A refractive error is the inability of light rays to be focused sharply on the surface of retina. Light, or objects, not focused sharply results in blurry vision.
Types of refractive errors include nearsightedness (aka myopia), farsightedness (aka hyperopia) and astigmatism.
- Myopia = nearsightedness
- Hyperopia = farsightedness
- Astigmatism – a common secondary optical error
Your refractive error is the measurement of the optical power of lenses needed to focus light sharply on the retina.
Focusing System of the Eye
In a normal healthy eye, light passes through the cornea, pupil, lens and vitreous before it is focused on the retina.
The cornea focuses about 75% of light coming into your eye. More specifically, it is really the surface of the cornea which is responsible for focusing light. Slight changes to the surface of the cornea can result in dramatic changes in focusing power of the eye.
Your natural lens is responsible for the balance of the focusing power of the eye.
The pupil reduces the amount of light entering your eye, but has no direct impact on the focusing power of the eye. The vitreous also does nothing to focus light.
The Retina Receives Light
The retina is the light sensitive tissue which lines the inside of the eye. Light gets focused and captured by the retina. The retina then sends electronic impulses through the optic nerve which then stimulates certain regions of the brain giving us “vision.”
Measuring Your Refractive Error
Using a phoropter, your eye doctor can determine the power of the lenses needed to correct your refractive error and can write you a prescription to obtain glasses or contact lenses so that you may see clearly.
Many offices now have an auto-refractor which can automatically determine your lens prescription.
While contact lenses and/or glasses are a common method of correcting your refractive error, laser vision correction (LASIK) can be an alternative and provide a long term solution as well.
What’s your refractive error?
We look forward to seeing you. Please call us (609.877.2800) for an appointment.