By Nancy M. Holekamp, MD
Age-related macular degeneration. The Eye Disease Prevalence Group has estimated that 1.75 million people in the United States have advanced age-related macular degeneration (AMD), including neovascular AMD or geographic atrophy, but not necessarily involving the foveal center, with the highest prevalence in adults older than 80 years of age.1 These numbers are estimated to increase substantially in the coming decades.
The numbers are huge, but what impact does AMD have on our patients? AMD is associated with an increased incidence of depression, mortality, and a greater need for assistance for daily tasks. In a quality-oflife study that was part of the Submacular Surgery Trials (SSTs), patients were asked to rate their current vision during phone interviews. Patient scores were converted to a preference value scale ranging from 1 (perfect health with perfect vision) to 0 (death). A mean preference value of 0.64 for subfoveal choroidal neovascularization (CNV) suggests a profound impact on quality of life. The impact is reported as greatest in those with the most severe loss of vision, but even patients with visual acuity of at least 20/40 in one eye had relatively low preference values.2 This is striking because it is right between having chronic renal failure and symptomatic HIV/AIDS (Figure 1). Clearly, AMD has a significant impact on the quality of life of individuals.
Diabetic retinopathy. It is well known that we are in the midst of an epidemic of obesity and diabetes in the United States. The rates of both have increased dramatically from 1990 to 2001, particularly in the southeast (Figure 2) and the increase in people with diabetes directly correlates to the rise in obesity.3 An estimated 18.2 million people had diabetes in the United States in 20023 and diabetes has been estimated to affect 151 million people worldwide, and is projected to increase to 324 million by 2025.4 It is also estimated that 35% of any diabetic population will have diabetic retinopathy.5 We know this from the Beaver Dam Eye Study. In terms of costs, the direct and indirect costs for diabetes were estimated at $132 billion in 2002.6 Almost $1 out of every $5 in the United States spent on healthcare is for patients with diabetes. Diabetes has an enormous impact on patients’ quality of life and represents a large economic issue.
Retinal vein occlusion. Retinal vein occlusion (RVO) is the second most common retinal disease after diabetic retinopathy. The Beaver Dam Study reported a prevalence of 0.6% in patients older than 43 years and the same study reported a 15-year cumulative incidence of BRVO of 1.8%.7 Although these numbers may sound low, the average age of these patients is 65 and this age group may have a host of comorbidities (eg, hypertension, vascular disease, diabetes). RVOs share risk factors with myocardial infarction (MI),8 stroke, and other arterial thrombotic events.9 In a study that is currently in press,10 we reviewed the records of 4,500 patients with RVO and compared them with 13,500 patients who were age-matched controls. We found that patients with RVO had significantly higher likelihood of having angina, cardiac arrhythmia, congestive heart failure, diabetes, heart disease, MI or stroke, hyperlipidemia, and hypertension (P=.001) The incidence of RVOs continues to increase as the incidence of diabetes increases and the population ages.
EVIDENCE-BASED MEDICINE
Evidence-based medicine is the practice of medicine based on the best scientific data available. The questions are, “How much evidence do you need?” and “How much science is behind it?”
These are the various levels of evidence. The weakest is the single-case report, which is level 5 evidence. The second weakest is the case series without a comparison group (level 4). Level 3 evidence consists of nonrandomized clinical trials that may compare two groups that are not concurrent or randomized. A level 2 clinical trial is similar to a phase 2 US Food and Drug Administration (FDA) clinical trial—it is randomized and controlled but it has a high type-1 error, where a trend is apparent and may be significant, but the number of patients is insufficient. A type-2 error is when a treatment difference likely exists but, again, there are not enough patients to isolate the difference.
Level 1 evidence is from randomized, prospective, controlled trials, with a low type-1 and type-2 errors. These are the phase 3 clinical trials that eventually lead to drug approval by the FDA. The key to level 1 evidence is a well-designed study and a large number of patients.
CLINICAL TRIAL DESIGN: WHY IS IT IMPORTANT?
In medicine we prefer level 1 trials because of random assignment to treatment or control; the concurrent enrollment that ensures patients are being treated in a similar manner; the large numbers of patients; and the masking of the investigators. The standardized follow up is also important to the significance of outcomes. By controlling these variables, we are able to clinically treat patients in the most scientific manner. My colleague Kuldev Singh, MD, who is a glaucoma specialist has said, “This term [randomized, controlled] allows the investigator to disarm the novice scientific critic, while impugning lesser prospective and all retrospective studies, not to mention case series and reports.” The randomized, controlled study is at the top of the food chain.
A case example of using low-level evidence-based medicine upon which to base treatment decisions is that of bevacizumab (Avastin, Genentech) for treating AMD. In August 2005, there was one case report (level 5 evidence) demonstrating improvement on optical coherence tomography (OCT) for a patient nonresponsive to pegaptanib sodium (Macugen, Eyetech/Pfizer) for AMD in the published literature.11 Simultaneously, Philip Rosenfeld, MD, PhD, one of the authors of the aforementioned case report, presented a paper (level 4 evidence) at the American Society of Retina Specialists in Montreal on a series of patients with exudative AMD who benefited from intravitreal bevacizumab. Clearly, the “bevacizumab for AMD” era was ushered in using the least convincing type of evidence.
Unlike bevacizumab, ranibizumab (Lucentis, Genentech) was subject to two phase 3 randomized, controlled clinical trials sponsored by industry (MARINA ANCHOR) that resulted in FDA approval. The extent to which the efficacy and safety of ranibizumab has been scrutinized is to the highest level.
But can you have a randomized, controlled trial for every disease and treatment? Paul Lichter, MD, said, “Authors of case reports, retrospective studies, and other manuscripts covering the gamut of imperfect clinical projects often conclude their papers by calling for a randomized, controlled, collaborative clinical trial. While I have no idea how many times such statements are made, there is no question that these pronouncements are abundantly more frequent then the clinical trials that result from them.”
