New Developments in Diabetes-Related Eye Disease
Studies find good news for "experienced" patients.
This last year has seen some very important developments regarding the prevention of diabetic retinopathy, treatment of diabetic retinopathy, and long-term risk for suffering severe diabetes-related eye disease and vision loss.
The ACCORD trial suggested that patients with type 2 diabetes and pre-existing cardiovascular disease may face increased cardiovascular risk by attempting to achieve tighter blood glucose control. It is important to know that this finding appears to apply primarily to patients who are not able to readily achieve A1C targets with additional blood glucose lowering therapy (see my previous dLife column). A separate part of this study, called ACCORD-Eye, did show that reducing average blood sugar levels does lower the incidence and progression of diabetic retinopathy in these same patients. A much less talked about part of of ACCORD-Eye also showed that adding triglyceride-lowering fenofibrate (Tricor) medication to the treatment of patients already on cholesterol lowering statin medications reduced the risk of worsening diabetic retinopathy by an amazing 32%. This is something that every patient with any level of diabetic retinopathy who is already on a statin medication should discuss with his or her doctor.
New research shows that people with diabetes are more likely to have inadequate levels of vitamin D; that those with diabetic retinopathy have lower levels than patients without retinopathy; and that even lower levels of vitamin D are associated with more severe retinopathy. Although this does not prove that supplementing with vitamin D will prevent or minimize retinopathy (only a long-term randomized, placebo controlled trial would do this — something that is unlikely to ever happen), it is very interesting to say the least. Because many patients with diabetes are vitamin D deficient (blood levels of less than 20 mg/dl [1.1 mmol/l]) or insufficient (levels less than 30 mg/dl [1.67 mmol/l]), and because lower blood levels of vitamin D are also associated with many cancers as well as multiple sclerosis (conditions which are also more common in people with diabetes), I encourage all of us with diabetes to have our serum levels assessed and supplement with vitamin D3, if appropriate (see my previous dLife column).
Fluid swelling of the most visually sensitive part of the eye's light-sensitive retina, called the macula, is a major cause of vision loss due to diabetes (causing a condition called diabetic macular edema, or DME). Standard therapy for this condition has included laser treatment and steroid medications, which are often injected into the eye. Unfortunately, these treatments often have side effects (laser-induced blind spots with the former, and development of cataracts and high eye pressure with the latter). A more recent advancement has been the use of so-called anti-VEGF medications to reduce swelling and improve vision. Groundbreaking studies now show that use of these newer medicines (Avastin or Lucentis) improves DME more so than laser or steroid treatment when compared head to head. Although there is risk with every therapy, including anti-VEGF drugs (see my dLife column), it is likely that a combination of these treatments will yield the best patient outcomes. Every patient with DME should thoroughly discuss the options, including drugs like Avastin and Lucentis, with his or her eye doctor.
New Thoughts on Risk
The major risk factors for developing severe eye complication from diabetes include: poorer blood glucose control, poorly controlled high blood pressure, abnormal blood lipids (high LDL and triglycerides), and duration of diabetes. Of great importance, new findings from the "Gold Medalist" study of patients with diabetes for at least fifty years show that diabetic retinopathy is unlikely to progress to sight-threatening severity if it has not already done so by 17 years after diagnosis. In fact, patients free of the most severe form of diabetic eye disease, proliferative diabetic retinopathy (PDR), after 17 years had only a 4% chance of developing PDR in subsequent years. The implication is that some patients have a unique set of protective genetic and biochemical factors that protect them from complications, factors that might be exploited to help protect the rest of us. Stay tuned for more news about this important study from the Joslin Diabetes Center.
1-American Academy of Ophthalmology (AAO) and Middle East Africa Council of Ophthalmology (MEACO) 2010 Joint Meeting: Abstract PO223. Presented October 17, 2010.
2-Chew, E.Y., W.T. Ambrosius, M.D. Davis, et al. 2010. Effects of medical therapies on retinopathy progression in type 2 diabetes. ACCORD Study Group; ACCORD Eye Study Group. N Engl J Med 363(3):233-44.
3-Googe, J., A.J. Brucker, N.M. Bressler et al. of the Diabetic Retinopathy Clinical Research Network. 2011. Randomized trial evaluating short-term effects of intravitreal ranibizumab or triamcinolone acetonide on macular edema after focal/grid laser for diabetic macular edema in eyes also receiving panretinal photocoagulation. Retina.
4. Sun, J.K., H.A. Keenan, J.D. Cavallerano. 2011. Protection from retinopathy and other complications in patients with type 1 diabetes of extreme duration: the joslin 50-year medalist study. Diabetes Care 34(4):968-74.
For more information on diabetic eye disease, consult Dr. Chous' book Diabetic Eye Disease: Lessons From a Diabetic Eye Doctor, Fairwood Press, Seattle, 2003.
Read more about Dr. Chous here.
Visit Dr. Chous' website here.
NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.
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