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Surface ablation, LASIK each have clinical advantages, disadvantages
As new technologies dominate, physicians are finding few faults and positive patient outcomes for most of them.
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CHICAGO – LASIK and corneal surface ablation approaches to refractive surgery are “complementary procedures,” each with their own set of advantages and disadvantages, said Scott M. MacRae, MD.
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Scott M. MacRae |
He spoke on the topic “Surface vs. lamellar: Which is best” during the Refractive Surgery Subspecialty Day here at the American Academy of Ophthalmology meeting.
Surface ablation allows the surgeon to treat patients with thin corneas who might be contraindicated for LASIK, Dr. MacRae said. A surface approach also “causes less tendency toward dry eye in patients with borderline tear film,” he said.
In addition, the newer surface procedures such as epi-LASIK offer faster recovery from neurotrophic dry eye, there is less risk of ectasia, no risk of flap complications, and the techniques are simpler and easier to teach than LASIK, he said.
The disadvantage of surface ablation compared with LASIK is the longer recovery period, Dr. MacRae said. In his experience, on average, patients need 3 to 5 days after surface ablation before returning to work, driving or recreational activities.
The disadvantage of surface ablation compared with LASIK is the longer recovery period, Dr. MacRae said. In his experience, on average, patients need 3 to 5 days after surface ablation before returning to work, driving or recreational activities.
“The biggest obstacle is really the slower recovery period,” he said. “It usually takes 1 to 8 weeks for full visual recovery.”
The surgeon also needs to quell patient anxiety during the recovery period, he said. And the surgeon cannot predict exactly how long it will take an individual to recover.
In his practice, Dr. MacRae said, the incidence of postoperative corneal haze has become minimal after PRK with the use of mitomycin and scanning-spot lasers.
Regarding the advantages of LASIK, Dr. MacRae noted that new microkeratomes now allow thinner flap creation.
“We’ve found that flaps under 100 µm have a better postop visual acuity compared with thicker flaps,” he said.
With customized LASIK, Dr. MacRae said, the postoperative induction of higher-order aberrations has been reduced. In a study in 48 eyes of 24 patients in whom one eye underwent conventional LASIK and one underwent customized LASIK, the mean induction of higher-order aberrations was 35% in the conventional LASIK eyes and 18% in the custom-treated eyes, he said.
Dr. MacRae said he still performs LASIK in about 85% of patients in his practice, and surface ablation procedures are reserved primarily for patients with dry eye or anterior basement membrane disease, patients with thin corneas and patients with higher myopia.
“LASIK offers a quicker recovery time, the patient is more comfortable immediately postoperatively, and it’s more accepted,” he said.
Other news in cataract and refractive surgery and practice management from the AAO meeting are recapped in the article below. Most of these items appeared originally as daily coverage from the meeting on OSNSuperSite.com. Look for more in-depth coverage of these and other topics in upcoming issues of Ocular Surgery News.
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Refractive Surgery
Presbyopia-correcting IOLs after refractive surgery
Three U.S-approved IOLs for the correction of presbyopia demonstrated good visual outcomes after implantation in eyes with previous refractive surgery, said Renee Solomon, MD.
She presented data from a series of 12 eyes with previous refractive surgery that were implanted with the Alcon AcrySof ReStor, the Advanced Medical Optics ReZoom or the eyeonics crystalens posterior chamber IOL. Seven eyes were implanted with the ReStor, two with the ReZoom and three with the crystalens.
There were no reported objective or subjective complications from the IOL implantation, Dr. Solomon said. Near UCVA was superior for the ReStor lens, she said, and intermediate UCVA was superior for the crystalens and the ReZoom lens.
Patient satisfaction was similar for all three lenses, with scores of 8 to 9 on a scale of 10 for all three.
“Before implantation of these lenses, you need to address the risk of glare and halos and that best corrected visual acuity may not be as good,” he cautioned.
She presented her results at the Refractive Subspecialty Day.
Retinal detachment risk factors in refractive lens exchange
A comprehensive literature review found a higher rate of retinal detachment in patients who have undergone refractive lens exchange or cataract surgery than in the general population.
Emanuel Rosen, FRCOphth, who performed the review, said patients who have previously undergone refractive lens exchange present with cataract almost 10 years earlier than people in the general population.
“There are about 12 cases of retinal detachment per 100,000 people in the general population,” he said during Refractive Subspecialty Day. Comparatively, the rate is 1.17% after phacoemulsification and 2% after refractive lens exchange, he said.
Mr. Rosen analyzed outcomes from 21 published papers; in a total of 6,522 eyes studied, 117 eyes with myopia suffered a retinal detachment. Mr. Rosen said the risk “increases to 1 in 12 if there was a capsular tear.”