CRITERIA FOR CONDUCTING A LEVEL 1 CLINICAL TRIAL
Clearly, a level 1 clinical trial cannot be conducted for every clinical situation. My four criteria for conducting a randomized, controlled clinical trial include the following:
* The disease must represent a significant health problem. An example of what can be called an questionable effort is in 1993 when the Canadian Ophthalmology Study Group conducted a multicenter randomized, controlled clinical trial to compare the argon green vs krypton red laser for choroidal neovascularization (CNV) in AMD.12 The comparison of these lasers was not a burning issue for the health care system.
* There must be scientific plausibility of benefit. In other words, there has to be some biologic basis for believing that a treatment works. An example from the AMD literature is subfoveal laser for CNV.13 There was no basis to suggest that applying laser to a patient’s fovea would be beneficial.
* A plausible, biologic benefit must exist. In other words, the early data on a new treatment should suggest the possibility of benefit. A good example of this is the Submacular Surgery Trials in AMD where early pilot data did not show any benefit to submacular surgery over laser photocoagulation.14 The eventual the long-term data supported this conclusion.
* Sufficient numbers of patients must be enrolled. If a study cannot recruit enough patients, it will not succeed. For example, it was almost impossible to recruit patients into the Macular Translocation clinical trial because they were randomized to either photodynamic therapy—a relatively painless 15-minute office-based laser procedure— or to macular translocation, which had a 25% complication rate at the time they were trying to enroll.15
The clinical trials’ registry, www.clinicaltrials.gov, currently lists 530 clinical trials for the treatment of AMD. Of those 200 trials are open and actively recruiting patients. Eighty-seven of these are randomized and controlled. Those of us in the field of ophthalmology and the subspecialty of retina are fortunate to be part of a profession that is committed to providing the best scientific evidence for its members. We have a long, proud history of practicing evidence-based medicine and performing randomized clinical trials in our field.
NON-INFERIOR CLINICAL TRIALS
There are basically three types of trial design: superiority, equivalence, and non-inferiority. The Comparisons of Age- Related Macular Degeneration Treatments Trials (CATT) is a non-inferiority trial comparing intravitreal ranibizumab to intravitreal bevacizumab. The margin of non-inferiority must be pre-specified in the design protocol to construct a two-sided, 95% confidence interval (CI) to determine the true difference between the agents. To be able to declare bevacizumab non-inferior, that interval must lay entirely on the positive side of the non-inferior margin.
Figure 3 helps illustrate how the results of a non-inferiority trial are interpreted. Applied to the CATT, if proved non-inferior, bevacizumab is either almost as good as, equivalent to, or better than ranibizumab. If bevacizumab fails non-inferiority then it is either equivalent, almost as good as, or inferior to ranibizumab. All of those possibilities exist.
The major criteria for non-inferiority clinical trials are:
1) historical evidence that the reference drug works (ie, MARINA and ANCHOR);
2) trial design must be the same as the reference trial (ie, the CATT has same design as MARINA and ANCHOR);
3) trial conduct must be the same (ie, many of the clinical sites from MARINA and ANCHOR are also sites for the CATT);
4) the non-inferior margin (minus delta) must be acceptable (ie, six letters for the CATT).
In addition to the CATT, there are two other non-inferiority trials in AMD: HARBOR (A Study of Ranibizumab Administered Monthly or on an As-Needed Basis in Patients With Subfoveal Neovascular Age-Related Macular Degeneration) and VIEW I (VEGF Trap-Eye: Investigation of Efficacy and Safety in Wet AMD). These are both similar to MARINA and ANCHOR in historical evidence, trial design and trial conduct, and have an acceptable non-inferior margin.
SUMMARY
The best way to practice evidence-based medicine is with phase 3, randomized, and controlled trials. The requirements for level 1 clinical trials do not necessarily constitute a “cookbook” for successful trials; rather, they provide guidelines for those who are designing and participating in clinical trials.
Finally, evidence alone is never sufficient information to make a clinical decision—there are many factors to be taken under consideration. When treating our patients, we consider several factors including a patient’s values, socio-economic status, and age; however we should rely on three main components: our years of clinical experience, the patient’s particular circumstances, and what we have learned from evidence-based medicine.
1. Friedman DS, O’Colmain BJ, Muñoz B, et al; The Eye Diseases Prevalence Research Group. Prevalence of age-related macular degeneration in the United States. Archives of Ophthalmology. 2004;122:564-572.
2. No authors listed. Submacular surgery trials randomized pilot trial of laser photocoagulation versus surgery for recurrent choroidal neovascularization secondary to age-related macular degeneration: II. Quality of life outcomes submacular surgery trials pilot study report number 2. Am J Ophthalmol. 2000;130(4):408-418.
3. National Institute of Diabetes and Digestive and Kidney Diseases. National Diabetes Statistics Fact Sheet: General Information and National Estimates on Diabetes in the United States. Bethesda, MD, US Department of Health and Human Services, National Institutes of Health, 2003.
4. King H, Rewers M. Global estimates for prevalence of diabetes mellitus and impaired glucose tolerance in adults: WHO Ad Hoc Diabetes Reporting Group. Diabetes Care. 1993;16:157–177.
5. Beaver Dam Eye Study.
6. Hogan P, Dall T, Nikolov P; American Diabetes Association. Economic costs of diabetes in the US in 2002. Diabetes Care. 2003;26(3):917-932.
7. Klein R, Klein BE, Moss SE, Linton KL. Beaver Dam Eye Study. Retinopathy in adults with newly discovered and previously diagnosed diabetes mellitus. Ophthalmology. 1992;99(1):58-62.
8. National Heart Lung and Blood Institute. Heart attack. Available at http://www.nhlbi.nih.gov/health/dci/Diseases/HeartAttack/HeartAttack_WhatIs.html.
9. Thom T, Haase N, Rosamond W, et al; American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics-2006 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Committee. Circulation. 2006;113:85-151.
10. Holekamp N. Arch Ophthalmol. In press.
11. Rosenfeld PJ, Moshfeghi AA, Puliafito CA. Optical coherence tomography findings after an intravitreal injection of bevacizumab (avastin) for neovascular age-related macular degeneration. Ophthalmic Surg Lasers Imaging. 2005;36(4):331-335.
