Strategies for managing glaucoma in black patients beginning to emerge

Glaucoma is present throughout the human race, but the disease clearly takes its heaviest toll among black patients.

The disease strikes blacks earlier, on average, than other populations. Many treatments are less efficacious because of physiological responses unique to blacks. But for years clinicians had nothing but such vague generalizations to guide them in treating individual patients.

Moreover, the attempt to quantify the differences between blacks and other groups has been confounded by the fact that glaucoma manifests itself differently in black populations of various global regions. More black Caribbean males have glaucoma than their American counterparts, for example, and blacks in South Africa frequently experience more severe secondary scarring caused by pigment.

At last, some glaucoma management strategies specifically designed for blacks are beginning to emerge. Amid the shifting opinions, Primary Care Optometry News has found some firm foundations for modifying traditional treatment strategies for the black population.

A "deadly quartet" in blacks

Researcher John C. Merritt, MD, wrote in an article in the December 1996 Journal of the National Medical Association about glaucoma blindness in blacks that, "A major health problem may be called the deadly quartet, which is characterized by

1. upper body obesity,
2. glucose intolerance,
3. hypertriglyceridemia and
4. hypertension.

Primary open-angle glaucoma may soon make this a deadly and blinding quintet."

According to Dr. Merritt, topical medications do not protect the optic nerves despite their effect on ocular hypertension, and laser trabeculoplasties have not been shown to be effective in blacks. These and other factors have made blacks around the globe a population at risk.

Faster, harder, earlier

Thom J. Zimmerman, MD, said glaucoma is a disease of individuals, with each patient requiring a separate regimen. Dr. Zimmerman works in Louisville, Ky., and his patient population is about 40% black, a figure that matches the racial composition of the surrounding region of Jefferson County.

Even with all the individual variations in glaucoma, Dr. Zimmerman says, there are general guidelines.

"It hits faster, it hits harder, it's more devastating," Dr. Zimmerman said. "You've got to be more aggressive about it. There are factors that many physicians, because of their socioeconomic or racial backgrounds, really don't understand or pay as much attention to as they should."

Researchers concluded in the Baltimore Eye Survey that the age-adjusted rate of blindness among blacks was 6.6 times that of whites, and the disease was four to five times more prevalent at every level of intraocular pressure (IOP).

Glaucoma's greater severity in blacks cannot be solely attributed to socioeconomic factors, said M. Roy Wilson, MD, MS, dean of the Charles Drew College of Medicine in Los Angeles, and a specialist in treating glaucoma patients referred after failing two or more types of treatment.

"If it were exclusively socioeconomic, then you might expect that you would have greater severity of the disease, but you wouldn't expect there would be a higher prevalence," Dr. Wilson said. "And you certainly wouldn't expect that it would be found at an earlier age. Blacks are usually diagnosed with glaucoma 10 years earlier than whites. If it were socioeconomic then you wouldn't expect that."

Dr. Wilson also practices in the affluent Westwood area of the city, where he is a professor of ophthalmology at the Jules Stein Eye Institute, University of California at Los Angeles (UCLA). His practice is about 40% black patients; the rest of his patients are white or Asian.

"The patients that I see in Westwood are probably not much different from what occurs in most referral glaucoma practices," he said. But, his patients from South Central Los Angeles typically present at Drew with more severe progression of glaucoma.

For example, Dr. Wilson participated in a multicenter clinical trial, the Ocular Hypertension Treatment Study, which recruited patients with high IOP but no signs of glaucoma. "We couldn't find very many study candidates at Drew because everyone who came in had signs of glaucoma. Almost all of the patients were recruited from the Jules Stein, UCLA site."

Clinical signs

Whether genetic or socioeconomic reasons are to blame, a handful of glaucoma symptoms are notably worse in the black population than in other races, said Brad Shingleton, MD, a glaucoma specialist practicing in Boston.

He said the largest difference is the higher cup-to-disc ratio in young blacks with normal IOP. The discs have large cups but maintain intact neural rims and have no nerve fiber layer dropout. Still, these patients may be predisposed to optic nerve damage.

"We tend to see it more commonly, we tend to see it earlier [in the disease progression] and we tend to see it at an earlier age with glaucoma in the black patient," Dr. Shingleton said.

However, several studies disagree about the vascular implications of hypertension and diabetes and whether or not they offer a tip-off to follow up on glaucoma screens and cup-to-disc ratios.