Pseudophakia in myopic eyes “carries a higher risk of retinal detachment than in formerly emmetropic or hyperopic eyes, consequent upon the intrinsic vitreoretinal pathology associated with longer eye globe axial length and the consequent stretching or degeneration of both the vitreous and the retina,” he said.
Surgeons should discuss fully with potential refractive lens exchange candidates the risk factors, Mr. Rosen said. He said long-term case-control studies are warranted to help physicians further identify and quantify risk factors.
Wavefront-optimized equals wavefront-guided for patients
Wavefront-guided and wavefront-optimized LASIK with the WaveLight Allegretto Wave laser achieved nearly identical visual outcomes at 3 and 6 months postop, and neither treatment induced higher-order aberrations, according to information from WaveLight.
In an instructional course, Bill Bond, MD, presented 3- and 6-month results of a randomized study comparing the two techniques, according to a WaveLight press release. Patients with myopia of up to 7 D and astigmatism of up to 3 D were eligible for participation in the multicenter study.
In the 81% of participants with less than 0.3 µm of preoperative higher-order aberrations, equivalent outcomes were achieved with either laser platform, according to WaveLight. For those with preop higher-order aberrations greater than 0.3 µm, aberrations were reduced slightly more with wavefront-guided treatment than with wavefront-optimized treatment on the Allegretto Wave laser. Neither platform induced aberrations after treatment.
“Approximately 82% of all patients reported postoperative visual acuity better or equal to preoperative BCVA, and 55% of patients gained one or more lines of vision. No loss of contrast sensitivity was observed with either platform,” the press release stated.
Wavefront-optimized treatment is the standard treatment on the Allegretto Wave laser. Dr. Bond noted in the press release that “wavefront-optimized LASIK provides considerable benefits to all patients without inducing spherical aberrations. Only a small proportion of patients benefit from wavefront-guided treatments, and it is still unclear how much benefit is achieved.”
NearVision CK after LASIK
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Conductive keratoplasty for the treatment of presbyopia in patients with previous LASIK has shown an “excellent safety profile” in 23 patients with 1 month follow-up, according to Daniel S. Durrie, MD.
Dr. Durrie presented results of a phase 3 multicenter trial of 150 patients with previous LASIK who underwent NearVision CK (Refractec) for the correction of presbyopia. Dr. Durrie presented his results at a press briefing sponsored by Refractec during the AAO meeting.
The first 23 patients showed no flap complications or adverse events at the 1 month follow-up, according to a press release from Refractec. In addition, 96% could read J3 or better, and 96% achieved binocular intermediate vision of 20/20 or better. Preoperatively, 65% of patients achieved that level of visual acuity.
All patients achieved binocular UCVA of 20/25 or better at distance and more than 90% achieved binocular uncorrected near vision allowing them to read J2-sized print or smaller.
NearVision CK is approved in the United States for the treatment of presbyopia and hyperopia; Refractec is seeking to expand approval to include near vision improvement in post-LASIK patients, according to the press release.
Refractec also announced the launch of a study of NearVision CK with LightTouch during the AAO meeting. According to the company, the LightTouch technique “enhances the absorption of the radiofrequency energy” in CK.
Dilation may cause unnatural pupil centroid shift
Use of a dilating agent before refractive surgery may cause problems with wavefront measurements, according to one surgeon.
“Pharmacologics may well interfere with the custom treatment process and shift the pupil centroid from a naturally dilated pupil,” said K. Ashley Tuan, MD, speaking at Refractive Subspecialty Day.
Dr. Tuan examined 32 eyes to determine the effect of medical dilation on wavefront measurement and pupil centroid. Baseline measurements were first performed on the patient’s dark-adapted pupil. Then one drop of 0.05% tropicamide was administered, and wavefront measurements were taken after 10, 20 and 30 minutes.
The average dark-adapted pupil was 6.4 mm in diameter. After administration of the tropicamide, the pupil centroid was found to have shifted with no discernable pattern, Dr. Tuan said.
“After dilation, the pupil center shifted in both the right and left eyes,” she said. “A pupil shift of more than 0.2 mm will reduce contrast sensitivity.” Up to 45% of participants had a shift of more than 0.2 mm, she said.
A diluted tropicamide formula induced less root-mean-square change in higher-order aberrations, but it also resulted in less dilation effect, she said.
“Caution should be exercised” when using medication to dilate the pupil in conjunction with wavefront measurements, Dr. Tuan advised.
Shape change and accommodative mechanism
A previously undescribed “accommodative arching” theory helps to explain the accommodative mechanism of action of both the natural crystalline lens and the crystalens, one researcher said.
Kevin Waltz, OD, MD, described accommodative arching as a nonsymmetrical response when the eye accommodates, “resulting in a characteristic wavefront pattern and increase in higher-order aberrations.” He discussed this theory at a press breakfast hosted by eyeonics during the AAO meeting.
“Accommodative arching is a phenomenon that we have observed in crystalens originally. We then looked back at natural human crystalline lenses to see if the same thing occurred in the normal state, and it does,” he said.
