This article is more than 5 years old. Information may no longer be current.
Steroid injection, vitrectomy may be laser alternatives for diabetic retinopathy
Click Here to Manage Email Alerts
Diabetic retinopathy has long been studied in clinical trials as researchers have sought innovative new treatments that would slow or halt the progression of the disease. While strides have been made involving laser treatment, practitioners are looking even further ahead to new procedures and agents that will continue to reduce the risk of vision loss.
Before doctors can look to the future for cutting-edge procedures, they should look to the past at numerous clinical studies performed over the past few decades, said Jerry Cavallerano, OD, PhD, staff optometrist and assistant to the director of the Beetham Eye Institute at the Joslin Diabetes Center in Boston.
“The first thing to do is stress the importance of the major clinical trials that were conducted in the United States and the United Kingdom,” he told Primary Care Optometry News. “These trials, essentially, are the diabetic retinopathy study, the Early Treatment Diabetic Retinopathy Study (ETDRS), Diabetic Retinopathy Vitrectomy Study, Diabetes Control and Complications Trial and the U.K. Prospective Diabetes Study. In the past 30 years, these studies have shown that with the proper examination and treatment — predominantly laser treatment — for proliferative retinopathy and focal laser treatment for diabetic macular edema, the risk of severe vision loss can be reduced substantially, to less than 2% over a 5-year period. When eyes are amenable to treatment, usually there is no change in vision or symptoms, so the importance of annual examinations and adherence to the American Optometric Association (AOA), American Diabetes Association (ADA) and American Academy of Ophthalmology (AAO) guidelines is crucial.”
--- High risk: This is an image of high-risk proliferative diabetic retinopathy. The use of silicone oil may help resolve the bleeding in this condition when a vitrectomy cannot.
The same basics apply to clinically significant diabetic macular edema, Dr. Cavallerano said. The Diabetes Control and Complications Trial showed that strict control of blood sugar levels “reduced the risk of onset of retinopathy of those patients who have no retinopathy and the progression of retinopathy for those patients who already have retinopathy,” he said. “In addition, it reduces the need for laser treatment and has a positive effect on reducing other microvascular complications from diabetes.
“What’s new is that we need to continue to reinforce the importance of these studies, the value of regular eye examinations, the benefit of good control of diabetes and collateral medical problems that may be associated with diabetes, such as elevated cholesterol levels, kidney disease and hypertension,” he continued. “We know that hypertension is a risk factor for the progression of retinopathy as well.”
Steroid injection, vitrectomy
While laser treatment is widely used for diabetic retinopathy patients, intravitreal injection of steroids is a new option for those are resistant to it, said Bert M. Glaser, MD, in private group practice in Maryland. “Some eyes with diabetic macular edema are recalcitrant to laser treatment. Occasionally, in these eyes, the condition seems to continue in spite of laser,” he said. “Two exciting things are being used now and seem to have potential for good efficacy: intravitreal injection of steroids and silicone oil. Injecting steroids into the vitreous cavity can significantly reduce diabetic macular edema. In some cases that you can’t control with laser, it can help enormously.”
There are cases where thickening of the vitreous overlying the retina will not resolve upon laser treatment, Dr. Glaser said. Those may be treated by removing the thickened vitreous gel with a vitrectomy. “That’s a little different from the vitrectomy that we do when there’s scar tissue growing all over it in a more advanced case,” he said. “But in some of those early cases where there’s just a thickening of the vitreous gel, that particular surgery can help.”
Silicone oil
In proliferative diabetic retinopathy, said Dr. Glaser, massive amounts of blood vessels on the surface of the retina grow abnormally and often bleed continually. While a vitrectomy can halt the bleeding, the remaining blood vessels experience substantial leakage and bleeding can continue, he said. In these cases, instillation of silicone oil in the vitreous cavity can resolve the bleeding. “If you fill up the center of the vitreous cavity with a clear silicone oil, it kind of holds the bleeding back and prevents it from continuing,” he said.
While the oil may be removed after 3 to 6 months, it is usually left in the vitreous cavity indefinitely, he said. “It depends on how well the eye can handle it,” he said. “It really gets the bleeding under control in some cases where otherwise it would not be impossible.
“This silicone oil remains contained in the eye and, unlike breast implants, causes no systemic reactions,” he said. “We haven’t seen any reactions, at least any that are systemic. It has been well tolerated. I think laser surgery and vitrectomy are still first-line, but this gives us an important second line of defense that we really didn’t have before, so that’s a major improvement.”
