We offer vision tests at our office in Lincoln, NE
What is a refractive eye exam?
Refractive eye exams in Lincoln, NE are a routine part of an eye examination and are often referred to as a vision test. According to Dr. Forgey, these tests may also be called contact lens exams. Refractions or contact lens exams are the part of the eye exam that measures a patient’s exact prescription for when they need contact lenses or glasses. For patient to be considered to have optimum vision, a 20/20 value is needed. This is also what doctors referred to as perfect vision, which means that these individuals will be able to read and see objects clearly even from a distance. On the other hand, if the patient does not have 20/20 vision then they will have what doctors refer to as a refractive error. When a patient has refractive error, it means that light is not being bended properly as it passes from the cornea into the retina of the patient’s eye. The result of refractions or contact lens exams determines what prescription the patients must use on their glasses or contact lenses so that they can achieve 20/20 vision.
Who is a candidate for refractive or contact lens exams?
Patients who are considered healthy, but have vision problems and are wearing prescription glasses or contact lenses should submit themselves to a refraction or contact lens exam every one to two years to properly asses changes in their vision problems over time and set the appropriate grade for the glasses or contact lenses that they wear to correct their vision. If the patient experiences any disturbances in their vision in between the assigned times for the exams, they must also have the test repeated at the soonest possible time. Patients over the age of 40 who have problems with nearsightedness are also advised to undergo refractions to help determine the correct grade for their reading glasses.
What happens during contact lens exams?
During the initial stages of a contact lens exam, the doctor checks how light is being refracted as it moves through the patient’s cornea and through the lens of the eye.
- To conduct refractions, the doctor may use a computerized refractor where the patients are asked to look through a refractive machine that measures the amount of light that their retinas are able to reflect. Alternatively, the doctor may employ the manual use of a light source that is shined directly into the patient’s eyes so that the amount of light that is being bounced off the retina can be measured to come up with a refractive score.
- In determining the exact prescription grade that the patient needs, the patient will be asked to sit in front of a Phoroptor, which is a piece of equipment that resembles a large mask with holes through which the patient can look through. The patient will then be asked to look at a Snellen chart that is situated 20 feet away and read out the smallest row of letters that he can make out. The doctor then switches lenses one at a time, each one with a different strength, until the patient is able to identify which one of these gives him the clearest vision. This process can be done, as many times as is necessary, until the patient is sure of his choice. This test will be repeated, one eye at a time, until they reach the combination that gets the patient as close to 20/20 vision as possible.
What is the purpose of refractive or contact lens exams?
Refractive or contact lens exams are normally done as a part of a routine eye examination. The result of refractions or contact lens exams, aside from determining the appropriate grade for prescription glasses or contact lenses, are also able to help diagnose the presence of the following conditions:
- Hyperopia, or farsightedness
- Myopia, or nearsightedness
- Presbyopia, which is a condition characterized as the inability of the lenses of the eyes to focus properly on objects, a condition due primarily to aging
- Astigmatism, or the abnormal curvature in the normally smooth surface of the cornea that causes a patient to have blurry vision.
- The presence of ulcerations or infections on the cornea
- Retinal vessel occlusion, or the blockage of the smaller blood vessels around the retina
- Retinal detachment, a serious condition that is described mainly as the detachment or separation of the retina from the rest of the eye
- Retinitis pigmentosa, or a rare genetic disorder that seriously damages the retina.
- Macular degeneration, a condition that occurs mainly in the more elderly patients and is associated to the deterioration of the patient’s sharp, central vision