged, and there were no changes in endothelial cell density or corneal thickness.
“It would be difficult to find an easier or more effective procedure, and in my experience with refractive surgery for presbyopia, I have never seen such amazing safety and quality of vision,” said Dr Ruiz.
The wavefront data provide an explanation for the outstanding results and reveal the treatment results in a true multifocal corneal with a decrease of defocus that results in a myopic shift and an increase in spherical aberration yielding increased depth of field.
Dr Ruiz concluded his talk by acknowledging the need for further studies, but Jorge Alio MD, PhD, chairman of the session commented that if the promising outcomes being achieved with this important innovation are confirmed in subsequent research, it will completely change the way refractive surgeons approach the treatment of presbyopia.
Myopia prevention
Donald Tan MD, Singapore, discussed prevention of myopia progression in schoolchildren using a treatment called Neurovision. This approach is particularly relevant in Singapore where myopia progression in children occurs at a rate of about 100 degrees per year so that by age 18, about 80 per cent of Singaporeans are myopic.
“As myopia progresses in young children, their spectacles fail to keep up with the progression rate and visual acuity is suboptimal. Neurovision aims to enhance visual acuity without changing the refraction so that theoretically, visual acuity can be shifted toward a more normal level. And, maybe if we are successful in preventing myopia evolution, we will not need to perform so much refractive surgery in the future,” he said.
The approach involves a computerised, Internet-based program that uses visual stimuli to optimise image processing by the visual cortex, enhancing contrast sensitivity by neural adaptation and repetitive visual memory exercise to result in enhanced visual acuity. The exercises use a visual psychophysics tool and are performed every other day for a total of 30 sessions.
More than 1,300 patients have been treated with the Neurovision approach to date both in clinical trials and commercially. Patients have included mild myopes, children and adults with amblyopia, presbyopes, post-refractive surgery patients, and people with high functional visual demands aiming for sharper vision. Results have been published in the literature showing consistently that patients gain more than two lines of ETDRS visual acuity and maintain a majority of the benefit after 12to 18 months.
Its efficacy in reducing myopia progression in schoolchildren was evaluated in a pilot study that had a prospective non-comparative design. Thirty children ages seven to nine years performed the sessions using a treatment adapted to a computer game and were followed for 18 months after completing the program.
The results were consistent with other studies in showing a mean improvement of logMAR visual acuity of about 2.2 lines along with improvement in contrast sensitivity that enabled the children to wear spectacle undercorrection and still get good vision.
“This may be the first effective treatment modality to reduce myopia progression in children without medical or surgical treatment. The results of this pilot study provide the basis for a large-scale, placebo-controlled randomised clinical trial that will be launched in four schools this year,” said Dr Tan.
Ultra-thin corneal inlays
Placement of a corneal inlay represents another approach under investigation for the treatment of presbyopia. Relative to some other techniques, it has a major advantage of being reversible and exchangeable, said Perry Binder MD, US.
Dr Binder discussed the ACI 7000 (AcuFocus) corneal inlay, a small, ultra-thin device placed within a pocket that works via a pinhole effect to increase depth of focus. The goal of this procedure is to create less of a blurred image on the retina up close without interfering with distance vision. The surgery takes just five minutes and cosmesis is excellent.
Almost 400 eyes have been implanted with this inlay and up to three years of follow-up is available. Results show no change in distance uncorrected visual acuity but a significant improvement in near vision with most eyes achieving J1 or better. Similarly positive results are being achieved in a smaller series of patients who have received a thinner model inlay (5 vs 10 microns thick).
“Lots of questions need to be answered, including what is the best material to use, what is the best method to centre the device, and should it be placed through a flap or pocket. However, we have found patients are happy and achieve the benefit of a +1.5 D lens without handicapping their distance visual acuity,” Dr Binder said.
Considering that it takes 10 to 12 years between the time an investigational IOL is first implanted in human eyes and then achieves approval by the US FDA, David F Chang, MD, US, reviewed four accommodating IOLs that have the potential to be available in 2020 because they have already entered clinical trials.
Accommodative IOLs
The Synchrony dual optic accommodating IOL (Visiogen) combines a +32 D moving front optic with a posterior optic of variable minus power based on the individual patient’s needs. It is a silicone, bag-filling IOL that comes pre-loaded in an injector system for delivery through a small incision. The implant is designed to work according to the Helmholtz theory and delivers +2 to +2.5 D of accommodation.
