Frequently Asked Questions - Eye Treatments and Procedures
- Do treatments for age-related macular degeneration (AMD) work for PXE eye problems?
- Are Macugen treatments, approved for use in people with wet AMD, an option for PXE?
- Will the drug Lucentis, used to treat wet macular degeneration, work with PXE?
- Can the anti-VEGF drug Avastin be used to treat PXE?
- What is the difference between hot laser and cold laser?
- How effective is Photodynamic Therapy (PDT) laser surgery?
- Do PXE´s medical advisors have an opinion on the short- and long-term effectiveness of PDT?
- Why do some people have regrets about traditional laser surgery or PDT?
- Is LASIK OK for people with PXE?
- How often should a person with PXE have an angiogram?
- What are the potential side effects of repeat fluorescein angiograms?
- Is feeder vessel treatment successful with PXE?
- Is the over-the-counter eye vitamin lutein useful in preventing eye problems in PXE?
- Are any other nutritional supplements helpful for PXE eye health?
- Is conductive keratoplasty (CK) to correct presbyopia a viable alternative for PXEers?
- Can people with PXE benefit from the artificial retina now under development?
- Will stem-cell research help people with PXE?
1. Do treatments for age-related macular degeneration (AMD) work for PXE eye problems?
Although there are some similarities between AMD and PXE in the eye, and often the same treatments are offered for both, ophthalmologists and retinologists caution their PXE patients that PXE has a different cause and a different process. PXE does not respond to treatment in exactly the same way. Individuals affected by PXE may benefit from treatments that are often used for AMD.
PXE is extremely variable, and even the experience of one PXE patient may be of little help in predicting results for another. This is partly because as yet we do not have PXE clinical trials to draw on for conclusions about what works best, and for whom. [September 2006]
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2. Are Macugen treatments, approved for use in people with wet AMD, an option for PXE?
On December 18, 2004, the U.S. Food and Drug Administration approved the use of Macugen as a new therapy to slow vision loss in people with neovascular (wet) age-related macular degeneration (AMD). Treatments require injections into the eye approximately every six weeks. While Macugen represents a breakthrough in treatment for AMD, it has not been officially shown to improve vision. Rather, Macugen helps to preserve vision and to slow vision loss. In addition, there has been no formal testing of Macugen on patients with PXE; therefore, the efficacy of Macugen on vision loss in PXE patients is unknown. As with any drug, it is important to establish its usefulness in PXE. Anecdotal reports are important; however, we need to evaluate a series of patients with choroidal neovascularization secondary to PXE to establish its efficacy.
For a detailed description of Macugen treatments and the results of the clinical trials, see the article titled Macugen Facts from our Spring 2005 MemberGram, and Treatments for Retinal Bleeding Caused by PXE from our Summer 2006 MemberGram. [September 2006]
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3. Will the drug Lucentis, used to treat wet macular degeneration, work with PXE?
Lucentis is another anti-VEGF (vascular endothelial growth factor) drug designed to inhibit a growth factor that operates on blood vessels. It is injected into the eye every four weeks. Lucentis was approved for treatment of AMD by the FDA on June 30, 2006, after Genentech, the manufacturer, reported on May 23, 2005 that Lucentis either maintained or improved vision in 95% of patients with wet AMD participating in the Phase III trial. According to Genentech, it is the first time in a Phase III trial that a drug was shown to be statistically significant in improving vision for patients with wet AMD.
There has been no formal testing of Lucentis in PXE, and as with any drug, it is important to establish its usefulness in PXE. We need to evaluate a series of patients with choroidal neovascularization secondary to PXE to establish its efficacy.
For a detailed description of Lucentis treatments and the results of the clinical trials, see the article titled Treatments for Retinal Bleeding Caused by PXE from our Summer 2006 MemberGram. [September 2006]
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4. Can the anti-VEGF drug Avastin be used to treat PXE?
