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Endophthalmitis should not overshadow other severe complications, surgeon says
Annual ESCRS meeting featured continuing debate over and new findings from the endophthalmitis study 1 year later.
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STOCKHOLM – Endophthalmitis is generally considered the most severe complication of cataract surgery, but there are other complications that occur more frequently and have similarly devastating consequences, according to the Binkhorst Medal Lecturer here. Cataract surgery has become a safer and more effective procedure over the last 10 years, Ulf Stenevi, MD, said.
“We are now operating on the right patients, at the right time and with the right technology,” he said. But the potential for complications remains.
Antibiotic prophylaxis for endophthalmitis was introduced in Sweden between 1997 and 1998, and since then the rate of this complication has decreased to 0.04%.
“However, visual results remain poor, with 40% of patients not regaining useful vision and 20% achieving 20/40 or better,” he said.Other conditions, such as unintentional aphakia, posterior bullous keratopathy or late lens dislocation, may occur, and final visual outcomes are statistically not better.
Unintentional aphakia is 10 times more frequent than endophthalmitis, occurring in 0.5% of cataract patients, he noted. Visual outcomes are equal to those of endophthalmitis.
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Dr. Stenevi said that bullous keratopathy also has a fairly high incidence. Onset can be immediate, but may occur several years after surgery.
“Most of these cases end up having a corneal graft, with a high chance of subsequent graft failure,” Dr. Stenevi said.
In the corneal register, of the 273 patients who received a corneal graft for bullous keratopathy, graft failure was reported in 32% of the cases and 49% had less than 20/200 vision. Vision of 20/40 or better was achieved by 50% of the patients.
Late dislocation of IOLs may occur years after surgery. A survey from 2005 found that the incidence of this complication has increased in recent times.
“This increase might be due to the fact that we now use more capsular tension rings, do more refractive surgery and inject more drugs into the eye, with side effects that have not been properly investigated,” Dr. Stenevi said.
Data show that the visual outcomes of this complication are also poor.
Below are additional highlights from the ESCRS meeting as first published on the OSN SuperSite. Look for in-depth coverage of selected items in upcoming issues.
Cataract Surgery
Current IOL models leave no ‘moving space’ for pseudoaccomodation
High frequency ultrasound technology provides accurate, dynamic views of how IOLs fit in and interact with ocular structures, and shows where and how most of the problems of currently available IOL models originate.
“We are at a turning point, where we cannot any longer follow the usual pathways,” Philippe Sourdille, MD, said. “IOL technology must evolve on the basis of what we have been able to see through these advanced viewing systems.”
Although we know that capsular bag diameter varies considerably between patients, we still produce IOLs with the same diameter, Dr. Sourdille said.
Ultrasound anterior segment analysis of 26 patients followed for 10 months showed excellent central PCO prevention, but some adherence of the anterior capsule to the IOL optic, leading to a not perfectly transparent, partially fibrotic system.
Inappropriately-sized IOLs deform the anatomy of the capsular bag/zonule/ciliary body system, causing IOL-related complications and preventing a potential restoration of accommodative movement, he added.
“The excellent studies carried out in Rome with the HiScan Optikon 2000 system by Marina Modesti, MD, demonstrated that accommodation movements disappear with age, but partially reappear after cataract surgery,” he said. “With the currently available IOL models, we don’t exploit this possibility.”
Most conventional IOLs are in fact too large, he said. They stretch the capsular bag, and settle in a backward position which certainly does not encourage pseudoaccommodation.
“A properly-sized IOL should always leave a ‘moving space’ between the ciliary ring and the capsular bag’s equator. If the implanted bag is behind the ciliary ring, there is no space, and therefore no movement is possible,” Dr. Sourdille said.
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Image: Mullin D, OSN |
Experts debate pros and cons of intracameral cefuroxime
Concerns about the unavailability of cefuroxime in single sterile doses for intracameral injection are the main reason why U.S. cataract surgeons do not use this antibiotic for prevention of postoperative endophthalmitis, according to a surgeon speaking at a pros and cons debate.
In the ESCRS endophthalmitis study, intracameral injection of cefuroxime at the end of cataract surgery was shown to be a powerful agent in preventing this severe complication, reducing by a factor of five the risk of contracting endophthalmitis after phacoemulsification. Intracameral cefuroxime was therefore included in the recent ESCRS endophthalmitis prophylaxis guidelines.
“This technique was first developed in Sweden, and its efficacy was demonstrated retrospectively and prospectively in over 400,000 Swedish patients,” Peter Barry, MD, ESCRS study coordinator said.
Despite this evidence, intracameral cefuroxime is not approved by the U.S. Food and Drug Administration and is therefore not used in the United States.
“There are several concerns about the use of cefuroxime. First is its inability to provide coverage for pseudomonas,” Randall J. Olson, MD, said. Allergic reactions were also reported in some patients treated with this antibiotic.
“However, the main problem is the fact of not having single-unit sterile doses of the drug for intracameral use. Preparing our own dilution exposes us to the risks of kitchen pharmacy, with potential medical-legal consequences, which are probably even more an issue in the U.S. than they are in Europe,” he said.
Dr. Barry, on the other hand, expressed concern about the wide preoperative use of intracameral vancomycin and topical latest-generation fluoroquinolones. As stated in the ESCRS guidelines, these antibiotics should be strictly reserved to treatment.
Resistance to antibiotics, including the latest-generation fluoroquinolones, is becoming a major concern, Dr. Barry noted, and increasingly so because these agents are widely used in the animal husbandry business in the United States.
“In 2 years time, the fourth- generation fluoroquinolones will become useless if you have this antibiotic drug policy,” he said.
“I don’t think that vancomycin should be used for prophylaxis, and personally, I am not convinced it works because it is very slow in its action. The fluoroquinolones are rapid, but the sad news is that the cat is out of the bag already. The government should have blocked their use in animal husbandry 3 or 4 years ago,” Dr. Olson said.
He said he believes that if unit doses were manufactured and approved, intracameral cefuroxime would become the international standard.
In an interview with Ocular Surgery News, Dr. Barry explained that there is a manufacturing problem in preparing cefuroxime in small doses.
“Biological stability is a problem, but some small companies are trying to solve it, and I truly hope that over the next several months the preparation we need will be available,” he said.
Introduction of intracameral cefuroxime defeated endophthalmitis in one hospital in England
The introduction of intracameral cefuroxime and povidone iodine wash at the end of surgery, as indicated by the ESCRS endophthalmitis study, have proven effective in reducing the incidence of this complication to low numbers at one hospital in England.
“Following a cluster of cases (nine in a 4 month period), certain changes were made since May 2004 to our protocol in terms of perioperative management, including disposable bimanual irrigation/aspiration handpieces, the use of intracameral cefuroxime and povidone iodine wash at the conclusion of the case,” Richard Packard, MD, said.