A Phase III US FDA trial including 475 eyes was completed in November 2007. While data are not available from that study, Ivan Ossma, MD, has reported a randomised clinical trial comparing the dual optic accommodating IOL with the ReSTOR multifocal IOL (Alcon Laboratories) in 100 patients. Its results favoured the dual optic IOL for better intermediate vision, contrast sensitivity, reading speed, and problems with haloes. High-definition UBM studies confirm movement of the anterior optic, said Dr David Chang.
Two shape-changing lenses (NuLens, Power Vision) have the potential to provide +8 to +10 D of accommodation. The NuLens features a deformable substance between two rigid plates that is pushed forward through a small aperture by ciliary muscle contraction to create a change in lens curvature. The anticipated commercial design will consist of a haptic unit and a base unit assembled inside the eye.
Jorge Alio MD, PhD, has conducted a pilot trial in 10 blind eyes with BSCVA of 20/200or worse and showed attainment of up to +10 D of accommodation that provided enough magnification so patients could read large print.
The Power Vision accommodating IOL is based on movement of fluid from a reservoir and has been evaluated in five blind eyes. Proof of concept has been demonstrated by anterior segment OCT imaging after pharmacological stimulation of accommodation.
Based on the unexpected finding that a patient implanted with the Light Adjustable Lens (Calhoun Vision) achieved J1 reading vision after treatment for residual myopia, this platform is also being considered as a presbyopia-correcting lens. The algorithm would involve creation of an aspheric design that is gradually sloping off into the periphery with a blend, like a Varilux lens, to create a multifocal lens without discrete rings.
“This approach would reduce problems with glare or haloes and would simultaneously allow guaranteed treatment of residual sphere and cylinder,” Dr Chang said.
Future directions in science, and marketing
Ioannis Pallikaris MD, PhD, Crete, discussed the emerging field of “Presby-optics”. He described evolving knowledge of the underlying physiology of presbyopia that has developed as a result of improved technology for studying the dynamic accommodative process.
“Understanding Presby-optics is about merging this basic knowledge and clinical experience and then applying it to identify the best overall solution for each patient,” he said.
Richard Lindstrom MD, US, concluded the session by providing his thoughts on the future directions for market growth in IOLs for presbyopia correction. Currently, monofocal implants account for 95 per cent of the pseudophakic market with multifocal IOLs accounting for four per cent and the remaining one per cent represented by accommodating IOLs. Looking ahead, Dr Lindstrom expects to see a significant market share shift as monofocal IOLs undergo a steady decline, multifocoal IOLs enjoy an initial surge but then disappear completely, and accommodating IOLs enjoy increasing growth to account for 20 per cent of implants by the year 2020.
“While revenue growth in the cataract IOL market has been occurring at a rate of about three per cent a year, 59 per cent of the growth in IOL revenue in 2006 came from presbyopia-correcting lenses. I expect we will continue to be seeing these new growth patterns into the future. However, surgeons should also remember that monovision with monofocal IOLs remains a popular option that should be offered to patients,” Dr Lindstrom said.
Dr Lindstrom is not alone in his belief that multifocal IOLs are the future of presbyopia-correcting implants. In the 2007 survey of ASCRS members, 76 per cent of respondents said they would favour an accommodating IOL for themselves if they had a presbyopia-correcting lens.
There is also clinical trial evidence that accommodating IOLs can generate satisfactory objective and subjective patient outcomes when used symmetrically or asymmetrically with other types of implants. His outlook for an advance in accommodating IOL market share is also based on the promise of IOLs in development that can provide a greater range of accommodative amplitude.
Seven well-known researchers offered their prognostications for what refractive surgery might look like in 2020.
Luis Ruiz MD, a true LASIK pioneer, described a new procedure he has developed which promised to dramatically alter the treatment of presbyopia. The technique, which he calls intraCOR, provides flapless intrastromal ablation using the Femtec femtosecond laser (20/10 Perfect Vision) to achieve reshaping of the cornea without touching epithelium, endothelium, Bowman’s membrane, or Descemet’s membrane.
