Future of refractive surgery looks promising, surgeon says

New treatments, technologies reviewed at the German Ophthalmic Surgeons meeting.

NUREMBERG – The future of refractive surgery looks promising for ophthalmologists and patients, according to Emanuel S. Rosen, FCOphth.

Introduced by meeting president Armin Scharrer, MD, as “possibly the most influential ophthalmic surgeon of the past 30 years,” Mr. Rosen, of Manchester, England, delivered the Ridley Medal Lecture here at the German Ophthalmic Surgeons meeting.

“The future of refractive surgery is assured due to increasing safety and effectiveness of treatment, the developing range of options and ever-increasing acceptance by the public,” Mr. Rosen said.

“The future will be customized vision,” he continued. “We’re coming to the era of customized vision for all. Personalized choice is the true legacy of Harold Ridley.”

Of particular note, Mr. Rosen said, is that lenticular approaches to refractive surgery are now “catching up with corneal options.” Mr. Rosen predicted that a future trend in refractive surgery will be to address a patient’s refractive error initially with a lenticular approach and to refine the result with laser corneal techniques.

He cited the recently released 2003 Leaming survey of the American Society of Cataract and Refractive Surgery to compare current trends with past “quantum leaps” in technological innovation.

Among recent technological advances is the phakic IOL, but Mr. Rosen stressed that “the search is on for the presbyopic solution.”

While he noted that LASIK remains the most commonly used refractive technique, Mr. Rosen said that was because current multifocal and “pseudoaccommodating” IOLs for presbyopia are only an interim solution. He explained that he calls the current crop of accommodative lenses pseudoaccommodating because the accommodation occurs by changing the location of a fixed-power lens.

“Truly accommodating IOLs will be those with actual accommodation achieved by change of the curvature of the lens,” he said. “We’re looking for an uncompromised presbyopic solution. When a permanent solution such as this is discovered, the floodgates will open for (refractive lens exchange).”

For the time being, Mr. Rosen said, monofocal IOLs will remain the standard.

Excimer laser for glaucoma

A form of glaucoma surgery that uses an excimer laser probe may be a minimally invasive alternative to other filtering procedures, according to one surgeon.

Jens Funk, MD, discussed the procedure, called excimer laser trabeculotomy (ELT).

In ELT, an excimer laser is used in combination with an endoscope. The probe, inserted into the anterior chamber, is used to deliver 20 pulses of 308-nm laser light at 10 locations around the trabecular meshwork. The endoscope allows the operating surgeon to view the procedure as it is performed.

According to Dr. Funk, the excimer laser delivers low energy into the eye, which helps to prevent a thermal effect from the procedure. This has been confirmed by electron microscopy, he said.

Once the trabecular meshwork is penetrated, blood perfuses, indicating adequate penetration has been achieved. The blood also absorbs laser energy, preventing thermal damage, he said. The blood is rinsed from the chamber when the laser treatment is completed.

“It is hopeful that the new pores will not scar,” allowing for continued efficacy over the long term, he said.

Dr. Funk noted that the procedure can be performed on its own but has shown the best efficacy when combined with phacoemulsification. Cumulative data gathered from several users in Germany have shown that ELT combined with phacoemulsification can generate consistent IOP reduction, from a mean of about 27 mm Hg to a mean of 16 mm Hg, he said.

Used alone, ELT has been shown to reduce IOP to an average of 18 mm Hg, often without the need for additional IOP-lowering medications, he said.

He noted that there are relatively few complications associated with the procedure, and there are fewer reoperations compared to phacoemulsification combined with trabeculectomy.

The laser used in ELT has received the CE mark in Europe and Food and Drug Administration approval in the United States, Dr. Funk said.

New CustomCornea software

The most recent CustomCornea software update from Alcon is rejuvenating surgeons’ confidence in wavefront procedures, according to Jan Daniel, MD, of Oberhausen, Germany.

In an interview with Ocular Surgery News, Dr. Daniel explained the specific improvements the new software gives to the refractive surgeon.