Telemedicine for diagnosis
A useful tool in diagnosing diabetic retinopathy in the future is the telemedicine initiative, said Dr. Cavallerano. He works with the Joslin Vision Network, part of the Joslin Diabetes Center, in which digital images of a patient’s retina are captured without requiring dilation of the pupils. “We know that many people who require eye care don’t always receive it,” he said. “With this system, we evaluate the images from remote sites and prepare a management strategy based on the level of retinopathy. The management strategy may be continued observation or an initial examination. The Joslin Vision Research Network has been shown to determine ETDRS level of diabetic retinopathy and diabetic macular edema similar to the diagnosis from ETDRS seven-standard field stereo photography through dilated pupils (Journal of Ophthalmology, March 2001).”
A similar technology is the Inoveon Digital Disease Detection and Tracking Service (3DT — Oklahoma City, Okla.). Rather than a screening tool, the technology is more of a disease-management tool, said Sherry Bellack, business development manager for Inoveon.
--- Bleeding resolution: Silicone oil is used to replace the blood-stained vitreous gel and prevent future bleeding from the blood vessels growing into the vitreous.
“Screening programs have lower sensitivity thresholds and traditionally only provide information indicating if results are normal or abnormal,” she told Primary Care Optometry News. “Using this method, it is very difficult to stage retinopathy. In the ETDRS, the accepted levels for staging disease were established, and the Inoveon 3DT technology was based on this scientific foundation. Now, our technology matches pathology that we find in the eye from these digital photos to the ETDRS stage, so we can actually maintain a patient in our system until he or she reaches the optimal time for treatment according to the AAO guidelines.”
Recommended for medical centers with large populations of diabetic patients, the technology uses seven-field color stereo photography for dilated retinas. After acceptable images — based on focus, clarity, stereo and field definition — have been captured for all seven fields, the digital images are transferred via the Internet to the Inoveon Evaluation Center in Nashville, Tenn.
The images are read and the pathology related to diabetic retinopathy and macular edema are identified. The proprietary 3DT Analysis Application processes the reader findings to derive an ETDRS Final Severity Score and a macular edema stage and map these to a clinical stage from the AAO guideline with the corresponding clinical management recommendation for return evaluation or referral for treatment to an eye care specialist.
“Within 48 hours of the patient’s evaluation, Inoveon’s iScore report is sent to the referring physician, relaying the diabetic retinopathy and macular edema stages along with the appropriate AAO recommendation for return evaluation or referral,” Ms. Bellack added.
The system is recommended for optometric offices if the practice has a large enough diabetic patient base, she said. “Some optometrists have an extremely large practice and see a lot of diabetic patients,” she said. “We’re just beginning to enter that market. We have a few optometry practices that are up and running, and we’ve had a tremendous amount of interest with international accounts with a high level of diabetes incidence. They like the idea of having someone in the United States reading their images; they are much more confident in our capabilities and expertise.”
Referral criteria
When considering referring a patient, a practitioner’s first concern should be adhering to the AOA, ADA and AAO guidelines, which state that a person with diabetes requires lifelong regular eye care and — at the least — an annual eye examination, said Dr. Cavallerano. “Patients with macular edema or any level of diabetic retinopathy should certainly be referred to an ophthalmologist for consideration for laser photocoagulation and consultation, as indicated,” he said. “Patients who have suffered recent vision loss in diabetes should be referred for visual rehabilitation and low vision evaluation with low vision specialists. The most important thing is to educate them on the importance of regular eye exams.”
Patients with any evidence of diabetic macular edema, as well as neovascularization, are candidates for referral, agreed Dr. Glaser. “If there is any question about swelling, the patient should be referred,” he recommended. “Any development of new blood vessels also should be referred. Any severe non-proliferative diabetic retinopathy — and severe usually entails not only hemorrhages and micro-aneurysms but also venous beading, as well as IRMA (intraretinal microvascular abnormalities) — really warrants a referral.”
New clinical trials
New oral agents for the treatment of both conditions are being tested in clinical trials, said Dr. Cavallerano. “Some of the laboratory work has been very promising,” he said. “Oral agents are being tested to determine their efficacy for managing diabetic macular edema and diabetic retinopathy.”
For Your Information:
- Jerry Cavallerano, OD, PhD, may be reached at 1 Joslin Place, Boston, MA 02215-5306; (617) 732-2554; fax: (617) 732-2545.
- Bert M. Glaser, MD, is a member of the Editorial Board of Primary Care Optometry News. He may be reached at Glaser & Murphy PA, 5530 Wisconsin Ave., Suite 835, Chevy Chase, MD 20815-4401; (301) 986-8747; fax: (301) 986-8944.
- Sherry Bellack is the business development manager for Inoveon. She may be reached at 800 Research Pkwy., Suite 370, Oklahoma City, OK 73104-3698; (405) 271-9025; fax: (405) 271-9026.