Avastin received FDA approval in December 2004 for intravenous use for the treatment of colon cancer. Because Avastin´s molecular structure is similar to that of Lucentis, and in the absence of the availability of Lucentis while waiting for FDA approval, Avastin was given in the eye intravitreally in an off-label use to treat wet AMD. Both Lucentis and Avastin target a specific type of protein thought to cause abnormal blood vessel growth.
Genentech, the manufacturer of both Avastin and Lucentis, does not plan to submit Avastin for FDA approval for treatment of wet AMD. There have been no clinical trials of Avastin in AMD or in PXE.
For a more detailed description of Avastin´s use in the treatment of wet AMD, see the article titled Treatments for Retinal Bleeding Caused by PXE from our Summer 2006 MemberGram. [September 2006]
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5. What is the difference between hot laser and cold laser?
Hot (conventional or thermal) and cold (photodynamic) lasers differ in wavelength. This means that the light used for the surgical treatment is different, although they have a similar effect. Photodynamic therapy requires injection of a drug that makes the bleeding vessels more sensitive to the laser, allowing the laser to distinguish it from surrounding tissue. The cold laser does not damage the healthy tissues of the eye. One of these treatments may be recommended over the other based on the location of the vessels to be targeted. Neither has been studied in a clinical trial as a treatment for PXE. [September 2006]
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6. How effective is Photodynamic Therapy (PDT) laser surgery?
There is no clear-cut answer for this question. People often tell PXE International that they used laser for their first eye, it held for a while, and then they progressively lost vision and decided not to laser the second eye. Many claim the second eye retained more sight.
PXE International has no scientific comparisons or analysis, only anecdotal experience. Photodynamic Therapy (PDT) is being used more frequently, but it has never been studied formally in PXE. Some of PXE International´s medical advisors have said that PDT is not very effective and they will not use it on people with PXE because they believe the outcome is similar to traditional laser, and that the anti-VEGF treatments are more promising. This is not a scientific answer, just an anecdotal one. [September 2006]
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7. Do PXE´s medical advisors have an opinion on the short- and long-term effectiveness of PDT?
PXE International´s ophthalmologists think that using PDT is not very effective. However, there are no studies specific to PXE. [September 2006]
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8. Why do some people have regrets about traditional laser surgery or PDT?
Individuals with PXE who received traditional laser surgery or PDT expressed a few types of misgivings:
(1) They went to the trouble of surgery and lost vision anyway, so that effort was wasted.
(2) They feel if they had done nothing – had decided against surgery – then they may have lost less vision. They believe the surgeries caused them to lose more vision or become blind sooner. People consistently feel that they would have retained more vision with no treatment, but there is no scientific study corroborating this.
(3) They felt they were misinformed about the surgeries – they thought they were being cured instead of treated to buy time. [September 2006]
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9. Is LASIK OK for people with PXE?
LASIK is a laser treatment to improve vision for people with myopia. There are mixed opinions about individuals with PXE having LASIK. One of our advisors suggests that with eyes that are not healthy to start with, why introduce another potential for vision loss. For example, the suction rings that stabilize the eye during the LASIK procedure may increase the intraocular pressure to several hundred millimeters of mercury. Theoretically, fracture of blood vessels can occur with such high pressures. Other advisors say there is no reason why a person with PXE cannot have LASIK safely. An individual affected by PXE must balance the risk of side effects from LASIK against the expected improvement in vision. Each person contemplating LASIK should discuss individual risks with his or her ophthalmologist. [September 2006]
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10. How often should a person with PXE have an angiogram?
An angiogram of the eye is useful in detailed diagnosis of the eye, but it is not a routine examination. If a retinal specialist sees abnormalities in the eye or if an individual notices a new distortion while using the Amsler grid, then an angiogram may be recommended to aid in planning treatment. However, the angiogram procedure involves injecting a dye into the vein of the arm. The fluorescein travels rapidly into the eye circulation, which can then be imaged. An angiogram is performed when needed to assess the symptoms or signs suggesting neovascularization, and not as a routine test. The use of color photographs alone is usually sufficient to document peau d´orange and angioid streaks; the angiogram is necessary only if there is a suspicion of new blood vessel membranes under the retina threatening the fovea. [September 2006]
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11. What are the potential side effects of repeat fluorescein angiograms?
