Every year, the AGS meeting features presentations of the best in glaucoma research. This year, more than 600 registrants enjoyed 68 poster and 24 paper presentations as well as a glaucoma surgery day, several symposia, roundtables, workshops, and many other opportunities to share ideas and information. Highlights of the meeting included lectures by Douglas E. Gaasterland, MD; Harry A. Quigley, MD; Joel S. Schuman, MD; and Guest of Honor Richard P. Wilson, MD. Among the many excellent studies presented, I have chosen several with the most immediate clinical relevance.
TUBE SHUNT SURGERY
Steven J. Gedde, MD, and James L. Brandt, MD, presented the 5-year results of the Tube Versus Trabeculectomy (TVT) study.1,2 With longer follow-up, tube shunt surgery continues to show a higher success rate compared with trabeculectomy using adjunctive mitomycin C. A total of 212 patients were enrolled—107 in the tube group and 105 in the trabeculectomy group. At 5 years, IOP (mean ±standard deviation) was 14.2 ±6.3 mm Hg in the tube group and 12.8 ±5.8 mm Hg in the trabeculectomy group (P = .19).
The cumulative probability of failure was 26% in the tube group and 47% in the trabeculectomy group (P = .002). Reoperations for glaucoma were needed in 9% of those in the tube group and 19% in the trabeculectomy group (P = .025). Of those in the tube group requiring reoperation, 50% received a second tube, and 50% underwent a cyclodestructive procedure, whereas most of those needing reoperation in the trabeculectomy group received a tube shunt.
Overall, late postoperative complications developed in 34% of those in the tube group and 37% of those in the trabeculectomy group (P = .67). Five (4.8%) of those in the trabeculectomy group developed blebitis or endophthalmitis, compared with none in the tube group. Cataracts progressed at a similar rate in both groups, and about half of phakic patients underwent cataract surgery during the first 5 years of follow-up.
In summary, the TVT study supports the continued use of tube shunts as a good alternative to trabeculectomy surgery in patients who have undergone previous glaucoma or cataract surgery. It remains to be seen which procedure is best as an initial surgery, and the primary TVT study is ongoing. Cost considerations will likely play an increasing role in glaucoma management over the coming years, and cost consequence analysis will be a part of current and future clinical trials. Pratap Challa, MD, presented this analysis for the TVT study. He found that the total cost of all medical and surgical treatment was higher for tube surgery compared with trabeculectomy, at least over the first 5 years.3 Costs are constantly changing, especially with the increased use of new equipment and devices in glaucoma surgery. In the future, we will probably have to show not only whether a new device or procedure is beneficial to our patients but also whether it is cost-effective.
REPEAT SELECTIVE LASER TRABECULOPLASTY
Two studies presented at this meeting addressed the repeatability of selective laser trabeculoplasty (SLT). We know that SLT can work well when repeated (unlike argon laser trabeculoplasty), but how well? Brian A. Francis, MD, and colleagues looked back at the results of a second 360° SLT procedure in 137 patients who had responded well to a first SLT.4 After the first SLT, mean IOP decreased from 20.3 mm Hg to 16.4 mm Hg at 1 year, with a later gradual diminution of response. After the second treatment, mean IOP decreased from 19.4 mm Hg to 16.7 mm Hg at 1 year. A similar number of medications (about two) were needed before and after treatment. The use of a prostaglandin analogue did not seem to affect the response to a first or second SLT.
Ben J. Harvey, MD, and colleagues also looked back at 86 patients undergoing repeat SLT.5 Mean IOP prior to the first SLT was 22.5 mm Hg and prior to the second was 21.7 mm Hg. A response to SLT was defined as a decrease in IOP of more than 20% at 3 to 6 months; 54% of eyes responded to the first treatment, and 56% responded to the second. The incidence of IOP spikes was similar after a first or second treatment. Surprisingly, the investigators found that the response to initial SLT was not predictive of the response to the subsequent treatment, although it seems unlikely that patients who did not respond to SLT would undergo this laser treatment a second time.
These studies provide further evidence that SLT is a safe and reasonably effective adjunct to medications when repeated, at least for a second time.
