Beta blockers remain most doctors’ first choice for initial glaucoma therapy

Issue: February 1999

With so many glaucoma medications available, it can be difficult to just choose one to prescribe to your patients. After considering the potential side effects, cost and convenience of each drug, the anticipated result is treatment that is tailor-made for each patient. Primary Care Optometry News discussed with three practitioners how they treat their glaucoma patients.

“My primary concern when choosing a glaucoma medication is safety. It’s nice to lower someone’s eye pressure, but you must weigh the benefits against the potential side effects,” said Alan Robin, MD, PA.

In fact, he said, make sure that elevated eye pressure is not the only factor involved when you begin treatment. “I don’t treat people who don’t have glaucoma,” he said. “That’s a very important issue. Elevated eye pressure alone is not a reason to treat.”

Beta blockers: first-line therapy

Dr. Robin said that using beta blockers, often the first-line therapy of ophthalmologists and optometrists, should be done with care. “If a patient has asthma or cardiovascular problems, I don’t use nonselective beta blockers,” he noted.

George Comer, OD, chief of staff and chief of Family Practice Optometry Service at the Eye Care Clinic/Optometric Center of Fullerton, Southern California College of Optometry, agreed that medical therapy varies with the needs of each particular patient. “I don’t really like to use beta blockers, particularly nonselective beta blockers, in patients with low-tension glaucoma,” he said.

“There is some concern that any patients who have pigmentary glaucoma might not do so well with medications that reduce pressure in the posterior chamber of the eye such as beta blockers,” he said. “Beta blockers also have a number of systemic contraindications: they can exacerbate asthma or diabetes and they can lower blood pressure and heart rate. Some patients tend to get overlooked in that type of situation, such as a patient who is a runner and tends to have a lower pulse rate and looks really healthy. You usually wouldn’t think twice, but that’s the patient who tends to have the problem with the beta blockers and goes undetected.”

Keeping those considerations in mind, beta blockers are still the first choice of many doctors. “Ocupress [carteolol, Otsuka] is a beta blocker that comes in a 1% solution and has intrinsic sympathomimetic activity [ISA],” said Anthony Litwak, OD, residency program director at the Baltimore VA Medical Center and editor of The Glaucoma Handbook. “ISA results in fewer systemic side effects on both pulmonary and cardiac systems. Another potential advantage is that it may not affect the good cholesterol, the high density lipoproteins, as much as some of the other beta blockers.”

Dr. Robin agreed: “When selective beta blockers are not enough, my drug of choice, because of compliance, would be timolol maleate or carteolol.”

“Cost is also an issue,” Dr. Litwak continued. “Certain beta blockers that are now available in generic form will probably be available at a reduced cost. For example, Betimol [timolol hemihydrate, Ciba Vision] is similar to Timoptic [timolol maleate, Merck] but is available at a lower cost.”

Dr. Comer said that he tends to go with Timoptic, “the gold standard of topical glaucoma medications,” as a first-line therapy. “Timoptic has been around for nearly 20 years, so there’s not too many undocumented or unexpected side effects with it,” he said. “Beta blockers are a good first-line medication for most chronic open-angle cases, as a general rule.”

Second-line therapy options

If beta blockers are not appropriate, or additional medications are warranted, the practitioners opt for either alpha-2 agonists, prostaglandins or carbonic anhydrase inhibitors as second-line therapy.

“If we still want to achieve a lower target pressure, then we’ll add a second medicine to the beta blocker,” said Dr. Litwak. “I would choose Xalatan [latanoprost, Pharmacia & Upjohn] or Alphagan [brimonidine tartrate, Allergan] as my next line of therapy. Xalatan is a prostaglandin agonist, and it is only prescribed once a day, usually in the evening. It doesn’t have many systemic side effects, so it’s a good choice for first-line therapy in a patient with a contraindication to a beta blocker. However, because it is a prostaglandin agonist, there is the potential for it to induce inflammation, although that has not been reported to a high degree in any clinical study. I would probably avoid it in a patient who had a history of iritis, or was pseudophakic because of a potential risk of cystoid macular edema.”

Dr. Comer concurred with the two choices, but said there is more research to be done on the two “newer” medications. “I think either is a good choice as a second-line medication,” he said. “Xalatan might be a little bit better for some patients because it tends to have a little bit better pressure-lowering effect than Alphagan, or than beta blockers for that matter. But it’s a brand-new class of medications, the prostaglandin analogs, and because of that, we really don’t know much about it in long term, daily use.”

Dr. Robin, however, expressed a greater resistance to Alphagan. “I do not use brimonidine as a primary therapy, because in 10% of people it could cause sedation, and most people never link their eye drops to sedation. I have had individuals on Alphagan who actually went to a psychiatrist because they were so tired. That’s a real danger of the drug.”

Rather, Dr. Robin stated his preference for either Xalatan or a topical carbonic anhydrase inhibitor such as Azopt [brinzolamide, Alcon]. “I think compliance is a key issue here,” he noted.

He said that all medications prescribed are topical, with the exception of systemic carbonic anhydrase inhibitors recommended for people with poor manual dexterity who live alone.

