AGE RELATED MACULAR DEGENERATION

As a retinal disease affecting more than 15 million people worldwide, age related macular degeneration (AMD) is the leading cause of blindness in the Western world. In addition to being linked to people of age fifty and over, age related macular degeneration is associated with nutritional abnormalities as well as genetic defects among a variety of risk factors. Due to these reasons, pioneering therapeutic interventions for age related macular degeneration continues to be an active area of research within the Canadian Centre for Advanced Eye Therapeutics.

CLASSIFICATION

There are two forms of age related macular degeneration, namely the dry version and the wet version.

The dry version of age related macular degeneration is caused by the breakdown of cells overtime in the blood vessels around the macula. Due to the leakage of fluid from dying cells, deposits called drusen build underneath the retina leading to central vision loss in both eyes. The disease is always found in both eyes, although one eye may be more advanced than the other. Over time this progressive disease continues to lead to further degeneration of sight. While the severity of vision loss caused by the dry form of age related macular degeneration increases with age, the speed of its progression widely varies from patient to patient.

About 10% to 20% of patients with the dry form develop the wet form of age related macular degeneration. Instead of involving dried out blood vessel as in the dry form, the wet form is caused by the growth of abnormal blood vessels or abnormal choroidal neovascular membranes which are quick to rupture and leak into the macula. The leaked fluid actively blocks light from reaching the macula and thus leads to abrupt vision loss within a matter of weeks or months. And despite the fact that the wet form tends to stabilize after a few months or years, it can result in permanent central vision loss.

Genetic Testing

OCC Eyecare's research shows the significant role of genetics in AMD treatment. Your genetic profile can account for over 60% of the risk of developing AMD. Having a first-degree relative (mother, father, brother, sister) with AMD significantly increases your risk. In addition to genetics, lifestyle factors such as age, smoking history, Body Mass Index (BMI), and AMD status also play a role in progression to advanced AMD. With current treatments, AMD may be arrested and in some cases improved. At-risk patients may benefit from frequent monitoring by their eye care physician and by taking the appropriate eye vitamin supplement.

Determining a patient’s genetic profile through DNA testing has shed light on the way we treat, manage and make nutritional recommendations to help preserve vision.

Macula Risk and Vita Risk
Macula Risk is a DNA test intended for patients who have a diagnosis of early or intermediate AMD. Combined with a routine clinical eye examination, results of the Macula Risk test will determine your risk of progression to advanced AMD with vision loss over 2, 5 and 10 years.

Vita Risk is available as part of Macula Risk, or as a stand-alone test. Test results help your eye care physician prescribe the safest and most effective eye vitamin formulation for you based on your genetic profile. The test is a non-invasive swab of the inside of your mouth.

If you are taking eye vitamins for AMD or you think that you or your family members may be at risk for AMD, talk to your eye care physician and discuss whether Macula Risk is right for you.

OCC Eyecare's latest AMD therapy was featured in a CTV health feature. Check it out below.

TREATMENTS

Typically, a drusen heavy case of the dry form of age related macular degeneration is treated by a drusen specific laser. The wet form of age related macular degeneration however, has several treatment options including intraocular injections of Kenalog, three different anti-VEGF’s (vascular endothelial growth factors), high intensity laser treatment and/or surgery. In particular, although Kenalog and anti-VEGF’s are safe for the eye, the intraocular injection of a fluid into the macula carries with it the risk of developing glaucoma, cataracts, retinal detachment, and/or blindness.

Treatments for Dry Form

DRUSEN SPECIFIC LASER

Drusen specific lasers are typically used to treat patients with a large amount of drusen in their dry form of age related macular degeneration. Presently, modern micropulse lasers are used to treat the dry form at the OCC Eyecare. This is because micropulse lasers are more effective at improving vision due to lower drusen formation and carry a reduced risk of developing the wet form of age related macular degeneration than infrared lasers.

