At Press Time

Mini Shunt vs. Trabeculectomy

ARVO presentation shows results are similar

By Jerry Helzner, Senior Editor

■ Some top glaucoma specialists have recommended that ophthalmologists seeking to introduce tube shunts to their arsenal can first become proficient using Alcon's Ex-Press Mini Shunt and then acquire the skills to implant more advanced and complicated shunts. The reason for this suggestion is that ophthalmologists who are already performing trabeculectomies will find it fairly easy to transition to the Ex-Press.

Now, researchers at the University of Indiana University School of Medicine in Indianapolis have found that the clinical results achieved from Ex-Press procedures are quite similar to those of trabeculectomy. Their data from a retrospective analysis were presented at the recent ARVO meeting.

The researchers compared outcomes from 51 standard trabeculectomies performed by supervised resident physicians over a three-year period against 22 Ex-Press procedures done by supervised residents in one year using a partial-thickness scleral flap. All of the procedures were performed at a veterans' hospital affiliated with the university. Patient populations were similar based on all relevant metrics.

Intraocular pressures were recorded on a regular schedule over a six-month period. The average IOPs at six months were 9.9 mm Hg for the trabeculectomy patients and 12.1 mm Hg for the Ex-Press cohort. In patients who completed the study, 85% of the trabeculectomy group (34/40) met the target for reduced IOP in an allowable range between 5 mm Hg and 21 mm Hg. Eighty-one percent of the Ex-Press patients (13/16) also were within that target range. There were no statistically significant differences among a range of potential complications.

The Ex-Press Mini Glaucoma Shunt.

The researchers concluded that "at six months postoperative, there were no statistically significant differences in pressure-lowering efficacy, need for medications, complications, need for laser suture lysis or success between the two groups."

What's Next for FS Lasers?

Presbyopia-correction could be big new breakthrough

By Jerry Helzner, Senior Editor

■ The role of the femtosecond (FS) laser in ophthalmic surgery has been growing quickly and impressively over the past few years. From its early use in cutting flaps for vision-correction laser surgery, femtosecond lasers are now being used to cut tissue for corneal transplants and, more recently, to shape the capsulorhexis in cataract surgery.

Though some of these uses for FS lasers are still in relative infancy, re searchers are already exploring the next big potential breakthrough — employing femtosecond laser energy to reverse presbyopia by restoring flexibility to the crystalline lens.

Three recent ARVO presentations highlighted the possibilities of this indication.

► Researchers from the Cleveland Clinic, Vanderbilt University and LensAR Inc. first noted that FS laser treatment of the crystalline lens has been studied in computer modeling, porcine and human cadaver eyes, and also in living rabbits and monkeys for up to three years.

Compiling results from all of these studies, the researchers found repeatable reductions in lens stiffness in human cadaver lenses (ages 55 to 77 years). They also found no evidence of cataract in any of the treated animals, though there were faint pinpoint opacities. Laser safety was also assessed, with no adverse findings noted.

The researchers concluded that FS lasers "show promise for reducing lens stiffness in preclinical studies." Further human studies are planned for the future.

► A report on in vitro lens flexibility tests and live animal research using the FS laser supported by the German government and a consortium of industry, institutes and clinics concluded that "as the results of experimental in vivo and in vitro tests are promising, they might open the way to clinical trials in humans."

► Finally, another group of researchers from Hannover, Germany, used FS lasers on the crystalline lenses of pig eyes to determine if such presbyopia-reversal treatments could cause thermal damage to the retina. They found no evidence of thermal damage when using wavelength, pulse duration and pulse energy settings of the FS laser comparable to what levels would be needed in a human presbyopia-reversal treatment.

DSAEK Gets Favorable Reviews

Studies show better outcomes than PK

■ Patients who had penetrating keratoplasty (PK) performed on one eye and a Descemet's stripping automated endothelial keratoplasty (DSAEK) procedure on the fellow eye had much better outcomes with the DSAEK eye based on relevant objective and subjective metrics.

Researchers from North Shore Long Island Jewish Hospital, Great Neck, NY, presented a retrospective review of 12 patients (mean age 76.9) at the recent ARVO meeting. There were five graft failures in PK eyes, with one rejection that was classified as graft failure. There was a single DSAEK graft rejection that surgeons successfully reversed.

Of the 10 patients with good visual potential, the average BCVA in the DSAEK group was 20/50 while average BCVA in the PK patients was 20/60. The DSAEK patients, on average, had less corneal astigmatism. Subjectively, the researchers reported that "patients all preferred the vision in their DSAEK eye as compared to their PK eye, even if the Snellen acuity was not comparable."

The researchers concluded that DSAEK has "many advantages" over PK, including decreased incidence of graft failure and rejection, a greater number of neutral refractions and patient preference for the vision provided by DSAEK.

In another ARVO presentation, this one offered by researchers at Yamaguchi University in Japan, outcomes of 22 DSAEK-treated eyes were compared to 21 PK-treated eyes.

