Conditions like macular degeneration and diabetes can cause damage to the eyes, sometimes leading to blindness. When you have an illness that affects your eyes, you can sometimes lose your sight because the rods and cones in your eyes die or stop working properly. Your body cannot replace these specialized cells once they die. Rods and cones are very important because they allow your eyes to detect light. Also called photoreceptors, rods and cones change light into electrical impulses that can then travel along your optic nerve to your brain. Your brain then interprets these impulses and creates a picture, and that is how you are able to “see.”
So far, when rods and cones stop working properly or die, doctors have only been able to slow down the rate at which these two things happen. And, often, the condition that is causing problems for the rods and cones remains untreatable. Many common forms of blindness are the result of problems with photoreceptor cells. But the good news is that these types of blindness usually leave the optic nerve and other eye structures undamaged.
A British research team has capitalized on this selectivity by experimenting with stem cells. The research team wanted to find out if stem cells, which are cells that can grow into any type of cell, would be able to grow new rods and cones.
The researchers harvested stem cells from healthy mice and transplanted them into the eyes of mice that were blind. After the transplants, the researchers discovered that the mice’s pupils began to dilate when exposed to light. The researchers believed that this was evidence that the blind mice were able to see.
The researchers are confident that they are on the right track for discovering how to restore sight in humans. The only difficulty lies in how to find donor retinal cells that won’t be rejected. Ideally, you should be able to donate your own stem cells to restore vision. However, if your eye condition is genetic, your stem cells will contain the same genetic coding and the same defects as the cells that have caused your eyesight problems in the first place. Also, according to the study, the stem cells used for transplanting need to be at the right stage of development in order to grow rods and cones successfully.
The answer may lie in growing human embryonic cells to the right stage for transplanting. If this technique can be perfected, doctors may be able to restore the vision of those whose eyesight has been lost due to retinal damage.