Compared with existing refractive surgery techniques, intraCOR has multiple advantages that include simplicity, speed and safety. The procedure would avoid complications related to flap ablation and surface ablation, can be performed in thin corneas, does not weaken corneal biomechanics nor induce dry eye, and has a reduced risk of infection.
Dr Ruiz has experience with intraCOR in more than 700 patients who have been treated for presbyopia, myopia, hyperopia and astigmatism using customised patterns. Although this new procedure is still being refined, he presented results from a study of presbyopia treatment that included 45 eyes treated with an identical ablation protocol. All had at least one month of follow-up with a range up to six months. Simultaneous UCVA distance and near results showed 100 per cent of eyes achieved 20/25 or better and J2 or better. At three months no patient had lost even one line of distance best corrected visual acuity. Contrast sensitivity was improved in both photopic and mesopic conditions.
Safety data are encouraging – hysteresis was increased, the corneal resistance factor was unchanged, and there were no changes in endothelial cell density or corneal thickness.
“It would be difficult to find an easier or more effective procedure, and in my experience with refractive surgery for presbyopia, I have never seen such amazing safety and quality of vision,” said Dr Ruiz.
The wavefront data provide an explanation for the outstanding results and reveal the treatment results in a true multifocal corneal with a decrease of defocus that results in a myopic shift and an increase in spherical aberration yielding increased depth of field.
Dr Ruiz concluded his talk by acknowledging the need for further studies, but Jorge Alio MD, PhD, chairman of the session commented that if the promising outcomes being achieved with this important innovation are confirmed in subsequent research, it will completely change the way refractive surgeons approach the treatment of presbyopia.
Myopia prevention
Donald Tan MD, Singapore, discussed prevention of myopia progression in schoolchildren using a treatment called Neurovision. This approach is particularly relevant in Singapore where myopia progression in children occurs at a rate of about 100 degrees per year so that by age 18, about 80 per cent of Singaporeans are myopic.
“As myopia progresses in young children, their spectacles fail to keep up with the progression rate and visual acuity is suboptimal. Neurovision aims to enhance visual acuity without changing the refraction so that theoretically, visual acuity can be shifted toward a more normal level. And, maybe if we are successful in preventing myopia evolution, we will not need to perform so much refractive surgery in the future,” he said.
The approach involves a computerised, Internet-based program that uses visual stimuli to optimise image processing by the visual cortex, enhancing contrast sensitivity by neural adaptation and repetitive visual memory exercise to result in enhanced visual acuity. The exercises use a visual psychophysics tool and are performed every other day for a total of 30 sessions.
More than 1,300 patients have been treated with the Neurovision approach to date both in clinical trials and commercially. Patients have included mild myopes, children and adults with amblyopia, presbyopes, post-refractive surgery patients, and people with high functional visual demands aiming for sharper vision. Results have been published in the literature showing consistently that patients gain more than two lines of ETDRS visual acuity and maintain a majority of the benefit after 12to 18 months.
Its efficacy in reducing myopia progression in schoolchildren was evaluated in a pilot study that had a prospective non-comparative design. Thirty children ages seven to nine years performed the sessions using a treatment adapted to a computer game and were followed for 18 months after completing the program.
The results were consistent with other studies in showing a mean improvement of logMAR visual acuity of about 2.2 lines along with improvement in contrast sensitivity that enabled the children to wear spectacle undercorrection and still get good vision.
“This may be the first effective treatment modality to reduce myopia progression in children without medical or surgical treatment. The results of this pilot study provide the basis for a large-scale, placebo-controlled randomised clinical trial that will be launched in four schools this year,” said Dr Tan.
Ultra-thin corneal inlays
Placement of a corneal inlay represents another approach under investigation for the treatment of presbyopia. Relative to some other techniques, it has a major advantage of being reversible and exchangeable, said Perry Binder MD, US.
Dr Binder discussed the ACI 7000 (AcuFocus) corneal inlay, a small, ultra-thin device placed within a pocket that works via a pinhole effect to increase depth of focus. The goal of this procedure is to create less of a blurred image on the retina up close without interfering with distance vision. The surgery takes just five minutes and cosmesis is excellent.
Almost 400 eyes have been implanted with this inlay and up to three years of follow-up is available. Results show no change in distance uncorrected visual acuity but a significant improvement in near vision with most eyes achieving J1 or better. Similarly positive results are being achieved in a smaller series of patients who have received a thinner model inlay (5 vs 10 microns thick).
