glaucoma therapy

Fine-Tune Your Glaucoma Management

Glaucoma experts weigh in on therapy, side effects and medication adherence.

Richard Mark Kirkner, contributing editor

At one time, glaucoma management was rather straightforward: Monitor intraocular pressure (IOP), watch for deterioration in the visual field, and adjust therapy accordingly. Now, glaucoma management is more nuanced. Thanks to advances in technology, such as scanning laser polarimetry, confocal scanning laser ophthalmoscopy and optical coherence tomography to analyze the retinal nerve fiber layer and the partnering of automated perimetry with comparative databases to track progression, you now have more finite tools for managing your glaucoma patients. As a result, yesterday's glaucoma patient may be today's glaucoma suspect.

Meanwhile, the World Glaucoma Association (WGA) held its annual Global Consensus on Medical Therapy in Glaucoma meeting this past May to develop practitioner guidelines for the therapeutic treatment of glaucoma. If the list of section meetings is any indication, this statement may address who should be treated, treatment goals, drug selection and delivery, non-pharmaceutical therapies and approaches and neuroprotection, among other related issues, according to the WGA website (www.worldglaucoma.org). Optometrist Murray Fingeret, a section member at the consensus meeting and chief of optometry at Veterans Affairs New York Harbor Health Care System in Brooklyn, N.Y., says a draft consensus statement should appear in the fall.

Conference participants have been guarded about speculating on what the statement will include, so in anticipation of the new guidelines, we put the following four questions to some optometric glaucoma experts not affiliated with the conference.

1. When do you initiate therapy?

Optometrist Elizabeth Muckley, of Kent, Ohio, says she determines whether to start therapy by comparing the patient's optic nerve head imaging and visual field testing with the baselines of both tests and by performing fundoscopy.

"I look for whether the neuroretinal rim tissue is thin at any points and whether there is any change in the banking of the blood vessels there," she says.

Specifically, she looks to see whether the blood vessels are changing direction and bending in a more horizontal fashion around the neuroretinal rim and cup edge of the optic nerve.

"I also have a good look at whether the optic nerve is average in size or whether it's large or small," she says.

Dr. Muckley adds that she uses the inferior, superior, nasal and temporal (ISNT) rule in evaluating the margins of the neuroretinal rim tissue for deterioration.

"Optic nerves can be large, small or average in size, but what you want to see [in a healthy optic nerve] is the rim tissue following a specific pattern of thickness," she says. "Typically, the thickest area of rim tissue should be in the inferior quadrant followed by the superior, then nasal, then temporal quadrant. Any deviation from this is an alert for glaucoma."

When optometrist Eric Schmidt, of Elizabethtown, N.C., is "kind of wavering back and forth" on when to start therapy, he says he uses an iPhone application called P.R.E.D.I.C.T. This is an acronym for Patient Risk Estimator Directing Individual Care and Treatment. The application utilizes results from the Ocular Hypertension Treatment Study and the Early Treatment Glaucoma Study to help direct management. (See http://mibsoftware.us/predict.)

"I input the patient's age, intraocular pressure (IOP), central corneal thickness standard deviation, visual field results and vertical cup-to-disk ratio," he explains.

PREDICT then calculates the patient's probability of conversion to glaucoma in five years.

"This application has taken all the emotion out of the decision to treat," he says.

2. How do you evaluate drug effectiveness?

Optometrist Ian Ben Gaddie, of Louisville, Ky., says he assesses three measures to determine whether the prostaglandin he's prescribed is working: IOP reduction, optic nerve changes, visual field results and retinal imaging.

He says it's easy to lose focus of the baseline pressure.

Notice the thinning of the inferior neural retinal rim in this glaucomatous optic nerve.

"I know this sounds kind of basic, but there are a lot of doctors who get into treating a glaucoma patient for 10 years, and unless they go back and do a thorough review of the chart, they may have no idea of the factor that initially triggered their treatment plan," he says.

In regards to the optic nerve, Dr. Gaddie says he can tell whether a specific prostaglandin has been effective if the optic nerve head (ONH) lacks signs of hemorrhaging or progressive thinning or knotting of its neuroretinal rim.

Finally, he says he's a firm believer in using visual field results and spectral domain optical coherence tomography in tandem to assess whether the drug he prescribed is working. For him, visual fields results are still the main "decision-making factor," he says.

"I feel like I see more sensitivity to progression on the visual field results than I do on [ONH] imaging," he explains. "A lot of people might not agree with me on that; theoretically it's the other way around, but practically speaking, in the trenches, I still rely on visual field results."

