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Although the terminology used in describing an eye examination will differ somewhat from one doctor to another, a general eye exam is normally a comprehensive examination of the eyes that includes a vision check (visual acuity) and a variety of tests for overall health of the eye. A comprehensive examination normally takes about two hours. Many of the tests done in a general exam are also included in exams for specialized problems such as cataracts or glaucoma.
Patients should prepare for an exam by taking to the doctor's office any information that may be needed for their permanent medical record. This will include address and telephone numbers, insurance information, names of other doctors, a list of medications being taken, and past medical records if available. Some doctors will even ask the patient to bring to the exam all medications currently being taken. Patients who wear glasses or contact lenses should also bring their most recent pair to the exam. Because most comprehensive exams include dilating the eyes, it's a good idea to bring sunglasses to wear during the trip home. If the exam is for a child, the parent should consider bringing along favorite books and/or small toys to keep the child occupied during the wait.
At a first examination with a new doctor, several minutes will be spent in gathering a detailed patient history. This will include patient's age, gender, race, past medical problems, including any surgery or injuries, medications and allergies, family medical history, and any current symptoms that could indicate a medical problem. If this is not a first visit, the doctor will still ask some of the same questions, especially relating to current symptoms of any eye problems. Questions may also be asked about special visual requirements that result from a patient's occupation or recreational activities.
Following the history-taking, various tests will be performed to check near and distance vision, color vision, depth perception, alignment of the eyes, eye muscle coordination, response of pupils to light, side (peripheral vision), intraocular pressure, eyelids and the internal structure of the eye including the retina. The tests conducted during a general eye examination are generally noninvasive and cause no pain or discomfort to the patient. The doctor will perform some of the tests, while a trained technician may conduct others. The doctor, however, will examine the results of all tests and determine what if any treatment is required.
Tests performed during a comprehensive exam can be generally divided into two parts:
The doctor will initially perform several tests to define the patient's visual abilities and ocular health. This will include an overall look at the appearance of the eye and surrounding area, checking for signs such as squinting, drooping of eyelids, facial muscles that do not appear to be working properly, and signs of irritation such as redness or swelling. A check of pupil function will also be done at this point using a pen light to see if the pupil responds normally. In addition, the eye care professional will perform the following checks:
If any of these initial tests indicate a potential problem, more extensive testing may be done later in the exam.
Visual acuity is a measurement of how well a patient sees. Most patients equate this measurement to a test using the Snellen Eye Chart, a chart with rows of letters, numbers and symbols in standardized graded sizes, with a designated distance at which each row should be legible to a normal eye. A person with a normal optical system (20/20 vision) can see standardized symbols on the chart at a distance of 20 feet. A person with 20/30 vision can see symbols on the chart from 20 feet that a person with normal vision could see from 30 feet.
Another chart is used to measure "near vision" or reading vision. This chart is held about 16 inches from the eyes, while the distance vision chart is placed at a distance (often by using mirrors) of 20 feet.
Refraction is a measure of nearsightedness, farsightedness and astigmatism. Two types of tests are normally used to evaluate the refractive status. One of those tests, using an instrument called a phoropter, requires input from the patient as several different combinations of lenses are placed in front of the eye. The patient is asked to tell the doctor which of the combinations of lenses provides the clearest and most comfortable vision. This is called a "subjective" test because it requires judgment on the part of the patient.
When the comprehensive examination is complete, the doctor provides an assessment of the findings and a follow-up plan, which may include a prescription for glasses or contact lenses, further testing if necessary, treatment for diseases or disorders, or a referral to another health care specialist. The patient may also be directed to a contact lens fitting specialist or to the optical area to be fitted for new frames and prescription lenses.
With the huge array of eyeglass frames and lenses now available, selecting a new pair of eyeglasses can be a time-consuming affair. It's important to work with an optician who knows about frame and lens materials and who knows how to properly measure for, fit and adjust eyeglasses. Eye-appealing frames, including many designer lines, are now available at most optical shops and, with a little searching, you should be able to find an attractive frame you like.
It's the optician's job to assure that the frame is the right size for your face, is comfortable, and that your lenses are properly made. The optician should also introduce you to extra features that may make your eyeglasses more comfortable and easier to care for. For instance, lens coatings are available to minimize scratching and provide protection from glare. High-Index eyeglass lenses manufactured from higher refractive index plastics allow a thinner, lighter lens while maintaining the same optical qualities. For those who require bifocals and trifocals, no-line multifocal eyeglass lenses are available with progressive powers that graduate from distance to reading power with no lines in between.
Eyeglass prescriptions may take from one hour to several days to fill, depending on the frame selected and the complexity of the prescription. Eyeglasses are usually guaranteed to fit correctly and to provide you with the best vision correction possible. If your glasses are uncomfortable or you can't see well, don't hesitate to return to your eye doctor and/or to the optical shop where you purchased the glasses until you are satisfied.
If a patient prefers contact lenses instead of eyeglasses, additional evaluation is required to find the right type and size of contact lens. This is referred to as a contact lens evaluation and can probably not be completed in one visit. The first step involves measuring the patient's eye to determine the correct size of the contact lens. Trial lenses are then placed in the eye and the fit is evaluated with a biomicroscope. Patients new to contact lens wear will then be instructed on proper cleaning, insertion and removal of the lenses. A wear schedule is also prescribed to allow the patient to gradually adapt to the lenses by leaving them in for longer periods each day. The eyes must be carefully monitored over a three-month period of time in order to determine a proper fit and to ensure that there are no complications. After the completion of the fitting process, contact lens wearers are encouraged to schedule semi-annual eye examinations.
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