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General ophthalmologists discuss glaucoma at Las Vegas meeting
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LAS VEGAS – More than 150 ophthalmologists attended the First Annual Ocular Surgery News Symposium — Glaucoma: Improving Your Odds, held here.
Rather than presenting information for the glaucoma specialist, the symposium focused on topics of importance to general ophthalmologists treating glaucoma “on the front lines.”
“Your attendance here has already made this a successful meeting, and we look forward to this meeting continuing,” said Louis B. Cantor, MD, co-course director.
The 2-day program featured presentations on glaucoma pathophysiology, nerve assessment, the importance of intraocular pressure and sessions on medical and surgical treatment options.
“We wanted to follow a logical continuum with the program. Start with basic science, then go on to nerve assessment, through lasers, drugs, then surgery,” said John R. Samples, MD, co-course director.
The program concluded with a practice management and coding and reimbursement session led by Kevin J. Corcoran, COE, CPC, FNAO.
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Following are some highlights of the meeting. Many of these presentations were reported first on the OSN SuperSite from our onsite coverage during the meeting.
Population studies
The epidemiology of glaucoma can help physicians understand both the disease and the people at risk of developing the disease, said Eve J. Higginbotham, MD.
“Certainly, we don’t know everything about glaucoma,” Dr. Higginbotham said. “But … the patterns of glaucoma will help us determine who is at risk for glaucoma.”
She noted that 67 million people worldwide have some form of glaucoma and that the disease has been recognized as an independent risk factor in serious motor vehicle accidents.
Large cohort studies have sought to clarify which members of a population are at risk for glaucoma, but each study has had different parameters. A study in Olmstead County, Minn., showed that despite treatment, 9% of patients with glaucoma experienced disease progression.
“Locations are disparate; the criteria, age, ethnicity and prevalence all differed,” Dr. Higginbotham said. “So there is going to be a wide range of reports.”
Still, risk factors for certain types of glaucoma have emerged, she said. For primary angle-closure glaucoma (POAG), ethnicity, age and gender should all be considered, as well as hyperopia and a positive family history. Even climate should be considered.
IOP is a significant risk factor for POAG, according to the Baltimore Eye Survey. Age is a significant risk factor, for instance when comparing 70- to 79-year-olds vs. 40- to 49-year-olds, she said. Studies have shown higher risks for men, for women, or no difference, depending on the study. Ethnicity, family history and diabetes are also risk factors.
For POAG, there is no consensus on the risk of glaucoma based upon systemic hypertension, myopia, migraines and thyroid disease.
“Why study epidemiology? It is important to recognize these patterns of disease,” she said. “However, when we look at a patient in our office, the person in front of us may not represent a study. Age and family history are clearly supported as risk factors. Genetic analyses will undoubtedly reshape our consideration of race and ethnicity in the future.”
PI in pigmentary glaucoma
Patients with early pigmentary glaucoma (a secondary form of open angle glaucoma) should be considered candidates for peripheral iridectomy, Dr. Cantor said.
“We are aware of descriptions that suggest the concave posterior bowing of the iris is characteristic of pigmentary glaucoma and it may revert to a more planar confirmation following iridectomy,” he said.
Research also suggests that “reverse pupillary block” exists in eyes with an abnormal iris that acts like a valve, Dr. Cantor said.
Ultrasound biomicroscopy can be used to confirm the concave bowing of the iris and thus the diagnosis, he said.
“What is the role of iridectomy in this syndrome? The evidence and the science are not there,” he said. However, he noted, “I consider a peripheral iridectomy in early pigmentary glaucoma or in eyes with ocular hypertension and pigment dispersion syndrome. In eyes with firmly established pigmentary glaucoma and significant damage we are probably too late.”
He noted that eyes with pigmentary dispersion syndrome and normal IOP should not be considered candidates for iridectomy.
Pachymetry for all
Pachymetry should be performed on all patients with glaucoma and glaucoma suspects, according to one physician.
This information “should be placed in the patient’s chart where it is easily referenced,” said Steven T. Simmons, MD.
Dr. Simmons noted that the Ocular Hypertension Treatment Study (OHTS) found that central corneal thickness is a risk factor in the development of glaucoma. He said Goldmann tonometry is not as effective as pachymetry, and that tonometry showed several “errors” in many patients in the OHTS.