“Prior to now, previous lasers did not match to the wavefront system, and a lot of people lost faith in the wavefront principle because they were not getting predictable results,” Dr. Daniel said. “Now, with the new CustomCornea software improvements we are able to match the software with the laser.” The software update has been available to German surgeons since April, he said.

Treatment decentration has been a problem in the past with wavefront-guided ablation, according to Dr. Daniel. He said problems that caused decentration with other systems have been addressed by the new CustomCornea software.

Dr. Daniel said one of the most important aspects of LASIK is the need for a fast eye tracker to keep up with a patient’s eye movements and rotation. Alcon’s new system features a 4,000-Hz tracker, which creates a much smoother and more predictable ablation pattern, he said. This can be especially important in correcting higher-order aberrations, he said.

Marking and centering from the iris can lead to decentration and unpredictable results because the iris itself is unpredictable, he said. “With the CustomCornea system, the marks are made on the limbus, and then I can predictably center on the cornea from a more fixed distance than if I were using the iris,” Dr. Daniel said.

These improvements to the LADARVision system, Dr. Daniel said, have led to predictable results with little regression; only 10% of patients had a postop refraction greater than –0.5 D.

He said 50% of patients have shown an improvement in best corrected visual acuity postoperatively, and none have shown a decrease.

The good results with the system have led to what Dr. Daniel calls a “revival of wavefront technology.” He added that the learning curve for the new system is very short, especially for doctors who are already performing LASIK.

Triamcinolone injections

Albrecht Hennig, MD, of Kathmandu, Nepal, discusses his experiences with cataract surgery in developing countries. Images: David Mullin, OSN

A second injection of triamcinolone acetonide may further improve visual acuity in patients with exudative age-related macular degeneration, according to a study.

Ingrid Kreissig, MD, and colleagues conducted a nonrandomized, prospective, comparative study to determine whether a second injection of triamcinolone can have a therapeutic effect additional to that of an initial injection. The researchers compared 13 eyes of 13 patients with exudative AMD to 24 control eyes of 24 patients also with exudative AMD. All patients received an initial injection of 20 mg of triamcinolone. The study group received a second injection of triamcinolone an average of 7.2 months after the first injection.

Preoperatively, no significant differences were noted between the two groups in IOP, age or refraction, Dr. Kreissig said.

Visual acuity improved in 10 of the 13 eyes in the study group (77%), and three eyes showed no change. The improvements in VA were statistically significant after 2 months, Dr. Kreissig said.

Following the second injection, there was again a significant improvement in VA of 0.15 to a maximum of 0.23, she said.

“In six eyes, or 46%, there was a repeated improvement in visual acuity of more than two Snellen lines,” Dr. Kreissig said.

In the control group, VA did not significantly improve during the follow-up period.

None of the eyes required cataract surgery, she added.

After the initial triamcinolone injection, a maximum increase in IOP of 20.2 mm Hg was seen at the 4-month follow-up. Increases were readily controlled with antiglaucoma medications, Dr. Kreissig said.

After the second injection, mean IOP increased to a maximum of 19 mm Hg at 3 and 9 months. Three eyes (23%) had IOP above 21 mm Hg, and one eye required trabeculectomy. Dr. Kreissig said the differences in pressure after the first and second injections were not statistically significant.

Dr. Kreissig added that patients who showed improvement in VA after the first injection can be expected to have a subsequent improvement after the second injection. Likewise, patients whose ocular hypertension did not increase after the first injection were not expected to show an increase after the second.

Wavefront-corrected IOLs

Wavefront-corrected IOLs allowed patients to achieve better reaction times in a night-driving simulator than standard biconvex IOLs, according to a speaker.

Jonathan C. Javitt, MD, MPH, described a study in which 29 patients were randomly assigned to receive the Pfizer Tecnis Z9000 in one eye and a standard biconvex Alcon AcrySof SA60AT lens in the other.