"If I see a broad cup in the younger patient, I flag that patient as one we need to watch closer," Dr. Shingleton said. "I query them as to their medical history with hypertension and diabetes."

Dr. Zimmerman said his staff meets weekly to refine the team approach with black patients.

"We try to use every millisecond — from the time they walk in the door to the time they leave — in supporting them," he said. "The ones who are likely to get into trouble the quickest are likely to get the full load of our attention.

"We take blood pressure, pulse and social history in all of our patients, but we really pay attention in our [black] patients," he continued. "We are vigilant about asking questions about diabetes in the family and their eating habits. When we see an African-American patient at whatever stage of the disease we realize that patient has a higher probability of turning into an ‘I'm in trouble' patient."

Drug regimen

Dr. Shingleton said that drug regimens for glaucoma patients do not differ greatly between blacks and other populations; however, some regimens are less efficacious.

Miotics in particular need higher dosing concentrations in blacks than in other populations to achieve the same effect. But younger patients do not tolerate drugs such as pilocarpine as well, and blacks typically experience glaucoma earlier in life.

Dr. Wilson said that patients whose glaucoma is detected early enough can undergo a drug regimen, usually a beta-blocker, with a second-line treatment consisting of a number of different medicines. But because patients typically present late in the disease, physicians do not have the time to try medication after medication, month after month.

Instead, in many instances of advanced disease Dr. Wilson attempts only one or two medications for a week apiece before recommending surgery.

"Most of us have a target pressure that we go for," Dr. Wilson said. "If you have a patient with very advanced disease, particularly a black patient, your target pressure is going to be lower. If it's not likely that you're going to reach your target pressure, then you may be doing a disservice by wasting time and going through all the medications with that patient."

A pressure of 15 mm Hg might be fine in the early stages of the disease, but an eye with advanced glaucoma might need to be lowered to 7 or 8 mm Hg.

Also, Dr. Wilson said he is more likely to use adjuvant therapies, instead of discontinuing one drug in favor of another. "With the black patient with advanced disease and difficult socioeconomic circumstances, we may put them on two or three medications at one time, just because it's hard to follow up. By putting on as many as two or three at one time you know in a few weeks if the medicine is going to work or not."

Surgical modes

Compliance issues, which creep up repeatedly as a complicating factor, make physicians more prone to recommend surgery sooner in blacks than in other races. Although more of a social issue than a clinical one, the threat of losing patients to follow-up means physicians are more likely to offer surgery to patients with lower pressures and who are earlier in the disease progression.

"Glaucoma does progress more rapidly in the black population," Dr. Shingleton said. "I find myself doing surgery more commonly in the black population because of that factor alone."

Surgical success does not come easily

"Surgical success is more difficult to obtain in the black population primarily due to a scarring phenomenon," Dr. Shingleton said. "There's a more exuberant healing tendency in the more heavily pigmented eye, and when we create a filtering bleb we want just the opposite to happen. We do see less success overall in the patients who are black."

Ophthalmologists worldwide attempt surgery earlier in their black patients, but those efforts are foiled by the more aggressive wound healing response that closes the drainage routes necessary to create the dramatic drops in pressure needed to save vision.

Dr. Shingleton said laser trabeculoplasties work less frequently in blacks. Some studies suggest that laser trabeculoplasties have only half the success rate in blacks as in whites. Because they are temporary procedures, they require follow-up every 3 months. Yet blacks are more likely to be lost to follow-up.

Also, peripheral iridotomy has shown little benefit in patients with pigmentary glaucoma, a condition that affects blacks especially. A randomized study at Wills Eye Hospital in Philadelphia followed patients with pigmentary glaucoma who had undergone the procedure and compared them with a control group. Although the research was not conducted specifically in black patients, the research concluded pigmentary glaucoma patients received little benefit from peripheral iridotomy.

New methods

Despite the surgical challenges, researchers are attempting several other new glaucoma treatments.

For example, new trabeculectomy procedures are in development. Selective laser trabeculoplasty has been found to cause no thermal damage or coagulation burns to the trabecular meshwork, unlike conventional argon laser trabeculoplasty.

Drug research underway at The Johns Hopkins University in Baltimore is investigating Betoptic Pilo (Alcon), a combination therapy of 0.25% betaxolol and 0.75% pilocarpine. The drug may be more effective because patients are less likely to miss a dose.