Of the 7,584 cases operated between May 2004 and April 2007 by 24 different surgeons, only one developed culture-negative endophthalmitis. The patient recovered after intravitreal antibiotics to achieve an unaided vision of 20/30 at 3 weeks postoperatively.
“This incidence of 0.013% is well below that reported in the peer reviewed literature,” Dr. Packard said. He noted that this low rate was obtained despite many surgeons of varying skill levels performing the surgery.
“Surgeons included six consultants, three associate specialists and 15 trainees of varying skills,” he said.
Use of intracameral cefuroxime growing rapidly in Ireland
Since the publication of the ESCRS endophthalmitis study, a high number of cataract surgeons have introduced the use of intracameral cefuroxime in Ireland, according to a survey.
“More than 50% of the surgeons have altered their practice to date, and about 36% are waiting for intracameral cefuroxime to become commercially available,” P. O’Reilly, MD, said.
All 51 consultant ophthalmic surgeons in Ireland were invited to participate in the survey, and all of them responded to the questionnaire.
“All surgeons were aware of the ESCRS study results. Only three surgeons used intracameral cefuroxime already, while 26 adopted this practice after seeing the results of the study. The majority of them have the single doses for injection prepared by hospital pharmacies,” he said.
Of the surgeons who don’t use intracameral cefuroxime, a minority don’t believe it to be superior to what they currently use or feel that intracameral antibiotics are unnecessary.
“However, the majority don’t use it because it is not licensed and because they are concerned of the potential drawbacks. A commercially available and biologically stable product would greatly increase the use of intracameral cefuroxime,” Dr. O’Reilly said.
Silicone confirmed as significant risk factor for endophthalmitis
The ESCRS endophthalmitis study also shows that patients receiving a silicone IOL are three times more likely to develop endophthalmitis than patients implanted with an acrylic IOL, according to a speaker.
“We re-examined the data of the ESCRS study concerning the role of lens material in determining the risk rate for endophthalmitis. The question was whether it was the hydrophobic nature of the silicone IOL or the silicone material itself that was responsible for an increased rate of endophthalmitis,” Peter Barry, MD, the study coordinator, said.
By comparing the endophthalmitis rates of hydrophobic silicone lenses with other hydrophobic and hydrophilic lenses, the researchers concluded that the hydrophobic/hydrophilic character of the optic material is not significant. However, silicone, unlike other materials, was significantly associated with endophthalmitis.
“For total endophthalmitis, the rate of ‘other’ hydrophilic materials is 0.17%, for ‘other’ hydrophobic [materials] it is 0.11%, while for silicone it is 0.32%. For proven endophthalmitis, the rate of ‘other’ hydrophilic [materials] is 0.1%, for ‘other’ hydrophobic [materials] it is 0.07%, while for silicone hydrophobic it is 0.25%,” Dr. Barry said.
New aspheric IOL shows excellent quality of vision but high capsulotomy rate
A multicenter European study demonstrates that the aspheric Akreos Advanced Optics (AO) IOL from Bausch & Lomb produces a significant improvement in functional vision — contrast sensitivity and low contrast visual acuity — in the early postoperative months.
“Results tend to overlap at 6 months, but at 1 and 3 months they are significantly better than with the standard Akreos Adapt,” Ann Haustermans, MD, said.
In the study, a total of 69 patients requiring bilateral cataract surgery received either a standard Adapt IOL or the Adapt AO, randomly assigned to the right or left eye.
Total higher order aberrations and spherical aberration were also significantly reduced from the early days.
The Akreos Advanced Optics IOL is based on the Akreos Adapt lens that has been on the market in Europe for 7 years. It is made of the same hydrophilic acrylic polymer and has four haptics to ensure stability and centration in the capsular bag. In addition, the Adapt AO lens offers a 360º posterior square edge in order to reinforce its mechanical barrier against PCO formation.
“The barrier effect remains a weak point of the lens. In the 40 patients who have completed the study, 21 eyes with the Adapt and 13 eyes with the AO lens have already had a Nd:YAG laser capsulotomy,” Dr. Haustermans said.
Surgeon: Lens for pseudophakic eyes shows promise as adjunct
Early results for an IOL designed for implantation in pseudophakic eyes show the lens’ potential for use in a variety of indications, according to Michael Amon, MD, of the University of Vienna.
Dr. Amon discussed the important role that the Sulcoflex lens from Rayner could have in modern ophthalmology.
“There is a great demand for exact refractive results after cataract surgery, especially after refractive lens exchange,” he said.
The lens is a single-piece hydrophilic acrylic IOL with a 6.5-mm diameter, a haptic diameter of 13.5 mm and an angulation of 10°, according to Dr. Amon. It is designed for implantation under the iris in the sulcus.
Dr. Amon implanted the lens in six eyes and followed them for 4 months. Patients averaged 55 years of age.
According Dr. Amon, the results showed that eyes maintained normal IOP, ranging from 11 mm Hg to 22 mm Hg. Decentration was less than 0.5 mm, and laser flare cell meter results showed that the surgery caused less trauma than IOL explantations.
The lens can be used for enhancements after refractive lens exchange, or it can be combined with toric IOLs or with blue light filters, Dr. Amon said. “I think this lens concept is promising,” he said.
Macular integrity maintained after posterior capsulorrhexis, optic buttonholing
Cataract patients with no macular pathology can maintain macular integrity after surgery involving a posterior capsulorrhexis and posterior optic buttonholing, according to Rupert M. Menapace, MD. Optic buttonholing also produced similar outcomes to conventional in-the-bag IOL implantation, he noted.
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Dr. Menapace discussed the results of a study he conducted with colleague Eva M. Stifter, MD. The study included 100 eyes of 50 patients with age-related cataract and normal macular function, all of whom underwent same-day bilateral cataract surgery.
One eye of each patient was randomly assigned to cataract surgery involving posterior optic buttonholing. In the contralateral eye, surgeons performed conventional in-the-bag IOL implantation, with an intact lens capsule.
Optical coherence tomography imaging was performed at 1 day, 1 week and 1 month postop to evaluate changes in macular integrity.
The researchers found that no qualitative changes occurred in any patients at 1 month follow-up compared with baseline. Macular thickness measurements were also statistically similar, Dr. Menapace said.
No patients experienced vitreous herniation into the anterior chamber. Also, postoperative visual acuity and IOP were similar between groups.
In 58% of cases, a small, round central anterior vitreous surface puncture was seen. However, no cases showed prolapse out of the vitreous body, and the puncture did not significantly affect macular thickness measurements, Dr. Menapace said.
“Compared to standard in-the-bag implantations, primary posterior buttonholing of the optic through the primary posterior capsulorrhexis does not increase macular stress in terms of retinal thickness and morphology changes, as measured by high-resolution OCT,” he said.
