EyeNet Magazine



   
 
News in Review
A Look at Today's Ideas and Trends
By Linda Roach, Contributing Writer
 
 

Vitamin E Bears Little Risk for AMD Patients

Fetal Tissue Transplant Saves One Woman’s Sight

Computer Use May Have Repercussions for Myopes

Third-World Surgery, First-Class Beach

Replacements of Wydase Come to Market


Vitamin E Bears Little Risk for Patients

A recent report linking high-dosage vitamin E supplementation and all-cause mortality has raised concerns for people taking a high-dose vitamin and mineral supplement that prevents blindness. But researchers at the NEI are confident that eye patients may keep taking the supplement that contains high-dose vitamin E, without undue fear of dying.

The authors of the recent vitamin E study “needlessly frightened [eye patients],” said Emily Y. Chew, MD, deputy director of the division of Epidemiology and Clinical Research at the NEI, and one of the principal investigators of the Age-Related Eye Disease Study.

The AREDS findings, reported in October 2001, resulted in the commercial formulation of a high-dose daily regimen of vitamins and minerals that includes 400 International units of vitamin E. The supplement reduces the risk of developing advanced AMD by about 25 percent compared with placebo.
 
The new vitamin E study in Annals of Internal Medicine found that high-dosage vitamin E poses a higher overall risk of dying, between 0.5 percent and 4 percent.1 The meta-analysis is based on combined data from 19 clinical trials (including AREDS) that used vitamin E as a possible treatment for different diseases.

However, that risk may not exist for persons taking the AREDS supplements. “Participants taking the AREDS supplements’ had lower risk of dying in the study,” Dr. Chew said.

She noted that the AREDS results showed a 16 percent decrease in mortality in participants taking the high-dose antioxidant vitamins (C, E and beta-carotene) and zinc. 

In fact, of the 19 studies in the analysis, three tested about 400 IU. They showed “no evidence of harm,” said Frederick L. Ferris III, MD. Among those three studies, there were 801 deaths in the antioxidant group (n = 7,564), and 806 deaths in the no antioxidant group (n = 7,598). “Relative risk is 0.998—about as close to no difference as you can get,” said Dr. Ferris, who is clinical director at NEI and AREDS study chairman. 

A letter to AREDS participants, prepared by the NEI in the wake of the new vitamin E study, recommends an individualized approach to continuing on the high-dosage regimen, based upon consultation with a physician. (A copy of the NIH letter to AREDS participants may be found at http://spitfire.emmes.com/study/areds.)

In the meantime, Dr. Chew will advise her patients to keep taking the supplement. “I feel strongly enough that I will continue to say that you need to take this for your eyes,” she said.

“I don’t think we’re killing patients with our formulation,” Dr. Chew said.

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1 Miller, E. R. et al. Ann Intern Med 2005;142(1):37–46.

Cornea
Fetal Tissue Transplant Saves One Woman’s Sight
Objectively, Elizabeth Bryant of Louisville, Ky., sees better than she did before a 1.5 x 3.1 millimeter sheet of fetal neural retina was transplanted to her left eye as a treatment for retinitis pigmentosa. However, the jury is still out on the technique.

And—conscious of the skeptical reception that earlier retinal transplants received —the ophthalmologists involved in this pioneering research are being careful not to overstate their case.

“We’ve done 13 patients, and we’ve had one very successful patient and one that appears she’s going to be successful as well,” said Norman Radtke, MD, of the Retina Vitreous Resource Center at Norton Audubon Hospital in Louisville. “But the other 11 patients had little or no effect from the transplant. Just one patient may be a fluke—but this patient is definitely seeing better.”

At her exam two years and two months after surgery, the 65-year-old Mrs. Bryant’s ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity had held steady at 20/200 for more than a year, compared with 20/800 before the implant, Dr. Radtke said. The other patient, who has the dry form of AMD, improved from 20/640 preoperatively to 20/240 six months later.

In Ms. Bryant, visual improvement first became measurable six months after surgery, according to one-year results that Dr. Radtke and colleagues published last summer in the Archives of Ophthalmology.1 The researchers speculated that the transplant succeeded because of a trophic effect on host cones, or because of local synaptic connections between the transplant and the host retina.

Unlike previous retinal transplant efforts, the Louisville team’s work is part of an FDA-supervised trial. The procedure inserts intact fetal neural retina, with its adjacent retinal pigment epithelium, into the subretinal space under the fovea, between the neurosensory retina and retinal pigment epithelium. It uses a custom instrument with a flat plastic nozzle tip at a 130-degree angle. Tissue donation is sought only from women who already have decided to terminate pregnancy.

The fetal retinal sheets carry both the structure and natural biochemistry of the retina, bypassing a key barrier to using stem cells for treating retinal diseases: understanding the complex molecular signals they would need to be used therapeutically.

