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Tools of the anterior segment trade: pharma, technology highlighted at Hawaiian Eye
An OSN editorial board member provides readers an anterior segment view of the meeting through his daily meeting reports presented here.
WAILEA, Hawaii — For a physician-attendee, Hawaiian Eye 2006 offered a wealth of practical information, from updates on the recent pharmaceutical developments in retina/vtireous to tips on more effective practice management.
I submitted to the editors of Ocular Surgery News daily summaries of selected presentations I attended at the meeting. As the editor of the OSN Back to Basics column, I concentrated on anterior segment topics at the meeting. My daily summaries are presented here. Most of these items first appeared on OSNSuperSite.com as daily reports from the meeting.
Improved phaco technologies may lead to improved outcomes
Recent advances in phacoemulsification technology, including novel methods of phaco power delivery using new software and hardware, may bring improvements in clinical outcomes of cataract surgery, surgeons speaking here said.
In separate presentations, Steven H. Dewey, MD, described recent upgrades in the software of the Advanced Medical Optics Sovereign phaco platform with WhiteStar technology, and Richard J. Mackool, MD, outlined new software and hardware for the Alcon Infiniti phaco machine.
The AMO Sovereign has been upgraded with new software called WhiteStar ICE, which stands for increased control and efficiency, Dr. Dewey said. The WhiteStar ICE will improve phaco performance and safety by allowing micropulse power delivery via three new modalities, he said.
The first innovation is Variable WhiteStar, which allows the surgeon to move through four preset duty cycles selected from a set of choices. The second power modification is ICE pulse shaping, which allows the surgeon to deliver a 1-ms spike of power at the beginning of each micropulse. This spike maximizes the cavitational effect of the ultrasound energy for more efficient nucleus removal, Dr. Dewey said. The spike can increase, decrease or remain constant with increasing phaco power.
The third innovation is WhiteStar Chamber Automated Stabilization Environment, or CASE, which enables the phaco machine to anticipate situations in which surge may occur and to reduce the vacuum level before occlusion breaks, thereby decreasing surge. Dr. Dewey referred to this mechanism as “intelligent anticipation,” and the effect is virtual elimination of anterior chamber “bounce” or instability, he said.
Dr. Dewey also described a Radius phaco tip he designed, the edges of which are rounded instead of straight-cut, as is typical with traditional phaco needles. He noted that in his experience, to break a capsule with the phaco tip requires a sharp edge, and a rounded radius tip would likely decrease that risk. Dr. Dewey said he has used the Radius phaco tip in hundreds of cases, achieving a seemingly higher level of safety with no changes in machine settings or technique. He referred to the Radius tip as his “bicycle helmet.” He said not every case tests its effectiveness, but he is more comfortable knowing that he has the added safety it affords, should he need it.
Dr. Mackool spoke about Alcon’s torsional phaco technology for its Infiniti phaco machine, in which the phaco needle oscillates in a torsional manner at a frequency of 32 kHz. The tip can also move in the traditional axial manner, and the torsional and axial movements can be combined. The torsional technology may, in effect, double the cutting rate of traditional phaco with axial movement because the oscillating needle can cut in both directions, he said.
To enhance the effect of the torsional oscillations, Dr. Mackool uses a bent phaco needle, and he said he often combines torsional ultrasound with traditional ultrasound in alternating pulses, one with 80-ms duration and one with 20-ms duration. Torsional phaco requires the use of a new handpiece and updated software for the Alcon Infiniti platform, he added.
Dr. Mackool said that in his experience with 500 patients “there is far less heat at the incisions” which are 2.2 mm wide and watertight. He said he expects to see widespread acceptance of the torsional technology in the next few years.
Relationship with refractive cataract patients
Potential candidates for refractive cataract surgery have high expectations, and the surgeon must understand and address these expectations to keep the patient satisfied, said Rosa Braga-Mele, MEd, MD, FRCSC, who spoke at a Bausch & Lomb-sponsored symposium.
During a potential patient’s first clinic visit, surgeons must “create a 10-minute relationship,” she said.
“Because there is no prior history between the doctor and the patient, it’s a unique opportunity for the surgeon to be perfect,” Dr. Braga-Mele said.
Her simple advice to achieve perfection: “Be nice.”
Effectively addressing the patient’s expectations is paramount, she said.
“A happy patient is better than achieving an arbitrary Snellen acuity value,” she said.
Dr. Braga-Mele said understanding the patient’s personality is far more important that the medicine. She defined patient success as consisting of “10% medicine, 90% personality.” Easygoing patients may be easier to please than those who are demanding and perfection-oriented, she said.
When the surgeon is determining IOL power for refractive cataract patients, Dr. Braga-Mele advised dividing common activities into zones of vision. For instance, she said, zone 1 would include the most demanding of up-close activities, such as reading a drug label or a phone book, and sewing. Zone 2 includes reading the newspaper or a menu, and using the computer. Zone 3 includes activities such as watching TV, cooking and common household tasks. Zone 4 involves vision used during daylight hours, such as playing golf. Zone 5 includes the most demanding of scotopic vision, such as night driving or dim illumination such as candlelight, she said.