Another glaucoma drug "cocktail" of Trusopt (dorzolamide hydrochloride ophthalmic solution) and Timoptic (timolol maleate) is being investigated by Merck & Co. of West Point, Pa.

Contact diode lasers are being used to give long-term improvement of IOP and preserve visual acuity in intractable glaucoma. The treatment offers an alternative to cryotherapy, which causes severe postop pain and phthisis.

Along with the surgical trials, researchers around the globe are tracking glaucoma as it affects different black populations in an effort to understand the disease and develop new treatments and protocols tailored to the population that suffers it the most.

The Baltimore Eye Survey

Since 1984, the Baltimore Eye Survey has examined thousands of patients in east Baltimore, in a longitudinal study addressing the differences in eye diseases among white and black populations in this coastal city midway along America's East Coast.

Baltimore Eye Survey researcher James M. Tielsch, PhD, described why scientists undertook the study.

"There had been no population-based information about ocular disease in the United States since the early 1970s," he said. "There were some important issues that needed to be updated, and there was absolutely no information about anybody except white, middle-class individuals living in suburban areas."

So in the mid-80s researchers began door-to-door surveys through which they identified candidates and assessed 2,395 black residents and 2,913 white residents 40 and older in east Baltimore.

Since its inception, the survey has reported results prolifically. Among its many conclusions, the study found that primary open-angle glaucoma accounted for 19% of all blindness among blacks, is six times as frequent among blacks as among whites and begins on average 10 years earlier.

Genetic link

Dr. Tielsch said the Baltimore Eye Survey led researchers to conclude that the occurrence of glaucoma in blacks is not driven by socioeconomics, but probably by genetics. Once blacks acquire the disease, however, socioeconomic factors such as access to health care play a role.

"We don't see lots of associations of socioeconomic status among African-Americans and whites with glaucoma," he said. "That doesn't seem to be what's driving the story. What's driving the story actually is racial difference. It's ethnic in origin, not socioeconomic.

"There is a large pool of patients in the population who have optic nerve damage due to glaucoma who don't fall across that magical 21-mm Hg barrier that often are missed in a standard clinical examination."

What drives glaucoma?

The 8-year follow-up data from the Baltimore Eye Survey, which have not yet been fully compiled, should provide the number of new incident cases per year and reveal how much this differs between blacks and whites.

For example, said Harry Quigley, MD, director of glaucoma services at the Dana Center for Preventive Ophthalmology, "there's not only more disease, there's more blindness. Ophthalmologists clinically have the impression, some of which is supported by laboratory or clinical research, that a black person's eyes respond less well to topical eye medication and that possibly their eyes respond less well to the surgical treatment for glaucoma."

Dr. Tielsch added, "There's a lot more than IOP that is driving both the onset of this disease and probably the prognosis as well. What those factors are is of very high interest on the part of the research community."

He offered hypotheses such as cell apoptosis, a difference in the tolerance of changes to blood flow to the optic nerve and neuroprotective qualities associated with genetics.

Dr. Tielsch is not alone in holding these theories. Researchers are examining the link between blood flow and its effects on glaucoma. One question is whether poor blood flow leads to glaucoma or glaucoma impedes blood flow.

The Massachusetts Eye and Ear Infirmary is investigating the role of glutamate toxicity in cell apoptosis. If glutamate, which is toxic to ganglion cells, could be controlled after high IOP is treated with conventional medications, then glutamate-induced ganglion cell death could be prevented.

To conduct the follow-up, researchers first re-examined glaucoma patients from the original Baltimore study and identified new cases. They then tracked severity of the disease and examined similarities in risk factors for the new glaucoma cases.

Researchers also brought in 270 glaucoma patients to compare by age and gender with normal patients to test the efficacy of several diagnostic methods, such as subjective functional visual capacity or objective exams of the optic disc.

"We're comparing which of those screening instruments identify glaucoma patients and at what efficiency," Dr. Quigley said. "We know that present methods of screening aren't good enough."

He added that lack of knowledge about the effects of glaucoma are his biggest barrier to overcome as a clinician. "One of the most striking things about this study was that the actual characteristics of these diseases are very different from what the eye care professional thinks they are, based on the people who are in your office at this moment. This study has done a lot to change people's minds about the fundamental nature of glaucoma."

In other regions of the globe, researchers have attempted to define the disease progression in their respective populations.