12. The Canadian Ophthalmology Study Group. Argon green vs krypton red laser photocoagulation of extrafoveal choroidal neovascular lesions. One-year results in age-related macular degeneration. Arch Ophthalmol. 1993;111:181-185.
13. Macular Photocoagulation Study Group. Visual outcome after laser photo- coagulation for subfoveal neovascularization secondary to age-related macular degeneration. The influence of initial lesion size and initial visual acuity. Arch Ophthalmol. 1994;112:480–488.
14. Bressler NM, Bressler SB, Hawkins BS, Marsh MJ, Sternberg P Jr, Thomas MA; Submacular Surgery Trials Pilot Study Investigators. Submacular surgery trials randomized pilot trial of laser photocoagulation versus surgery for recurrent choroidal neovascularization secondary to age-related macular degeneration: I. Ophthalmic outcomes submacular surgery trials pilot study report number 1. Am J Ophthalmol. 2000;130(4):387-407.
15. Hawkins BS, Bressler NM, Miskala PH, et al; Submacular Surgery Trials (SST) Research Group. Surgery for subfoveal choroidal neovascularization in age-related macular degeneration: ophthalmic findings: SST report no. 11. Ophthalmology. 2004;111(11):1967-1980.
Wednesday, August 18, 2010
Monday, August 9, 2010
Retinitis pigmentosa treatment
As human beings, there is very little more universally feared than the dark, and few disabilities more frightening than blindness which would leave us trapped in it. Retinitis pigmentosa is a condition which, to many people, might sound like a nightmare. Retinitis pigmentosa refers to a group of genetic conditions in which the eye progressively degenerates over time. The first symptoms of retinitis pigmentosa are night blindness. This night blindness worsens over time, eventually developing into tunnel vision which little by little narrows the sufferer’s peripheral vision until finally they become legally – and perhaps totally – blind.
Progression is different in each case of retinitis pigmentosa. The night blindness phase of the disease can proceed tunnel vision by years or even decades, and many people with retinitis pigmentosa do not legally go blind until their forties or fifties. Some never retain some level of vision throughout their lives. At the same time, others may go blind as early as during childhood.
Retinitis pigmentosa diagnosis come as a fearful shock to some people, which is why retinitis pigmentosa treatments are so important.
Since time out of mind, people have struggled to treat the diseases around them. They have relied on everything from superstition, prayer, spells and religious chants to herbal remedies, surgeries and medicines, some of which are still in use today. Unfortunately for people before the modern era, there was very little to be done for loss of sight. Our ancestors had very few options in terms of treatment for retinitis pigmentosa. Retinitis pigmentosa is caused by abnormalities in the receptors in the eye, the rods and cones which allow us to see color, light and movement. As these abnormalities increase over time, the sufferer’s eyesight diminishes. There was very little for even our grandfathers and grandmothers to do when faced with this sort of disease. It has only been recently that our understanding of how the eye works, our understanding of how the body as a whole operates, and our technology has reached a point where retinitis pigmentosa treatments have become something of a reality and moved out of the realms of witchcraft and hope.
Retinitis pigmentosa treatments are still relatively few. There is no true cure for retinitis pigmentosa, only treatments which may help to slow the progression of this degenerative disease.
Among the first treatment options for people diagnosed with retinitis pigmentosa are medications and supplements. For example, vitamin A therapies can support eye health and slow the progression of this disease. People who receive these should have their liver enzymes checked annually, since in too great of doses, vitamin A can become toxic to the system. Other retinitis pigmentosa treatment options include omega-3 polyunsaturated fatty acid and antioxidant, docosahexaenoic acid, acetazolamide, lutein, and calcium blockers.
In the event that medication proves an ineffective retinitis pigmentosa treatment, there are also surgical treatments to consider. What kind of surgical options a patient may have for their retinitis pigmentosa treatment depends on many factors, as the progression of the disease varies greatly from person to person, and as the disease is associated with a number of other genetic and structural conditions. For some people, partial retinal transplants can be a useful retinitis pigmentosa treatment. The possibility of a retinal prosthetics
have also been under consideration for several years now. While there are currently no prosthetics available for clinical use as retinitis pigmentosa treatment, they may present a promising future for those with this degenerative disease.
Since retinitis pigmentosa is a genetic disorder, it should not be surprising that when considering retinitis pigmentosa treatments, speculation might turn to the possibilities of gene therapy and stem cell research. These treatments are, as yet, still in the research and investigation phases, but may well represent the future of retinitis pigmentosa treatment.
Progression is different in each case of retinitis pigmentosa. The night blindness phase of the disease can proceed tunnel vision by years or even decades, and many people with retinitis pigmentosa do not legally go blind until their forties or fifties. Some never retain some level of vision throughout their lives. At the same time, others may go blind as early as during childhood.
Retinitis pigmentosa diagnosis come as a fearful shock to some people, which is why retinitis pigmentosa treatments are so important.
Since time out of mind, people have struggled to treat the diseases around them. They have relied on everything from superstition, prayer, spells and religious chants to herbal remedies, surgeries and medicines, some of which are still in use today. Unfortunately for people before the modern era, there was very little to be done for loss of sight. Our ancestors had very few options in terms of treatment for retinitis pigmentosa. Retinitis pigmentosa is caused by abnormalities in the receptors in the eye, the rods and cones which allow us to see color, light and movement. As these abnormalities increase over time, the sufferer’s eyesight diminishes. There was very little for even our grandfathers and grandmothers to do when faced with this sort of disease. It has only been recently that our understanding of how the eye works, our understanding of how the body as a whole operates, and our technology has reached a point where retinitis pigmentosa treatments have become something of a reality and moved out of the realms of witchcraft and hope.
Retinitis pigmentosa treatments are still relatively few. There is no true cure for retinitis pigmentosa, only treatments which may help to slow the progression of this degenerative disease.
Among the first treatment options for people diagnosed with retinitis pigmentosa are medications and supplements. For example, vitamin A therapies can support eye health and slow the progression of this disease. People who receive these should have their liver enzymes checked annually, since in too great of doses, vitamin A can become toxic to the system. Other retinitis pigmentosa treatment options include omega-3 polyunsaturated fatty acid and antioxidant, docosahexaenoic acid, acetazolamide, lutein, and calcium blockers.
