Eye Implant Allows the Blind to See Again
Isn't that exciting?! I probably wouldn't have been as excited if I didn't have RP, but regardless of whether I did or didn't have it, I would definitely have been excited for those who were blind or suffering from the condition - both from an empathic position and a scientific one. I'm no scientist, but I am all for scientific advancement and breakthroughs and it's moments like these where science can be considered beautiful; it doesn't just destroy and cause pain but also brings life and joy.
The article isn't the only route for people with RP to regain their sight; an alternative is highlighted in the following:
Sight Restored to Mice Afflicted with Retinitis Pigmentosa
Looking at that title, it sounds straightforward, but it doesn't say the how...not like the first one. Also it's full of geek-speak, so I'll try and translate/summarise:
A Swiss team have been able to reactivate the cone cells of mice with RP. They have achieved this by introducing a protein via Gene Therapy, which switches the cells 'On'...
...Perhaps I should elaborate on the condition a little; Retinitis Pigmentosa is a genetic condition, thus inherited, which slowly degenerates the vision of a person with the condition to the point of eventual blindness. It mainly presents itself first by severely impairing the person's night vision, but can overlap with impairing the person's day vision as well. My night vision is pretty bad - I think I can compare it with my day vision, in that during the day the fringes of my field of view are a little hazy; it looks like the feathered edge you would give to an image. These hazy spots, however, are complete blind spots in low light and at night - I think it'll be better illustrated if I were to use an image...I've been meaning to make one for a while now. Anyway, the stages are different depending on the type of RP a person has and I'm writing about what I'm experiencing.
To understand the process, you need to remember the structure of the eye and how it works to help you see. Light bounces onto the retina, from the pupil, where it is transmitted to the brain via the optic nerve. The retina is made up of rod and cone cells - their properties are listed in the table below:
| Rods | Cones |
|---|---|
| Used for scotopic vision | Used for photopic vision |
| Very light sensitive; sensitive to scattered light | Not very light sensitive; sensitive to only direct light |
| Loss causes night blindness | Loss causes legal blindness |
| Low visual acuity | High visual acuity; better spatial resolution |
| Not present in fovea | Concentrated in fovea |
| Slow response to light, stimuli added over time | Fast response to light, can perceive more rapid changes in stimuli |
| Have more pigment than cones, so can detect lower light levels | Have less pigment than rods, require more light to detect images |
| Stacks of membrane-enclosed disks are unattached to cell membrane directly | Disks are attached to outer membrane |
| 20 times more rods than cones in the retina | |
| One type of photosensitive pigment | Three types of photosensitive pigment in humans |
| Confer achromatic vision | Confer color vision |
Source: Wikipedia
Did you understand any of that? To summarise, rods are used for vision in the absence of light and take a while to adjust. They are very sensitive and have a lot pigment, though it is only one type of pigment, thus they are well suited to determine depth-perception. They are present in high numbers in the outer regions of the retina - generally considered the "white's of the eye"; the fovea is the central part located around where the optic nerve attaches to the eyeball. In contrast, the cones are used to determine colour and have three types of pigment to do this; they aren't very sensitive and only work when light is present. They are very good at seeing detail and spotting sudden changes in the environment.
That's GCSE Science baby, with a hint of A-Level Biology - ka-chow!
Anyway, taking the functions of the two cell-types into account, it's interesting how RP affects them - rods die completely, while cones simply "switch off". This is the basis of the second article, so hopefully now you can understand what happens.
Since my eyes seem to be a ways off from completely losing sight, I'm not really sure which of the two treatments I'd go for. I guess I can't really give my choice since perhaps by the time I do lose my sight, new treatments will have come into being.
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