Why Is My Vision Blurry? Refractive Errors Explained
Myopia (Nearsighted) – you can see up close (sometimes only very close), but you cannot see clearly in the distance. This is due to the fact that your eye is longer than the average eye and when light shines into your eye it focuses in front of the retina. This is corrected with a minus power lens. For more information about Myopia, click here.
Hyperopia (Farsighted) – you can see far away (unless you are very farsighted), but up close is blurry or causes eye strain. This is due to the fact that your eye is shorter than the average eye and light focuses behind the retina. This is corrected with a plus power lens.
Astigmatism (sometimes corrected with a Toric lens) – instead of the front of your eye (cornea) being spherical (like a basketball), it is more oval (like a football). This is normal and most people have some degree of astigmatism. This can cause light to focus on two different parts of the retina, sometimes causing blurry or double vision. This is corrected with a lens that has cylinder and axis.
Presbyopia (Greek for “old eyes”) – the lens inside your eyes that normally adjusts shape and size to focus images up and close can no longer do that. Every year there are layers added to your lens, so eventually (around 40-50 years old) it loses elasticity and you cannot see clearly up close with your distance glasses on. This is corrected with an ADD, which is where the top of the lenses in your glasses is for distance and the bottom of your lens has plus power added to it. This can be in a bifocal, trifocal, progressive lens or separate distance and reading glasses.