Pediatric primary IOL implantation challenging but possible
Cataract surgery and primary IOL implantation in children younger than 2 years of age is safe, although it is associated with a high incidence of visual axis opacification requiring additional surgery, according to a study presented by Anju Rastogi, MD.
Dr. Rastogi and N.R. Bamrolia, MD, evaluated outcomes for 30 eyes of 30 children younger than 2 years of age who were treated for visually significant congenital cataract.
The researchers randomly assigned eyes to one of two treatment groups. The first group of 15 eyes underwent surgery involving anterior and posterior continuous curvilinear capsulorrhexis and anterior vitrectomy. Surgeons then implanted an acrylic foldable IOL in-the-bag. The second group of 15 eyes received an acrylic foldable IOL implanted in the ciliary sulcus after undergoing pars plana lensectomy and anterior vitrectomy, according to the study.
All children had at least 6 months of follow-up.
Drs. Rastogi and Bamrolia found that most eyes — 29 of 30 — had an improvement in fixation. However, four of 15 eyes (26.66%) in each group developed visual axis opacification at an average of 10 weeks postop and required pars plana membranectomy, Dr. Rastogi said.
Uveitis was the most common complication and was experienced by 60% of eyes in the first group and 53.3% of eyes in the second group. In all cases, the uveitis had resolved by 1 month follow-up.
“Primary IOL implantation in children less than 2 years of age is feasible and safe,” Dr. Rastogi said.
Antibiotic-soaked IOLs possibly more effective than topical, intracameral delivery
Antibiotic-soaked hydrophilic IOLs may be an alternative to intracameral antibiotics in the prevention of endophthalmitis following cataract surgery, according to Dr. Olson.
“The emerging resistance to antibiotics, topical and intracameral, may push this more aggressive approach,” he said.
In a study, the efficacy of antibiotic-soaked IOLs using 0.3% gatifloxacin and 0.5% moxifloxacin was evaluated and compared with topical administration of the same agents, according to Dr. Olson. Antibiotic concentration was evaluated at 4, 8 and 12 hours.
IOL-delivered antibiotic concentration was significantly higher at all three time points with gatifloxacin, and at 4 and 8 hours with moxifloxacin. No sign of toxicity was reported.
“IOLs soaked with antibiotic can provide a high level of antibiotic concentration for 8 to 12 hours. If an even more aggressive approach is needed, supplementation with topical or even intracameral delivery can be provided,” Dr. Olson said.
In the future, new IOL materials could be developed for better penetration and concentration of antibiotics, and pre-soaked lenses could be provided.
“We should also create an IOL that releases antibiotics more slowly for prolonged effect,” Dr. Olson said.
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Intracameral delivery of mydriatics safe, effective
Swedish experience demonstrates that intracameral delivery of mydriatics is safe and effective, according to Anders Behndig, MD, of Umea University Hospital.
“Mydriatics can be injected into the anterior chamber directly, thus bypassing the corneal barrier, which slows down and limits drug penetration,” Dr. Behndig said.
The effect is very rapid and a smaller dose of the active agent can be used.
“You need only about 20% of the dose used for topical instillation,” he said.
Pupil diameter will not be as large as with topical delivery, but this slight drawback is counterbalanced by the more durable effect, which prevents the pupil from constricting during surgery, according to Dr. Behndig.
“We found that the duration of the mydriatic effect was in fact a bit too long, so we modified the formulation of our mydriatic cocktail by omitting cyclopentholate and epinephrine infusion,” Dr. Behndig said.
The final formula is a combination of xylocaine 1% and methaoxedrine 1.5%.
“We use it routinely in our surgery, with no local side effects and less systemic side effects than topical instillation,” he noted.
Patient feedback on first eye important to success of bilateral IOLs
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Waiting for patient feedback on the outcomes of the first eye is the best way to choose the optimal IOL for the second eye when considering bilateral implantation, according to Richard L. Lindstrom, MD, Chief Medical Editor of Ocular Surgery News.
Dr. Lindstrom explained a concept he called “staged implantation,” which is based on patient input.
“This is a concept that makes sense clinically,” he said.
Dr. Lindstrom described his clinical experience with the concept and said that he found the best method is to implant the first lens and then schedule the second eye 2 to 4 weeks later.
“If the patient is happy, use the same lens in the second eye,” he said.
However, he recommended mixing IOLs if the patient is unhappy with the first lens. For example, he said that if a patient is implanted with one type of multifocal and says near vision is great, but he has trouble with night vision, then it is best to choose something different to compensate in the second eye.
“I encourage you to take a look at utilizing staged implantation,” he said.
Preoperative aberration measurement determines customized aspheric IOL selection
Aspheric IOLs can effectively be selected on the basis of preoperative corneal spherical aberrations, according to a study presented here.
“Although based on a small number of eyes so far, this study demonstrates the feasibility of customizing the selection of aspheric IOLs based on corneal spherical aberration,” Mark Packer, MD, said. “Additional psychometric testing will be carried out to analyze the effect of customization on functional vision.”
Patients presenting for cataract surgery who desired monofocal distance correction were offered aspheric IOL implantation based on a postoperative total ocular spherical aberration of zero. Preoperative corneal elevation measurements obtained with the iTrace corneal topographer (Tracey) were used to determine Z(4.0).
The appropriate aspheric IOL was selected for each eye based on the best complementary fit to the cornea. Postoperative total ocular wavefront measurements were compared with predicted residual spherical aberration to ascertain the accuracy of customization.
“Mean postoperative total spherical aberration was very near to zero. Predictability was very high, with a very small difference between the predicted and achieved total ocular spherical aberrations,” Dr. Packer said.
Of the selected IOLs, the Tecnis Z9000 (Advanced Medical Optics) proved to be the best suited in two-thirds of the cases.
The study is ongoing, and a larger number of patients will be recruited.
Study: Blue-light filter does not affect contrast sensitivity, color vision
The blue-light filter found in one blue-blocking IOL does not affect color vision or contrast sensitivity, according to Ulrich Mester, MD.
“Color vision and contrast sensitivity under different lighting conditions were measured with two HOYA IOLs, the AF 1UV and AF 1UY, which are identical with the exception of a blue-light filter in the AF 1UY,” Dr. Mester said.
A total of 102 eyes of 51 patients were included in the prospective, randomized intraindividual multicenter study.
Contrast vision was assessed with the F.A.C.T. and low contrast ETDRS charts. Color vision was assessed using the Farnsworth-Munsell 100 Hue Test. All tests were performed under photopic and mesopic lighting conditions at different follow-up time points.
“No difference in contrast sensitivity was found between the two lenses. Evaluating color vision, the total error score (TES) was found to be significantly higher in the eyes implanted with the blue-blocking IOL at 3 and 6 months, both under mesopic and photopic lighting condition. This difference, however, was no longer found at the 12-month visit,” Dr. Mester said.
