For people with diabetes, cataract surgery poses serious risks, as a recent British study explains.
Surgery for cataracts involves removing all or part of the lens and replacing it with an intraocular lens implant (IOL). Cataract removal is the most frequently performed surgery in people over age 65 and is considered by many doctors to be the most effective surgical procedure in all of medicine. If the eye is normal except for the cataract, surgery will improve vision in more than 95% of cases.
Cataract surgery is remarkably safe. Significant post-surgical complications, such as inflammation, infection, bleeding, swelling, retinal detachment, and glaucoma are rare: They occur in only 1-2% of people. People with other eye diseases and serious medical problems are most at risk for complications.
For example, cataract surgery in diabetics is often followed by complications such as macular edema, retinopathy, and iris neovascularization (abnormal blood vessel growth in the iris). In a recent British study, reported in the British Journal of Ophthalmology (Volume 90, page 697), researchers were able for the first time to correlate such outcomes with a rise in levels of blood vessel growth factors following cataract surgery.
The researchers used fluorescein angiography, an eye test that uses orange dye and a camera to take pictures of the retina, and measured growth factor levels in water-based samples taken from six diabetic patients before cataract surgery and three times following cataract surgery, on days one, seven, and 90.
In four patients, retinopathy in the macula, the center of the retina, worsened. Levels of two factors that promote blood vessel growth -- vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) -- also increased significantly. A different growth factor -- pigment epithelial derived growth factor (PEGF), which discourages new blood vessels from forming -- decreased after cataract surgery. An inflammatory chemical messenger called interleukin 1B also increased, which is normal after cataract surgery but can stimulate the release of VEGF and HGF. The next step, researchers say, is to study whether new anti-VEGF treatments ranibizumab and bevacizumab can control growth factor levels following cataract surgery.
