When I was in Grade 2, my parents were called in to talk to my teacher. This scared me quite a bit, I mean sure I maybe-accidently pushed that kid while playing soccer cause he “missed the ball” and “accidentally” hit my shin, but other than that, I was a pretty good student and I didn’t see why the teacher had to talk to my parents. My parents went inside while I waited, tapping my feet nervously for an anxious 15 minutes. They walked out, their faces’ sullen. My heart was pumping. My mom turned to me and said the sentence which changed my life.
“Hebah, you’re going to need glasses.”
First, how exactly does the eye work? The first thing light touches when entering the eye is a thin veil of tears that coats the front of the eye. Behind this lubricating moisture is the front window of the eye, called the cornea, which bends and retracts the rays which pass through it. After the cornea, the light passes through the aqueous humor keeping the cornea moisturized and constant pressure within the eye. The light passes through the pupil and the iris. Depending on how much light there is, the iris opens and closes which makes the pupil bigger or smaller, regulating the light entering in the eye. The light goes through the lens which focuses the light, as well as changes shape to focus on light from objects which are closer or farther away. The light is focused through the center of the eye, and the light is bathed in moisture in a clear jelly called the vitreous. The retina, a thin layer of tissue, surrounds the retina. The retina contains millions of tiny light-sensing nerve cells called rods and cones. Cones are in the center of the retina in an area called the macula, while rods are located outside the macula. Cones provide clear, sharp central vision and detect colors and fine details. Rods provide peripheral and side vision, as well as being able to detect motion and help see at night. The cells convert light to electrical impulses, and these impulses are sent to the brain where an image is produced.
This video by the KidsHealth explains it quite well in very simple terms:
So why do people need glasses? Since everyone’s eyes are different, they also work differently. Corrective lenses (the collective term for glasses and contact lenses) are needed for some people. Nearsightedness and farsightedness are two common problems, and in both cases, this is because the image is not properly focused on the retina.
– Nearsightedness or myopia means that people can see things which are nearby, but they have trouble seeing things far away. In the retina, the image becomes focused in front of it.
– Farsightedness or hyperopia means that people are able to see things that are farther away clearly, but they have trouble seeing things close by. In the retina, the image is focused behind the retina.
– Another common problem is astigmatism, where the cornea is an uneven shape, and the light is bent in different directions. This distorts what a person sees and makes things look blurry.
Corrective lenses are curves; the curvature of the lens bends the light rays as they approach the eye. This helps the rays focus on your retina, instead of behind/in front of it. Two types of lenses are used, depending on if you are nearsighted or farsighted. Nearsighted people require convex lenses, which bend the light towards the bottom and the top of the lenses, and pushes the focal point (the point where the rays or waves meet after a reflection or refraction) towards the retina. Concave lenses are for farsighted people; the light passes through a concave lens is bent towards the center, and pushes the focal point forward.
\What kinds of careers are there in optometry?
– An opthalmologist is a trained medical doctor to treat vision problems, as well as doing eye surgery.
– An optometrist is a licensed professional who specialized in eye exams and they figure out the correct prescription for eye glasses and contact lenses.
– An optician makes and sells corrective lenses based on a given prescription.
I recently came across an organization, Child ViSion, which brings glasses to those who cannot afford them. I think this is one of my favorite concepts, especially because I can relate to how important vision is to me.
Glasses and more recently my contacts have become a necessity for me. I can’t even see 10 feet in front of me without them, needless to say the front of the board at school is a blur. I’m grateful to be able to live in a time and world where these resources are available for me.