Although the tests reported this transient effect on colors, no patient reported impaired color vision in daily life.
The second arm of the same study will investigate the efficacy of blue-blockers for protecting against age-related macular degeneration and cataract.
Surgeon: Opacification from silicone oil contact can occur in IOLs
A case study showed the presence of silicone oil from pars plana vitrectomy with silicone oil remaining in the eye damaged a posterior chamber IOL enough to require explantation, according to Milan G.J. Izak, MD.
Dr. Izak presented a case in which a posterior chamber IOL required explantation following contact with silicone oil that remained in the eye after four previous pars plana vitrectomies.
A 20-year-old man presented with decreased vision from opacification of an Aqua-Sense hydrophilic acrylic posterior chamber IOL. He had previously undergone four pars plana vitrectomies, and silicone oil was left in the posterior chamber due to repeating preretinal re-proliferation, according to Dr. Izak.
The patient was then implanted with an Aqua-Sense posterior chamber IOL 26 months after the fourth vitrectomy. Eighteen months after the implantation, he presented with decreased visual acuity from lens opacification.
“A unique pattern of dystrophic calcification on the lens surface only was observed under light microscopy,” Dr. Izak said.
Dr. Izak also noted that since this case in his hospital, he has observed other cases of opacification occurring with both silicone and hydrophilic acrylic IOLs when they were exposed to silicone oil.
“At the presence of silicone oil in the vitreous cavity, neither silicone nor hydrophilic acrylic IOLs should be implanted because of the risk of IOL opacification,” Dr. Izak said.
Study: Three microincision lenses show similar results to refractive surgery
Three microincision lenses, combined with small-incision surgery, produced results similar to refractive surgery for reduced astigmatism and minimally induced aberrations, according to a study presented by Danielle Deidier, MD.
Dr. Deidier prospectively looked at 400 eyes: 300 implanted with the Akreos MI60 (Bausch & Lomb), 50 implanted with the Microslim (Physiol) and 50 implanted with the Quatrix (Corneal). The hydrophilic acrylic IOLs were inserted through a 1.7-mm corneal incision.
In addition to low levels of induced astigmatism, low aberrations and stability in the capsular bag, the lenses had good best corrected visual acuity at 3 months, with the Akreos at 0.93, the Microslim at 0.98 and the Quatrix at 0.88, she said.
“This study demonstrated the smaller incision site provides excellent patient outcomes,” Dr. Deidier said. “These new IOLs available on the market provide stability over time, as well as reproducible and efficient injection.”
Study: Even small amount of iodine on silicone IOLs causes opacification
According to a surgeon speaking here, even a small amount of povidone iodine coming into contact with a silicone IOL during cataract surgery may cause opacification.
Siddhartha Goel, MD, recommended “extreme caution” in the prophylactic use of povidone iodine for infection at the end of cataract surgery and said that surgeons need to be careful to ensure complete wound closure.
In the study Dr. Goel presented, he and his colleagues exposed silicone IOLs to a number of chemicals used at each stage of cataract surgery. One IOL not exposed to chemicals was used as a control. All of the IOLs were then photographed against the same background in a medical photography studio.
The researchers found that all of the samples photographed were as clear as the control, except for those exposed to povidone iodine. Dr. Goel said that exposure to as little as 5% povidone iodine caused IOL opacification.
The hypothesis for this study arose from four cases of early postoperative opacification of silicone IOLs reviewed by the researchers, Dr. Goel said.
In those cases in which early postoperative opacification occurs, there could be an unobservable backflow process into the anterior chamber because such a low amount was able to cause opacification in the study, he said.
“We would recommend those who use povidone iodine to take every precaution they could possibly take to avoid allowing it into the anterior chamber at the end of surgery,” he said.
Dr. Goel said while the toxifying effects of povidone iodine on the corneal endothelium are well known, the researchers were not aware of any studies of the effects of povidone iodine on IOLs. He recommended that more studies be performed on all IOL types.
All of the silicone IOLs tested were from the SI40 series and Clariflex model provided by Advanced Medical Optics, and all were made from the same silicone material.
Double-pass optical analysis could aid in selecting cataract patients for surgery
A double-pass optical analysis system objectively evaluates the intraocular quality of eyes for different grades of cataract, according to Jose Ruiz-Colecha, MD.
Dr. Ruiz-Colecha presented a study that he and colleagues conducted on 34 eyes of 24 patients. These patients were divided into three groups according to the Lens Opacity Clarification System III: Group 1 included 12 eyes with NO1NC1 lens opacification grade; group 2 included 12 eyes with NO2NC2 grade; and group 3 included 10 eyes with NO3NC3 grade.
Intraocular quality was measured with VOL-CT software (Saver and Associates). The modulation transfer function was measured by a double-pass method, the OQAS (Visiometrics).
The researchers found that there was an increase in lens density according to cataract grade, with statistically significant differences between group 3 and group 1, and between group 3 and group 2.
“An objective method to characterize the early to moderate grades of cataract is shown in this study,” Dr. Ruiz-Colecha said. “This method may help us to make a better choice in the future about the best moment to perform cataract surgery in eyes with low-grade cataracts.”
Careful surgical planning minimizes endothelial damage in cataract surgery
Prevention of endothelial cell damage in cataract surgery requires accurate preoperative assessment and careful surgical planning, according to Rudy Nuijts, MD, of Maastricht University Hospital.
“Endothelial cell loss after cataract surgery varies from 4% to 25% in the literature and has been demonstrated to continue for at least 10 years after the operation at a rate of 2.5% per year, which is four times the normal rate of the aging endothelium,” Dr. Nuijts said.
Preoperative conditions of compromised endothelial function, such as Fuchs’ dystrophy or post-penetrating keratoplasty, increase the risk of endothelial decompensation and should always be analyzed in view of the appropriate surgical planning and predictability of results, he said.
Intraoperatively, the use of well-balanced irrigating solution, resembling the natural components of the aqueous, is crucial to endothelial survival.
“I recommend the use of BSS (Alcon) and, in more difficult cases, of BSS Plus. Both solutions have been demonstrated to have a higher protective effect than Ringer’s lactate,” he said.
Dr. Nuijts also recommended the use Arshinoff’s soft-shell technique, which combines two viscoelastic substances (OVD), one dispersive and one cohesive, to create a protective cushion between the endothelium and the space where surgical maneuvers are carried out.
“The use of this technique has been shown to significantly decrease endothelial cell loss (6.4% vs. 16.3%) compared with the injection of a single OVD,” he said.
Small corneal incisions are correlated with a slightly lower rate of endothelial cell loss. However, scleral tunnel incisions are preferable in patients at risk of endothelial damage.
A review of a case series of different surgeons comparing coaxial and bimanual phacoemulsification showed that there is no significant difference in endothelial cell loss between the two techniques.