“This was to the best of my knowledge an unintended, incredibly beneficial observation with the design of the crystalens,” he said. “We think some of the unique structures of the crystalens contribute to this observed benefit.”
To validate the theory, Dr. Waltz used the iTrace by Tracey Technologies to measure phakic and aphakic patients focusing on targets at near and distance. Image data from the iTrace showed that the refraction and accommodation from near to distance is asymmetrical.
“After doing thousands of these tests, I have never once seen a symmetrical response,” he said.
One criticism of the crystalens, according to Dr. Waltz, has been that there is no way to show mathematically how it achieves 3 D to 5 D of accommodation, “yet we achieve this,” he said.
Dr. Waltz illustrated the accommodative arching phenomenon by describing a sphere, which has a set surface area. If one area of the sphere is flattened, a compensatory part of the sphere must also change, he said.
“It takes about 0.3 mm of forward motion to account for 10 D [of accommodation], but if you actually change the curvature, then you just need fractions of a millimeter of forward motion to account for diopters of accommodation,” he said. “We know now this can occur sometimes with the crystalens.”
Perceptual training sharpens contrast sensitivity
A vision-training regimen based on visual stimulation and repetition may help sharpen contrast sensitivity and visual acuity in low myopes and patients with residual refractive error after refractive surgery, said Donald T.H. Tan, FRCS.
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Harry A. Zink, MD, AAO’s president elect, addresses the audience at the opening session. Image: Mullin DW, OSN |
Prof. Tan described his experience with the NeuroVision NVC vision correction technology here during Refractive Subspecialty Day. The technology is a noninvasive, patient-specific treatment based on visual stimulation and facilitation of the neural connections responsible for vision, Prof. Tan said. The system uses an Internet-based, computer-generated visual training exercise regimen of patient-specific stimuli to sharpen contrast sensitivity and visual acuity, he said.
“I think for the whole field of ophthalmology this open up essentially a new treatment paradigm,” Dr. Tan told Ocular Surgery News in an interview. “As an ophthalmologist we’re always focusing on treating the eye, but that’s just half of the equation. To see, you need the eye as an optical instrument, but you also need the visual cortex.”
Patients undergo treatment three times a week “until there is no more visual improvement,” Prof. Tan said during his podium lecture. The average treatment lasts 2 to 3 months.
“How we see involves a complex interaction of optics and image processing pathways in the visual system from the cornea to the cortex,” Prof. Tan told attendees.
The system can be used “to enhance contrast sensitivity and hence improve visual acuity in mild to moderate states of visual blur, such as amblyopia, myopia or residual refractive error,” Prof. Tan said.
“The whole concept is now called perceptual learning – learning how to perceive,” Prof. Tan said during his interview. “You do the same thing when you learn how to ride a bike or train for a marathon … you do repetition and you get better at it. The brain remembers how to ride faster and balance better, and this is the same thing.”
At his clinic, 20 patients with an average refractive error of –1.5 D underwent treatment; 15 patients have been followed for at least 6 months.
“Their mean unaided contrast sensitivity function improved to within the normal range,” he said during his lecture.
More than 300 patients have completed treatment with the NeuroVision system at sites in Brazil, China, Korea, Japan, Malaysia, Singapore and the United Kingdom, Prof. Tan said. Some patients had mild myopia at baseline while others had residual refractive error after LASIK, he said.
“The post-LASIK group showed worse contrast sensitivity function in comparison to the low myopia subgroup, although their refraction and unaided visual acuity were similar,” he said.
Of those with low myopia, (mean –1.34 D), after undergoing the Neuro- Vision treatment, a 2.7-line improvement on a visual acuity chart was noted. The average residual refractive error in the LASIK group was –1.14 D, and those patients had a mean improvement of 2.6 lines after the treatment, Prof. Tan said.
“On average, 92% of the eyes had one logMAR line or more improvement after treatment, 72% had two lines, 42% had three lines. The mean manifest refractive error remains unchanged,” he said.
Incremental improvements and patient outcomes
Technological improvements in refractive surgical equipment have led to faster treatment, better registration and a better ability to compensate for pupil centroid shift, according to a surgeon speaking here.
“Incremental improvements in technology” have reduced the amount of higher-order aberrations surgeons induced during refractive surgery and, therefore, have given patients better quality of vision, said Steven C. Schallhorn, MD. He spoke during Refractive Subspecialty Day.
Technology improvements have allowed surgeons to correct mixed astigmatism, higher myopia and even hyperopia, he said. Refractive lens exchange with toric IOLs has “excellent results” as well, he said.
“About the same percentage of patients are 20/20 or 20/26 when they’re implanted with a toric IOL or when they’ve undergone wavefront-guided treatment,” he said.
Other advances seen in the past year include better iris and scleral recognition software on laser refractive systems and better flap creation technology, Dr. Schallhorn said.