Treatments for Wet Form

Intraocular Injection

KENALOG

Kenalog is an anti-vascular and anti-inflammatory steroid that is widely used to treat the wet form of age related macular degeneration. The intraocular injection of Kenalog is often accompanied by the use of anti-glaucoma medication to prevent glaucoma from developing in the eyes after an ocular injection. Kenalog has been used in combination with other treatments such as PDT(photodynamic therapy) and anti-VEGF (vascular endothelial growth factors). The use of Kenalog is anticipated to decline however in favor of using anti-VEGF focused treatments.

ANTI-VEGF’S: MACUGEN, LUCENTIS & AVASTIN

The basis of anti-VEGF treatment is the use of medicines, Lucentis, Eylea, and Avastin, which reduce the risk of developing the wet form of age related macular degeneration by reducing the amount of vascular endothelial growth factors within the macular region of the eye. While Lucentis has been FDA approved as an effective treatment against the wet form of age related macular degeneration, the high cost and frequency of injections required has made it impractical and unaffordable for many patients. As a solution, the National Eye Institute is currently comparing the effectiveness and safety of a more cost-effective anti-VEGF Avastin with Lucentis. Although Avastin is traditionally used in the treatment of advanced colon cancer, it is proving to be as beneficial as Lucentis in its first year of clinical trials by the National Eye Institute. Moreover, the Canadian Centre for Advanced Eye Therapeutics is the first site in Canada where Avastin was injected into patients to treat the wet form of age related macular degeneration. Inspection of our patients post-treatment has clearly showed that it is as effective a treatment for the wet form as Lucentis. Therefore, the Canadian Centre for Advanced Eye Therapeutics currently offers Avastin as a treatment for the wet form of age related macular degeneration.

HIGH INTENSITY LASER

High intensity coagulative or blood clotting lasers use high energy light to cauterize the abnormal blood vessels within the macula to prevent them from rupturing and bleeding. Although this treatment was once commonplace, the side effects of developing permanent blind spots coupled with the statistic that 50% of patients still developed the progressive wet form of age related macular degeneration after treatment have allowed this treatment to go into disuse.

SURGERY

Using surgery to treat the wet form of age related macular degeneration involves the physical removal of abnormal choroidal neovascular membranes from the eye. This treatment is particularly known to be effective sub foveal for patients with ocular histoplasmosis. Also, research done by Dr. Armogan as a fellow of the University of Toronto has showed that patients with the wet form of age related macular degeneration and choroidal neovascular membranes, especially around the peri papillary and or surrounding the optic nerve benefit more from surgery than treatments involving lasers. Treatment using surgery however carries the risk of blindness, retinal detachment, further bleeding within the eye, irreversible retinal damage and more due to the complexity of the procedure. Thus surgery remains a treatment option only for patients with specific medical conditions in addition to the wet form of age related macular degeneration, as well as for those who cannot handle intraocular injections or lasers.

PROGNOSIS

The prognosis for patients with age related macular degeneration is that this disease almost always leads to further deterioration in sight in both the dry and the wet form of disease. However one must be aware that despite the inevitable progression of the disease, it never leads to complete blindness. However, patients may lose their central vision, which can lead to the inability to recognize faces, read, or drive a car. While the disease inevitably progresses, everyone progresses at different rates. This is especially true for patients who have the dry form of age related macular degeneration. In the dry form of age related macular degeneration, some patients may progress at a rate which is so slow that over a period of ten to fifteen years they may not notice any further deterioration of sight. However with specialized testing available at OCC Eyecare, it is possible to determine the nature of this progression. As such, it is essential that early diagnosis occurs since earlier treatments can be offered. In the wet form of the disease, bleeding occurs underneath the retina. The progress tends to be more rapid with patients rapidly losing sight in the first several weeks or months after the bleeding first starts. After a period of several months or years, the wet form of age related macular degeneration becomes stabilized, but there is usually permanent loss of central vision.