Gel Treatment for Macular Degeneration

The innermost coating of the eye (or back of the eye) referred to as the retina. Gel (vitreous) within the eye holds the retina in place by pressure. The retina captures light rays through millions of photoreceptors, which are converted into electrical impulses that travel through the optic nerve to the brain, where they emerge into images. The photoreceptors in the retina contain rods and cones. The cones are responsible for central vision especially in bright light. Approximately 125 million rods are located in the retina and provide peripheral and night vision but best function in dim lighting (1, 2 & 14). A portion of the retina contains the macula, responsible for seeing fine detail (reading), facial features and interpreting different colors. The Macula is affected by age attributing to macular degeneration (3).

Many elderly people or those over 60 years old have macular degeneration (AMD) or age -- related macular degeneration (ARMD) (4) an eye disease, severe vision loss. Also, AMD is susceptible for those having shortsighted vision, more common in women (tend to live longer than men) than men, smokers, obesity, and possible hereditary link. In the United States every three minutes a case of AMD is diagnosed or 1.2 million people a year (5 & 6). "The government estimates that by 2002 there will be 2.9 million people with advanced AMD" (7). Macular degeneration affects the central part of the vision, and side or peripheral, but never leads to complete blindness (3). Symptoms of macular degeneration include: Blurred vision and increase blind spot area over a period of many years attributing to a decrease in central visual acuity (8). Two types of macular degeneration: Dry and Wet (3). Approximately ninety percent of AMD have dry (atrophic) form, according to National Eye Institute, attributed to gradual loss of central vision, starting in one eye (May or may not affect the other eye), over a period of many years (8). Wet macular degeneration is less common but attributed to severe vision reduction. Blood vessels in the back of the eye, grows abnormal and intrude into the macular area. These blood vessels may leak or bleed attributing fast and rapid eyesight reduction or retinal detachment. The condition may spread from one eye to the other over a period of months (3 & 9). In the United Kingdom, wet macular degeneration is the leading cause of blindness (9). In the United States, more than 200,000 new cases of wet macular degeneration occur each year (6). Treatment for wet macular degeneration directly injecting medication into the back of the eye, contrary to taking eye drops, less than five percent effective to reach the retina (9)

In June 2006, Food and Drug Administration approved Lucentis developed by Genentech, reducing the risk of loosing vision from abnormal blood vessels growth under the retina or wet age - related macular degeneration. (10 & 11)

An electroretinogram (ERG) is diagnostic measurement evaluate for certain retinal diseases. The device measures the retina's response to light stimulus, under normal lighting and in the dark. The evaluation requires pupils to be dilated and eyelids propped open. The duration of the test takes a couple of hours (12). Also, Amsler grid, used since 1945, evaluates or test for macular degeneration. A grid of vertical and horizontal lines used to monitor a person's central visual field (15 & 16). People older than 45 years old should have a complete eye examination every two to four years (6).

Ph.D. Researcher Yvonne Chen from the University of East Anglia's School of Pharmacy, developed a better treatment to deliver drugs to age related retinal diseases including wet macular degeneration. Administering drugs to the retina based on "Smart" polymers: Injected (introduced) as liquids at room temperature but rapidly transforms (in less then a minute) to a gel at body temperature. Thus the process offers the advantage for adding a drug to treat effectively the retina. The liquid is injected (administered) under the eyelid and deposits on the white of the eye. The liquid is converted to a gel as a result of the increased temperature of the body. The gel provides a reservoir (depot) for the drug to slowly travel towards the retina over several hours, and thus during the duration of time, providing a controlled drug release (9). Mr. Chen said regarding previous injection treatment for retinal diseases: "Available treatment for retinal disease needs to be administered through an injection into the eye, which is highly invasive and can be distressing to patients, as well as potentially causing further complications." Also, he said: "Experiments have shown that this new gel well prove to be a breakthrough in treating retinal diseases, with major benefits to patient comfort and healthcare outcomes (13)."

The new gel delivery of drugs to treat age -- related retinal diseases, will be presented to the British Pharmaceutical Conference (BPC) in Manchester, taking place from September 10 - 12, 2007 (13).

1 - StLukesEye.com - Eye Anatomy

2 - Blindbabies.org - Pediatric Visual Diagnosis Fact Sheet - Retinal Diseases

3 - netdoctor.com.uk - Age -related macular degeneration

4 - Wikipedia - Macular degeneration

5 - Artificial Retina Project - Retinal Diseases: Age-Related Maculzr Degeneration and Retinitis Pigmentosa

6 - eMedicineHealth.com - Macular Degeneration

7 - AHAFHome.org - Macular Degeneration

8 - healthwomen.org - Macular Degeneration

9 - News-Medical. Net - New gel to treat retinal diseases in development - Published September 11, 2007

10 - MedicalNewsToday.com - Lucentis (R) is first therapy to improve vision in patients with wet age-related macular degeneration (AMD), 2 studies - July 26, 2005

11 - blindness.org - Macular Degeneration - Treatments

12 - Blindbabies.org - Pediatric Visual Diagnosis Fact Sheet - Retinal Diseases

13 - medicinenewstoday.com - New Gel Could Make Eye Injections a Thing of the Past, UK - September 11, 2007

14 - Answers.com - retina

15 - Wikipedia - Amsler grid & BellaOnline

16 - BellaOnline.com - Age - related Macular Degeneration - AMD