“We can’t neglect the influence of the flap on outcomes,” he said. “More and more studies are showing that. The thinner flap we’re now able to make allows a wider range of treatment indications.”
He called the femtosecond laser keratome a “significant improvement” from blade technologies.
“Faster treatment times are just as important,” Dr. Schallhorn said. Faster treatment time should improve outcomes because it lessens corneal hydration variability and allows better patient fixation.
In the future, Dr. Schallhorn said, he would like to see better cyclotorsional eye tracking and customized treatments based on individual corneal biomechanics.
LASIK still most common refractive procedure
An annual survey indicates that LASIK is performed by about 90% of refractive surgeons, said Richard J. Duffey, MD, during Refractive Surgery Subspecialty Day.
After LASIK, the most common refractive surgical procedure is PRK, performed by 68% of respondents, followed by limbal relaxing incisions/IOL (57%), refractive lens exchange (39%) and limbal-relaxing incisions alone (26%). Other refractive procedures were performed by less than 25% of respondents to the survey.
The survey was sent to the 2,000 members of the International Society of Refractive Surgeons; 246 responses were received, a response rate of 16.4%.
The survey asked respondents what their preferred surgical approach would be for several hypothetical refractive surgery candidates.
“For a 30-year-old, –10 D [patient], LASIK is preferred by 40% of surgeons, with phakic IOLs a close second, at 35%” Dr. Duffey said. “For a 45-year-old, +3 D [patient], LASIK is the preferred choice, but for a +5 D [patient], refractive lens exchange is the preferred method.”
The Bausch & Lomb Hansatome was the microkeratome preferred by the largest percentage (40%) of respondents, and 22% of respondents reported using the IntraLase FS femtosecond laser. The Visx Star S4 laser was preferred 2-to-1 over other laser systems, Dr. Duffey said.
Among the IOLs now available for presbyopia correction, “the (Alcon) ReStor lens has already surpassed the (eyeonics) crystalens,” he said.
Monovision is still the most common mode for refractive surgical correction of presbyopia, preferred by 53%. Modified monovision was the second most preferred technique at 23%.
Almost three-quarters of respondents (72%) said they require a minimum central corneal pachymetry between 480 µm and 500 µm for performing LASIK.
An ambulatory surgery center was overwhelmingly the preferred site for implantation of phakic IOLs (78%), Dr. Duffey said.
Comanagement of refractive surgery patients has increased, from 40% of respondents in 2004 to 60% in 2005, he said.
Fewer than half of respondents (44%) reported having a documented case of post-LASIK ectasia in their own surgical patients over the course of their careers. Of those who have seen ectasia, 23% said they have seen only one case, 10% have seen two, and 6% have seen three cases. None of the respondents reported seeing more than 10 cases of ectasia throughout their careers.
Results of this year’s survey will be available on www.duffeylaser.com, Dr. Duffey said.
Crosslinking with Intacs improves ectasia
Crosslinking of corneal collagen fibers, used in conjunction with implantation of an intrastromal corneal ring segment, can improve outcomes in ectasia or keratoconus after LASIK, according to a surgeon speaking here.
Munish Sharma, MD, MBBS, told attendees during a free papers session that corneal collagen crosslinking with riboflavin, dubbed C3-R, increases the number of corneal collagen molecules. Used in conjunction with one Intacs ring segment (Addition Technology) to treat ectasia and keratoconus after LASIK, the riboflavin significantly improves the lower-upper corneal curvature ratio, he said.
The lower-upper ratio is the relationship between the sums of five upper and lower keratometry values, he said.
In a study of 56 eyes treated with and without C3-R after implantation of single-segment Intacs, the mean postop lower-upper ratio and the difference from preop to postop lower-upper ratio significantly improved in the C3-R/Intacs group compared with the Intacs-alone group.
“Intacs causes a mechanical flattening, and C3-R augmented the reversal effect of Intacs,” Dr. Sharma said.
Corneal inlay shows promise for presbyopia in early trials
An intracorneal inlay is a “promising method” of improving near vision, said one surgeon speaking here.
Daniel S. Durrie, MD, spoke about the Acufocus Intracorneal Inlay during Refractive Subspecialty Day. The first human implants of the device were in 2001, and an updated product design was completed earlier this year, Dr. Durrie said.
The Acufocus is an ultrathin device, about 10 µm, he said. It features an opaque biocompatible polymer with optimized small-aperture optics.
An initial study included 57 eyes of 57 presbyopic patients whose mean age was 50 years. Patients in the study could either be natural emmetropes or have had previous LASIK; current refractive error could be between –0.5 and +0.5 D, with a maximum cylinder of 0.75.
Dr. Durrie said the device was implanted in the patient’s nondominant eye. A microkeratome was used to make a flap in the emmetropic patients, or the flap was lifted in those who had previously undergone LASIK. The Acufocus device can be placed under a corneal lamellar flap or in a corneal pocket, he said.
