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A Look at Nearsightedness, Farsightedness, and Astigmatism

Posted on April 9th, 2015

When it comes to your eyes, blurry or unclear vision is often caused by one of three distinct "refractive" errors that all affect different fields of sight: nearsightedness (myopia), farsightedness (hyperopia) and astigmatism.

To understand how these conditions can impair your vision, it's important to know the basics of how your eyes work. Simply put, light enters your eye through the clear cornea and travels through the aqueous humour while the lens adjusts the focus to clarify the image. Once the light hits the retina, an image is transmitted through the optic nerve to the brain, where it's interpreted as sight. Unfortunately, refractive errors can affect how these images are perceived. Below is a brief description of how these refractive errors can affect your sight.

1. Myopia
People with myopia can see close objects with clarity but not those which are far away. This occurs because the eye is too long, causing light to fall on a point in front of the retina. The problem is genetically inherited and typically identified in children around the age of 10.

2. Hyperopia
Hyperopia is the exact opposite of myopia—the eye is too short, so light lands at a point behind the retina, causing images to be clear at a distance but blurry when close. Hyperopia is not diagnosed as often as myopia because patients often squint unconsciously to focus on close up objects. The result is passable vision accompanied by headaches, which many people do not suspect to be a symptom of poor sight.

3. Astigmatism
Ideally, the eye should be perfectly spherical for light to evenly view objects at all orientations. However, the cornea may feature an asymmetrical curve and cause the refractive capabilities of the eye to vary depending on the position of certain objects. This is called astigmatism, and it is characterized by blurriness, tiredness of the eyes and headaches. No human eye is perfectly spherical, but those with higher degrees of asymmetry will cause difficulties with clear sight.

While myopia, hyperopia and astigmatism are three of the most common vision issues, the good news is that they are easily treatable. That's why it's important to schedule a regular exam with your optometrist to ensure your eyes are healthy. To book your exam, find the FYidoctors nearest you.