Refractive surgery caveats
Err on the conservative side when a glaucoma patient is interested in having refractive surgery, a refractive surgeon advised.
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According to Richard L. Lindstrom, MD, glaucoma and refractive surgery have a “cautious symbiosis. This is uncharted territory, and increased surveillance is needed. This is not business as usual.”
Dr. Lindstrom discussed how to manage glaucoma patients who were interested in refractive surgery.
“Patients with glaucoma are as handicapped by refractive errors as the normal population, but they are more likely to be contact lens intolerant. They also may have iatrogenic anisometropia,” he said.
He said there are numerous refractive surgical options for these patients, including LASIK, laser epithelial keratomileusis (LASEK), photorefractive keratectomy (PRK), conductive keratoplasty, refractive lensectomy and Intacs (Addition Technology).
Special precautions include measuring and recording IOP levels and pachymetry pre- and postoperatively. He added that the surgeon should also document the visual field and optic nerve status pre- and postop. He said to watch for steroid-induced IOP spikes postop.
Finally, Dr. Lindstrom said to perform extra informed consent. “The surgeon is at greater risk than the patient,” he warned.
SLT vs. medical therapy
A prospective multicenter study has been initiated to compare selective laser trabeculoplasty (SLT) to medical therapy, L. Jay Katz, MD, announced.
Patients will be randomized to receive SLT or topical medical therapy as first-line therapy for the treatment of glaucoma. Medications are not specified. Researchers will use their current first-line medication of choice.
The study protocol includes a stepping regimen with multiple SLT treatments, first 360°, then 180°, then another 180°, with a 6-week to 4-month wait between treatments.
Enrollment is ongoing in the study, dubbed the SLT/MED study.
Combination drugs and compliance
If a multiple drug regimen is creating a compliance problem for a patient, consider combination drugs, Eve J. Higginbotham, MD, said.
“A major rationale for considering combination drugs is compliance,” Dr. Higginbotham said. Other benefits of combination therapy include convenience, efficacy and cost, she said.
Dr. Higginbotham described a small study that examined the efficacy of combination drugs. Combination therapy resulted in higher levels of the drug in the aqueous humor, she said.
Additionally, Dr. Higginbotham said, if a patient uses a combination drug instead of two or more separate drugs, the number of health insurance copayments the patient must make are reduced.
Disadvantages to combination therapies for the patient include possible adverse reactions to a particular combination. When that happens, the entire bottle of medication is wasted, Dr. Higginbotham said.
Still use for beta-blockers
Although many no longer consider beta blockers the first-line medical therapy for glaucoma, the drugs still have numerous advantages, Dr. Higginbotham said. She encouraged physicians to use beta-blockers in selected patients.
“Beta blockers are effective, safe in most patients and not as expensive as other treatment options,” she said.
She also noted that beta-blockers work well in combination with nearly all other available glaucoma medications, they can be used once or twice per day, and they may also have neuroprotective qualities.
Dr. Higginbotham cited a study that investigated the cost of beta blockers. The study found that timolol costs between 30 cents and 46 cents per day, and betaxolol costs between 57 cents and 81 cents per day. She said this is a minimal price compared to other glaucoma medications.
Glaucoma genes and progression
The mt-1 variant of the myocilin gene is present in about 15% of individuals with progressing POAG, according to Jon R. Polansky, MD.
Using a Cox proportional hazard model, retrospective studies have shown that “the greatest risk factor for [glaucoma progression] was having this particular variant,” Dr. Polansky said. “We found a clear and statistically strong association for the mti-1 genotype and glaucoma progression using optic disc and visual field measurements of severity, controlling for glaucoma risk factors.”
According to Dr. Polansky, the practical aspect of this discovery is that an mt-1 test could be offered to patient, and they could decide for themselves to get this test done.
A positive test for the mt-1 variant, also known as the TIGR/MYOC, could alter patient management.
“Closer monitoring of disc, field and IOP and more aggressive treatment to lower IOP would become a factor … and this could justify the expense and effort involved,” Dr. Polansky said.
This work by Dr. Polansky and coauthors R.P. Juster, PhD, and George L. Spaeth, MD, will be published next month in the Journal of Clinical Genetics.
Laser trabeculoplasty underused?