Preoperatively, distance visual acuity in all eyes was 20/20; visual acuity remained unchanged at up to 9 months postoperatively, Dr. Durrie said. Preoperative uncorrected near visual acuity was J9; at the 9-month follow up, all eyes had improved to J1 or better, he said.
“This device is making us think about depth of field and depth of vision,” Dr. Durrie said.
Study pits mechanical, laser microkeratomes
LASIK flaps created with a mechanical microkeratome achieved more consistent and accurate intended flap thickness with a lower total surgery time than flaps created with a femtosecond laser, a study presented here found. But the manufacturer of the laser microkeratome pointed out in response to the study that the standard deviation of the flap thickness was greater with the mechanical device.
Hung Ming Lee, MD, of Tan Tock Seng Hospital in Singapore, discussed the prospective, randomized, contralateral trial of corneal flaps for LASIK using the Zyoptix XP microkeratome (Bausch & Lomb) and the IntraLase FS 15 kHz femtosecond laser during a press event hosted by Bausch & Lomb here during the AAO meeting.
Dr. Lee performed bilateral surgery in 50 patients using the Zyoptix XP to create the flap in one eye and the IntraLase FS in the other.
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Virgilio A. Centurión, MD, left, and I. Howard Fine, MD, moderated a session titled “Intraocular refractive surgery: New frontiers of refractive lens exchange” during the Refractive Surgery Subspecialty Day. Image: Mullin DW, OSN |
Users of the Zyoptix XP “can expect to achieve the same level of precision, predictability and outcomes that have been ascribed to the latest generation laser flap-creation technology,” Dr. Lee said.
For the study, Dr. Lee used an intended flap thickness of 120 microns. The Zyoptix flaps were a mean 4 microns thinner than the IntraLase flaps, according to ultrasound pachymetry, and 11 microns thinner according to optical coherence pachymetry (OCP), he said.
The study found similar standard deviations in flap thickness with the two devices, Dr. Lee said. The Zyoptix XP flaps had a standard deviation of 16.1 microns as measured with ultrasound and 14.4 microns as measured with OCP, while the IntraLase flaps had a standard deviations of 16.2 microns with ultrasound and 15.9 microns with OCP.
Dr. Lee said he still uses both the IntraLase and the Zyoptix microkeratomes in his current practice, and he estimated that he uses them in an equal number of procedures.
“The results of this contralateral study have demonstrated that both technologies deliver excellent performance and precision,” Dr. Lee said, “but more importantly to me, the visual outcomes are equivalent in both high and low contrast conditions.”
During the AAO meeting, officials at IntraLase commented on the findings of Dr. Lee’s study. They said the femtosecond laser keratome flaps had a smaller standard deviation than those produced by the mechanical keratome. IntraLase also noted in a press release that its newest laser, with a speed of 30 kHz, was not used in the study.
Ronald Kurtz, MD, IntraLase vice president and medical director, noted in an interview with Ocular Surgery News. that Dr. Lee measured the achieved flap thickness with both ultrasonic pachymetry and OCP. He said OCP is “consistently more accurate” than ultrasonic pachymetry, and he went on to discuss the flap thickness achieved results as measured by OCP.
Using the data reported by Dr. Lee - that the Zyoptix XP flaps had a standard deviation on OCP of 14.4 µm and the IntraLase flaps had a standard deviation of 15.9 µm - Dr. Kurtz calculated these standard deviations into percentages. The Zyoptix XP flap SD was 13.2%, and the IntraLase flap SD was 11.5%, he said.
Endothelial cell loss with phakic IOL
Phakic IOLs are associated with an elevated rate of endothelial cell loss in the first year after implantation, but the cell loss returns to normal in subsequent years, said Helen K. Wu, MD. She warned surgeons, however, that “ongoing monitoring of endothelial cell loss is imperative” in patients with phakic IOLs.
Dr. Wu, spoke at Refractive Surgery Subspecialty Day about endothelial cell loss after implantation of both anterior and posterior chamber phakic IOLs.
Central endothelial cell density decreases at a rate of about 0.6% annually throughout adulthood, so that by age 40 years people tend to have about 3,000 cells/mm2, and by age 70 the count has decreased to about 2,000 cells/mm2.
After phacoemulsification, Dr. Wu said, “generally speaking, there is a 10% cell loss.”
Two studies of the Artisan/Verisyse (Ophtec/Advanced Medical Optics) iris-supported phakic IOL found cell loss of 10.9% at 36 months and 17.6% at 24 months postoperative. Eyes with anterior chamber depths of less than 3.2 mm exhibited the greatest cumulative cell loss at 3 years, at 9%, according to Food and Drug Administration data, she said.