Between 3 and 6 months after surgery, patients were tested for time from stimulus to reaction on a validated driving simulator. The simulator tested patients in both rural and urban night-driving situations.

Dr. Javitt reported that while there was a slight difference in visual acuity between the wavefront-corrected lenses and the standard lenses, there was a significant difference in the recognition of objects and reaction time on the driving simulator.

Dr. Javitt said the largest difference in recognition occurred with pedestrians in the picture. According to Dr. Javitt, night-driving testing is important because patients with only standard IOLs have been shown to be “on the edge of safety.”

He said that in the United States the third brake light on automobiles has been shown to improve braking time by 0.35 seconds, and now the Tecnis lens has been shown to improve braking time by at least that much.

“Wavefront-corrected IOLs show slightly better Snellen acuity, decreased postop spherical aberration and therefore improved night-driving skills,” Dr. Javitt said.

New phaco approach

A phacoemulsification technique that first removes nuclear material from around the periphery of a posterior polar cataract may reduce the rate of complications associated with surgery for this type of lens opacity, said one surgeon.

M.D.K. Ramalingam, MD, said that posterior subcapsular cataracts are often challenging to remove because the lens capsules can be particularly weak, increasing the risk of dropping the nucleus. The risk is increased when surgeons use hydrodelineation or hydrodissection, which can cause a capsular tear or enlarge an existing one, he said.

To avoid such complications, Dr. Ramalingam developed a technique he calls encirclage phacoemulsification. In the procedure, phaco begins with a standard scleral tunnel incision and a continuous curvilinear capsulorrhexis. During phaco, however, the probe is moved in a circular fashion around the periphery of the lens. Low ultrasound power and a low vacuum setting of 50 mm Hg are used to remove the peripheral nuclear material, leaving the central core overlying the opacified area of the lens, Dr. Ramalingam said.

He said this procedure is possible because the nuclei in such eyes are always soft and do not need to be mobilized for phaco to proceed.

After the peripheral lens material is removed, the remaining island of opacified lens material is removed using an irrigation and aspiration handpiece and high vacuum of 400 mm Hg, he said.

“One can also use the ultrasound tip to remove the entire nuclear core,” he said.

Dr. Ramalingam said he has used this surgical approach in 20 eyes of 20 patients, including six eyes with existing capsular defects. He said no eyes suffered a loss of cortical material and no nuclear fragments fell into the vitreous cavity. Five eyes required limited anterior vitrectomy.

Dr. Ramalingam noted that visual acuity improved to 6/6 in 17 of the 20 eyes (85%) at 6 weeks follow-up.

Role of scleral buckling

Robert Stegmann, MD, at the German Ophthalmic Surgeons meeting.

Until studies show primary vitrectomy to be a superior surgical intervention, scleral buckling procedures will continue to play an important role in treating retinal detachment, according to a surgeon.

Michael H. Foerster, MD, said the use of scleral buckling has declined since the introduction of vitrectomy, mainly because the latter procedure has been associated with fewer complications, such as scleral necrosis, motility disorders and changes in refraction. He said effective buckling requires proper patient selection and is highly dependent on surgical skill, making the procedure time-consuming.

Dr. Foerster noted that the technique has not changed much since its introduction, and success rates have also not improved. He said 5% of eyes after buckling have no function or complete functional loss despite revision, and only half of eyes will achieve reading vision postoperatively. In contrast, vitrectomy, which is increasingly being taught to vitreoretinal surgeons, is much faster and less skill-intensive.

Other advantages of primary vitrectomy include better control, the ability to remove nuclear opacities immediately and the ability to identify foramen and macular holes easily, Dr. Foerster said. An external drainage site, which might result in choroidal hemorrhage, is also not required, he said.

However, he noted that buckling procedures have a long history of use and require few surgical devices, making surgical costs quite low. Also, because it is not an intraocular procedure, there is less risk of cataract formation.