“With our current technology, we are able to effectively give patients about three continuous zones of vision: zones 1 to 3, zones 2 to 4, or zones 3 to 5. Multifocal IOLs tend to work better for zones 1 to 3, single-optic accommodating IOLs tend to work better for zones 2 to 4, and aspheric monofocal IOLs tend to work better in zones 3 to 5,” she said. “Understanding which zones are most important to your patient is critical to achieve success with refractive cataract surgery.”
Routine NSAIDs
Should ophthalmologists use topical nonsteroidal anti-inflammatory drugs routinely when performing cataract or lens surgery? Eric D. Donnenfeld, MD, and John Wittpenn, MD, presented their thoughts on the subject here at an Allergan-sponsored symposium.
Dr. Wittpenn said patients now expect excellent vision immediately after surgery, with no pain or discomfort, no reduction in contrast sensitivity and no complications from the surgery. He suggested that ophthalmologists revise their definition of cystoid macular edema (CME) to include any decrease in visual function as a result of macular thickening.
Dr. Wittpenn recommended using NSAIDs in patients undergoing any lens-based surgery, particularly those at higher risk, such as patients with a history of diabetes, vascular occlusion, uveitis, macular pucker, previous ocular surgery or CME in the fellow eye after previous surgery.
He added that with numerous topical ophthalmic NSAIDs available to physicians, corneal melting is “not an issue” as it was briefly in the late 1990s.
Dr. Donnenfeld said the multipurpose topical NSAID is “the cataract surgeon’s best friend,” and its use results in better outcomes and more efficient surgery.
Among the benefits of NSAIDs, he said, are inhibition of intraoperative miosis, reduction of pain during and after surgery when the NSAID is given preoperatively, and easier management of postop inflammation. They also help in the treatment of CME after surgery and can help to prevent intraoperative complications during surgery, Dr. Donnenfeld said.
He presented results from a randomized, double-masked study of 100 patients divided into four groups. Three groups received ketorolac 0.4% before surgery at 3 days, 1 day or 1 hour; all three groups received the NSAID four times daily after surgery for 2 weeks. The fourth group, which received no NSAIDs, served as control.
The patients who received ketorolac 3 days before surgery had significantly less pupil constriction, a lower mean surgical time, a lower mean ultrasound time, a lower mean effective phaco time, reduced inflammation, improved corneal clarity and improved visual outcomes compared with the other groups, he said.
“NSAIDs as a surgical tool are as vital as the choice of the phaco handpiece or the viscoelastic in improving cataract surgery outcomes,” he said.
Latest fluoroquinolones have higher potency
The minimum inhibitory concentrations of the newest generation of ophthalmic fluoroquinolones are significantly lower than those of previous generations, indicating higher potency, speakers here said. Laboratory and clinical test results with these fluoroquinolones were the subject of separate symposia sponsored by Allergan and Alcon.
Francis Mah, MD, conducted in vitro tests of gatifloxacin 0.3% preserved with benzalkonium chloride (BAK) and moxifloxacin 0.5% self-preserved. He said both these fluoroquinolones have a broad spectrum with improved activity against gram-positive bacteria compared to earlier-generation fluoroquinolones, as well as retaining the earlier generation’s activity against gram-negative bacteria.
“Certain pathogens that are resistant to previous generation fluoroquinolones are susceptible to the fourth-generation drugs,” he said.
In a study, Dr. Mah compared formulations of both of these fluoroquinolones, both with and without BAK, to determine whether the BAK has the ability to potentiate the effect of the antibiotic. He compared the four antibiotic formulations to BAK as a standalone antiseptic agent.
Comparing the results of time-to-kill tests, Dr. Mah found that BAK complemented gatifloxacin 0.3% in eliminating certain gram-positive bacteria, such as Staphylococcus aureus, and coagulase-negative Staph species, but it had no effect on gram-negative Pseudomonas aeruginosa bacteria.
In another presentation, Randall Olson, MD, said BAK activity is likely a superficial effect on the ocular surface, but perhaps not an intraocular effect due to its inability to effectively penetrate the cornea. This effect of BAK being additive to the antibiotic’s effect would be helpful in minimizing the bacterial load on the ocular surface prior to surgery, he suggested.
The current standards of comparing bacterial susceptibility to antibiotics is based upon systemic serum standards, which may not be directly applicable to ophthalmic use, Dr. Mah said, and therefore the bacterial resistance may be overstated. He gave an example of a strain of methicillin-resistant Staph aureus (MRSA) that was shown to have in vitro resistance to gatifloxacin in the laboratory, but with frequent ocular dosing, the same strain of MRSA in a clinical setting was effectively killed using the same antibiotic. He suggested that ophthalmologists need new methods to evaluate the clinical efficacy of topical antibiotics.