Three models of angle-supported anterior chamber phakic IOL – the Morcher ZSAL-4, the Domilens-Chiron ZB5M and the Bausch & Lomb NuVita – showed endothelial cell loss of 4.2% at 24 months and 12% loss at 2 years, with stabilization between years 1 and 2, she said.
A posterior chamber phakic IOL, the STAAR Surgical Visian ICL, showed endothelial cell loss of between 2% and 6.57% at 2 years, and 12.3% at 4 years, Dr. Wu said. She noted, however, that the number of patients included in the 4-year data was not high enough to achieve statistical significance.
Dr. Wu said that the safety concerns in the labeling of the Aritisan/Verisyse lens indicate that “if endothelial cell loss continues at the rate of 1.8% per year, 39% of patients are expected to lose 50% of their corneal endothelial cells within 25 years of implantation.”
“The long-term effect on the cornea’s health is unknown,” she said.
Dr. Wu said anterior chamber phakic IOLs tend to be associated with more cell loss than posterior chamber phakic IOLs. She said the ICL’s cell loss “is well below the worry level,” although no long-term data is available. She advised surgeons to continually monitor their patients well beyond the first year after implantation.
Cataract Surgery
MICS complications subside after learning curve
Once a surgeon has completed the learning curve, the complications of microincision cataract surgery (MICS) are similar to those of standard phacoemulsification, said Paul S. Koch, MD.
“This is really a bit of an easy talk because there are no complications with MICS,” he joked to attendees during a free paper session. While the surgeon is learning the technique, however, there are some potential obstacles to overcome, he added.
By definition, the technique requires small and tight incisions, he said, and surgeons should be wary of separation of Descemet’s membrane upon entry into the anterior chamber.
Dr. Koch said many surgeons use three incisions for MICS: two 1.5-mm incisions for cataract removal and one 2.8-mm incision for lens implantation, bringing the cumulative incision length to 5.8 mm.
“Standard phaco uses 3.2 mm,” he said. “MICS requires 52% more incision, not less.”
Infusion volume is less than in standard phaco, but if there is a single bore at the tip of the irrigating instrument it can push away tissue, he said.
“That’s not necessarily a bad thing,” Dr. Koch said. “If there’s a double bore at the sides, it can come out of the anterior chamber if the instrument is pulled towards the incision.”
Aspiration must be controlled to prevent chamber collapse, Dr. Koch said, and lower levels of vacuum are needed compared to standard phaco to maintain chamber stability.
Using MICS increases surgical time, Dr. Koch said.
“It is a less cost-effective and more expensive procedure than standard phaco for the surgeon and the facility,” he said.
During the interactive session, audience members were polled electronically on their experience with MICS. A large majority, 81%, said they had never tried MICS; 16% said they had tried it, but preferred coaxial; and 3% reported preferring MICS. Another poll question showed that 71% of the audience said MICS is a “minor improvement” over standard phaco.
Small-sleeve technique allows 6-mm IOL through sub-2-mm incision
A phaco technique using a small coaxial irrigation sleeve, torsional ultrasound and a new IOL inserter allows the implantation of a standard 6-mm IOL through a sub-2-mm incision, according to Takayuki Akahoshi, MD. He described his technique at a symposium sponsored by ASICO during the AAO meeting.
Dr. Akahoshi said his coaxial phaco technique employs the Alcon Nano Sleeve, a small-diameter sleeve that provides sufficient irrigation and appropriate wound protection, and the new ASICO Royale II injector.
He said he prefers a coaxial approach to ultrasmall-incision surgery, rather than a bimanual technique, for several reasons.
“We can use conventional tools and conventional technique,” with a coaxial approach, he said. ”With bimanual incision you have to make the third incision just for implanting the lens. This is not reasonable.”
Dr. Akahoshi uses the Akahoshi Ultra diamond knife to make the 2-mm main incision, and he makes the side-port incision as small as possible using the Akahoshi Sideport diamond knife. Both knives are made by ASICO.
To allow more irrigation fluid into the anterior chamber, he makes an additional hole himself on the Nano Sleeve, he said.
“The additional hole in the posterior side of the tip pushes away the capsule and reduces the chance of capsule rupture,” Dr. Akahoshi said in an interview with Ocular Surgery News.
“I try to remove the cataract with minimum damage to the incision. This is critical” to protecting the structure of the incision," he said during the interview.
Dr. Akahoshi said he uses the ASICO Hybrid Combo Prechopper to prechop grade 1 and 2 nuclei prior to phacoemulsification. He uses a karate-prechop technique to slice the nucleus in half, rotates the lens and divides it in half again to create four quadrants that are easy to remove.
“The divide-and-conquer method is not suggested because it can damage the incision opening,” he said.
If the nucleus is a grade 3 or higher, Dr. Akahoshi supports the nucleus with a Nucleus Sustainer through the side port to protect the posterior capsule.