In the event that medication proves an ineffective retinitis pigmentosa treatment, there are also surgical treatments to consider. What kind of surgical options a patient may have for their retinitis pigmentosa treatment depends on many factors, as the progression of the disease varies greatly from person to person, and as the disease is associated with a number of other genetic and structural conditions. For some people, partial retinal transplants can be a useful retinitis pigmentosa treatment. The possibility of a retinal prosthetics
have also been under consideration for several years now. While there are currently no prosthetics available for clinical use as retinitis pigmentosa treatment, they may present a promising future for those with this degenerative disease.
Since retinitis pigmentosa is a genetic disorder, it should not be surprising that when considering retinitis pigmentosa treatments, speculation might turn to the possibilities of gene therapy and stem cell research. These treatments are, as yet, still in the research and investigation phases, but may well represent the future of retinitis pigmentosa treatment.
Monday, July 26, 2010
Commencement of CABERNET clinical trial
NeoVista, Inc announced the official commencement of the CABERNET (Cnv Secondary Amd Treated with BEta RadiatioN Epiretinal Therapy) clinical trial for the treatment of subfoveal choroidal neovascularization associated with wet age-related macular degeneration (AMD). Neovascular AMD is the leading cause of irreparable blindness in the elderly population, afflicting over 200,000 individuals each year in the U.S.
Dr. Nelson Sabates, Professor and Chairman, Department of Ophthalmology, University of Missouri-Kansas City (UMKC)/Truman Medical Centers and Director of Vision Research Center, University of Missouri-Kansas City at Truman Medical Centers performed the procedure on the first patient enrolled in the CABERNET study. When asked for initial feedback on the procedure, Dr. Sabates commented, "The procedure was no different than performing a common vitrectomy and the Epi-Rad device allowed me to deliver a well focused dose of radiation to the lesion. Treating neovascular AMD using a multi-faceted approach like the use of radiation and anti-VEGF therapy may well be the next frontier in combating this sight threatening disease."
The CABERNET clinical trial will involve clinical sites in the United States, Europe, Israel, and South America. The CABERNET trial protocol is divided into two treatment arms - investigational and control.
The investigational treatment arm consists of concomitant delivery of Beta radiation, via the proprietary NeoVista technology (Epi-Rad90™), and an FDA approved anti-VEGF agent. The investigational treatment is administered during an outpatient surgical procedure and delivers Beta radiation directly to the area of the retina that has been compromised by the disease. An injection of the anti-VEGF agent is administered at the time of surgery with one additional injection administered 30 days after surgery. The control arm is utilizing the FDA approved anti-VEGF agent alone.
The surgery was performed in collaboration with, Saint Lukes Hospital in Kansas City. Dr. Terry J. Wall, J.D., M.D. of the Saint Lukes Cancer Institute was the attending radiation oncologist involved with the procedure.
"This is a very good day for NeoVista employees and the investors who are supporting our work," stated John N. Hendrick, President and CEO of NeoVista. "More importantly, it is a potential harbinger of hope for those suffering from wet AMD." We remain optimistic that our treatment approach will provide maximum benefit to this patient population."
Dr. Nelson Sabates, Professor and Chairman, Department of Ophthalmology, University of Missouri-Kansas City (UMKC)/Truman Medical Centers and Director of Vision Research Center, University of Missouri-Kansas City at Truman Medical Centers performed the procedure on the first patient enrolled in the CABERNET study. When asked for initial feedback on the procedure, Dr. Sabates commented, "The procedure was no different than performing a common vitrectomy and the Epi-Rad device allowed me to deliver a well focused dose of radiation to the lesion. Treating neovascular AMD using a multi-faceted approach like the use of radiation and anti-VEGF therapy may well be the next frontier in combating this sight threatening disease."
The CABERNET clinical trial will involve clinical sites in the United States, Europe, Israel, and South America. The CABERNET trial protocol is divided into two treatment arms - investigational and control.
The investigational treatment arm consists of concomitant delivery of Beta radiation, via the proprietary NeoVista technology (Epi-Rad90™), and an FDA approved anti-VEGF agent. The investigational treatment is administered during an outpatient surgical procedure and delivers Beta radiation directly to the area of the retina that has been compromised by the disease. An injection of the anti-VEGF agent is administered at the time of surgery with one additional injection administered 30 days after surgery. The control arm is utilizing the FDA approved anti-VEGF agent alone.
The surgery was performed in collaboration with, Saint Lukes Hospital in Kansas City. Dr. Terry J. Wall, J.D., M.D. of the Saint Lukes Cancer Institute was the attending radiation oncologist involved with the procedure.
"This is a very good day for NeoVista employees and the investors who are supporting our work," stated John N. Hendrick, President and CEO of NeoVista. "More importantly, it is a potential harbinger of hope for those suffering from wet AMD." We remain optimistic that our treatment approach will provide maximum benefit to this patient population."
Treatment for Cataracts/ other eye diseases
What is a cataract?
There is only one known treatment for cataracts - surgery! A cataract needs to be removed only when vision loss interferes with your everyday activities, or the things you like to do such as driving, reading, sewing, playing golf or watching TV . You and your eye care professional can make this decision together. Once you understand the benefits and risks of surgery, you can make an informed decision about whether cataract surgery is right for you. In most cases, delaying cataract surgery will not cause long-term damage to your eye or make the surgery more difficult. You do not have to rush into surgery.
Additionally, Medicare and most commercial insurance carriers require that best corrected vision be reduced to some level (often 20/50 visual acuity) before they will approve the surgery for payment.
Sometimes a cataract should be removed even if it does not cause problems with your vision. For example, a cataract should be removed if it prevents examination or treatment of another eye problem, such as age-related macular degeneration or diabetic retinopathy.
If you choose surgery, your optometrist will refer you to an ophthalmic surgeon to remove the cataract. This is a very definite advantage over choosing an eye surgeon out of the phone book or from your friends because your doctor knows firsthand the quality of the cataract surgery performed by local eye surgeons. Because they work with the eye surgeons and usually perform some or all of the post-op care they truly know where to refer you for the best possible outcome. If you have cataracts in both eyes that require surgery, the surgery will be performed on each eye at separate times, usually four to eight weeks apart.
