Inside the Eye
Update on Macular Degeneration
Macular degeneration (AMD) is the leading cause of vision loss in Americans over the age of 65. With the advent of anti-vascular endothelial growth factors (anti-VEGF), such as Avastin and Lucentis, we now have treatment options that may lead to significant visual improvement in more than a third of AMD patients . Early diagnosis and prompt treatment, however, is more critical than ever for the best visual outcomes, as delays in treatment can lead to scar tissue formation that can limit long-term visual recovery.
Open-label treatment with Avastin is an effective treatment option to Lucentis, the FDA approved treatment for macular degeneration. In a large patient cohort of 1374 intravitreal treatments of Avastin, there were no significant side effects except for ocular inflammation noted at higher doses ( Lalin et al, American Academy of Ophthalmology 2006 ). In this study, the vision improved in 38% of AMD patients treated with Avastin, and no patient lost more than 2 lines of vision. This compares favorably with Lucentis treatment where 34-40% of AMD patients experienced a significant visual improvement and 94-96% maintained vision. This is a remarkable improvement from photodynamic therapy where only 6% had better vision and only 64% maintained vision. Previous stroke patients may have a mildly increased risk of additional strokes with anti-VEGF treatment, so it is important to use Avastin or Lucentis with caution and counsel these stroke patients appropriately. In AMD patients who develop large sub-foveal, sub-retinal hemorrhages, emergent vitrectomy with sub-retinal injection of t-PA to displace the hemorrhage may improve the patient's visual outcome.
Anti-VEGF therapy in combination with steroids appears to be a relatively effective modality in reducing cicatricial changes in persistent macular degeneration. Although PDT may still play a role, clinical trials using a combination of photodynamic therapy with Lucentis demonstrated slightly worse vision than Lucentis alone.
Cataract Surgery and Macula Degeneration
Epidemiological studies are often equivocal on the subject of "does cataract surgery lead to progression of macular degeneration?" Cataracts in patients with macular degeneration are, however, significantly more visually debilitating. Early cataract surgery with close monitoring and early treatment can often optimize the patient's visual outcome.
Ocular Nutrition For Macula Degeneration
Although smoking remains one of the highest risk factors for developing macular degeneration (AMD), there is increasing evidence that nutrition plays a significant role in the progression of AMD. The Age-Related Eye Disease study (AREDS) formulation of vitamins can decrease the progression of AMD by as much as 8% a year and 25% over 5 years. The National Institutes of Health is currently studying the effects of Lutein, Zeazanthein, and Omega 3 fatty acids on the progression of macular degeneration. We recommend AREDS vitamins with Lutein and Omega 3 fatty acids ( or at least 2 servings of fish weekly) for preserving vision in moderate to advanced dry macular degeneration.
New Frontiers in Diabetic Eye Disease
The last decade has led to new insights into the biological changes that can lead to blindness in diabetic eye disease. We now know that vascular factors, such as vascular endothelial growth factor and protein kinase C, play a critical role in the formation of new blood vessels and macula edema. The new vessels can lead to bleeding and scarring in proliferative diabetic retinopathy. In contrast, macula edema, the most common cause of vision loss in diabetes, causes distortion and decreased vision from fluid leaking into the center of vision.
Conventional Laser Therapy
The bedrock of treatment for diabetic eye disease, however, still remains laser based on two large clinical studies from the 70's and 80's-"the Diabetic Retinopathy Study" and the "Early Treatment of Diabetic Retinopathy Study." Laser significantly decreases the risk of vision loss in patients with macula edema and proliferative diabetic retinopathy. New micropulse laser with sub-threshold burns as well as pattern-generating lasers based on military technology may prove to be more effective and less destructive than conventional therapy.
The use of intravitreal steroids has led to a marked improvement in vision, especially with macula edema. In contrast, laser treatments, for the most part, only stabilizes vision and reduces the risk for vision loss. However, the side-effects of glaucoma, and secondary cataracts limits the use of steroids. Recently, the low cost and availability of Avastin, an anti-VEGF molecule, has made it an effective adjunctive therapy for macula edema and proliferative diabetic retinopathy which has reduced the need for destructive laser.
Surgery remains an important component of complex cases. Proliferative diabetic retinopathy with tractional retinal detachments and chronic vitreous hemorrhages can now be managed with small gauge and high speed vitrectom.
Fig 5 (above) : Scar tissue in the OCT image superimposed on a fundus photo helps delineate margins for surgery. Persistent macula edema is often due to traction from epiretinal membranes or vitreomacular traction that causes leakage and chronic edema that affects the vision. Vitrectomy and membrane peeling can be helpful in treating such cases of recalcitrant edema.
The individually tailored combinations of pharmacologic agents with conventional laser and vitrectomy have improved outcomes in complex cases of diabetic eye disease.