The Barbados Eye Study

The Barbados Eye Study shares many similarities to the Baltimore Eye Survey. Both are longitudinal population-based studies of the incidence and progression of the disease, although the Barbados study involves a larger black population. Both studies will undergo the peer review process this year concerning publication of results and follow-ups that could draw important conclusions.

Unlike the Baltimore survey, however, the Barbados Eye Study includes other diseases, such as cataracts, and also tracks family history, said primary investigator M. Cristina Leske, MD, chair of the Department of Preventive Medicine at the State University of New York (SUNY) at Stony Brook.

Dr. Leske, an epidemiologist, said the large number of patients identified with glaucoma from the Barbados study allows tremendous potential to identify the risk factors for glaucoma in blacks.

"As an epidemiologist I realized that since the prevalence of glaucoma in blacks is much higher than in the white population, it would be important to find out the reasons in a place such as Barbados, where this type of study could be done."

Barbara Nemesure, PhD, an assistant professor in the SUNY Stony Brook Department of Preventive Medicine with formal training in statistical genetics, has joined the study to carry it forward through its next steps, which will evaluate both disease progression and family history of glaucoma.

Risk factors

The Barbados Eye Study began in 1988 as a major study to evaluate the prevalence of eye diseases among the predominately black residents of Barbados. By the time it ended in 1992, the program sampled 4,709 black adults in a prevalence study for glaucoma, cataracts, macular degeneration and diabetic retinopathy.

Of the original group, 302 people had visual field defects and optic disc damage and met the criteria of having open-angle glaucoma.

Since 1992, the study has been carried forward as a 4-year incidence study that followed the original population. A final phase, the family study, could have results reported soon.

Already, results of the initial phase concluded that blacks in Barbados had a 7% glaucoma prevalance rate, which was seven times higher than in U.S. whites and 1.5 times higher than U.S. blacks.

In Barbados, 3.3% of the mixed race population and 0.8% of the white population had glaucoma.

Clinical indicators

One goal of the Barbados Eye Study was to identify prevalence and risk factors, such as vascular disease, for this population and to identify potential clinical indicators.

One finding concluded that blacks in Barbados have a higher baseline IOP than other groups, although the role of that as a reason for the high glaucoma prevalance remains unknown.

Dr. Leske said that in Barbados the average IOP in blacks was higher, perhaps about 18 mm Hg, whereas the average for whites was about 16 mm Hg.

Researchers also tackled the question of vascular conditions and, in contrast to other published research, found no link between glaucoma and hypertension or diabetes, conditions which have been suspected but never proven as risk factors. Instead, what were very different were the links between glaucoma and gender, body mass and cataract history.

"Men had a higher risk," Dr. Leske said, at a rate 1.5 times that of women. Lean body mass and cataract history also were associated with glaucoma.

"We believe that they interplay, but no one knows for sure," Dr. Leske said. "That's the reason why we're doing a genetic familial study in that population. We think that glaucoma involves an interaction of risk factors, both genetic and environmental factors."

Continuing study

To understand more about how such factors intertwine, the Barbados Eye Study is finishing its follow-up of the original study population of more than 4,000 people. The results will identify prevalance and risk factors such as vascular disease and identify potential clinical indicators.

Dr. Leske explained, "In epidemiology the important data to collect is the follow-up data, which measures the risk of getting a disease. For example, if you had high blood pressure in 1988, your chances of getting glaucoma may be higher, lower or the same as someone in the general population. The purpose of following up these people is to measure the risk.

"You conduct the same measurements in both of the studies so that you actually get the same data at two points in time," she continued. "That's where the wealth of the information comes. The real implication will come when we have the results of the incidence study."

Researchers also hope to report on the Family Study of Open Angle Glaucoma, which is drawing blood from glaucoma patients and their relatives to study how the disease is transmitted from generation to generation.

The ultimate goal is to trace the genetic components of glaucoma.

According to Dr. Nemesure, "The family study is another example of how we're taking what we've learned from the Barbados Eye Study and trying to go further with it. Potentially, a genetic component exists with respect to glaucoma. The study is an example of the progress, as well as the frontiers, that we're exploring."

The noncompliance conundrum

In South Africa, ophthalmologists face the noncompliance conundrum and the fact that glaucoma patients typically present so late in the disease's progression that medication is unlikely to preserve sight.

Like Dr. Wilson in Los Angeles and Dr. Shingleton in Boston, surgeons in this country are more likely to perform surgery sooner upon diagnosis. Like their counterparts around the globe, South African physicians find that the more aggressive wound healing and darker iris pigments of the black population cause complications not found in the country's whites.