“What has not been clarified yet is the primary success rate, final success rate, functional results, [proliferative vitreoretinopathy] rates, macular pucker and overall costs, which we need to take into consideration,” Dr. Foerster said. “Only a few studies deal with the long-term results [of vitrectomy].”

Vitrectomy seems to have become the technique of choice, he said, perhaps because buckling surgery “has a long learning curve and is hardly ever taught in our universities today.”

“I think, though, that it will still play a role in the future. It will not become obsolete,” Dr. Foerster said.

Vancomycin, amikacin

Patients with postoperative endophthalmitis have better visual outcomes when treated with intraocular vancomycin and amikacin than with other antibiotics, a surgeon said.

Herminia Mino de Kaspar, PhD, told meeting attendees that in a study of 258 cases of postop endophthalmitis, the combination of vancomycin and amikacin was more effective in preserving visual acuity than either vancomycin plus gentamicin or gentamicin alone. Further, she said, the addition of pars plana vitrectomy reduced the rate of infection recurrence from 23% to 5%.

Dr. de Kaspar found that patients receiving intraocular vancomycin plus amikacin had best corrected visual acuity outcomes of 20/200, compared with 20/200 for patients treated with vancomycin plus gentamicin and count-fingers visual acuity for those treated with gentamicin alone.

Dr. de Kaspar said improving one’s preoperative endophthalmitis prophylaxis regimen may be a factor in reducing the incidence of postoperative endophthalmitis. There is currently no standardized treatment for management of endophthalmitis, she said.

While the incidence of postop endophthalmitis has declined in recent decades, “for such a dangerous disease the number of cases remains too high to be tolerated,” she said. There are about 2,000 cases per year in the United States, Dr. de Kaspar said.

Rayner toric IOL

Astigmatism of up to 3 D can be corrected with Rayner’s 571T toric IOL, said Tanja M. Rabsiler, MD.

According to Dr. Rabsiler, the lens showed excellent centering behavior with little rotation in a preliminary study of nine eyes of six patients implanted with the lens. Mean rotation was less than 3°, and on average there was less than 0.2 mm of decentration at 1 month postop.

While these initial results are favorable, Dr. Rabsiler said longer follow-up on the efficacy of the lens is needed.

1CU accommodative IOL

Most patients can gain independence from reading glasses when implanted with the HumanOptics 1CU accommodative IOL, according to Magda Rau, MD.

Dr. Rau reported on implantation of the 1CU accommodative IOL in 30 eyes of 18 patients. At 6-month follow-up, 92% of the patients reported being completely satisfied with their lenses, she said. Of the 8% of patients who said they were unsatisfied, Dr. Rau said, the reason given was that they expected better uncorrected visual acuity for near vision. She said no patients were dissatisfied because of glare or halos.

Toric phakic IOL for keratoconus

Implantation of a toric phakic IOL is a refractive surgical option for patients with keratoconus, according to a surgeon.

Camille Budo, MD, implanted six patients with keratoconus and astigmatism between 2 D and 6 D with the toric version of the Ophtec Artisan phakic IOL.

According to Dr. Budo, the patients’ mean preop astigmatism of 3.75 D was reduced to a mean of 2 D postop. Spherical equivalent decreased from a mean of –13.88 D preop to a mean of –0.98 D postop.

After a mean follow-up of 8 months, refraction is stable in all patients, he said.

Microkeratome for lamellar keratoplasty

Magda Rau, MD, reported on implantation of the 1CU accommodative IOL in 30 eyes of 18 patients at the German Ophthalmic Surgeons meeting.

A microkeratome can be used to remove the anterior layer of the cornea for lamellar keratoplasty, according to a surgeon.

Massimo Busin, MD, presented the results of a prospective study evaluating microkeratome-assisted superficial anterior lamellar keratoplasty.

The study included 16 eyes with superficial corneal opacities of no more than one-third corneal depth. A microkeratome was used to remove a 160-µm thick, 9-mm diameter corneal lamella from the patient’s eye. A graft of a similar size was created from a donor cornea, and the graft was fixed on the recipient eye using overlying sutures. The sutures were removed after 2 weeks.