As with any surgery, cataract surgery poses risks, such as infection and bleeding. Before cataract surgery, your doctor may ask you to temporarily stop taking certain medications that increase the risk of bleeding during surgery. After surgery, you must keep your eye clean, wash your hands before touching your eye, and use the prescribed medications to help minimize the risk of infection. Serious infection can result in loss of vision. Talk to your eye care professional about these risks. Make sure cataract surgery is right for you.
Cataract surgery slightly increases your risk of retinal detachment. Other eye disorders, such as high myopia (nearsightedness), can further increase your risk of retinal detachment after cataract surgery. One sign of a retinal detachment is a sudden increase in flashes or floaters. Floaters are little "cobwebs" or specks that seem to float about in your field of vision. If you notice a sudden increase in floaters or flashes, see an eye care professional immediately. A retinal detachment is a medical emergency. If necessary, go to an emergency service or hospital. Your eye should be examined by a retinal specialist as soon as possible. A retinal detachment causes no pain. Early treatment for retinal detachment often can prevent permanent loss of vision. The longer the retina stays detached, the less likely you will regain good vision once you are treated. Even if you are treated promptly, some vision may be lost.
There is only one known treatment for cataracts - surgery! A cataract needs to be removed only when vision loss interferes with your everyday activities, or the things you like to do such as driving, reading, sewing, playing golf or watching TV . You and your eye care professional can make this decision together. Once you understand the benefits and risks of surgery, you can make an informed decision about whether cataract surgery is right for you. In most cases, delaying cataract surgery will not cause long-term damage to your eye or make the surgery more difficult. You do not have to rush into surgery.
Additionally, Medicare and most commercial insurance carriers require that best corrected vision be reduced to some level (often 20/50 visual acuity) before they will approve the surgery for payment.
Sometimes a cataract should be removed even if it does not cause problems with your vision. For example, a cataract should be removed if it prevents examination or treatment of another eye problem, such as age-related macular degeneration or diabetic retinopathy.
If you choose surgery, your optometrist will refer you to an ophthalmic surgeon to remove the cataract. This is a very definite advantage over choosing an eye surgeon out of the phone book or from your friends because your doctor knows firsthand the quality of the cataract surgery performed by local eye surgeons. Because they work with the eye surgeons and usually perform some or all of the post-op care they truly know where to refer you for the best possible outcome. If you have cataracts in both eyes that require surgery, the surgery will be performed on each eye at separate times, usually four to eight weeks apart.
As with any surgery, cataract surgery poses risks, such as infection and bleeding. Before cataract surgery, your doctor may ask you to temporarily stop taking certain medications that increase the risk of bleeding during surgery. After surgery, you must keep your eye clean, wash your hands before touching your eye, and use the prescribed medications to help minimize the risk of infection. Serious infection can result in loss of vision. Talk to your eye care professional about these risks. Make sure cataract surgery is right for you.
Cataract surgery slightly increases your risk of retinal detachment. Other eye disorders, such as high myopia (nearsightedness), can further increase your risk of retinal detachment after cataract surgery. One sign of a retinal detachment is a sudden increase in flashes or floaters. Floaters are little "cobwebs" or specks that seem to float about in your field of vision. If you notice a sudden increase in floaters or flashes, see an eye care professional immediately. A retinal detachment is a medical emergency. If necessary, go to an emergency service or hospital. Your eye should be examined by a retinal specialist as soon as possible. A retinal detachment causes no pain. Early treatment for retinal detachment often can prevent permanent loss of vision. The longer the retina stays detached, the less likely you will regain good vision once you are treated. Even if you are treated promptly, some vision may be lost.
Monday, July 19, 2010
Foveal Macular Edema Treatments
Located in the foveal region of the retina, the macula is an important part of the visual system, responsible for clear central vision. A damaged macula means distorted vision when looking at objects straight ahead. Macular edema, one type of damage, occurs when fluid accumulates in the tissue under the macula. Causes of edema include ocular inflammation and, more commonly, complications from uncontrolled diabetes. Prompt treatment is crucial to preserving vision when macular edema occurs.
Laser Treatment
According to the Mayo Clinic, macular edema is the leading cause of decreased vision in patients with early diabetic eye complications, also called background diabetic retinopathy. Uncontrolled diabetes leads to leakage of blood vessels in the back of the eye. Fluids, such as blood and fatty lipid material called exudates, can then accumulate. This can lead to numerous complications, including swelling under the macula tissue. When this occurs, clinically significant macula edema requires treatment with a focal laser procedure, also called focal laser photocoagulation. Laser light focused on the macula targets the leaky vessels, resulting in laser scars or burns that help reduce further leakage and the amount of fluid accumulated. If laser treatment for both eyes is necessary, the treatments are usually scheduled a few weeks apart. Focal laser photocoagulation is the mainstay treatment for macular edema caused by diabetic retinopathy and, according to the National Eye Institute, reduces the chance for vision loss by 50 percent.
Anti-inflammatory Drugs
Macular edema can result from retinal inflammation. It often follows procedures such as cataract surgery. In this type of edema, cyst-like pockets of fluid build up in the macular region--hence its name cystoid macular edema--and the reason for its development is unknown. Often, steroidal anti-inflammatory eyedrops are prescribed to treat cystoid macular edema. An injection of steroids--such as cortisone--into the eye can be necessary in cases of more severe edema. According to the University of Michigan, injecting steroids intraocularly for macular edema caused by diabetes is an emerging treatment option. Repeat injections are often necessary.
Vitrectomy
The vitreous is the large, gel-like area that makes up a bulk of the back of the eye. It comes in contact with the retina and macular tissue. Sometimes tugging of the macula by the vitreous gel can lead to macular edema. When this occurs, it's recommended to have surgery to remove the vitreous gel. This procedure is called a vitrectomy. A vitrectomy is also performed when macular edema and other complications caused by diabetes result in significant blood accumulation in the vitreous. This procedure is usually recommended for advanced diabetic cases.
