About Age-related Macular Degeneration (AMD)

Patients with age-related macular degeneration (AMD) progressively lose their clear, central vision, as the cones within the macula degenerate. Currently afflicting 25-30 million people worldwide, AMD results in an irreversible loss of vision.

The Macula

The eye contains photoreceptor cells known as rods and cones. These photoreceptors convert light into electrical impulses that are sent via the optic nerve into the brain, which then interprets what we see. Rods allow us to see under low light conditions, while cones, which require brighter light, distinguish fine detail and color. Cones are highly concentrated within the macula, a small area at the center of the retina. Because the macula is predominantly made up of cones, this area of the eye facilitates the sharp, straight-ahead vision required for such tasks as reading, driving and recognizing faces.

AMD Image

AMD degenerates rods and cones

In AMD, central vision is lost when the cone cells within the macula deteriorate and eventually die.

Stem cells protect rods and cones

When human neural stem cells are transplanted, photoreceptor cells — and vision — are preserved.

Human neural stem cells, when transplanted into the sub-retinal space of animals with retinal degeneration, have been shown to protect photoreceptors from progressive degeneration and preserve visual function long-term, suggesting a promising approach to treating retinal degenerative disorders such as AMD.

HuCNS-SC® Cells

Optic Nerve
Pupil
Cornea
Macula
Retina (inner lining at back of eye)

Types of AMD

Wet AMD — Affecting only 10-15% of individuals with AMD, the “wet” (neovascular) type accounts for approximately 90% of all cases of severe vision loss from the disease. In wet AMD, abnormal blood vessels under the retina begin to grow toward the macula. These tend to break, bleed and leak fluid, damaging the macula and resulting in rapid and severe loss of central vision. Although there is no known cure, several treatments are now available for wet AMD.

Dry AMD — Affecting approximately 80-90% of individuals with AMD, the “dry” (atrophic) type tends to progress more slowly than the “wet” type. In dry AMD, small white or yellowish deposits, called drusen, form on the retina, beneath the macula, causing it to deteriorate or degenerate over time. There are currently no approved treatments for dry AMD.

Geographic Atrophy of AMD (GA-AMD) — The advanced form of dry AMD, which today affects 1.75 million Americans1, is referred to as “geographic atrophy.”  Instead of just scattered drusen, GA tends to form an “island” of lost retinal pigment epithelium (RPE) and photoreceptor cells. GA will progress relentlessly through the central macula and cause significant impairment of vision and quality of life.

  1. Friedman et al. Arch Ophthalmol. 2004 Apr; 122(4):564-72

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The Bigger Picture

As the “baby boom” generation ages, the incidence of AMD is expected to increase dramatically, tripling by 2025. Photoreceptor protection through neural stem cell transplantation may be viable as a future therapy for AMD. This approach may also hold promise for treating other retinal degenerative diseases such as retinitis pigmentosa, the most common inherited cause of blindness, affecting an estimated 1.5 million people worldwide and rendering many legally blind by the age of 40.