“Lots of questions need to be answered, including what is the best material to use, what is the best method to centre the device, and should it be placed through a flap or pocket. However, we have found patients are happy and achieve the benefit of a +1.5 D lens without handicapping their distance visual acuity,” Dr Binder said.
Considering that it takes 10 to 12 years between the time an investigational IOL is first implanted in human eyes and then achieves approval by the US FDA, David F Chang, MD, US, reviewed four accommodating IOLs that have the potential to be available in 2020 because they have already entered clinical trials.
Accommodative IOLs
The Synchrony dual optic accommodating IOL (Visiogen) combines a +32 D moving front optic with a posterior optic of variable minus power based on the individual patient’s needs. It is a silicone, bag-filling IOL that comes pre-loaded in an injector system for delivery through a small incision. The implant is designed to work according to the Helmholtz theory and delivers +2 to +2.5 D of accommodation.
A Phase III US FDA trial including 475 eyes was completed in November 2007. While data are not available from that study, Ivan Ossma, MD, has reported a randomised clinical trial comparing the dual optic accommodating IOL with the ReSTOR multifocal IOL (Alcon Laboratories) in 100 patients. Its results favoured the dual optic IOL for better intermediate vision, contrast sensitivity, reading speed, and problems with haloes. High-definition UBM studies confirm movement of the anterior optic, said Dr David Chang.
Two shape-changing lenses (NuLens, Power Vision) have the potential to provide +8 to +10 D of accommodation. The NuLens features a deformable substance between two rigid plates that is pushed forward through a small aperture by ciliary muscle contraction to create a change in lens curvature. The anticipated commercial design will consist of a haptic unit and a base unit assembled inside the eye.
Jorge Alio MD, PhD, has conducted a pilot trial in 10 blind eyes with BSCVA of 20/200or worse and showed attainment of up to +10 D of accommodation that provided enough magnification so patients could read large print.
The Power Vision accommodating IOL is based on movement of fluid from a reservoir and has been evaluated in five blind eyes. Proof of concept has been demonstrated by anterior segment OCT imaging after pharmacological stimulation of accommodation.
Based on the unexpected finding that a patient implanted with the Light Adjustable Lens (Calhoun Vision) achieved J1 reading vision after treatment for residual myopia, this platform is also being considered as a presbyopia-correcting lens. The algorithm would involve creation of an aspheric design that is gradually sloping off into the periphery with a blend, like a Varilux lens, to create a multifocal lens without discrete rings.
“This approach would reduce problems with glare or haloes and would simultaneously allow guaranteed treatment of residual sphere and cylinder,” Dr Chang said.
Future directions in science, and marketing
Ioannis Pallikaris MD, PhD, Crete, discussed the emerging field of “Presby-optics”. He described evolving knowledge of the underlying physiology of presbyopia that has developed as a result of improved technology for studying the dynamic accommodative process.
“Understanding Presby-optics is about merging this basic knowledge and clinical experience and then applying it to identify the best overall solution for each patient,” he said.
Richard Lindstrom MD, US, concluded the session by providing his thoughts on the future directions for market growth in IOLs for presbyopia correction. Currently, monofocal implants account for 95 per cent of the pseudophakic market with multifocal IOLs accounting for four per cent and the remaining one per cent represented by accommodating IOLs. Looking ahead, Dr Lindstrom expects to see a significant market share shift as monofocal IOLs undergo a steady decline, multifocoal IOLs enjoy an initial surge but then disappear completely, and accommodating IOLs enjoy increasing growth to account for 20 per cent of implants by the year 2020.
“While revenue growth in the cataract IOL market has been occurring at a rate of about three per cent a year, 59 per cent of the growth in IOL revenue in 2006 came from presbyopia-correcting lenses. I expect we will continue to be seeing these new growth patterns into the future. However, surgeons should also remember that monovision with monofocal IOLs remains a popular option that should be offered to patients,” Dr Lindstrom said.
Dr Lindstrom is not alone in his belief that multifocal IOLs are the future of presbyopia-correcting implants. In the 2007 survey of ASCRS members, 76 per cent of respondents said they would favour an accommodating IOL for themselves if they had a presbyopia-correcting lens.