“What is important is the amount of ultrasound energy used. The introduction of micropulse and microburst in modern phaco machines has tremendously enhanced safety in regard to the endothelium,” Dr. Nuijts said.
Torsional phaco was also demonstrated to produce lower levels of time and energy and less endothelial cell loss.
For nucleus fragmentation, the use of a chop technique with the appropriate chopping instruments, such as the Oshika Cobra Hook, prevents nuclear pieces from directly contacting the endothelium. “Mechanical contact with nucleus fragments is the principal cause of endothelial injury,” he said.
Finally, surgeons should be aware of the toxic effects of topical antiseptic solutions, intraocular medications, preservatives and residuals of detergents on surgical instruments. All these agents can be the cause of toxic endothelial cell destruction.
“The guidelines for recommended cleaning procedures should be followed scrupulously, and we should consider restricting the utilization of reusable cannulas,” Dr. Nuijts said.
Dislocation, decentration most common causes of foldable IOL extractions
Dislocation and decentration were cited as the most common reasons for foldable IOL lens extractions, according a surgeon who reported on the results of a joint survey.
 Nick Mamalis |
Nick Mamalis, MD, presented results of the ongoing foldable IOL survey. He said the joint survey, which has been available to members of the American Society of Cataract and Refractive Surgery (ASCRS) and ESCRS, were filled out by surgeons throughout 2006.
Survey results found that the most common complications with one-piece and three-piece acrylic IOLs were dislocation and decentration, followed by glare, aberrations and uveitis, Dr. Mamalis said. One-piece plate and three-piece silicone IOLs showed similar results. For hydrogel and hydrophilic acrylic lenses, calcification or opacification were the main reasons for removal, he said. For multifocal lenses, glare and optical aberration were the main reasons for removal.
Dr. Mamalis requested that any surgeon performing a foldable IOL removal take part in the study by visiting the ASCRS or ESCRS Web site and filling out and submitting the survey form.
Pupil size could have correlation with visual performance in a multifocal IOL
The smaller the size of a patient’s pupil, the better it performed for both near and distance vision with a multifocal IOL, according to Kjell Gunnar Gundersen, MD.
Dr. Gundersen presented the results of a study that compared Alcon’s Acry-Sof IQ monofocal IOL and AcrySof ReSTOR multifocal, diffractive IOL. He found that patients who had a small pupil size and were implanted with the ReSTOR IOL had significantly less spectacle dependency at near and intermediate distance.
“It is my opinion that all potential candidates for ReSTOR lenses should have pupil measurements on preoperative examination,” he said.
The randomized, prospective study looked at 98 eyes divided into two groups. The first group consisted of cataract patients who received the Acry-Sof IQ monofocal IOL. The second group consisted of cataract patients who received the AcrySof ReSTOR multifocal, diffractive IOL.
Postoperatively, patients filled out a questionnaire to assess their preoperative expectations and overall postoperative satisfaction with their IOL.
Dr. Gundersen found that ReSTOR patients were slightly more satisfied than IQ patients, but the difference was not statistically significant. IQ patients had significantly better uncorrected and best corrected visual performance at distance, he said.
Prismatic lens improves vision and quality of life in AMD patients
The prismatic telescopic IOL-VIP (intraocular lens for visually impaired people) has the potential to improve visual acuity and quality of life in patients with age-related macular degeneration, according to a clinical study carried out in Italy.
The IOL-VIP system is an intraocular Galilean telescope consisting of two IOLs, one highly negative and one highly positive placed in the anterior chamber.
“The two lenses together have the effect of both magnifying and deviating the image to a peripheral area, more often temporal in respect to the macula. This new ‘preferred retinal locus’ becomes the patient’s new macula,” Giuseppe Ravalico, MD, explained.
In the 3 months after surgery, the patient follows an intensive program of visual training to adapt the eye and the brain to the new eccentric fixation. Part of the training is guided by low- vision experts, and part is carried out by the patient at home, using a special rehabilitative software.
The results of 19 eyes of 17 patients aged between 49 and 83 years have been published. All patients underwent classic phaco and IOL implantation, with a basal iridectomy. The follow up varied between 6 and 12 months.
“Visual acuity improved from 20/100 to 20/40. An improvement in contrast sensitivity and fixation capability was also observed. All patients reported a higher visual comfort, with increased distance from handwork and an overall better quality of life,” Dr. Ravalico said.
Improved results with aspheric IOL
Intraindividual comparison of the new aspheric Acri.Smart 46LC with the conventional Acri.Smart 46S showed comparable results in terms of visual acuity, but better contrast sensitivity and higher patient satisfaction, according to a study carried out in Germany.
In 50 patients undergoing bilateral cataract surgery, the two lenses were randomly assigned to the right or the left eye.
At 2 months postop each eye was tested for UCVA, BCVA and contrast sensitivity using the Tester 1800 from Vision Sciences Research. Wavefront analysis was carried out using the AMO WaveScan. At the same time patients filled in a questionnaire on photic phenomena, glare, halos and overall satisfaction.
“Contrast sensitivity gave better results in the 46LC group with low spatial frequencies. Subjectively, the lens was ranked slightly higher by the patients, though they were not informed on the different optic design,” said Josef Reiter, MD.
Refractive Surgery
Good European results reported for phakic IOL
A multicenter European clinical investigation of the Alcon AcrySof angle-supported phakic IOL shows that this lens model has excellent visual results and, so far, none of the drawbacks of other angle-supported IOLs, according to two surgeons.
In particular, endothelial cell density seems to remain relatively stable, with a minimal loss of 1.7% per year from 6 months to 2 years.
 Joseph Colin |
“Thanks to this new lens, there might be a future for angle-supported lenses,” Joseph Colin, MD, said.
The unique design of this IOL seems to be capable of maintaining a safe distance from the endothelium and to have a firm but gentle hold to the angle, he said.
Unilateral implantation was performed in 190 patients, 99 with 2 years of follow-up. Follow-up is planned for 5 years.
“At 2 years, best corrected visual acuity of 20/25 or better has been achieved by 98.4% of the patients. Refraction is within ±0.5 D of target in 78% of the patients. More than half of the patients gained one to two visual acuity lines,” Michael C. Knorz, MD, said.
The most common complication was increased IOP due to incomplete viscoelastic removal, Dr. Knorz said. No persistent cases of corneal edema, cystoid macular edema or iritis were reported.
Post-LASIK ectasia concern may dwindle
Post-LASIK ectasia is not a major concern if guidelines are followed and an accurate analysis of preoperative topography and wavefront data is performed, according to a panel of surgeons here.
Presenting a retrospective review of 140 high myopic patients operated in the early years of LASIK over a period of up to 20 years, Patrick Condon, MD, said that despite the relatively greater risk of high myopia, ectasia can be a minor problem.
