Pulse oximetry is a form of testing that measures the amount of oxygen present in the blood as well as the pulse rate without having to take a blood sample. Your doctor will use a medical device known as a pulse oximeter to get this reading through your skin. This test is non-invasive and there is no pain or discomfort associated with it. Pulse oximetry takes only a few minutes to perform.
To conduct pulse oximetry testing, your physician will place a small device on your fingertip to perform the reading. Using special lights and sensors, the machine can measure the oxygen saturation of your blood. In cases where this test is indicated for very young children, adhesive strips are applied to the skin to obtain the reading.
Positive results are those that fall below the normal range for oxygen levels in the blood. For most people, a reading between 95 and 100 percent is considered normal. If the result is below 90 percent, it could indicate a problem in the function of the cardiovascular or pulmonary system. More testing will be required to determine the exact nature of the condition. Your doctor may recommend an echocardiogram to obtain clear visualization of the heart’s structures and cardiac blood flow or tests to measure lung function.
Low levels of oxygen in the blood may or may not produce symptoms. The most common symptom of this condition, known as hypoxemia, is shortness of breath.
Tests of visual acuity are used to assess eyesight. Visual acuity testing may be performed on its own or as part of a comprehensive eye examination. It is generally done to determine if a patient’s vision is sharp and accurate or if it is blurry.
Visual acuity tests can evaluate how well a person can see objects close up as well as at a far distance. Most visual acuity testing involves identifying letters or symbols on an eye chart at a certain distance. One eye is typically tested at a time because we do not always have equal vision in both eyes. The eyes may be tested together, with and without corrective lenses if they are necessary, as well.
Visual acuity may be tested as part of a routine examination, to establish whether vision correction is needed and to monitor the progression of an existing eye condition. A visual acuity test may also be performed if an eye has experienced trauma or injury. These tests typically take only a few minutes to perform.
There are several different types of visual acuity tests commonly used. During a standard examination, your doctor may perform:
- The Snellen test. This evaluation method is used to measure distance vision. The patient is positioned approximately 20 feet away from a chart printed with rows of letters. As you look from the top of the chart to the bottom, the rows of letters progressively become smaller. The patient will cover one eye, using the other eye to read each row until the letters are too small to see clearly. The test is then repeated with the other eye, but the patient may be asked to read the letters in a different order to ensure no memorization took place.
- The E chart test. Similar to the Snellen test, the E chart test is an alternative for those who cannot read. The rows on this chart show the letter E facing different directions. These rows also feature the largest lettering on the top and get slightly smaller with each successive row. Testing one eye at a time, the patient is required to point in the same direction as the lines of each E seen.
- The Near test. To test close up vision, this evaluation involves holding a small card printed with several lines of typeface. The print on this card also diminishes in size as you move down each row. The card is positioned approximately 14 inches from the patient’s face. The patient is then asked to read the words on the card aloud until they are no longer clearly visible. For this test, both eyes are assessed together. If you wear eyeglasses or contact lenses, the test may be performed while you wear them. Since presbyopia, a natural loss of flexibility in the lenses of the eyes that causes a loss of near vision, tends to occur in those 40 and older, this test is typically begun at that age.
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