There is also clinical trial evidence that accommodating IOLs can generate satisfactory objective and subjective patient outcomes when used symmetrically or asymmetrically with other types of implants. His outlook for an advance in accommodating IOL market share is also based on the promise of IOLs in development that can provide a greater range of accommodative amplitude.
Friday, June 27, 2008
Dr John Chang appointed medical editor of EuroTimes China at WOC in Hong Kong
Dr John Chang has been appointed medical editor of EuroTimes China. Dr Chang, who takes up his position from today, June 27, will have responsibility for the editorial content of the magazine working with the newly appointed Editorial Board of EuroTimes China.
The appointment was announced to coincide with the WOC meeting in Hong Kong.
“We are delighted to invite Dr Chang to join our editorial team," said Dr Emanuel Rosen, chairman of the International Editorial Board of EuroTimes. “EuroTimes China is published by the ESCRS and offers Chinese ophthalmologists a forum for discussion, learning and the development of global ophthalmology,” said Dr Rosen.
“EuroTimes China has now reached 8,000 circulation and is still growing and we are confident that with Dr Chang’s guidance we will enhance the communication between the European and Chinese ophthalmologists,” he said.
Dr Chang said he was honoured to accept the position. “EuroTimes China is highly regarded in the ophthalmological community, and I hope to build on its growing reputation, working closely with the ophthalmologists of great talent, influence and learning on the EuroTimes China editorial board,” said Dr Chang.
The members of the Editorial Board of EuroTimes China are:
Dr Yansheng Hao, Dr Ningli Wang, Dr Ying Li, Dr Yuegou Chen, Dr Haike Guo, Dr Yizhi Liu, Dr Jian Ge, Dr Zheng Wang, Dr Dong Fangtian, Dr Xiaoxin Li, Dr Chenjin Jin, Dr Gezhi Xu,Dr Xun Xu, Dr Peiquan Zhao, Dr Zhenping Huan, Dr Jinsong Zhang, Dr Yi Lu, Dr Zinghuai Sun, Dr Jingcai Lian, Dr Xingtao Zhou, Dr Kanxing Zhao, Dr Yan Wang, Dr Ke Yao, Dr Ye Shen, Dr Qinmei Wang, Dr Yaohua Sheng, and Dr Yuehua Zhou.
For more information contact Mr Colin Kerr, executive editor of EuroTimes, at 00 353 86 0473478.
The appointment was announced to coincide with the WOC meeting in Hong Kong.
“We are delighted to invite Dr Chang to join our editorial team," said Dr Emanuel Rosen, chairman of the International Editorial Board of EuroTimes. “EuroTimes China is published by the ESCRS and offers Chinese ophthalmologists a forum for discussion, learning and the development of global ophthalmology,” said Dr Rosen.
“EuroTimes China has now reached 8,000 circulation and is still growing and we are confident that with Dr Chang’s guidance we will enhance the communication between the European and Chinese ophthalmologists,” he said.
Dr Chang said he was honoured to accept the position. “EuroTimes China is highly regarded in the ophthalmological community, and I hope to build on its growing reputation, working closely with the ophthalmologists of great talent, influence and learning on the EuroTimes China editorial board,” said Dr Chang.
The members of the Editorial Board of EuroTimes China are:
Dr Yansheng Hao, Dr Ningli Wang, Dr Ying Li, Dr Yuegou Chen, Dr Haike Guo, Dr Yizhi Liu, Dr Jian Ge, Dr Zheng Wang, Dr Dong Fangtian, Dr Xiaoxin Li, Dr Chenjin Jin, Dr Gezhi Xu,Dr Xun Xu, Dr Peiquan Zhao, Dr Zhenping Huan, Dr Jinsong Zhang, Dr Yi Lu, Dr Zinghuai Sun, Dr Jingcai Lian, Dr Xingtao Zhou, Dr Kanxing Zhao, Dr Yan Wang, Dr Ke Yao, Dr Ye Shen, Dr Qinmei Wang, Dr Yaohua Sheng, and Dr Yuehua Zhou.
For more information contact Mr Colin Kerr, executive editor of EuroTimes, at 00 353 86 0473478.
Thursday, June 26, 2008
ESCRS symposia at WOC in Hong Kong
The ESCRS is hosting two symposia at the World Ophthalmology Congress in Hong Kong, which runs from 28 June until 2 July.
