glaucoma

Glaucoma Patients: Know When to Hold Them and When to Refer Them

Uncontrolled progression, personal comfort, quality of life and maximum medical therapy all play roles in this decision

CHARLES ALDRIDGE, O.D., Burnsville, NC

When Kenny Rogers sang the "Gambler's" "You got to know when to hold ‘em, know when to fold ‘em …", he wasn't referring to managing glaucoma patients, but the lyrics easily could apply.

Once you initiate a treatment, a process begins. A process that involves many variables, such as the treatment itself, the patient's response to the treatment, the patient's physical health, the progression rate of the disease and the topic of this article: when to refer the patient to a glaucoma specialist.* (See "Choosing a Glaucoma Specialist," below.)

Uncontrolled progression

The most important consideration in deciding when to refer the patient to a glaucoma specialist is actually based on the definition of glaucoma. It is "a progressive neuropathy with characteristic structural damage that is frequently accompanied by a specific type of vision field defect."^1,2 "Progression" is the key. Your diagnosis of glaucoma means you've verified structural damage to the optic nerve. To validate this diagnosis, progression must exist.

Progressive damage to the optic nerve is the normal process of glaucoma. Our inability to impede the functional vision loss this damage causes with topical and/or oral medications often warrants a referral. (See "Measuring Glaucoma Structure and Function," below.)

Other important considerations

We, as individual optometrists, have our own personal comfort zone regarding how we choose to treat our glaucoma patients, making management relative not only to the patient's disease state, but also to our experience level, interest and expertise. In other words, we must base our decision to refer, in part, on our comfort level in treating the patient.

Also, we should consider the "quality of life" concept when making the decision to refer to a glaucoma specialist. We need to consider the risk vs. benefit ratio. For example, if the burden of treatment (e.g. adverse effects, cost, inconvenience) outweighs the benefit of the treatment, why compromise the patient's quality of life any further?

In addition, we should weigh the "maximum medical therapy" concept. Most of us recommend two bottles of eye drops (one is generally a combination medication, which equals three drugs total) as "maximum medical therapy" for glaucoma. This is because we, as eyecare practitioners, recognize that patients generally have a very difficult time complying with, using (physical instillation) and affording more than two glaucoma medications. So, if the patient is unacceptably progressing, despite the use of two medications, a referral to a glaucoma specialist is often warranted.

Example cases

Here are four cases to illustrate the above points:

CASE #1: Slight Intraocular Pressure Increase in Long-Time Patient.

You've been treating an 85-year-old male for primary open-angle glaucoma for more than 30 years. He's currently using one prostaglandin.

His medical history is positive for a pace maker and mild emphysema. Aside from his glaucoma, the patient's ocular history is positive for bilateral cataract surgery, and his visual acuity is 20/30 O.U. with glasses.

His visual fields, ocular coherence tomography scans and intraocular pressure (IOP) measurements (16 mm Hg to 17 mm Hg) have undergone minimal changes through the last five years. His medication has successfully kept him below his target IOP of 18 mm Hg. At his last two examinations, however, his IOP measurements have been in the low 20s.

What should you do? First, I would ask the patient whether he's had any recent "slips" in taking his prostaglandin. I've found that this is a non-threatening, and therefore, successful way of inquiring about noncompliance.

If the patient confesses to a slip in medication use, I would re-educate him on the importance of complying to his medications, and schedule him for a follow-up visit in a couple weeks to re-check his IOP. If, however, the patient says he's been in full compliance with his prostaglandin, I would switch the patient to a different prostaglandin, and schedule him for a 30-day follow-up visit to evaluate the effect. Keep in mind that some patients who use prostaglandins do experience a drift from baseline IOP after years of using a particular drug. In addition as a result of his medical history, I'd be hesitant to add another type of glaucoma medication. This is because the other glaucoma drug classes are associated with possible risks of systemic side effects. Beta-blockers, while extremely beneficial for several patients, likely wouldn't be a good choice for this patient, for example, as researchers have found they can decrease one's heart rate.

This fellow hasn't gone blind in his more than 30 years of treatment. As a result, the probability of him doing so anytime soon with a slight rise IOP is remote. So, I don't feel that adding another medication to his treatment regimen or referring him to a glaucoma specialist is necessary at this time.

CASE #2: Newly Diagnosed Patient Progressing Despite Desirable IOP.