Dr. Olson said if two commercially available ophthalmic fluoroquinolones are compared, their commercial formulation, including preservatives, should be used for testing. For some organisms, he said, BAK may help to lower the minimum inhibitory concentrations (MICs) and therefore improve the kill rate of susceptible pathogens.
Dr. Mah suggested that ophthalmologists should look at the minimal bactericidal concentration, or MBC, which he said tends to be three to four times the MIC. He said this number better reflects the killing power of an antibiotic. Levels of the drug in tissue must be above the MIC; any level below is subinhibitory and ineffective for bacterial eradication, he said.
Dr. Mah said an in vivo study of moxifloxacin showed its ability to eradicate endophthalmitis-causing organisms in rabbit eyes. He noted that the use of moxifloxacin in the perioperative period for prophylaxis against endophthalmitis is an off-label indication for the drug.
Terry Kim, MD, presented results of a study evaluating the corneal concentrations of the newer fluoroquinolones in patients undergoing corneal transplantation. He said moxifloxacin achieved significantly higher corneal concentrations than gatifloxacin, “easily achieving levels above the MIC of major bacterial isolates.”
Managing cataract surgical complications
Cataract surgery is a safe procedure with a low incidence of complications, but recognizing the complications and performing early intervention can lead to better outcomes, said Carmen A. Puliafito, MD, MBA, in a keynote presentation.
Because the incidence of endopthalmitis is low, ophthalmologists are uncertain whether it occurs more often in clear corneal cataract surgery or in scleral tunnel surgery, Dr. Puliafito said. At the Bascom Palmer Eye Institute, a retrospective review showed an incidence of endophthalmitis of 0.04% overall, with the rate in clear corneal surgery at 0.05% and the rate in scleral tunnel surgery at 0.02%.
The risk factors for endophthalmitis include diabetes mellitus, use of lidocaine jelly prior to povidone-iodine application, vitreous loss during surgery, inferior location of the surgical wound and pre-existing blepharitis. It is essential to treat blepharitis and other lid disorders prior to cataract surgery and to perform a thorough preparation with povidone-iodine of the eyelids, the ocular surface and the conjunctival cul-de-sacs, he said.
Current preferred antibiotics are vancomycin (1 mg) for treatment of gram-positive bacteria, ceftazidime (2.25 mg) for gram-negative bacteria and possibly dexamethasone for inflammation control. Amikacin or other aminoglycosides should be used with caution, as they can cause retinal infarction, Dr. Puliafito said.
Methicillin-resistant Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus are resistant to the newer broad-spectrum fluoroquinolones moxifloxacin and gatifloxacin but are still susceptible to intravitreal vancomycin, he said.
Bleeding can occur in the suprachoroidal space, and risk factors for this include hypotony, high myopia, glaucoma, advanced age, hypertension and a rapid heart rate. There is no set time for onset, Dr. Puliafito said. In severe cases, the blood can be drained and the anatomy restored by a vitreoretinal surgeon, he said.
Difficult cataract cases may leave the patient with fragments of cataract still in the eye. If the fragments are small and less dense, the pieces will tend to be absorbed or melt over time, Dr. Puliafito said. Hard nuclear material left in the eye will require additional surgery, however, he said. Patients with retained lens fragments are at risk for macular edema and corneal edema. If the patient also suffers a rise in IOP, pars plana vitrectomy should be recommended to remove the fragments.
Posterior chamber IOLs can become dislocated, particularly in eyes with a capsular rupture, pseudoexfoliation, asymmetrical haptic placement and late trauma. In addition, silicone plate-haptic IOLs may become dislocated after Nd:YAG capsulotomy. These IOLs can be repositioned and sutured back into position, but Dr. Puliafito noted that these sutures do not last the life of the patient, and the IOL will likely dislocate in the future.
While many cataract surgeons have switched to topical anesthesia, a significant number still perform retrobulbar and peribulbar anesthetic injections, Dr. Puliafito said. The potential complications of these injections include retrobulbar hemorrhage, optic nerve damage, retinal vein occlusion, inadvertent intravitreal injection, strabismus and needle penetration into globe. The risk factors for inadvertent ocular penetration from injection anesthesia include axial myopia, existing scleral buckle, posterior staphyloma, multiple injections and previous ocular surgery.
For Your Information:
- Reported by Uday Devgan, MD, FACS. Dr. Devgan is an assistant clinical professor at the Jules Stein Eye Institute at UCLA and in private practice in Sun Valley, Calif. He can be reached at 9375 San Fernando Road, Sun Valley, CA 91352; 818-768-3000; fax: 818-504-4463; e-mail: devgan@ucla.edu. Dr. Devgan has no financial interest in the products mentioned in this article and does not accept funds or honoraria for his involvement in ophthalmic consulting.