On Sunday 29 June, from 9am to 10.30am, Paul Rosen will chair a session on The Cutting Edge of Cataract Surgery. This will be followed on Sunday afternoon from 4pm to 5pm with a discussion on IOL Based Refractive Surgery chaired by Ioannis Pallikaris.
The full timetable is:
Sunday 29 June
09.00 – 10.30
The Cutting Edge of Cataract Surgery
Chairperson: Paul Rosen UK
09.00 Charlotta Zetterstrom Norway
Paediatric cataract surgery
09.10 Marie-Jose Tassignon Belgium
Bag-in-the-lens in a child’s eye
09.20 Peter Barry Ireland
ESCRS Endophthalmitis Study – further results
09.30 Clive Peckar UK
Toric IOLs
09.40 Richard Packard UK
Phacodynamics
09.50 Gerd Auffarth Germany
Multifocal IOLs
10.00 Jorge Alio Spain
Quality of incision in cataract surgery
10.10 Ioannis Pallikaris Greece
Apodized versus aspheric multifocal IOLs
10.20 Discussion
10.30 End of session
..........
Sunday 29 June
16.00 – 17.30
IOL Based Refractive Surgery
Chairperson: Ioannis Pallikaris Greece
16.00 Ioannis Pallikaris Greece
Introduction
16.08 Klaus Ditzen Germany
Overview of different IOLs in refractive surgery
16.16 Jose Guell Spain
Veryflex Phakic IOL and LAL Light Adjustable Lens: Two years' follow-up
16.24 Joseph Colin France
Update on anterior chamber and posterior chamber IOLs
16.32 Camille Budo Belgium
Artiflex lens
16.40 Michael Knorz Germany
Keys to LASIK in monofocal and multifocal pseudophakes
16.48 Matteo Piovella Italy
Nine pearls to improve outcome in advanced multifocal IOL implantation
16.56 Rudy Nuijts Netherlands
Astigmatism management in cataract surgery with Toric Intraocular Lenses
17.04 Manfred Tetz Germany
Refractive Lens Exchange: Short and long term results
17.12 Discussion
17.30 End of session
On Sunday 29 June, from 9am to 10.30am, Paul Rosen will chair a session on The Cutting Edge of Cataract Surgery. This will be followed on Sunday afternoon from 4pm to 5pm with a discussion on IOL Based Refractive Surgery chaired by Ioannis Pallikaris.
The full timetable is:
Sunday 29 June
09.00 – 10.30
The Cutting Edge of Cataract Surgery
Chairperson: Paul Rosen UK
09.00 Charlotta Zetterstrom Norway
Paediatric cataract surgery
09.10 Marie-Jose Tassignon Belgium
Bag-in-the-lens in a child’s eye
09.20 Peter Barry Ireland
ESCRS Endophthalmitis Study – further results
09.30 Clive Peckar UK
Toric IOLs
09.40 Richard Packard UK
Phacodynamics
09.50 Gerd Auffarth Germany
Multifocal IOLs
10.00 Jorge Alio Spain
Quality of incision in cataract surgery
10.10 Ioannis Pallikaris Greece
Apodized versus aspheric multifocal IOLs
10.20 Discussion
10.30 End of session
..........
Sunday 29 June
16.00 – 17.30
IOL Based Refractive Surgery
Chairperson: Ioannis Pallikaris Greece
16.00 Ioannis Pallikaris Greece
Introduction
16.08 Klaus Ditzen Germany
Overview of different IOLs in refractive surgery
16.16 Jose Guell Spain
Veryflex Phakic IOL and LAL Light Adjustable Lens: Two years' follow-up
16.24 Joseph Colin France
Update on anterior chamber and posterior chamber IOLs
16.32 Camille Budo Belgium
Artiflex lens
16.40 Michael Knorz Germany
Keys to LASIK in monofocal and multifocal pseudophakes
16.48 Matteo Piovella Italy
Nine pearls to improve outcome in advanced multifocal IOL implantation
16.56 Rudy Nuijts Netherlands
Astigmatism management in cataract surgery with Toric Intraocular Lenses
17.04 Manfred Tetz Germany
Refractive Lens Exchange: Short and long term results
17.12 Discussion
17.30 End of session
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