If you need to have any kind of vision exam for the first time, you might feel a little nervous at first-this is completely normal. However, by learning exactly what to expect, you will discover that there is nothing to fear.
Optometrists and ophthalmologists use a wide variety of tests and procedures to examine your eyes. These tests range from simple ones, like having you read a chart, to complex tests, such as using a high-powered lens to visualize the tiny structures inside of your eyes.
A comprehensive exam can take an hour or more, depending on the doctor and the number and complexity of tests required to fully evaluate your vision and the health of your eyes. Following are just a few tests you may encounter while there.
Among the first tests performed in a comprehensive eye exam, are visual acuity tests that measure the sharpness of your vision. These usually are performed using a projected chart to measure your distance visual acuity and a small, hand-held acuity chart to measure your near vision.
A screening test that checks your color vision often is performed early in a comprehensive exam, to rule out color blindness. In addition to detecting hereditary color vision deficiencies, color blindness tests also can alert your doctor to possible health problems that may affect your color vision.
While there are many ways for your ophthalmologist to check how your eyes work together, the cover test is usually the simplest and most common. It is also very simple.
During a cover test, they will probably have you focus on a small object across the room, and then he or she will cover each of your eyes alternately while you stare at the target. While doing this, they will then assess whether the uncovered eye must move to pick up the fixation target, which could indicate strabismus or a more subtle binocular vision problem that could cause eye strain or amblyopia ("lazy eye").
The test may then be repeated up close. They may perform this test early in the exam to obtain an approximation of your potential eyeglass prescription.
In a retinoscopy, the room lights will be dimmed and you will be given a large target (usually the big "E" on the chart) to fixate on. As you stare at the "E," they will shine a light at your eye and flip lenses in a machine in front of your line of vision.
Based on the way the light reflects from your eye, they will probably be able to "ballpark" your prescription-sometimes they can get it dead on. This test is especially useful for children and patients who are unable to accurately answer the doctor's questions.
A refraction test is sometimes used to determine your exact eyeglass prescription. During a refraction, the optometrist puts the instrument called a phoropter in front of your eyes, and shows you a series of lens choices.
He or she will then ask you which of the two lenses in each choice looks clearer. Based on your answers, they may continue to fine-tune the lens power until reaching a final eyeglass prescription.
The refractions determine your potential level of hyperopia, or farsightedness, or myopia, known as nearsightedness. It can also determine if you have astigmatism or presbyopia.
They may also use an autorefractor or aberrometer to automatically determine your prescription. With both devices, a chin rest stabilizes your head while you typically look at a pinpoint of light or other image.
An autorefractor, like a manual refraction, determines the lens power required to accurately focus light on your retina. Autorefractors are especially useful in certain cases such as evaluating young children who may not sit still, pay attention, or interact with the doctor adequately for an accurate manual refraction.
Studies have shown that modern autorefractors can be very accurate. They also can save time.
The autorefraction takes only a few seconds, and the results obtained from the automated test greatly reduce the time required for your doctor to perform a manual refraction and determine your eyeglass prescription. An aberrometer uses advanced wavefront technology to detect even obscure vision errors, based on the way light travels through your eye.
Aberrometers primarily are used for custom or wavefront LASIK vision correction procedures, but many doctors are now incorporating this advanced technology into their routine exams as well. Now that you know better what to expect, you can relax and go along with the appointment as planned.
Author Resource:-
Tommy Greene has worked in surgical equipment sales for the past 15 years. He has great advice and information on an Electrosurgery system.
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