Preventive Care
The most serious type of macular edema is connected to diabetic retinopathy, because there is a high risk for vision loss. Therefore, doctors strongly recommend control and care of blood sugar through diet, exercise and medication. Other preventive measures include annual eye exams and controlling other diseases such as high blood pressure and high cholesterol. The National Eye Institute reports that macula edema can often occur without symptoms of blur, so preventive care is essential to detecting it before lasting damage can occur.
Laser Treatment
According to the Mayo Clinic, macular edema is the leading cause of decreased vision in patients with early diabetic eye complications, also called background diabetic retinopathy. Uncontrolled diabetes leads to leakage of blood vessels in the back of the eye. Fluids, such as blood and fatty lipid material called exudates, can then accumulate. This can lead to numerous complications, including swelling under the macula tissue. When this occurs, clinically significant macula edema requires treatment with a focal laser procedure, also called focal laser photocoagulation. Laser light focused on the macula targets the leaky vessels, resulting in laser scars or burns that help reduce further leakage and the amount of fluid accumulated. If laser treatment for both eyes is necessary, the treatments are usually scheduled a few weeks apart. Focal laser photocoagulation is the mainstay treatment for macular edema caused by diabetic retinopathy and, according to the National Eye Institute, reduces the chance for vision loss by 50 percent.
Anti-inflammatory Drugs
Macular edema can result from retinal inflammation. It often follows procedures such as cataract surgery. In this type of edema, cyst-like pockets of fluid build up in the macular region--hence its name cystoid macular edema--and the reason for its development is unknown. Often, steroidal anti-inflammatory eyedrops are prescribed to treat cystoid macular edema. An injection of steroids--such as cortisone--into the eye can be necessary in cases of more severe edema. According to the University of Michigan, injecting steroids intraocularly for macular edema caused by diabetes is an emerging treatment option. Repeat injections are often necessary.
Vitrectomy
The vitreous is the large, gel-like area that makes up a bulk of the back of the eye. It comes in contact with the retina and macular tissue. Sometimes tugging of the macula by the vitreous gel can lead to macular edema. When this occurs, it's recommended to have surgery to remove the vitreous gel. This procedure is called a vitrectomy. A vitrectomy is also performed when macular edema and other complications caused by diabetes result in significant blood accumulation in the vitreous. This procedure is usually recommended for advanced diabetic cases.
Preventive Care
The most serious type of macular edema is connected to diabetic retinopathy, because there is a high risk for vision loss. Therefore, doctors strongly recommend control and care of blood sugar through diet, exercise and medication. Other preventive measures include annual eye exams and controlling other diseases such as high blood pressure and high cholesterol. The National Eye Institute reports that macula edema can often occur without symptoms of blur, so preventive care is essential to detecting it before lasting damage can occur.
Friday, July 16, 2010
Gene Therapy for Eye Diseases
The pharmaceutical giant Genzyme has started a clinical trial to see whether a drug to treat macular generation could be delivered via long-lasting gene therapy rather than monthly injections.
Eye colors: Drusen, the yellow flecks in this image of the retina, are common in people with age-related macular degeneration. These flecks are made up of proteins involved in the part of the immune system called the complement system, which has also been implicated in the disease by genetic studies.
A drug called Lucentis, made by Genetech, has proved effective at treating the wet form of age-related macular degeneration, which can lead to blindness. Some 200,000 Americans a year are diagnosed with the disease. But Lucentis has to be injected into the eye every month or two, a burden for patients and doctors.
Lucentis binds to and neutralizes a wound-healing growth factor known as VEGF. This binding action stalls the excess growth of blood vessels in the eye that characterizes age-related macular degeneration. Genzyme's gene therapy drug, officially called AAV2-sFLT01, would insinuate itself into the patient's retinal cell to produce the same VEGF-binding protein as Lucentis over far longer periods--up to several years.
A phase 1 clinical trial of Genzyme's gene therapy treatment began at the end of May. Three patients received the treatment, according to Sam Wadsworth, a Genzyme group vice president in charge of gene and cell therapy. Preliminary results should be available in about a year.
The trial is one of a handful worldwide seeking to prove the effectiveness of gene therapy for eye diseases. The Genzyme trial also involves using new type of virus as the delivery mechanism. Early results of a federally funded trial to deliver normal-functioning genes to patients with a rare retinal disease known as type 2 leber congenital amaurosis, or LCA, have confirmed that this "viral vector" has merit for eye treatments, several researchers say.
The LCA trials "demonstrated success both in terms of safety and ability to introduce the gene and have efficacy and success," said Jeffrey S. Heier, an assistant professor at Tufts University School of Medicine and director of retinal research at Ophthalmic Consultants of Boston, a private practice group, who is involved in the Genzyme research. "This study is taking the virus vector that they used, and [Genzyme has] taken what has really been the success of the anti-VEGF story and they've packaged the two together."
Eyes have been an early target for gene therapy because they are small--meaning they require relatively little active dose, they are self-contained, and because the tools of eye surgery have advanced enough to make the treatments possible. The drug has to be delivered to the retina, a thin film lining the inner wall of the eye. Instrumentation has improved in recent years to allow injections through the retina without piercing it, said Shalesh Kaushal, chairman of ophthalmology at University of Massachusetts Memorial Medical Center and UMass Medical School.
To Kaushal, who is involved in the Genzyme study as well as the LCA research, the big challenge will be broadening the use of gene therapy to dozens more diseases, and using that understanding to eventually reach beyond the eye. "If one could understand those fundamental cellular, biochemical events and identify targets, you might have the chance to treat many diseases with a single gene-therapy construct," Kaushal said.
Earlier gene therapy programs used a type of virus called adenovirus to target genes, but both the LCA and Genzyme trials are using adeno-associated virus, which is far less inflammatory and which expresses itself over longer periods than adenovirus, therefore making the treatment last longer, Wadsworth said. Viruses are used to deliver gene therapies because they are adept at getting through cell walls.