South Africa is a country of 45 million people, about two-thirds of them black or mixed race. Many of the black glaucoma patients seen by ophthalmologists come from rural or tribal regions and already have visual field loss at the time of referral.

Neville Welsh, FRCS, emeritus professor of ophthalmology who practices at Oxford Health Centre in Johannesburg, said the problem is particularly severe among the rural or tribal blacks who do not have regular access to health care.

"The majority of these patients have 6/60 vision or less," Dr. Welsh said. "They are waiting for their vision to decrease, particularly if their vision is good in one eye. Then they will allow the other eye to decrease quite readily."

So physicians send the patients directly into surgery, where complications such as fibrosis occur.

Justin Van Selm, MD, a former university professor from Capetown, now works in a clinic in Plattenberg Bay with a patient base that is about 75% black, many of whom come from South Africa's tribal regions. He described one typical scenario he encounters in his clinics.

"Sometimes an elderly person is brought in by one of the grandchildren, and if they are from what we call our tribal areas, [the glaucoma can be] pretty advanced," he said. "In those cases, if we're going to save any useful vision at all we have to have surgery. Though one might try to keep them for a few days, you've got to find accommodations for them in the village or town."

Drug regimens fail

Both physicians said they try drug regimens, but noncompliance diminishes their efficacy.

Dr. Welsh has researched glaucoma and its effects in black patients since the early 1970s. In his country the assumption is that 2% of the adult population over age 40 has glaucoma, a figure that holds true for both black and white populations.

But in the blind population, 22% of people lost their sight to glaucoma, a figure about twice the average of other countries who keep records of the causes of blindness in their citizens.

"I'm not terribly certain that means the incidence of glaucoma is higher," Dr. Welsh said. "What is happening is that we've got too many patients who aren't getting treatment, so there is a greater number of patients at any one time who are not getting or not responding to glaucoma treatment."

Even for young patients who might benefit from medical regimens, the likelihood of noncompliance makes doctors reluctant to choose them. The need to travel long distances for medical care, high cost and the lifetime commitment take their toll on the compliance level of young black South African patients.

"If you treat them with drops to reduce the inflow of aqueous to reduce the pressure they don't see any difference as far as their eyes are concerned," Dr. Van Selm said. "There's no improvement in their vision, and the result is they tend to be noncompliant. You're forced to operate on these patients, where normally if they were under your control or lived in an urban area you could keep an eye on them and keep them on medication."

Dr. Welsh reported in one study of 194 black patients that the average person presented for the first time with glaucoma at age 50. Half of the patients had a visual acuity of 6/60 or worse, 40% had IOP of more than
35 mm Hg, and 57% of them had extensive disc cupping.

"These patients are coming at a very advanced stage," Dr. Welsh said. "No matter how you try, medical therapies are not going to reduce their pressure to normal levels. Medical treatment is only going to help patients if they present with their pressures in the middle 20s at most."

Throughout the years, Dr. Welsh has worked with a variety of medications to reduce pressure. Still, black patients treated medically are less likely to drop to a safe level of IOP, and thus they are more likely to need surgery.

Dr. Van Selm added that drug regimens that reduce pressure by reducing aqueous production are like fixing a clogged drain by turning off the tap.

"It's unphysiological," Dr. Van Selm said. "Normally you have that secretion of aqueous that's doing a job. Now you've got to turn off the tap."

Surgical modes

Because of noncompliance and advanced progression, Dr. Van Selm said that more ophthalmologists are accepting surgery as a first-line attack against glaucoma.

"We see it so often that patients have been jollied along on drops for years, and by the time they come to surgery they have no field of vision or very little," he said. "Sometimes you rub out what's left by dropping their pressures. When the black person comes in from the country, you know jolly well that they're not going to use their drops, so you might just as well operate."

Dr. Welsh added that blacks also require more surgery because they generally present with higher IOP.

"I feel over the years that a lot of people operate at too late a stage," Dr. Welsh said. "Surgery in black patients is very close to being a top-of-the-list, first-line treatment. It's probably unique to black patients. It's unique to Africa in general."

However, black patients experience more surgical complications, making these options less efficacious.

"The black patient will not do as well as the white patient in any kind of glaucoma surgery where you drain the aqueous under scleral and conjunctival flaps, because there's no question they have more fibrosis," Dr. Welsh said. "They do scar down more readily compared to white patients."