Dr. Akahoshi uses the Alcon OZil torsional ultrasound handpiece for phacoemulsification in custom burst mode on the Alcon Infiniti Vision System. Dr. Akahoshi explained that with a conventional handpiece the tip moves in and out, but with torsional ultrasound it swings back and forth. The OZil handpiece is capable of both movements, he said.
It is important to use a bent tip when using torsional ultrasound, Dr. Akahoshi said during the symposium. The 1.1 mm standard Akahoshi tip is commercially available from Alcon, but a straight tip can also be altered, he said.
“You can make your own Akahoshi tip by bending it with needle-nose pliers,” he said. “If you bend too much, the tip may be broken. This is a small modification on the torsional handpiece.”
Dr. Akahoshi said he has implanted more than 4,000 of the 6 mm AcrySof IOL through 2-mm and sub-2-mm incisions using his counter-traction technique.
He uses the new ASICO Royale II injector, placing the lens into an Alcon Monarch C-cartridge manually, making sure he inserts the IOL so that the leading haptic bends and creates an elbow.
“The elbow is key,” he said.
He inserts only the tip of the cartridge into the sub-2-mm incision and allows the sharply bent haptic elbow to enter into the incision. It is also necessary to have a firm eye, or the IOL will not inject into the chamber, he said.
The IOL unfolds in a controlled fashion, and the wound is self-sealing, Dr. Akahoshi said.
Beware potential complications with intracameral medications
Intracameral lidocaine and steroids are effective adjuncts in cataract surgery only if the surgeon pays strict attention to both timing and concentration, said James P. Gills, MD.
“If either lidocaine or steroids are left in the eye for a long period of time, you could end up with toxic anterior segment syndrome [TASS],” Dr. Gills said. His research team at the University of South Florida has “only observed TASS in patients who received intraocular lidocaine,” he said.
He has been using intraocular lidocaine in cataract surgery since 1991 and began using it routinely in 1995, he said.
“Like all medications, it’s great in proper dilutions,” he said.
With experience now in close to 50,000 cases in which intracameral injection of triamcinolone acetonide was used, Dr. Gills said he has found the effective dosage to hover around 0.5 mg.
“Using Kenalog (triamcinolone acetonide, Bristol-Myers Squibb), we saw less endothelial cell loss with dilution and ascorbic acid,” he said.
He warned that Kenalog “decreases the ability of the eye to fight infection” if left in the eye for too long.
Dr. Gills said cataract patients with Fuchs’ dystrophy “did better with intraocular Kenalog; only 10% needed a transplant post surgery.”
In general, he said, blurred vision may be a complication of Kenalog use even if the patient’s visual acuity is has 20/20.
“Always consider the dosage and time in the eye,” he said. “Use intracameral medications, but carefully and judiciously.”
Viscoelastic technique aids trypan blue staining
Applying trypan blue dye to the anterior lens capsule with a modified soft-shell viscoelastic technique can aid in the performance of capsulorrhexis in mature cataracts, a speaker said here.
Capsulorrhexis can be challenging in advanced white or black cataracts because visualizing the capsule is difficult, said Steve A. Arshinoff, MD. He described a modification of his ultimate soft-shell viscoelastic technique that he said facilitates staining of the capsule in these cases.
Dr. Arshinoff said the original method for trypan blue capsule staining described by Gerrit Melles, MD, involves injecting the dye into the anterior chamber under an air bubble and then washing it out. While this method successfully stains the capsule, it uses a large amount of dye and results in staining of other anterior segment structures, as well as possibly penetrating to the vitreous, he said.
In Dr. Arshinoff’s technique, before trypan blue is injected, the chamber is filled to about 90% with Healon5 (sodium hyaluronate 2.3%, AMO). A space is left above the lens capsule, and into this space “a tiny bit” of dye is injected, he said.
“We paint trypan blue over the capsule with a tuberculin syringe and then wash out the excess with balanced salt solution,” he said. “This avoids injecting too much dye and provides a crystal clear view for performing the capsulorrhexis.”
Dr. Arshinoff’s presentation was given during the symposium Spotlight on Cataract Surgery 2005, which featured interactive polling of the audience. During his presentation, the audience was asked, “What is your preferred dye for capsule staining?” The preferences were 13% for indocyanine green, 60% for the commercially available Vision Blue formulation of trypan blue from Dutch Ophthalmic International and 27% for trypan blue formulated by a pharmacy.
Practice Management
Public perception matters in ophthalmic political issues
The public is the newest ally in ophthalmologists’ battle to limit optometric scope of practice, according to H. Dunbar Hoskins, MD.
Dr. Hoskins said a recent survey by the National Consumers League showed that “people are confused about who is doing eye care.”
“(The survey showed) that people want to know who is doing (surgery), and they do care who does what to them,” he said during the AAO meeting’s opening session. “The battle continues, and everyone must participate.”