Fluorescein has been available as a chemical since about 1878. As a diagnostic tool for angiography of the retina, it has been used since the late 1950´s. The current preparations by the several national suppliers are chemically more pure than ever, and the risk rate for a serious adverse reaction is quoted at about 1 chance in 20,000, and for death 1 in 225,000. Minor reactions are more common, with nausea occurring in 2% and hives in less than 1%. There does not appear to be any cumulative effect of fluorescein. It is water-soluble and about 99% is excreted by the kidney in the urine in less than 36 hours in all people with normal kidney function. It is dialyzable for those who are on kidney dialysis since it is water-soluble. The other 1% is compounded in the liver and excreted in bile. Thus there is no long-term effect, since the drug does not remain in the body long enough to cause other effects. [September 2006]
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12. Is feeder vessel treatment successful with PXE?
This treatment is called “feeder-frond” photocoagulation, using a rapid video angiogram to find the incoming vessel, and then coagulating it with laser. Unfortunately, this cannot work if the retinologist cannot see the feeder, and he or she often cannot image or visualize the feeder vessel. The prolific growth of blood vessels in PXE probably makes this a less useful treatment. No individuals affected by PXE report receiving this treatment anymore. Perhaps with a combination of a VEGF inhibiting drug and feeder vessel therapy, there may be a higher likelihood of benefit for eyes with PXE. [September 2006]
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13. Is the over-the-counter eye vitamin lutein useful in preventing eye problems in PXE?
No information is available from any randomized clinical trial that demonstrates that supplemental dietary lutein has any beneficial or detrimental effect on any retinal disease, despite many theories as to why it might be beneficial. [September 2006]
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14. Are any other nutritional supplements helpful for PXE eye health?
Several supplements used in combination have been used in randomized clinical trials in people with age-related macular degeneration (AMD). Results of these studies have shown some benefit in individuals at high risk for vision loss, and they are safe to use. There is, however, no evidence that they are beneficial in PXE. It is possible that these supplements would be helpful.
It is important to consult your primary care physician before you begin taking any new medication or nutritional supplement. [September 2006]
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15. Is conductive keratoplasty (CK) to correct presbyopia a viable alternative for PXEers?
Conductive keratoplasty is a treatment to reduce presbyopia, which is the loss of the ability to focus the eyes on near objects that occurs naturally with age, because of loss of elasticity of the lens of the eyes. It is performed by an anterior segment surgeon. In this procedure, energy is delivered to the eye. If a retinal bleed or choroidal neovascularization (CNV) is noted after this procedure, the patient may believe it was a complication of the keratoplasty. Reading glasses may be a better choice. You and your physician should always weigh the risks of a procedure against the benefits and the alternatives available. [September 2006]
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16. Can people with PXE benefit from the artificial retina now under development?
No one knows. The artificial retinas or retinal implants are exceedingly primitive at this time. They showed promise for light and shadow and now seem to be allowing some people to distinguish the big E on the eye chart. While this is good news for people with some kinds of blindness, it may be less important for people with PXE, because the macular damage in PXE only causes loss of central vision. [September 2006]
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17. Will stem-cell research help people with PXE?
Stem-cell research is an area of science that can assist in understanding how cells in the body develop, and that may help to find ways to reliably grow tissues that can be used for transplants. Stem cells may also help develop other treatments for disorders and conditions, and experiments are already under way to test treatments for vision loss using tissues developed with the help of stem cells. While every retina seems to have about 10,000 stem cells, it is not known how to stimulate those cells to differentiate into retinal cells and their derivatives. Adult stem cells are not inducible into all other cell types. [September 2006]
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Disclaimer
These are replies to general and specific questions which have been submitted to us in the past. Our responses may not apply to any particular individual´s situation and are not a substitute for medical advice given by a physician who is familiar with the individual´s case and who has examined the patient. In addition, the responses are updated on a periodic basis but may not be current.