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Argon laser trabeculoplasty (ALT) may be falling into relative disuse, but it is still effective in glaucoma management, according to co-course director Dr. Samples, of the Oregon Health and Sciences University in Portland.
“[ALT] does have its benefits. It can avoid the side effects that are possible with medication, and there is no issue with noncompliance. It is particularly effective in some types of glaucoma, and it can be repeated if there is a good initial response,” Dr. Samples said.
He noted that ALT has fallen into relative disuse for a variety of reasons.
“Some say it is inconvenient, but that may depend on the physical location of your laser. There is a perception that it is not effective; prostaglandins are on the scene and are effective pressure-lowering agents,” Dr. Samples said. Other reasons for decreasing use may include the tendency towards earlier surgery and the lower cost of some medications.
Since the development of ALT, several theories have emerged on how it works. Mark Latina, MD, took his theory further by developing selective laser trabeculoplasty (SLT), which treats only pigmented cells.
“We think that SLT works the same as ALT, but with the SLT there does not seem to be a lot of histologic damage to the meshwork,” Dr. Samples said. “We are still working out the theories of laser trabeculoplasty.”
Treat early, aggressively
Glaucoma progresses more in untreated patients than in patients who are given IOP-lowering medications, according to co-course director Dr. Cantor.
“IOP-lowering treatment should be aggressive,” Dr. Cantor said.
Elevated IOP is not always associated with glaucoma, he said, but patients with high pressures are at an increased risk for glaucoma. He stressed that they should be treated if other risk factors are present.
“You should always think about the long term,” he said.
Dr. Cantor stated that every 1 mm Hg counts when trying to lower IOP. He said that in one study, for every 1 mm Hg in IOP reduction at month 3, there was a 10% decrease in progression rate of the disease. He added that patients with a lower long-term mean IOP reduction had a 13% decrease in progression rate for every 1 mm Hg of IOP lowering.
When determining how aggressive a physician should be in treating the disease and how low the IOP should go, Dr. Cantor noted that the American Academy of Ophthalmology recommends setting an initial target IOP reduction of between 20% and 30%. He added that lowering the IOP by 40% from baseline may be warranted if the patient shows optic nerve damage.
“Lower is always better,” he said.
Cataract in glaucoma patients
Clear corneal cataract surgery has an added benefit for patients who also have glaucoma, according to Dr. Lindstrom.
“Cataract surgery alone usually lowers IOP from 2 mm Hg to 4 mm Hg,” he said. Dr. Lindstrom gave several pearls and observations on cataract surgery in one of his presentations.
Clear corneal surgery “clears the media, making optic nerve testing more effective,” he said. “Glaucoma patients and surgeons may be the most significant beneficiaries of clear corneal incisions.”
Dr. Lindstrom explained that cataract incisions can take several forms: paracentesis style, two-plane, modified Langerman, nasal in the left eye or on-axis in astigmatic patients.
One concern with patients who have glaucoma undergoing cataract surgery is that they may have low endothelial cell counts.
Dr. Lindstrom also said to watch out for cystoid macular edema in these patients. In cases of inflammation, Dr. Lindstrom advised attendees to treat with a beta blocker or alpha-agonist.
Methodical approach in small pupils
A glaucoma patient with small pupils can undergo successful cataract surgery, Dr. Samples said.
“A methodical approach is best,” he said.
To minimize inflammation, surgeons should use “lots of Pred Forte” (prednisolone acetate, Allergan) or any nonsteroidal anti-inflammatory drug, he said. Aspirin should be discontinued preoperatively.
To maximize dilation, 10% Neo-Synephrine (phenylephrine HCl, Bayer) “is useful, but only with close monitoring, since deaths have been reported with its use,” Dr. Samples said. He added that 2% Cyclogyl (cyclopentolate HCl, Alcon) is also “surprisingly helpful.”
Dr. Samples said a clear corneal incision is not advisable with small pupils because it may preclude the use of a sulcus-fixated lens.
For successful pupil stretching, Dr. Samples said he uses a Graether collar button on one side and a Sinskey hook on the other. These devices stretch the pupil while controlling against overexpansion, he said.
The meeting was designated for up to 11 hours of category 1 credit toward the AMA Physician’s Recognition Award.
Next year’s meeting is scheduled to be held June 11-12, 2004, at The Venetian Resort, Hotel and Casino, Las Vegas.