One of the top questions that I get at The Spectacle Shoppe is, "What is an Astigmatism"? In short, Astigmatism is a common type of refractive error. It is a condition in which the eye does not focus light evenly onto the retina -- the light-sensitive tissue at the back of the eye. Instead of creating one focus point, the rugby ball shaped cornea creates multiple focus points (see diagram). To help illustrate further, I've sourced The National Eye Institutes explanation of the facts on astigmatism.
Refraction is the bending of light as it passes through one object to another. Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see.
As the weather begins to change I tend to start thinking about sun protection. For my family this means hats, sun screen, UV protective clothing for my toddler and sun glasses. I think it’s safe to say that most people are now fairly aware of the damaging effects of ultra violet radiation. I’m not so sure that everyone includes protective eyewear on their sunny day checklists. In fact today as I look out our office window there are very few people walking by with appropriate sun eyewear.
As a Licensed Optician I love interacting one-on-one with clients. One of the most common complaints that I hear about is dry eyes from contact lens wear.
I've got a few handy tips to help with this problem, but in order to get there I need to first tell you about the composition of tears and the role tears play in eye health.
Tears are made up of 3 layers: lipid, aqueous and mucin. These 3 layers each have a part to play in preventing dry eye. The lipid (fatty) layer prevents evaporation. The aqueous or lacrimal layer makes up most of the volume of the tear film. This layer carries nutrients, washes away unwanted or dangerous bacteria or foreign objects. The mucin layer is the glue holding the tears to the cornea. If there is a problem with any of these layers which prevents optimal functioning then you end up with dry eyes.