Healthy vision and impaired vision
How does healthy vision work?
In a healthy human eye, reflected light is focused through the cornea, pupil, crystalline lens and vitreous
humour, onto the retina, which converts the light into electrical impulses, and sends them along the optic
nerve to the brain, where they are decoded by the visual cortex into sight.
The area at the centre of the retina is the macula, where fine visual detail is captured, at the centre of
which lies an area, smaller again, called the fovea, which captures the very finest visual detail.
If any of the eye’s light-collection, capture and processing components are damaged or missing, through
injury or illness, vision is impaired.
The anatomy of a healthy human eye. Medical drawing copyright Beth Croce, CMI
What is retinitis pigmentosa?
Retinitis pigmentosa refers to inherited eye disorders involving gradual damage to and loss of
photoreceptor cells in the retina. This causes a gradual degeneration of sight, particularly of peripheral
vision, often resulting in tunnel vision.
Damaged photoreceptor cells (the rods and cones) leave the retina unable to process and transmit visual
information. With a prevalence of one in 5000 people and affecting 1.5 million people worldwide, retinitis
pigmentosa is the predominant cause of inherited blindness.
What is age-related macular degeneration (AMD)?
AMD is a condition whereby the photoreceptor cells in the retina gradually degenerate and die, thereby
losing the ability to convert light into electro-chemical signals. Consequently, nerve signals are no longer
transmitted through the optic nerve to the brain.
AMD severely compromises central vision, crucial for tasks such as reading and facial recognition.
Usually affecting people over 65, AMD is the root cause of nearly half the cases of legal blindness in
Australia.
The layers of the retina contain the rods and cones, or photoreceptors. These cells are lost or cease to function in
patients with retinitis pigmentosa and age-related macular degeneration. Medical drawing copyright Beth Croce, CMI
Who could use a bionic eye?
The bionic eye requires patients to have a developed visual cortex, intact optical nerve, and some intact
retinal cells. To benefit from this technology, patients will have had to see in the past.
Bionic Vision Australia is developing retinal prostheses for patients with advanced stages of retinitis
pigmentosa and age-related macular degeneration.
Researchers are available for comment and interviews.
For further information or assistance, please contact the BVA Marketing and Communications Manager, Veronika
Gouskova: e) veronika.gouskova@bionicvision.org.au | ph) +61 3 9035 3517 | m) +61 4 22 303 284
www.bionicvision.org.au
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