Refractive errors and treatments

Saturday, November 7th, 2009 at 2:31 pm Post in Eye Exams and Vision Screening

Some people may be diagnosed with refractive errors after an eye exam, which means the eyes can not refract or focus light properly. The eye’s ability to focus light is decisive for one’s vision sharpness. Refractive eyeglasses, contact lenses as well as refractive surgeries can be used to correct a refractive error.

It is commonly known that light rays can be deflected, reflected, bent or absorbed by different objects. Light is essential for vision. Like the way that water or curved lens refracts light rays, certain eye structures such as cornea, crystalline lens, tear film and internal fluids can refract light rays into a precise point of focus, which is critical for sharp vision. The focus point should be centered on the retina, which lines the inside of the eye back. The light-sensitive cells in the eye back capture images and then transmit them through the eye’s optic nerve to the brain for interpretation. In this process, the eye’s pupil is responsible for controlling the amount of light that reaches the retina, by widening or constricting itself.

Both eye length and cornea curvature can affect the eye’s refractive ability. Myopia is always caused by too long eyes, which focus images in front of the retina, and farsightedness is caused by short eyes, which can never focus light on retina in time. Astigmatism is created by aspherical eyes, which bring irregular light refraction. All of these defects are called refractive errors. The new invented wavefront technology is used to detect poor contrast sensitivity caused by another refractive error: higher-order aberrations.

Eyeglasses, contacts with precise curvatures can intercept and refract light rays and provide a more accurate focus point on the retina. Refractive surgeries such as LASIK achieve the same effect by changing the corneal surface.