MEDICAL TREATMENT OF LOW-PRESSURE GLAUCOMA
Theodore Krupin, MD, reported results from the Low- Pressure Glaucoma Treatment Study (LoGTS),6 which were recently published in the American Journal of Ophthalmology.7 The study was a prospective randomized trial of brimonidine 0.2% versus timolol maleate 0.5% dosed twice daily in patients with glaucoma and baseline IOPs of 21 mm Hg or less. A total of 178 patients were recruited and observed for 30 ±2 months (mean ±standard error). Importantly, the primary outcome was visual field progression. Although there was a high discontinuation rate due to adverse events (28% in the brimonidine group and 11% in the timolol group), a sufficient number of patients finished the study. The reduction in IOP was similar between those who dropped out and those who completed the study.
Despite a similar mean diurnal IOP reduction of about 12.5% in both groups, fewer brimonidine-treated patients (9/99 or 9.1%) had visual field progression compared with timolol-treated patients (31/79 or 39%). Three methods were used to determine visual field progression, and five patients in the brimonidine group and 18 in the timolol group progressed by all three criteria. The results are fascinating, but the reason for these findings is unclear. Possibilities include (1) better nocturnal IOP lowering with brimonidine, as timolol has little or no effect on nocturnal IOP, (2) adverse effects of timolol on ocular perfusion, and (3) a pressure-independent neuroprotective effect of brimonidine. Although pretreatment blood pressures were the same in the brimonidine and timolol groups, measurements were not repeated while patients were on treatment. It would be intriguing to repeat the study comparing other agents with similar diurnal IOP profiles such as brimonidine versus a topical carbonic anhydrase inhibitor or a fixed-combination agent versus a prostaglandin analogue. Even then, it might be impossible to determine an IOP-independent neuroprotective effect. Nonetheless, a possible implication of this study is that timolol monotherapy may not be the best choice for the treatment of low-pressure glaucoma.
MEDICATION ADHERENCE
How can we best identify those patients who are not using their eye drops effectively, and how can we help them do better? Michael Boland, MD; Dolly Chang, MD; and colleagues addressed these questions in the Automated Dosing Reminder Study (ADRS).8,9 They studied 323 patients treated with once-daily prostaglandin drops. The use of drops was electronically monitored over a 3-month period. The investigators found that most patients used the drops as prescribed, but about 20% of patients used their drops less than 75% of the time. These patients reported using 86% of their drops on average but actually used only 47%. Among other factors, nonwhite race and having no relatives with glaucoma were independent risk factors for poor adherence.
Patients were also asked a series of questions about their drops. Three were strongly correlated with nonadherence:
• Over the past month, what percentage of your drops
do you think you took correctly?
• Did you forget to take your drops some days?
• What are the names of your drops?
If patients stated that they used their drops less than 95% of the time, missed “some days,” or did not have a reasonable idea of the medication's name, they were much less likely to be adherent.
In this study, 47 patients were found to be poorly adherent and were randomized either to no intervention or to receiving daily, automated reminders via text or voice message. The messages were scheduled for the prescribed time and medication via a personal health record set up for each patient. The control group remained about 50% adherent, while the intervention group improved from 51% to 67% adherence. This approach did not turn poorly adherent patients into ones with excellent adherence, but it did have a significant impact. With appropriate software, such a system would be relatively easy and inexpensive to implement within the structure of an electronic health record.
CHANGING GLAUCOMA DEMOGRAPHICS
In coming years, ophthalmologists will care for everincreasing numbers of patients with glaucoma. The face of those patients will also be changing from that of older white women to that of older Hispanic men. Currently, about 2.7 million people in the United States have glaucoma. By 2050, this number is expected to increase to 7.3 million. Thasarat Vajaranant, MD, and colleagues applied glaucoma prevalence rates from published studies to the current US population and expected future demographic changes. They found that the largest demographic group with glaucoma is currently non-Hispanic white women aged 70 and older; this will shift by 2050 to older Hispanic men.
At present, the highest rates of glaucoma prevalence are in New Mexico, Texas, and Florida. These states will retain their top positions in coming years but with prevalence rates of 5% or more. The demand for glaucoma care will continue to rise across the country, particularly in the South and Southwest.10
Geoffrey T. Emerick, MD, is an associate clinical professor of ophthalmology at the University of Connecticut School of Medicine in Farmington. Dr. Emerick may be reached at (860) 678- 0202; gtemerick@gmail.com.