“Only one patient with a thicker than anticipated flap and therefore a residual stromal bed of only 120 µm developed ectasia,” Dr. Condon said. “In all the other cases, where residual stromal bed was within the safety limits, there was no sign of this complication.”
In another retrospective review of 22 cases of post-LASIK keratectasia followed in the Eye Clinic of Bordeaux, the risk factors that were potentially at the origin of this complication were examined.
“Topographic abnormalities, like keratoconus, form fruste keratoconus and pellucid marginal degeneration, were found in 14 cases,” Julien Kerauret, MD, said. “High myopia, in connection with astigmatism or dry eye, was observed in four cases. Predicted residual stromal bed was less than 249 µm in one case.”
In all the cases in which preoperative topographies were available, a pre-ectatic condition was always present, he noted.
As Michael Knorz, MD, said, “This analysis demonstrates that in most cases post-LASIK ectasia could be prevented by accurate analysis of topographic data.”
Together with Antonio Marinho, MD, he recommended the use of all available technologies for preoperative evaluation of the cornea.
“Forme fruste keratoconus remains the most important risk factor to be considered,” Dr. Marinho said.
When post-LASIK ectasia develops without any apparent risk factor, surgery-induced oxidative stress should be considered as a potential cause, according to Nataliya Maychuk, MD.
Toric phakic IOLs predictable, safe for use in previous PK, DALK eyes
Implanting toric phakic IOLs may be a safe, reliable surgical option for correcting refractive errors in phakic and aphakic patients previously treated with corneal grafting procedures, according to a study presented by José L. Güell, MD.
 José L. Güell |
Dr. Güell and colleagues in Spain reviewed outcomes for 14 phakic and 10 aphakic eyes implanted with the Verisyse (Advanced Medical Optics) toric phakic IOL to correct moderate to high residual spherical and astigmatic errors after previous penetrating keratoplasty or deep anterior lamellar keratoplasty (DALK).
“This lens provides good centration, stable fixation, safe distance from the endothelium and it is small and foldable, which means it can be implanted through a small incision, thus avoiding further induction of astigmatism,” Dr. Güell said.
In all cases, implantation of the toric phakic IOL produced an increase in visual acuity of several lines. Spherical equivalent decreased to near plano from an average of –6 D to –5 D preoperatively. The astigmatic error also had progressively decreased during follow-up to a maximum of 1.25 D, he said.
Patients experienced rates of endothelial cell loss similar to the rates reported for all Verisyse phakic IOLs, with a 6% to 7% reduction at 3 years.
Dr. Güell noted that evaluating the reference axis both preoperatively and intraoperatively is mandatory because even small displacements can produce an undercorrection or even an increase in the astigmatic error.
Modern imaging technologies, such as the Visante anterior chamber OCT (Carl Zeiss Meditec), also provide valuable support in evaluating the lens performance during follow-up. Central and peripheral anterior chamber depth, as well as the distance of the IOL from the endothelium and from the crystalline lens should be measured at least once a year, he said.
“These toric [phakic] IOLs are, in my opinion, the best method for correcting medium-high ametropia after corneal transplantation,” Dr. Güell said. “[The lenses] create predictable and stable vision and have the advantage of being a reversible procedure. In these eyes, I much prefer them to laser refractive surgery.”
LASEK safe for patients with controlled diabetes
It is safe to perform LASEK in patients with diabetes, but the epithelium may take longer to heal, according to Hamid Norouzi, MD, of Shahid Beheshti University in Iran.
Dr. Norouzi presented outcomes of a retrospective study in which he analyzed the charts of 58 patients with controlled diabetes who underwent LASEK.
Forty patients had type II diabetes and 80 patients had type I diabetes. Mean patient age was 41 years and the mean preoperative spherical equivalent was –3.25 D, according to Dr. Norouzi. Patients were excluded if they had diabetic retinopathy.
Mean follow-up was 8 months.
Results showed 75 eyes had achieved an uncorrected visual acuity of 20/20 or better and 39 eyes were within ±0.75 D of the intended refraction. Two eyes lost one line of best corrected visual acuity.
Despite the good refractive results, the epithelial healing time increased more than 4 days in 40 eyes, but diabetic retinopathy did not advance in any eyes, Dr. Norouzi said.
“LASEK is safe in patients with controlled diabetes,” he said. “Epithelial defect and increased epithelial healing time was noticeable.”
Toric phakic IOL safely corrects residual astigmatism after DLK
Implantation of a toric posterior chamber phakic IOL can safely and predictably correct residual myopic astigmatism following deep lamellar keratoplasty, according to Alaa El-Danasoury, MD, of the Magrabi Eye & Ear Hospital in Saudi Arabia.
Dr. El-Danasoury presented a prospective study of 17 eyes of 17 patients with previous deep lamellar keratoplasty (DLK) implanted with a toric ICL.
Inclusion criteria included stable manifest refraction for at least 3 months after removal of all corneal sutures, a spherical equivalent between –8 D and –16 D, spectacle-corrected visual acuity of 20/40 or better and an endothelial cell count of more than 2,200 cells/mm², according to Dr. El-Danasoury.
Each eye was implanted with a STAAR Surgical toric ICL through a 3-mm temporal clear corneal incision under topical anesthesia.
“I like to put a little viscoelastic on the cornea to enhance visualization,” he told attendees. “It is also important to perform an iridectomy.”
According to the results, mean SE refraction at baseline was –8.27 D and seven eyes could see 20/20 or better without correction.
Follow-up rate at 12 months was 85.7%. The mean SE refraction at 12 months was –0.3 D, ranging from –1.25 D to 0.5 D, uncorrected visual acuity was 20/40 or better in 75% of cases at day 1 postop, according to Dr. El-Danasoury. Twenty five percent of patients gained 2 or more lines of spectacle-corrected visual acuity, and there was a 2.3% mean endothelial cell loss.
“Toric ICL implantation is effective, predictable and relatively safe for the correction of the residual compound myopic astigmatism after DLK,” he said.
Preop spherical equivalent, BCVA among possible risks for haze after PRK
Preoperative spherical equivalent and preop best corrected visual acuity are a few of the risk factors that may predict corneal haze after PRK, according to Alireza Peyman, MD, of Isfahan University of Medical Sciences in Iran.
Dr. Peyman presented the results of a study of 95 eyes of 50 patients with preoperative spherical equivalent (SE) refractive error of at least –6 D. The patients underwent PRK for myopia and myopic astigmatism and were followed for 8 months when they were evaluated for corneal haze formation.
Corneal epithelium was removed with ethanol 20% and standard surface ablation was performed with the Technolas 217z excimer laser (Bausch & Lomb), Dr. Peyman told the audience. He created a 6-mm optical zone in 80% of patients.
The results showed that at the 8-month follow-up, only 16% of patients were without haze, according to Dr. Peyman.