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Susan H. Day |
In her address during the opening session, outgoing AAO President Susan H. Day, MD, said that the issue of maintaining patients’ trust is perhaps the most important facing ophthalmologists today.
While this is impossible to quantify, “we are in an age of increasing accountability” as the public begins to question and notice ophthalmologists’ relationships with industry, she said.
“We must understand that these things matter whether we want to believe it or not,” Dr. Day said. “The public has a knack for judging our trustworthiness.”
Randolph L. Johnston, MD, OCS, the AAO’s senior secretary for advocacy, agreed that the public is starting to take notice of the AAO’s national Surgery by Surgeons campaign. He thanked the Academy’s coalition partners, including the state, subspecialty and local ophthalmology societies for their “generous contributions to the ophthalmologic surgical scope fund.”
The campaign seeks to bar optometrists from performing laser surgery and prescribing certain drugs, both of which are viewed by the AAO as the domain of ophthalmologists only.
Dr. Johnston specifically acknowledged James Rohack, MD, the American Medical Association’s immediate past chairman, and Philip Shettle, MD, president of the American Osteopathic Association, who also is an ophthalmologist, for their support of the Surgery by Surgeons campaign.
Aside from the scope-of-practice battle, Dr. Hoskins noted that the issue of reimbursement “remains our jobs (Nos.) 1, 2 and 3” in Washington.
He called on ophthalmologists to contact their representatives in Congress to cancel a proposed fee cut of 20% to 30% that is currently under consideration in the House of Representatives. He said ophthalmologists deserve a fee increase in light of rising costs.
“Simply cutting this to a net zero increase is not an effective solution,” Dr. Hoskins said.
Materials for recertification exam available next year
Study materials and review courses will soon be available to help ophthalmologists prepare for the new closed-book Maintenance of Certification exam, according to Richard L. Abbott, MD.
Dr. Abbott, the AAO’s secretary for quality of care and knowledge based development, summarized the structure of the exam. He explained that public pressure was the driving force behind the changes to the American Board of Ophthalmology recertification exam.
The Demonstration of Ophthalmic Cognitive Knowledge (DOCK) is a closed-book exam that will replace the current open-book exam, he said.
“This is going on medicine-wide; it is not just our board, but all boards in medicine. It has gone from a primitive model aimed at identifying substandard candidates toward an emphasis on reflective self-learning and self-improvement for all,” he said.
“We were asked to identify and define areas of knowledge that are important to deliver quality eye care,” Dr. Abbott said.
Topics for each subspecialty were ranked according to relevance. The curriculum consists only of the most relevant material; anything deemed below “most relevant” cannot be asked as a question on the exam, he said.
Online self-exams will be available for purchase next year, Dr. Abbott said. The Web-based self-reviews are called Periodic Ophthalmic Review Tests (PORT).
Two PORTs must be completed during the Maintenance of Certification cycle. The PORT exams are designed to identify strengths and weaknesses and also to reflect the content of the DOCK exams.
“I know everyone out there is concerned about this closed-book exam,” Dr. Abbott said. “The whole idea is that we have a curriculum. We’re the only specialty in all fields of medicine to have a clearly defined curriculum that you can put your arms around.”
All questions for the PORT and DOCK exams will be derived from the curriculum outlined by the AAO, he said.
Dr. Abbott said the first annual recertification exam is scheduled for September 2006, and a study course is being planned for next summer in Chicago. The actual exam will be computerized, with at least 250 testing sites around the country, he said.
A recertification timeline and information on exam preparation can be found at www.abop.org and www.aao.org/aao/ame.
Documentation is best protection against litigation
Meticulous documentation of patient encounters is the best defense against lawsuits stemming from retinal detachments, said Marvin F. Kraushar, MD.
During a free paper session, Dr. Kraushar outlined a number of risk-prevention strategies surgeons can employ to prevent being named in a lawsuit brought by a patient with a retinal detachment.
“This is a high-risk diagnosis for both the patient and for the ophthalmologist,” Dr. Kraushar said. “If there is any possibility of a retinal tear or detachment, be extremely careful.”
Clearly identifying the risks of surgery preoperatively and ensuring the patient’s comprehension of the risks is important, Dr. Kraushar said.
“Don’t think of informed consent as a legal obligation. It is a powerful opportunity for risk prevention,” he said.
Likewise, informed refusal should be documented, Dr. Kraushar said. He called it the physician’s “duty to disclose the risks of non-treatment.”
The physician should document every communication with the patient, he advised. This will help create a complete record of interaction with the patient.
“Every record you write is a potential legal document,” he said.
The physician can even be sued by a patient he has never seen, Dr. Kraushar said. For instance, he said, a person might call to make an appointment complaining of flashes and floaters, but not be given a timely appointment. If, subsequently, a retinal detachment occurs, the practice could be at risk for legal action.
“Instruct your staff about emergency symptoms,” he suggested.