New technologies may improve glaucoma management

Sustained glaucoma medication and constant IOP monitoring may help clinicians tailor treatment to the needs of individual patients, especially those who have difficulty adhering to treatment regimens and whose pressure varies over time.

The Punctum Plug Delivery System (QLT Inc., Vancouver) offers sustained time-release doses of glaucoma medication, and the Triggerfish Continuous IOP Monitoring system (Sensimed, Lausanne, Switzerland) performs around-the-clock IOP checks and telemetry through a contact lens.

Sustained dosing promises to help clinicians address nonadherence, a common problem in glaucoma treatment, experts told Primary Care Optometry News.

“These technologies get at one of the core problems in treating chronic diseases, specifically glaucoma, and that’s the issue of patient adherence and remembering to get medications in a timely fashion,” Robert J. Noecker, MD, MBA, said in an interview with PCON. “Arguably, this is the way of the future.”

Richard A. Lewis, MD, also pointed to the need to improve patient adherence with dosing instructions.

“It’s an interesting and novel approach to treating problems in patients who can’t comply with medications,” Dr. Lewis told PCON. “One of our big problems in chronic disease is that patients won’t take medications on a regular basis.”

Glaucoma specialist Alan L. Robin, MD, lauded the punctal plug system for offering physicians more hands-on control of glaucoma treatment.

“Ideally, it would be nice to take the actual administration of a medicine out of a patient’s hands and put it into the hands of a doctor,” Dr. Robin said in an interview. “It’s ideal to be able to obviate adherence, to be able to get around the patient’s remembering to take a drop and … getting the drop in their eye. I hope that this is the first of many steps of developing various techniques that will allow us to do that.”

Dr. Robin’s associate, Amy L. Hennessy, MD, MPH, embraced the concept of sustained glaucoma drug delivery. “It’s really exciting that technology is advancing to the point that we’re thinking about other delivery methods,” she said in an interview.

Though highly motivated, many glaucoma patients with low vision (poor visual acuity or visual field loss) are unable to take their medications correctly, Dr. Hennessy added.

Punctal plug safe, but concerns arise

QLT’s punctal plug glaucoma drug delivery system is undergoing U.S. Food and Drug Administration clinical trials for safety and efficacy. The company conducted a multicenter, randomized phase 2 proof-of-concept trial that included 61 patients older than 18 years.

The Safety and Efficacy of Punctum Plug Delivery System in Subjects with Open-Angle Glaucoma or Ocular Hypertension (CORE) study evaluated the safety and efficacy of three dosages of latanoprost 0.005%: 3.5 µg, 14 µg or 21 µg. Mean baseline IOP after a wash-out period was 24.4 mm Hg. Investigators measured IOP at baseline, weekly for 1 month and subsequently every 2 weeks out to final follow-up at 12 weeks.

Of the original patient group, 23 patients dropped out of the study before 12 weeks. Of those 23 patients, 19 had insufficient IOP control and four lost the punctal plugs from both eyes.

Among patients who completed the study, average IOP reduction was 5.4 mm Hg in the low-dose group, 4.8 mm Hg in the medium-dose group and 4.9 mm Hg in the high-dose group. Mean IOP reduction was 20%, the study data showed.

“Getting IOP reduction in that range over a 12-week period is acceptable for something that hasn’t been optimized,” Dr. Noecker said. “Latanoprost is arguably a tricky molecule to work with in terms of sustained drug delivery because you worry that the higher doses may not work as well. So, to get that degree of IOP reduction is very good.”

Ocular adverse events included increased lacrimation (14.8%) and ocular discomfort (9.8%). At 12 weeks, 89% of patients reported “no awareness” of the plug, and 78% of patients reported no tearing.

Dr. Lewis, an investigator in the study, said the plug’s retention rate needs some improvement.

“It points out that we have to maintain the plug a little more effectively,” he said. “The plug has to be in place 90% to 95% of the time, and we’re not quite there yet.”

He added that upper punctal placement has been considered for addressing tearing symptoms, plug retention and therapeutic efficacy.

“The problem with the punctal plug is that a patient is unaware of whether the punctal plug is in or not unless it’s uncomfortable,” Dr. Robin said. “So, if it was comfortable and you lose your punctal plugs, it’s not the greatest thing in the world because you’re unmedicated for that period of time.”

Dr. Robin voiced concern about the plug causing excess tearing in patients with normal tear formation and no ocular surface disease. He also pointed out that latanoprost is a close chemical relative of bimatoprost, the active ingredient in a new product designed to enhance eyelash growth. The U.S. Food and Drug Administration’s Dermatologic and Ophthalmic Drugs Advisory Committee recommended approval of Latisse (Allergan) in December. Dr. Robin questioned whether the latanoprost would enhance lash growth.

Future study will focus on the effectiveness of higher doses of latanoprost, Dr. Lewis said.

“The final thing [the early study] showed us is that we need to play with concentration more,” he said. “You get higher concentrations and you get lower pressures.”

Tracking fluctuations in IOP

The Triggerfish system comprises a disposable soft, hydrophilic silicone contact lens embedded with a sensor and tiny microprocessor located outside the line of sight. An antenna taped around the eye transmits data through a cable to a portable recorder that wirelessly uploads data to the clinician’s computer, according to an online Sensimed brochure.

The device monitors IOP continuously up to 24 hours during sleep and daily routines and enables the clinician to make an early diagnosis and tailor treatment to the patient, the brochure said. Triggerfish is not yet commercially available in the United States.

Dr. Noeker pointed out that many patients’ IOP levels peak at times other than when they are in the doctor’s office.

“Monitoring is important,” Dr. Noeker said. “It will also help us separate out our different therapies and how well they control IOP over the course of the day vs. just at 2 hours or some other arbitrary time point.”

Constant monitoring would also help clinicians assess the effectiveness of various drug therapies and surgical procedures, Dr. Lewis said.

For more information:

• Robert J. Noecker, MD, MBA, can be reached at the University of Pittsburgh Medical Center, Eye and Ear Institute, 203 Lothrop St., 8th Floor, Pittsburgh, PA 15213; (412) 647-2200; fax: (412) 647-5119; e-mail: noeckerrj@upmc.edu. Dr. Noecker has received grant/research support, is a consultant and is on the Speaker’s Bureau for Allergan.
• Richard A. Lewis, MD, can be reached at 1515 River Park Drive, Sacramento, CA 95815; (916) 649-1515; fax: (916) 649-1516; e-mail: rlewiseyemd@yahoo.com. Dr. Lewis is a paid consultant for QLT.
• Alan L. Robin, MD, and , can be reached at 6115 Falls Road, Suite 333, Baltimore, MD 21209; (410) 377-2422; fax: (410) 377-7960; e-mail: arobin@glaucomaexpert.com. Dr. Robin is a member of the Primary Care Optometry News Editorial Board. Dr. Robin has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Amy L. Hennessy, MD, MPH can be reached at 6115 Falls Road, Suite 333, Baltimore, MD 21209; (410) 377-2422; fax: (410) 377-7960; e-mail: ahennessy@glaucomaexpert.com. Dr. Hennessy has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.
• More information on the QLT Punctum Plug Delivery System is available at www.qltinc.com.
• More information on Triggerfish Continuous IOP Monitoring system is available at www.sensimed.ch/E/index.htm.