Unique side effect

One unique side effect with the prostaglandin Xalatan, however, is a possible change in iris color, most notably with hazel eyes.

“About 10% of the patients in the clinical studies with Xalatan developed a change in iris color,” said Dr. Litwak.

“It seems that patients who develop this change have mixed-colored irises, with a lighter color in the periphery and a light brown pigmentation near the pupillary border,” he said. “Over time, the irises of these patients developed a darker, browner color. It’s believed that this is an increase in the size of the melanosome and probably doesn’t represent any type of malignant change. So far, it doesn’t appear to have any real detrimental effects to the patient’s glaucoma or cause any other complications.”

Dr. Robin said that while a change in eye color may seem a small price to pay for successful treatment of glaucoma, the practitioner needs to make patients aware of the possibility. “It’s important for patients to know what the actual problems are,” he stated. “Some patients may not want brown eyes, while other patients with glaucoma don’t really care. They need to make the decision themselves.”

Set a goal

No matter what course of treatment is chosen for a patient, the practitioner should begin with a target eye pressure in mind, Dr. Robin said. “It’s important to have a goal. If one medicine isn’t enough, I will try another medicine — I try to simplify rather than add medicines.”

Another important concept is the “one-eyed therapeutic trial,” or to treat only one eye first, Dr. Robin noted. “If the pressure in both eyes is 30, you treat both eyes and the pressure next time is 23, you don’t know if that’s normal variation or whether the medicine gave you the effect,” he advised.

Following up

When scheduling a follow-up visit, taking a little precaution can help avert potential problems, Dr. Comer advised. “Typically, it’s a good idea to call the patient before the first follow-up after initiating a new medication just to make sure he or she can get the drops in and there are no unexpected side effects,” he said. “Then, see the patient in the office in approximately 2 or 3 weeks or — at the most — 1 month after the patient starts the medication.”

When it comes to scheduling a follow-up visit, “each case is individualized,” Dr. Litwak said. “It depends on how quickly we’re trying to achieve our target pressure so, to some degree, it depends on how advanced the glaucoma is. But typically we’ll see the patient back anywhere from 1 to 4 weeks after we prescribe the initial medication.”

Another consideration is what kind of medication was prescribed for the patient, Dr. Robin said. “Usually, I wait about 4 weeks for a topical beta blocker, because it takes about that long to stabilize, 2 to 4 weeks for a prostaglandin such as Xalatan, about 2 weeks for a topical carbonic anhydrase inhibitor and about 4 weeks for an alpha agonist,” he advised.

Check for proper administration

At that time, the doctor takes the intraocular pressure (IOP), checks on any side effects and makes sure that the patient is taking the medication in the correct manner. “Some patients may not be getting the medication in their eyes. In other cases, they’re not using it as prescribed. Some patients will take both doses of a twice-a-day medication at one time rather than about 12 hours apart,” Dr. Comer said.

Lifetime of therapy

The process of long-term monitoring is unique to each particular case. “If you’ve reached your target IOP, it then depends on how severe the glaucoma damage is. A patient who has more severe damage and is more fragile should be seen more often than someone with a less severe case,” Dr. Robin said.

Whether the monitoring is done frequently or occasionally, it becomes part of the patient’s regular routine, because glaucoma is a chronic condition. “Medications are usually lifelong; there’s no cure for glaucoma,” said Dr. Litwak.

Although Dr. Comer agreed that “glaucoma won’t go away by itself, nor is there any medication or surgery that will cure it,” the type of medication prescribed may or may not change over the years. “That’s why compliance is a tremendous issue in glaucoma. The classic issue with beta blockers is ‘long-term drift’; the IOP tends to drift up over time. In this case, we start looking at other types of medications to substitute for the beta blocker,” he added.

When to consider laser surgery

If the practitioner tests several types of medications and none seem to be very effective, the next step would be to consider laser trabeculoplasty, Drs. Robin and Litwak said. “Instead of going on to a third or fourth medication, we’ll use laser trabeculoplasty as our next line of therapy, just because of the compliance issues with patients having to take more than two or three eye drops a day,” Dr. Litwak said.

“That involves a laser treatment to the trabecular meshwork. The procedure is usually effective in the majority of patients. The main disadvantage to the procedure is that the effectiveness wears off over time, so usually by 5 years fewer than half of the patients are still controlled with the laser procedure,” he said.

For Your Information:

Alan Robin, MD, PA, can be reached at 6115 Falls Rd., Baltimore, MD 21209-2226; (410) 377-2422; fax: (410) 377-7960. Dr. Robin did not disclose whether or not he has a direct financial interest in the products mentioned in this article or if he is a paid consultant for any companies mentioned.

George Comer, OD, can be reached at SCCO, 2575 Yorba Linda Blvd., Fullerton, CA 92831; (714) 449-7405; fax: (714) 992-7811; e-mail: Gcomer@scco.edu. Dr. Comer has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

Anthony Litwak, OD, may be reached at VA Medical Center, 10 N. Greene St., Baltimore, MD 21201; (410) 605-7230; fax: (410) 605-7232; e-mail: litwak.anthony@baltimore.va.gov. Dr. Litwak has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.