Your Eyes and Refraction
Refractive errors, usually the cause of blurry vision, are the most common reason that a patient has to visit the ophthalmologist. We can see and witness the world around us due to the way our eyes bend the light they take in, also known as refracting. Refractive errors may cause blurred vision and optical imperfections that prevent your eye from focusing the light as it should.
The most common refractive errors include:
• Myopia - Nearsightedness
• Hyperopia - Farsightedness
Eyeglasses and/or contact lenses can correct most refractive errors. Refractive surgery such as LASIK or AST offers a long term solution, as does cataract surgery, which replaces the eyes natural lens.
How Your Eyes See
While our knowledge of the natural phenomena of light is not 100% complete, what is known is that for us to be able to see, we require it. Depending on the nature of the substance that light encounters and interacts with, a light-ray can be absorbed, refracted, reflected, or deflected. Light traveling through a lens (or water) will see its path refracted. The human eye is similar, and some structures within your eye have refractive properties similar to that of water or a lens. It is the bending (refracting) of this light into your eye that provides for sharp focus and vision.
Refraction in the eye happens when the light rays pass through your cornea (a clear, curved surface of your eye). Several structures within your eye bend the light that it intakes. The lens, the tear film, the aqueous humor, and vitreous also have refractive properties.
Seeing begins when the light rays that pass through the optic system refract and focus back into a point of sharp focus. When the focal point is on the retina, your vision tends to be good. Your retina is the tissue that is lining the inside of the back of your eye, where photoreceptors (light-sensing cells) capture what you see. Your optic nerve that transmits these images you see to the brain for you to process and interpret. The eye's pupil widens or constricts to control the amount of light that reaches the retina, similar to a camera's aperture adjusts the amount of light needed to expose film in just the right way. In dark conditions, your pupil will widen. In circumstances that are or become bright, your pupil will constrict.
Common Causes of Refractive Errors
• Eye Length - If your eye is elongated, light gets focused before it reaches your retina, causing myopia, which is commonly called nearsightedness. When your eye is shorter than average, light does not have the opportunity to be no focused by the time it reaches the retina. The result is hyperopia or farsightedness.
• Curvature of the Cornea - If your cornea is not a perfect sphere, then the image is refracted or focused irregularly, causing a condition called astigmatism. If you have been diagnosed with astigmatism, this does not exclude you from being nearsighted or farsighted.
• Curvature of the Lens - When the curve of your lens is too steep in relation to the shape of your cornea and the length of your eye, this results is nearsightedness. If the lens itself has no curve, the result is farsightedness.
Finding and Treating Refractive Errors
Your ophthalmologist can evaluate your vision for the type and degree of refractive error you may have. They can perform a manual refraction test that allows the ophthalmologist to show you one lens at a time. However, automated refraction is more common, performed with cutting-edge optical instruments. Your refraction issue may indicate that you possess more than one kind of refractive error. Your blurred vision may be attributed to both nearsightedness and astigmatism. Corrective lenses may be prescribed to compensate and adjust, where LASIK surgery, when applicable, would be a more permanent solution to your condition.
Contact an Ophthalmologist Today
If you would like to speak to someone at New Vision Eye Center or schedule an appointment with one of our board certified, world class ophthalmologists, Call us today at 772-257-8700.