When he analyzed the risk factors, he found that preop SE refractive error, size of optical zone, preop BCVA and axis of the preop astigmatism were statistically significant risk factors for corneal haze.
“Considering these factors may influence a surgical planning strategy,” Dr. Peyman said.
Corneal cross-linking effective without epithelium removal
Corneal cross-linking procedures can be performed without epithelium removal, according to Roberto Pinelli, MD.
Dr. Pinelli described for attendees his results in 30 keratoconic patients treated with corneal collagen cross-linking with no removal of the epithelium.
After following the patients for 6 months, Dr. Pinelli found the mean uncorrected visual acuity improved by 1.3 lines, mean best corrected visual acuity improved by 1.1 lines and there was a mean increase in central pachymetry of 13 µm, according to his results.
Furthermore, the progression of keratoconus stopped in all 30 eyes, and there was a mean decrease in mean refractive spherical equivalent of –1.27 D, he said.
“These results show that it is not necessary to remove the epithelium to allow the riboflavin to penetrate the cornea,” Dr. Pinelli said.
Topographic-guided LASIK enhancement treats high levels of corneal primary coma
A topographic-guided LASIK enhancement procedure makes corrections of the second order safely and effectively, significantly reducing primary coma, according to David Pablo Piñero Llorens, MD.
Dr. Llorens and colleagues studied 34 eyes of 29 patients who underwent a topographic-guided LASIK enhancement performed with the Esiris excimer laser (Schwind eye-tech-solutions) to correct residual myopia and astigmatism or hyperopia and astigmatism.
All patients had a high preoperative level of primary coma aberration; the root mean square (RMS) for primary coma was more than 0.5 µm for a 6-mm pupil. The researchers used the ORK-CAM software to calculate and program the ablation design.
They found statistically significant changes at 1 month, with a reduction of the total RMS, astigmatic RMS, primary coma RMS and negativization of the primary spherical aberration coefficient.
“Corneal wavefront-guided enhancements with the ORK-CAM system are safe and effective for the reduction of the corneal primary coma induced by previous decentered keratorefractive procedures,” Dr. Llorens said.
Cell deposits on phakic IOLs correlate with surgical experience
The presence of cell deposits on Artiflex iris-claw phakic IOLs after implantation is a relatively frequent complication that is correlated with no factor other than the surgical learning curve, according to a study.
“The Artiflex (Ophtec) has extremely good refractive results, and it is almost complication-free,” Dr. Marinho said. “Nevertheless, several surgeons report pigment cell deposits on the IOL or even giant cell deposits with mild uveitis.”
Dr. Marinho and colleagues in Portugal investigated the frequency of cell deposits and intraocular inflammation after implantation of the phakic IOL. The study included 133 eyes of 75 patients treated by four surgeons and divided into four groups.
The first group included 95 eyes (71.5%) that showed no detectable inflammation. In the second group, cell deposits were detected on the IOL in 23 eyes (17.3%), but the deposits caused no visual disturbances and disappeared spontaneously between 3 and 6 months postop. The third group included eight eyes (6%) that were similar to those in the second group. However, the cell deposits in the third group of eyes were more persistent, remaining on the lens for longer than 6 months after implantation. The fourth group included seven eyes (5.2%) that experienced inflammation, pigment deposits and giant cell deposits that required treatment with steroids, according to the study.
“We correlated these different types of eye behaviors with several factors, [such as] age, sex, anterior chamber depth, pupil size, IOL power and surgeon experience,” Dr. Marinho said. No correlation was found between the different degrees of ocular inflammation and any of the patient variables. However, a strong correlation was found with surgical experience.
“The most experienced surgeon (99 eyes implanted) had 77% of the patients in the group with no detectable inflammation and only 4% in the group requiring treatment, while the least experienced surgeon (eight implanted eyes) had 25% of the eyes requiring treatment and none without detectable inflammation,” Dr. Marinho said.
“The surgeon’s learning curve is an important point which should not be disregarded when patients are selected to receive this phakic IOL,” he said.
Study: No correlation between refractive indices, CCT
No relation between refractive error and central corneal thickness was found in a study of patients who underwent laser keratorefractive surgery, according to Shiva Mehravaran, MD.
Dr. Mehravaran and colleagues evaluated the correlation of CCT with refractive error and keratometry to determine if it can serve as a bias in IOP measurement studies. The cross-sectional observational study examined the right eyes of 340 patients.
Dr. Mehravaran and colleagues found the mean cycloplegic spherical equivalent was –3.2 ± 2.3 D and the mean CCT was 549.5 ± 33.6 µm. No other parameters, including age, sex or amount of refractive error, showed significant correlation with CCT in the study population, she said.
“In this group of refractive surgery patients, we didn’t see any significant correlation with the corneal thickness — only eight patients were borderline significant,” she said. “You can say that the correlation that they’re finding between IOP and central corneal thickness is not biased by the refractive indexes of the patients in this study.”
Variations in anterior layers of cornea can affect optic performance
The refractive index of the anterior layers of the human cornea is not uniform, leading to variations that can cause corneal light scatter and affect the eye’s optical performance, according to Sudi Patel, MD.
Dr. Patel spoke about a study he conducted with colleagues that examined the refractive index using the VCH-1 corneal hydrometer. The study included 11 patients who had PRK, LASEK or epi-LASIK and 30 patients who had LASIK. The refractive index was measured after topical anesthesia.
Dr. Patel said they found different measurements for the corneal epithelium, Bowman’s layer and stroma, which should be taken into consideration by laser manufacturers and surgeons alike. He said recognizing that there is a difference in individual corneas is important because of the different types of surgery that create refractive changes.
“So much attention is paid to complex optics of the eye that it’s a common assumption that the cornea is uniform,” Dr. Patel said. “We now believe that if you wish to further improve the optics of refractive surgery, you need to consider the refractive index of the cornea as an individual, not as an average, because of the diversity among subjects.”
Cornea External Disease
New technique uses alcohol to ‘scrape away’ pterygium
A simple procedure that uses alcohol 20% solution is proving effective in the treatment of pterygium, according to Erez Tsumi, MD, of Soroka University, Beer-Sheva, Israel.
In Israel, due to the dry, hot climate, the incidence of pterygium is high, and the difficulties in treating this condition are well known.
“Alcohol allows us to scrape the pterygium completely from the cornea, and we have had so far a very low recurrence rate,” said Dr. Tsumi.
The procedure, which Dr. Tsumi said was inspired by LASEK, is simple and straightforward.
After subconjunctival lidocaine injection, a metal ring is placed above the head of the pterygium to isolate the treatment area. A few drops of ethanol 20% are applied inside the ring and left in place for 40 seconds. The alcohol is then washed out with balanced salt solution.
“After having been soaked in alcohol, the pterygium is easily separated from the underlying cornea with a blunt spatula by scraping it away at the periphery and then at the center. At the end, mitomycin-C 0.02% is applied for 2.5 minutes,” he explained.