In fact, Dr. Gaddie says that when he sees a repeatable change in the patient's visual field results or deterioration in the optic nerve, he typically adds either a beta-blocker, an alpha-adrenergic agonist or a carbonic anhydrase inhibitor (CAI) to the prostaglandin the patient is already taking.

"Unfortunately, our only weapon against glaucoma is to lower IOP," he says. "When I'm adding a single drug to the prostaglandin, I'm looking for an additional 10% to 15% reduction in pressure."

If the patient can tolerate it, he typically adds a beta-blocker as a second drug because of its cost and availability. If that should fail to achieve the target IOP, Dr. Gaddie says he'll switch the patient to an alpha-adrenergic agonist or a CAI. If a third agent is indicated, he says he sets a goal of an additional 10% reduction in IOP.

"In the last two years I've been going more toward adding a combination agent as the second bottle of medicine," he says. "That's the maximum medical therapy: two bottles, three drugs. I truly don't want more than two bottles these days because of compliance issues. If I can't achieve target IOP with two medications, then I need to refer the patient for surgery."

Optometrist Michael Chaglasian, associate professor at the Illinois College of Optometry and chief of staff of the Illinois Eye Institute, in Chicago, says he uses Guided Progression Analysis (Carl Zeiss Meditec) and confocal scanning laser ophthalmoscopy to determine whether the therapy or therapies he's prescribed are effective. "You want to identify those who are progressing rapidly, and treat them very aggressively," he says. "Maybe 30% of patients fall into that category, while many other patients are relatively stable."

3. How do you manage drug side effects, particularly ocular surface disease?

The side effects of topical IOP-lowering drops have been well documented. A study out of the New Jersey Medical School and published this year concluded that about half of patients using glaucoma drops had some degree of ocular surface disease, and the severity of symptoms correlated with the number of drops they were taking.¹

Notice the optic nerve hemorrhage in this progressive glaucoma patient.

This moderately advanced chronic open-angle glaucoma patient has polar notching.

Optometrist J. James Thimons, chairman of the National Glaucoma Society and a private practitioner, in Fairfield, Conn., says he has managed this side effect by starting his appointment-compliant patients on an alternate-day prostaglandin regimen.

He says he implemented this regimen after reading studies that showed prostaglandins have a duration of action up to 60 hours.² In addition, he cites a Baylor College of Medicine study, which reveals too much prostaglandin can actually raise IOP.³

"I've found that starting the patient on an alternate-day regimen is actually a really good idea because you're getting the best of both worlds," Dr. Thimons says. "You get most of the [pressure] control you want, and, hopefully, in a world where compliance is everything and noncompliance is failure, you're going to get the patient to comply because the drug isn't bothering them too much."

He estimates that 15% of his glaucoma patients are now on alternative-day therapy.

Dr. Chaglasian says he manages drug side effects by consistently researching a drug's tolerability and then prescribing the drug that he feels offers both the best effectiveness and tolerability profile for the patient.

"Medications that are better tolerated and have less impact, in terms of side effects, are taken more regularly, and there's likely to be improved compliance," he explains.

That being said, he adds that he doesn't hesitate to discontinue a drug that bothers a patient. If the patient is using a prostaglandin, he says he would switch the patient to a formulation with a different preservative. With generics, he says he may switch the patient to drugs that have lower concentrations of the active agent.

Dr. Schmidt says he manages drug side effects by providing patient education.

"If you talk about the side effects and they don't happen, you look like a hero," he says. "If you don't talk about them and they happen, who's the fool?"

4. How can you instill medication adherence?

Due to the insidious nature of glaucoma, patient education regarding the importance of adherence to both treatment and follow-up appointments is paramount, says Dr. Muckley.

"Education about the asymptomatic nature of glaucoma is critical to help the patient understand that treatment is life-long," she says.

In addition to this patient education, she says she's found some success in getting patients to comply by:

► having them practice drop instillation in her exam room;
► supplying them with written instructions;
► encouraging them to align their drop instillation with a daily habit, such as getting dressed;
► supplying auto-droppers for those patients who have physical ailments;
► instructing patients to keep their drops refrigerated, so they can feel the drop enter their eye.

Dr. Schmidt adds that he reviews retinal images with his patients to instill appointment and medication adherence.

"Pictures speak a thousand words, and if we can show patients a ‘before’ and ‘after’ image, show them the thinning in the neuroretinal rim or changes in the optic nerve, we've made our case about the importance of complying to their medication(s) and follow-up appointments," he says.

Considering your colleagues have achieved success with the aforementioned practices, these same practices could very well be included in the WGA's consensus statement on medical therapy. Stay tuned. OM