The use of simple instruments to look at tissues near the surface of the body
Instruments that can be used to view body structures and organs directly have been developed and improved considerably over the past 100 years. Some of these instruments have been replaced by endoscopes (see Endoscopy). However, some basic viewing instruments are still frequently used in a doctor’s surgery as part of a routine examination because they are simple to use and cause minimal discomfort.
How do they work?
In order to examine the interior of a natural opening, such as the ear canal, your doctor will usually need a source of light that can be focused on the area to be examined and some form of magnification. These two elements are often incorporated into a single viewing instrument, such as an otoscope, which is used for inspecting the ear.
For other natural openings, such as the vagina or nose, your doctor may need to use an additional instrument, called a speculum, to hold the passage open and keep other structures out of the way during viewing. In some cases, a speculum may also be used to make access easier and to enable the doctor to take samples of tissue.
The light-sensitive retina at the back of the eye can be viewed from the outside through the pupil. The instrument used to do this, called an ophthalmoscope, incorporates magnifying lenses and a source of light.
What are they used for?
Your doctor may perform basic viewing techniques as part of a routine physical examination to assess a particular area of the body or to investigate symptoms in that area. For example, if you have earache, your doctor may examine your ear (see Otoscopy), and to investigate hoarseness, your doctor may look at your larynx (voice box) by using a procedure known as mirror laryngoscopy. Basic viewing techniques can also be part of screening procedures. For example, if you have a long-term disorder such as diabetes mellitus, which is associated with retinal damage, your doctor may examine your eyes by means of ophthalmoscopy and slit-lamp examination so that he or she can detect damage at an early stage. In addition, some types of tissue sample, such as tissue from the cervix, can be taken with the help of a viewing instrument (see Colposcopy).
In some cases, it is possible to take photographs through basic viewing instruments, such as an ophthalmoscope. Photographs taken at different times can be compared to monitor a condition.
What are the risks?
An examination using basic viewing techniques is completely safe and may be repeated as often as necessary to monitor or screen for a disorder. Most examinations cause little or no discomfort, and anaesthesia is not usually necessary. However, when viewing the larynx and throat, a local anaesthetic spray may be used to numb the throat.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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