VEGF is involved in vascular cell growth throughout the body, and its expression increases in the presence of a wound. Studies have shown that with Lucentis, virtually all the VEGF-binding protein stays within the eye, and does not significantly affect VEGF levels elsewhere in the body, Wadsworth says. Genzyme's drug will provide even lower levels of the VEGF-binding protein, so it's expected that the drug will not have any adverse affects throughout the body, he said.
The trick will be getting the cells to produce enough VEGF-binding protein to help patients, said Peter Campochiaro, a professor at the Wilmer Eye Institute at Johns Hopkins Medicine, who is involved in the research. In addition to establishing safety, the current phase 1 trial will explore four different doses of the study
Eye colors: Drusen, the yellow flecks in this image of the retina, are common in people with age-related macular degeneration. These flecks are made up of proteins involved in the part of the immune system called the complement system, which has also been implicated in the disease by genetic studies.
A drug called Lucentis, made by Genetech, has proved effective at treating the wet form of age-related macular degeneration, which can lead to blindness. Some 200,000 Americans a year are diagnosed with the disease. But Lucentis has to be injected into the eye every month or two, a burden for patients and doctors.
Lucentis binds to and neutralizes a wound-healing growth factor known as VEGF. This binding action stalls the excess growth of blood vessels in the eye that characterizes age-related macular degeneration. Genzyme's gene therapy drug, officially called AAV2-sFLT01, would insinuate itself into the patient's retinal cell to produce the same VEGF-binding protein as Lucentis over far longer periods--up to several years.
A phase 1 clinical trial of Genzyme's gene therapy treatment began at the end of May. Three patients received the treatment, according to Sam Wadsworth, a Genzyme group vice president in charge of gene and cell therapy. Preliminary results should be available in about a year.
The trial is one of a handful worldwide seeking to prove the effectiveness of gene therapy for eye diseases. The Genzyme trial also involves using new type of virus as the delivery mechanism. Early results of a federally funded trial to deliver normal-functioning genes to patients with a rare retinal disease known as type 2 leber congenital amaurosis, or LCA, have confirmed that this "viral vector" has merit for eye treatments, several researchers say.
The LCA trials "demonstrated success both in terms of safety and ability to introduce the gene and have efficacy and success," said Jeffrey S. Heier, an assistant professor at Tufts University School of Medicine and director of retinal research at Ophthalmic Consultants of Boston, a private practice group, who is involved in the Genzyme research. "This study is taking the virus vector that they used, and [Genzyme has] taken what has really been the success of the anti-VEGF story and they've packaged the two together."
Eyes have been an early target for gene therapy because they are small--meaning they require relatively little active dose, they are self-contained, and because the tools of eye surgery have advanced enough to make the treatments possible. The drug has to be delivered to the retina, a thin film lining the inner wall of the eye. Instrumentation has improved in recent years to allow injections through the retina without piercing it, said Shalesh Kaushal, chairman of ophthalmology at University of Massachusetts Memorial Medical Center and UMass Medical School.
To Kaushal, who is involved in the Genzyme study as well as the LCA research, the big challenge will be broadening the use of gene therapy to dozens more diseases, and using that understanding to eventually reach beyond the eye. "If one could understand those fundamental cellular, biochemical events and identify targets, you might have the chance to treat many diseases with a single gene-therapy construct," Kaushal said.
Earlier gene therapy programs used a type of virus called adenovirus to target genes, but both the LCA and Genzyme trials are using adeno-associated virus, which is far less inflammatory and which expresses itself over longer periods than adenovirus, therefore making the treatment last longer, Wadsworth said. Viruses are used to deliver gene therapies because they are adept at getting through cell walls.
VEGF is involved in vascular cell growth throughout the body, and its expression increases in the presence of a wound. Studies have shown that with Lucentis, virtually all the VEGF-binding protein stays within the eye, and does not significantly affect VEGF levels elsewhere in the body, Wadsworth says. Genzyme's drug will provide even lower levels of the VEGF-binding protein, so it's expected that the drug will not have any adverse affects throughout the body, he said.
The trick will be getting the cells to produce enough VEGF-binding protein to help patients, said Peter Campochiaro, a professor at the Wilmer Eye Institute at Johns Hopkins Medicine, who is involved in the research. In addition to establishing safety, the current phase 1 trial will explore four different doses of the study
Wednesday, July 7, 2010
Tyrosine Kinase inhibitor shows promise for AMD treatment
A new study finds that inhibition of CXCR4 may be useful in preventing neovascularization but does not appear to have an effect on already established angiogenesis, whereas a multiple receptor tyrosine kinase inhibitor (SU14813) reduced the size of previously formed lesions.
Endothelial precursor cells (EPCs) derived from hematopoietic stem cells (HSCs) have been shown to contribute to choroidal neovascularization (CNV) by signaling through the SDF-1 and its receptor, known as CXCR4. Hematopoietic stem cells are implicated in the formation of new pathologic vessels observed in wet AMD. Recruitment of endothelial precursor cells to the site of neovascularization is mediated, in part, by the chemokine SDF-1, and its receptor, CXCR4. CXCR4 is a G-protein-coupled receptor found on lymphocytes, monocytes, hematopoietic, endothelial progenitor cells, and mature endothelial cells.
Methods and Results
CNV in rats was generated by focal rupture of Bruch's membrane with an 810-nm diode laser. In the prevention mode, a CXCR4 antagonist (AMD3100) was delivered via an osmotic pump 1 day after laser induction. In the intervention mode, AMD3100 delivery commenced 14 days after laser induction. Inhibition of CXCR4 was determined through leukocyte and SDF-1 actin polymerization blood biomarker assays. Leakage was assessed by fluorescein angiography, and CNV lesion size was quantified after isolectin B4 endothelial cell staining. SU14813, an anti-VEGFR, PDGFR-beta, KIT, and FLT3 inhibitor, was also assessed in an intervention study protocol.
Related News
CCR3 is a target for AMD diagnosis and therapy
Integrin α5β1 inhibitor JSM6427 combats CNV in animal study
Stem cells show promise to restore vision
Inhibition of CXCR4 was demonstrated by an increase in the number of blood leukocytes, and diminished SDF-1 induced actin polymerization in whole blood. CNV leakage and neovascularization were inhibited when the dose regimen was initiated 1 day after laser-induced CNV induction. AMD3100 did not show efficacy when administered 14 days after lasering. Treatment with SU14813 significantly decreased CNV leakage and lesion size in an intervention modality.