You diagnosed primary open-angle glaucoma in a 44-year-old female one year ago. Her medical history is positive for obesity, migraines and hypertension. Her remaining ocular history is unremarkable. Her first IOP measurement was 24 mm Hg O.D. and 23 mm Hg O.S. You prescribed one prostaglandin, which has resulted in IOP measurements in the low teens at subsequent follow-up visits. Her visual acuity is 20/20 O.U.

In spite of these desirable IOP measurements, however, her OCT results have demonstrated statistically significant decreases, her visual field defects are worsening, and her cup/disc ratio is increasing.

What should you do? One thought that would cross my mind: Add more medication. After all, technically the patient isn't at the "maximum medical therapy" of at least two bottles. However, we must remember that we can't lower the IOP below the episcleral venous pressure (about 10 mm Hg to 12 mm Hg in most patients). She already has an IOP in the low teens. When a patient is in the low teens, I feel he/she is reaching the point of diminishing returns.

Although her IOP may be the result of non-compliance to her prostaglandin, I don't think a pep talk on compliance or discussing the alternatives of more medication and scheduling a follow-up visit is in her best interest at this point. If the patient admits to non-compliance, she may continue to skip doses, regardless of your pep talk, and present to you with major functional damage at her next follow-up visit. Because she is progressing and quickly, I would refer and fast! Damage to the optic nerve's axons is like toothpaste squeezed out of its tube. Once it occurs, you can't do anything about it.

CASE #3: Ten-Year Progression-Controlled Patient Seeks Surgery.

You've been managing a 60-year-old female for primary open-angle glaucoma for 10 years. Her medical history is unremarkable. Her ocular history is positive for early insipient cataracts, though it's not affecting her vision. She is currently using a prostaglandin. Her visual acuity is 20/20 O.U. The patient has shown good IOP control (18 mm Hg O.U.) with her current medication and no signs of progression.

At a recent follow-up visit, however, she tells you:
"I don't like the way my eye always looks so red after I use my drops. A friend of mine got this laser surgery for her glaucoma, and now she doesn't have to use drops. That is what I want done!"

What should you do? I would educate the patient on why you haven't mentioned surgery as a treatment before, the fact that surgery (e.g. argon laser trabeculoplasty, selective laser trabeculoplasty) doesn't always adequately control IOP without drops and that the patient may need to undergo these procedures again as a result.³ Also, mention that other drops exist that don't cause hyperemia. Most importantly, recognize and respect that the ultimate decision rests with the patient. If, in the presence of adequate information, the patient desires laser surgery, I would refer the patient.

CASE #4: Normal Tension Glaucoma (NTG) Patient Undergoing Structural Changes.

You've been treating a 50-year-old male for NTG for five years. His medical history is positive for obesity, sleep apnea and Type 2 diabetes. His ocular history is otherwise unremarkable. His visual acuity is 20/20 O.U. The patient has been taking a prostaglandin along with a combination drug that has lowered his IOP from 16 mm Hg O.U. to between 11 mm Hg and 12 mm Hg O.U.

In spite of this, his most recent follow-up visit reveals increased cupping of the optic nerve — a sign that functional vision loss will likely follow — and a Drance hemorrhage at the edge of the optic nerve — a visible sign nerve axons are dying.

What should you do? Because progression is happening despite the fact the patient is using "maximum medical therapy" and the IOP is as low as the medications can physiologically get it, I would move this patient out!

Simplification?

I realize these case examples, to some degree, simplify what can many times can be a very complex situation. In addition, I realize each clinician has his own comfort level with regard to these example cases — something that makes for wonderful debate. The bottom line is that they illustrate the importance of developing the ability to "know when to hold ‘em" and know when to refer ‘em." OM

* The purpose of this article is to provide guidance as to when a referral to a glaucoma specialist may be appropriate. The intent of it is not to establish a "standard of care," but rather to share my opinions on when to make this sometimes-difficult decision.

1. Medeiros, FA, Weinreb RN. Medical backgrounders: glaucoma Drugs Today (Barc). 2002;38:53-70.
2. Weinreb RN, Khaw PT. Primary open-angle glaucoma. Lancet 2004; 363:1711-20.
3. Atmaca LS, Simsek T. Efficacy of argon laser trabeculoplasty in primary open-angle and pseudoexfoliative glaucoma: long-term follow-up. Ann Ophthalmol. 2001 Sep;33(3):216-20.

Dr. Aldridge is in private practice in Burnsville, N.C., where he practices primarycare optometry and sees a great deal of glaucoma patients. E-mail him at ccaldridge@yahoo.com.