(Recently, it was shown that throughout life the human retinal ciliary margin contains stem cells that can differentiate into any retinal cell type.2)

But research using fetal tissue can’t be done with federal funds, and insurance companies won’t pay for experimental surgeries. Luckily for the Louisville team, an anonymous benefactor is paying for all the pre- and postoperative testing as well as the surgeries, Dr. Radtke said.

The other 11 patients in whom the surgeons saw little or no visual improvement had, at best, light-perception vision before surgery, Dr. Radtke said. To see if results improve in eyes that aren’t so severely affected, the FDA is allowing the trial to be extended into 20/400 eyes, and the researchers hope to lower that threshold further to 20/200.

“I don’t think this procedure should be widely done until we have an effect in six or seven patients on a consistent basis,” he said. 

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1 Arch Ophthalmol 2004;122 (8):1159–1165.
2 Coles B. L. et al. Proc Natl Acad Sci USA 2004;101(44):15772– 15777. Epub 2004 Oct 25.

Glaucoma
Computer Use May Have Repercussions for Myopes
In Japan, 75 percent of the people with glaucoma have normal IOP. Is it possible this could be a by-product of a high-technology economy filled with workers who tend to be myopic?

That is one of the questions raised by a recent study that found a statistically significant increase in glaucomatous visual field defects in Japanese workers who spend a lot of time looking at a computer screen.1

The cross-sectional, multicenter study of 10,202 people used frequency-doubling perimetry to assess visual fields and correlate them with the presence of refractive error (predominantly myopia) and the amount of computer use. Subjects were classified as light or heavy users based on a matrix that factored in both the number of years of computer work and the number of hours of work per day. A person who worked at a computer four to eight hours a day for 10 to 20 years was considered a heavy user. Light users worked that same amount each day for less than five years.

After various statistical adjustments, the researchers at the Toho University School of Medicine found that the odds ratio for visual field defects was 1.74 in heavy computer users with refractive error. Among a subset of 165 subjects in whom ophthalmologic exams confirmed glaucoma, the odds ratio was 1.82 for heavy computer users with refractive errors, and 1.07 for those without any errors.

The odds ratios calculated in the study had wide confidence intervals. And myopia itself has been associated with a higher risk of glaucoma, particularly for the normal tension type.2 The Japanese researchers nonetheless suggest that further study is needed.

Lead author Masayuki Tatemichi, MD, PhD, said it’s important to note the difference in subtypes of glaucoma between Western and Japanese people. More than 90 percent of glaucoma patients in Japan suffer from normal tension glaucoma, while IOP is elevated in most glaucomatous eyes of Westerners.

“Although many possible risk factors for glaucoma, including lifestyle, blood pressure, sleep apnea syndrome, migraine, myopia and so on, have been reported, these contributions are different among ethnic groups, so we should consider the ethnic differences in discussing risk for glaucoma,” said Dr. Tatemichi, professor of environmental and occupational health at the Toho University School of Medicine, Tokyo.

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1 Tatemichi, M. et al. J Epidemiol Community Health 2004;58(12): 1021–1027
2 Mitchell, P. et al. Ophthalmology 1999;106(10):2010–2015.

Trends in Medicine
Third-World Surgery. First-Class Beach
As if slow-pay insurance companies and Medicare reimbursement weren’t enough for an American physician to worry about, now there’s medical tourism.

One locale with an ophthalmic version of outsourcing is South Korea, where expatriates in the United States are returning to their native country to have cosmetic surgeries such as LASIK, according to a report by the BBC News.

And Singapore budget airline ValuAir began offering LASIK tours to Thailand, followed by three days of recuperation at the beach resort of Pattaya. The cost: $3,800 Singaporean dollars ($2,218 U.S.), plus airfare.

“There is a market, and we are seeing a steady increase in traffic of people flying to Bangkok for medical treatment,” ValuAir executive director Jimmy Lau told The Business Times of Singapore.

“Let’s say you go for a LASIK program in Bangkok, then decide to convalesce in Pattaya,” Mr. Lau said. “A seven-day, six-night trip would cost you about $600[S or $348 U.S.] in airfare, land transfers and accommodation. And the medical procedure will be around $3,800[S]. But it is all packaged together, and we make all the arrangements.”

Pharmaceutical Report
Replacements of Wydase Come to Market
Three years after losing access to Wydase when Wyeth Pharmaceuticals stopped making it, ophthalmologists face a relative embarrassment of riches. That’s because in October the FDA approved a second formulation of hyaluronidase as a spreading agent for ocular anesthesia and other drugs. The approval was for purified bovine hyaluronidase (Amphadase) in 150-unit, 1-milliliter vials of injectable solution, a dose commonly used in ocular surgery.

Then, in early December, ISTA Pharmaceuticals received FDA approval to sell Vitrase, the company’s ovine version of hyaluronidase for similar uses, in 150-unit, liquid form.

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