Discussion and Conclusions
In this study, CXCR4 inhibition was efficacious in the prevention of CNV, but failed to reduce choroidal leakage and angiogenesis in the intervention modality. This finding suggests that therapies targeting the SDF-1/CXCR4 axis may be beneficial in blocking the induction of ocular neoangiogenesis, but are unlikely to reduce already established angiogenesis.
There is strong evidence that CXCR4 inhibition disrupts the recruitment of endothelial precursor cells (EPCs) to sites of angiogenesis, most likely the major mechanism leading to efficacy in the prevention model.
In addition to suppressing CNV, CXCR4 inhibition reduced choroidal vascular leakage in the prevention modality (but not in the intervention modality). It is not known whether CXCR4 inhibition decreases leakage directly or as a secondary effect of the reduction of the angiogenic vessel area.
The observation that CXCR4 inhibition did not decrease choroidal leakage or angiogenic lesion size in the intervention modality suggests that after a 2-week generation of laser-induced CNV, there is limited, if any, contribution of EPC cells to the already established vessels
A multiple receptor tyrosine kinase (RTK) inhibitor may still be an effective monotherapy, as SU14813 reduced the size of previously formed lesions. In treatment mode, both leakage and angiogenesis decreased even after the pathologic effect was given 14 days to fully establish before drug intervention. This study suggests that blockade of the VEGF receptor is an effective alternative method of inhibiting the VEGF pathway compared to conventional anti-VEGF strategies.
SU14813 is a small molecule with broad target RTK selectivity, inhibiting the VEGF receptor (VEGFR), PDGFR-β, KIT, and FLT3. Although the primary mechanism that reduces preexisting angiogenesis and leakage is the blockade of the central VEGF pathway, the additional inhibition of PDGFR-β may augment efficacy in this model over single anti-VEGFR agents.
The investigators conclude that inhibition of CXCR4 may be useful in preventing neovascularization but does not appear to have an effect on already established angiogenesis. A multiple receptor tyrosine kinase inhibitor (SU14813) approach shows promise for the treatment of wet age-related macular degeneration.
Endothelial precursor cells (EPCs) derived from hematopoietic stem cells (HSCs) have been shown to contribute to choroidal neovascularization (CNV) by signaling through the SDF-1 and its receptor, known as CXCR4. Hematopoietic stem cells are implicated in the formation of new pathologic vessels observed in wet AMD. Recruitment of endothelial precursor cells to the site of neovascularization is mediated, in part, by the chemokine SDF-1, and its receptor, CXCR4. CXCR4 is a G-protein-coupled receptor found on lymphocytes, monocytes, hematopoietic, endothelial progenitor cells, and mature endothelial cells.
Methods and Results
CNV in rats was generated by focal rupture of Bruch's membrane with an 810-nm diode laser. In the prevention mode, a CXCR4 antagonist (AMD3100) was delivered via an osmotic pump 1 day after laser induction. In the intervention mode, AMD3100 delivery commenced 14 days after laser induction. Inhibition of CXCR4 was determined through leukocyte and SDF-1 actin polymerization blood biomarker assays. Leakage was assessed by fluorescein angiography, and CNV lesion size was quantified after isolectin B4 endothelial cell staining. SU14813, an anti-VEGFR, PDGFR-beta, KIT, and FLT3 inhibitor, was also assessed in an intervention study protocol.
Related News
CCR3 is a target for AMD diagnosis and therapy
Integrin α5β1 inhibitor JSM6427 combats CNV in animal study
Stem cells show promise to restore vision
Inhibition of CXCR4 was demonstrated by an increase in the number of blood leukocytes, and diminished SDF-1 induced actin polymerization in whole blood. CNV leakage and neovascularization were inhibited when the dose regimen was initiated 1 day after laser-induced CNV induction. AMD3100 did not show efficacy when administered 14 days after lasering. Treatment with SU14813 significantly decreased CNV leakage and lesion size in an intervention modality.
Discussion and Conclusions
In this study, CXCR4 inhibition was efficacious in the prevention of CNV, but failed to reduce choroidal leakage and angiogenesis in the intervention modality. This finding suggests that therapies targeting the SDF-1/CXCR4 axis may be beneficial in blocking the induction of ocular neoangiogenesis, but are unlikely to reduce already established angiogenesis.
There is strong evidence that CXCR4 inhibition disrupts the recruitment of endothelial precursor cells (EPCs) to sites of angiogenesis, most likely the major mechanism leading to efficacy in the prevention model.
In addition to suppressing CNV, CXCR4 inhibition reduced choroidal vascular leakage in the prevention modality (but not in the intervention modality). It is not known whether CXCR4 inhibition decreases leakage directly or as a secondary effect of the reduction of the angiogenic vessel area.
The observation that CXCR4 inhibition did not decrease choroidal leakage or angiogenic lesion size in the intervention modality suggests that after a 2-week generation of laser-induced CNV, there is limited, if any, contribution of EPC cells to the already established vessels
A multiple receptor tyrosine kinase (RTK) inhibitor may still be an effective monotherapy, as SU14813 reduced the size of previously formed lesions. In treatment mode, both leakage and angiogenesis decreased even after the pathologic effect was given 14 days to fully establish before drug intervention. This study suggests that blockade of the VEGF receptor is an effective alternative method of inhibiting the VEGF pathway compared to conventional anti-VEGF strategies.
SU14813 is a small molecule with broad target RTK selectivity, inhibiting the VEGF receptor (VEGFR), PDGFR-β, KIT, and FLT3. Although the primary mechanism that reduces preexisting angiogenesis and leakage is the blockade of the central VEGF pathway, the additional inhibition of PDGFR-β may augment efficacy in this model over single anti-VEGFR agents.
The investigators conclude that inhibition of CXCR4 may be useful in preventing neovascularization but does not appear to have an effect on already established angiogenesis. A multiple receptor tyrosine kinase inhibitor (SU14813) approach shows promise for the treatment of wet age-related macular degeneration.
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