Q: What exactly is astigmatism?
A: Astigmatism is usually caused by an irregularly shaped cornea, the front surface of the eye. Instead of being a perfect sphere, like a ball bearing or a marble, it can become a little more like a football, being more curved in one direction than the other. This brings light into focus at more than one point on the retina at the back of the eye, resulting in blurry or distorted vision.
Q: What is blue light and why is it dangerous?
A: Blue light is part of visible light and has a wavelength close to UV rays on the light spectrum. It is naturally produced by the sun, given off by fluorescent light bulbs, and emitted by LED screens on computer monitors, tablets, and smartphones. The eye's natural filters do not block blue light and chronic exposure may increase your risk for age-related macular degeneration. Evidence also shows that blue light exposure can lead to sleep problems.
Q: Does reading my smartphone or tablet in the dark damage my eyes?
A: Reading from a tablet or smartphone in the dark is okay for your eyes, as long as it's not for a long period of time. These devices have decent lighting and good contrast. However, they give off blue light, and long-term exposure may cause damage to the structures of the eye. As well, studies have shown that blue light at night disrupts melatonin production and interferes with healthy sleep cycles. Optometrists recommend wearing blue light blocking eyewear for extended digital device use, and limiting screen time during the last hour before bedtime.