After suture removal, 15 of the 16 eyes had a best corrected visual acuity of 20/40, and all had astigmatism of 4 D or less, Prof. Busin said.

Prof. Busin noted that some interface problems can develop with the lamellar grafts, but the main problem encountered with the technique was mismatched size between the donor graft and recipient bed. He said there generally is no problem if the donor graft is smaller than the recipient bed.

Optical coherence biometry

Optical coherence biometry is the most accurate method of performing biometry in eyes that are difficult to assess, such as those with extreme refractive errors, according to one surgeon.

William H. Hill, MD, of Mesa, U.S.A., said the Zeiss IOLMaster optical coherence biometer can perform more accurate biometric assessments than ultrasound in eyes with high to extreme axial myopia with posterior staphyloma, high to extreme axial hyperopia or silicone oil in the vitreous cavity after posterior segment surgery.

Prechopper for hard nuclei

A new hybrid prechopping instrument is effective in breaking up nuclei of harder grades, according to the designer of the device, Takayuki Akahoshi, MD.

Dr. Akahoshi presented his experience using the hybrid combo prechopper made by ASICO.

According to Dr. Akahoshi, the instrument combines aspects of a blunt prechopper and a sharp universal prechopper, allowing it to be used for both vertical “karate prechop” techniques and horizontal counter-prechop techniques. The tip of the prechopper was modified to be sharper on the inside of the blades, while the edges of the tip are blunted to protect the chamber.

When using the instrument, the surgeon presses the tip into the center of the nucleus. Once it is at the appropriate depth, the tip is opened, and the nucleus is split apart. After this maneuver is repeated several times, the lens fragments that have been created can be removed using aspiration and high vacuum, Dr. Akahoshi said.

In harder nuclei, a nucleus stabilizer can be used to reduce stress on the capsular bag and avoid damage to the chamber, he said.

Tecnis IOL, stereoacuity

The Tecnis IOL, which is designed to improve contrast sensitivity after cataract surgery, also improves the potential for patients to achieve stereoscopic vision, according to a study.

Wolfgang Lange, MD, and colleagues evaluated the stereoacuity of 55 patients implanted bilaterally with the Tecnis IOL (Pfizer).

According to Dr. Lange, many pseudophakic patients with poor contrast sensitivity after implantation with standard spherical IOLs do not achieve stereopsis. The exception to this has been patients implanted with multifocal lenses, he said. The Tecnis lens is designed with a modified prolate anterior surface that has been shown to improve contrast sensitivity, Dr. Lange noted.

In the study, stereopsis was achieved after cataract surgery by 48 of the 55 patients (87.3%) at 1 day postop.

Dr. Lange noted that the other seven patients had comorbidities that prevented them from attaining stereopsis. This included one patient with glaucoma, one with Parkinson disease, two with subnormal binocular vision and three with macular degeneration.

Late-onset endophthalmitis

Late-onset endophthalmitis after cataract surgery with a sutureless incision may often be caused by patients rubbing or touching their eyes, a study suggests.

Cosme N. Naval, MD, and Analyn T. Suntay, MD, reviewed six cases of endophthalmitis that developed 3 to 14 days after uncomplicated phacoemulsification.

Dr. Naval said all cases had positive isolates that indicated the source of the infection was the patient. In three cases, the bacteria were identical to those seen in a respiratory infection, two cases showed the source to be bacteria normally found on the skin, and in one case the source was related to a nasolacrimal duct tube implanted in the patient’s fellow eye.

Dr. Naval noted that in five of the six cases the primary site of the bacterial invasion was the vitreous, probably due to an intermittent postop wound leak.

He said touching of the eyes by the patients probably transmitted the infection.

“A sutureless incision may be closed at the time of surgery but may be opened by rubbing,” he said.

Early vitrectomy saved the eyesight in four of the six patients, but delayed treatment of the remaining two cases resulted in vision loss, he said.