Q: What exactly is astigmatism?
A: Usually it is related to the shape factor of the front surface of the eye called the cornea. Instead of being shaped spherically like a ball bearing or a marble, it is shaped like a football, being more curved in one direction than the other. This brings light to focus at more than 1 point. The root word stigma means point and the prefix A means without a point focus in the eye.
Q: What is blue light and why is it dangerous?
A: Blue light is part of visible light and close to UV on the light spectrum. It is naturally produced by the sun, used in fluorescent light bulbs and emitted by LED screens on computer monitors, tablets, and smartphones. The eyes’ natural filters do not block blue light and chronic exposure can cause age – related macular degeneration. Evidence also shows that blue light exposure can lead to sleep problems.
Q: Does reading my smart phone or tablet in the dark damage my eyes?
A: Reading from a tablet or smart phone in the dark is okay for your eyes, as long as this is not for a long period of time. There is good lighting from these devices, with good contrast. There is, however, blue light emitted from these devices. Blue light is a short wavelength light, with high energy that may cause damage to the structures of the eye if exposed for a long period of time. As well, studies have shown this blue light can disrupt melatonin production which is required for a healthy sleep cycle. Doctors of Optometry recommend limiting screen use during the last hour before bedtime.