Dr. Van Selm said surgeons have tried cilial trephines, but those block up because of aggressive wound healing, as did trabeculectomies. Pigmentary glaucoma is a major cause of surgical failure, as dark irides shed pigment cells that block drainage and cause secondary scarring.

In response to the accelerated progression, higher rates of noncompliance and surgical complications, researchers are investigating new ways of treating black South Africans.

To combat aggressive wound healing, Dr. Welsh has begun research into a nonpenetrating operation on Schlemm's canal. The technique involves removing the roof of Schlemm's canal via a deep sclerotomy and then placing a 2-mm collagen device under the scleral flap. The procedure started in Russia and has been used mainly in Switzerland and France.

"We're finding this is a safe operation," he said. "The results at the moment are showing that in white patients we're getting a 75% success rate with pressures under 20 mm Hg. In blacks it's about 70%, but then we get another 20% if we give them beta-blockers postoperatively."

However, in Los Angeles, Dr. Wilson is finding tremendous success enhancing trabeculectomy with an adjuvant anti-metabolite, typically mitomycin-C, to inhibit the aggressive wound healing.

"The size of the sclerostomy doesn't make much difference with the advent of mitomycin," Dr. Wilson said. "Wound healing is not as much of a factor as it used to be. I find that most of my surgeries are very successful and that wound healing is not much of an issue. Antimetabolites level the playing field a little bit more, and if there is a [racial] difference it's not that much."

No conclusions yet

Around the world, doctors and researchers are making progress in treating glaucoma in black patients. Through trial and error, doctors are learning what drugs and surgeries work most effectively to treat the specific needs of this population at risk.

At the same time, results from research such as the Baltimore Eye Survey and the Barbados Eye Study are homing in on identifying risk factors and the role of genetics in glaucoma. Although neither is a clinical treatment study, their results have influenced some clinical protocols and outreach methods used at The Johns Hopkins University.

However, Dr. Leske said, in some ways the results are too new to have had a major impact. So without the broad conclusions available from large-scale population studies, treatment rests in the hands of individual practitioners and will be as individual as each patient.

"It's nice to know that if I see a black patient I should be suspicious that this will progress more quickly than in a white patient," Dr. Zimmerman said. "But other than that it's one-on-one. You can write down protocols, but it falls on deaf ears if you're not artfully capable of getting that message understood, accepted, adopted and used."

For Your Information:

• Thom J. Zimmerman, MD, can be reached at 301 E. Muhammad Ali Boulevard, Louisville, KY 40202; (502) 852-5466; fax: (502) 852-5462. Dr. Zimmerman has no direct financial interest in the products mentioned in this article. He is a paid consultant for Alcon and Merck & Co.
• M. Roy Wilson, MD, MS, can be reached at 100 Stein Plaza, Los Angeles, CA 90059; (310) 825-7808; fax: (310) 537-9446. Dr. Wilson has no direct financial interest in the products mentioned, nor is he a paid consultant for any companies mentioned.
• Brad Shingleton, MD, can be reached at 50 Stanford St., Boston, MA 02114; (617) 367-4800; fax: (617) 589-0552. Dr. Shingleton has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• M. Cristina Leske, MD, can be reached at University Hospital and Medical Center, Stony Brook, NY 11794-8036; (516) 444-2140; fax: (516) 444-7525. Dr. Leske has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.
• Barbara Nemesure, PhD, can be reached at University Hospital and Medical Center, Stony Brook, NY 11794-8036; (516) 444-1293; fax: (516) 444-7525. Dr. Nemesure has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.
• Neville Welsh, FRCS, can be reached at 104 Oxford Road, Houghton, 2198 Johannesburg, South Africa; (27) 11-880-2152; fax: (27) 11-880-3610. Dr. Welsh has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Justin Van Selm, MD, can be reached at P.O. Box 126, Plattenberg Bay 6600 South Africa; (27) 21-4457-312-73; fax: (27) 21-4457-301-44.
• James M. Tielsch, PhD, can be reached at (410) 955-2436; fax: (410) 550-6733. Dr. Tielsch has no direct financial interest in any products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Harry A. Quigley, MD, can be reached at 600 North Wolfe/Maumenee B-110, Baltimore, MD 21205; (410) 955-6052. Dr. Quigley did not disclose if he has a direct financial interest in any of the products mentioned in this article or if he is a paid consultant for any company mentioned.