The researchers found greater improvement in corneal surface regularity in the DSAEK eyes but no significant difference in BCVA between the two groups. The researchers posited that "the presence of stromal opacity may limit visual acuity after DSAEK."

One cautionary note was sounded by University of Iowa researchers who found that, of 12 patients with Fuchs' dystrophy treated with DSAEK, nine saw significant cataract progression at an average of seven to eight months postoperatively and six eventually required cataract extraction within 16 months. The researchers conclude that phakic DSAEK may be a riskier procedure than staged cataract extraction before DSAEK or simultaneous DSAEK and cataract extraction.

Research Digest

New & Noteworthy Journal Articles

Compiled by Andrew E. Mathis, PhD, Medical Editor

► More ADAGES data. A pair of articles in the May 2010 issue of Archives of Ophthalmology present results from the African Descent and Glaucoma Evaluation Study (ADAGES) trial of over 1,500 patients who are both African-American and of European ancestry and who were enrolled to either an arm of glaucoma patients or a control arm of healthy eyes. These two articles follow the first ADAGES study group paper, which was published by Archives in September of last year.

The first paper reports on ancestry differences in optic disc, retinal nerve fiber layer (RNFL) and macular structure in 648 healthy patients. African-American patients had a mean optic disc area that was 2.06 mm² greater when measured with Heidelberg retinal tomography and 2.47 mm² greater as measured with OCT. RNFL thickness was greater among African-Americans, although when difference RNFL segments were measured, thickness of the temporal region was less among African-American patients. Central macular thickness and volume were also less in African-American patients.

The second paper provides results of visual-function assessment of 760 patients from the ADAGES cohort with normalappearing optic discs and IOPs lower than 22 mm Hg. These participants underwent two automated perimetry tests, with many of the patients also undergoing automated perimetry. Because mean age among African-Americans was lower (46.2 years vs. 49.5 years) and baseline hypertension higher (30.8% vs. 20.7%), results of perimetry were adjusted for these variables, as well as vertical cup-disc ratio and central corneal thickness.

African-American patients had worse mean deviation and pattern standard deviation and more points triggered as abnormal on all tests, compared to their counterparts of European heritage. Furthermore, a larger percentage of African-American participants had confirmed abnormal glaucoma hemifield test results on automated perimetry.

While additional research is needed (and will be generated) from the ADAGES patients, the findings clearly indicate that ancestry has a significant impact on visual anatomy. Future reports from the study group will focus on longitudinal data.

► A drop of prevention. Concerns persist over both the presence of preservatives in eye drops and the comparative efficacy of such drops when they are preservative-free. Now a study published online at the end of April by Acta Ophthalmologica may provide peace of mind for prescribing physicians.

A team of doctors in Germany and Scandinavia enrolled 158 glaucoma patients in an open-label study comparing latanoprost (Xalatan, Pfizer), which contains benzalkonium chloride as a preservative, to preservative-free tafluprost (Taflotan, Santen). Patients were already using latanoprost and were switched to tafluprost for 12 weeks, during which period they answered questionnaires and had IOP measured.

The patients in the study maintained almost the same mean IOP (16.4 ±2.7 mm Hg vs. 16.8 ±2.5 mm Hg) after 12 weeks, with percentages of patients experiences irritation, itching, tearing, and dry eye all decreasing. Tear breakup time improved from 4.5 ±2.5 seconds to 7.8 ±4.9 seconds.

The Acta study is notable because it is the first clinical trial using a preservative-free prostaglandin preparation, although the authors of the article concede that double-blind studies are needed to better determine whether or not preservative-free glaucoma medications can be as effective as drugs containing preservatives.

► Compliance with DR treatment guidelines lacking. A study of compliance with AAO preferred practice patterns for diabetic retinopathy at a Providence, R.I., medical center found that these guidelines were followed slightly more than half the time. Writing in the May 2010 issue of Retina, a team of ophthalmologists report that the compliance rate of 52% varied when broken down into 29 subcategories. Compliance was higher in the categories of examination (87%), diagnosis (82%) and treatment (74%) but lower in medical history (11%) and counseling/referral (34%).

The authors identify a key cause of low compliance being that residents are not being trained in accordance with the guidelines.

► Doing more with less. How well are surgeons who perform phacoemulsification in the United Kingdom being trained? An article from the May 2010 British Journal of Ophthalmology seeks some answers.

Doctors from Imperial College in London performed a literature search on five terms: phacoemulsification, training, curriculum, virtual reality and assessment. Other manual searches were conducted using the bibliographies from other papers. Trends in reporting from these papers were then compiled for the BJO report.

Citing the high rate of phaco being performed in the United Kingdom, the study authors report that, increasingly, training is taking place outside of the operating theater, in wet labs with cadaver eyes. This increase, however, is matched by a 10-year lag in guidelines, the current ones dating from the 1997 National Cataract Surgery Survey.

Much of the literature examined by the study authors faults the current wet-lab training as unrealistic and inaccurate. Some have made the case for virtualreality training as an alternative. However, the study authors caution that before any changes in training or assessment using virtual reality are made, curricula for basic, intermediate and advanced levels of training need to be improved and updated. OM