In a retrospective study of 29 eyes with primary pterygium and two eyes with recurrent pterygium that underwent this procedure, results were encouraging. There were no intraoperative complications, and no severe side effects were reported during the follow-up, which ranged from 6 to 12 months. No cases of recurrence were observed.
“This technique creates a very clear and smooth separation plane between the pterygium and the underlying cornea. The alcohol allows you an easy access to the dissection plane, which is so difficult to find with the more traditional blunt dissection technique,” Dr. Tsumi said.
Safety and efficacy of the technique will be further investigated in a prospective study at the same hospital.
Insertion technique for DSEK prevents endothelial damage
A new technique for donor insertion in cases of Descemet’s stripping endothelial keratoplasty can reduce the amount of endothelial damage caused by the folding and compression in standard techniques, according to Donald T. H. Tan, MBBS, FRCSG, FRCSE, FRCOphth, FAMS.
Dr. Tan described studies he conducted with human eye bank corneas in which scanning electron microscopy and dye staining of the endothelium showed patterns of damage at the folding point of the donor tissue.
“There was significant damage from folding amongst almost all the tissue we looked at,” he told the audience.
These findings led Dr. Tan and his colleagues at the Singapore National Eye Center to develop what he called the “glide insertion” technique in which the donor tissue is protected by viscoelastic and placed on a modified IOL sheet glide without folding. “This technique is a variation on the ‘pull through’ technique,” Dr. Tan explained. “We use an IOL sheet glide to insert the donor tissue in order to prevent iris prolapse.”
According to a spokesperson from Moria, the ‘pull through’ technique using a glide to insert the donor button was originally developed by Dr. Massimo Busin (Forli, Italy), and was presented for the first time during last year’s ESCRS meeting. The Busin Glide and forceps are produced by Moria.
Dr. Tan said he successfully performed the technique in 20 patients with good clinical outcomes and no complications associated with donor insertion.
Mean follow-up was 4 months, ranging from 1 to 16 months for combination of the standard technique group (20 patients) and the new technique group (20 patients). According to Dr. Tan, 64% of the patients reached 20/40 and slightly less than half achieved visual acuity of 20/30.
Dr. Tan noted that this procedure was particularly useful in Asian eyes which tend to be smaller and pose difficulties when unfolding the donor tissue.
“Taco folding is unacceptable in Asian eyes,” he said.
Big bubble technique achieves better results than manual for DALK cases
Deep anterior lamellar keratoplasty performed with the bubble technique garners better graft survival and visual results than a manual technique or penetrating keratoplasty, according to Anand Parthasarathy, MD.
Dr. Parthasarathy presented a study in which he compared 32 corneal grafts performed with the deep anterior lamellar keratoplasty Anwar big bubble technique (DALK-A) with 32 grafts performed with a manual technique (DALK-M) and 64 PK cases. The PK cases were selected from the Singapore Eye Bank database and matched with the DALK groups for age and diagnoses.
The diagnoses included keratoconus, anterior corneal stromal dystrophies and anterior corneal scarring, Dr. Parthasarathy said.
The results showed no statistically significant differences in visual improvement between the PK and DALK-A groups, but outcomes in the DALK-M group were statistically significantly poorer, Dr. Parthasarathy said.
Results showed that 69% of the eyes in the DALK-A group achieved best corrected visual acuity of 6/9 or better compared with 44% in the PK group and 41% in the DALK-M group. Similarly, more eyes in the DALK-A group achieved BCVA of 6/6 compared with the other two groups.
Dr. Parthasarathy also noted better performance in the amount of steroids needed and in graft survival in the DALK-A group.
“There was a definite trend toward better graft survival in the Anwar group, and there was less duration of steroids, which is important in patients with pre-existing glaucoma,” he said.
Amniotic transplant with fibrin glue stabilizes globe for later PK in cases of ALK
Amniotic membrane transplant with fibrin glue decreases inflammation and promotes healing in cases of anterior lamellar keratoplasty for such diseases as corneal melt and descemetocele, according to Thomas John, MD.
 Thomas John |
Dr. John described the efficacy of anterior lamellar keratoplasty (ALK) with amniotic membrane transplant.
The study included 10 ALK procedures performed in eight eyes of seven patients. The mean age of the patients was 66 years. Diagnoses included six cases of diabetes mellitus, one patient with pellucid marginal degeneration in both eyes and three cases of failed PK, according to Dr. John.
All patients suffered from corneal melt, 86% suffered from descemetocele and 71% suffered from corneal perforation. All patients underwent ALK with amniotic transplant and fibrin glue, Dr. John said.
According to the results, all the globes were stabilized and the fibrin glue resulted in adherence of the donor disc to the corneal defect created by corneal melt in all cases.
A decrease in ocular inflammation related to amniotic transplant occurred in 71% of the eyes, and two were able to undergo PK when the eye became stable after ALK, Dr. John said.
“The purpose of this technique is not to visually rehabilitate the whole of Descemet’s membrane, just to stabilize the globe … and then at a later stage perform penetrating keratoplasty,” Dr. John said.
DSEK volume rapidly growing in the U.S.
Descemet’s stripping endothelial keratoplasty (DSEK) is becoming a widely accepted alternative to penetrating keratoplasty (PKP) in patients with endothelial deficiency syndromes like Fuchs’ dystrophy.
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“The percentage of endothelial keratoplasties in the U.S. has rapidly increased from 4.5% of all corneal graft procedures in 2005 to 18% in 2006. Endothelial grafts represent now more than 45% of tissue requests in U.S. eye banks. To date, 850 DSEK procedures have been performed,” Francis Price, MD, said.
The increased use of this procedure has produced increased innovation in donor’s graft preparation and insertion technique.
“We have developed special forceps to handle the delicate endothelial tissue, we have learned that insertion is better through a clear corneal incision and we have refined our technique of using an air bubble to unfold the graft and to obtain a good donor attachment,” Dr. Price explained.
The learning curve of DSEK is undoubtedly steep, and results are strictly surgeon-dependant, he noted.
“The proper surgical management can greatly increase the rate of endothelial cell survival. By improving my technique, and thanks to the use of single point fixation forceps, I have achieved a rate of cell loss between 1 and 3 years that is considerably lower than that reported in most studies,” he said.
Since the preparation and implantation of the DSEK donor graft requires more manipulation than a PK corneal button, early cell loss occurs more with DSEK than with PK, he noted. However, subsequent cell loss is moderate, and by 2 to 3 years it is within the range of PK.
Graft rejection, however, is considerably lower than with PK.
“According to our data, graft rejection at 2 years is 7.5% in a total of 199 eyes. The Swedish graft registry of PK reports a rate of 13% in 708 eyes,” he said.
A note from the editors:
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