Flashing Lights and Visual Floaters
Last month I discussed visual distortion caused by migraine. This month I would like to talk about the other common problem that causes great anxiety among my patients … sudden onset of floaters and flashing lights in your peripheral vision. In the back of your eye there is the retina. The retina converts light into electrical signals that go to the brain where they are processed into the images we perceive. There are two optical lenses in each eye, the cornea and a flexible lens inside the eye. Between the flexible lens and the retina is a jelly-like substance called the vitreous humor. When we are young, the lens inside the eye and the vitreous humor are both clear. As we get older the lens starts to discolour and become less flexible, and gradually becomes opaque and eventually turns into a cataract. The vitreous humor normally stays clear throughout our lives but it can slowly split into a much more watery liquid with small cloudy bits floating around. It can also become slightly cloudy due to inflammation inside the eye. The most likely cause of floaters is when the vitreous humor shrinks and separates from the retina. This is called a posterior vitreous detachment and is very common. When the vitreous detaches from the retina floaters may suddenly appear. These are usually due to the glue that sticks the vitreous to the retina coming away from the retina and then drifting around the eye. Occasionally vitreous detachments can cause a tear in the peripheral retina. That’s why, when you have floaters suddenly appearing, you need to have them checked out urgently. The likelihood of a retinal tear is low but it can cause severe loss of vision. Your optometrist will put drops in your eyes and examine all the structures of your eye.