An indirect ophthalmoscope is a medical device which is used in indirect ophthalmoscopy, an examination which is designed to provide a care provider with a view of the back of the eye, known as the fundus. Many people are familiar with direct ophthalmoscopy, a related procedure, because it is often a part of routine physical exams. The indirect version of this test requires more training and skill on the part of the person administering it, but it can provide more meaningful and complete information about eye health and function.
The indirect ophthalmoscope uses an adjustable head band to hold a bright light on the forehead. A lens is positioned between the care provider and the patient, and adjusted to provide a clear view. The level of magnification provided by the lens varies. Looking through the lens, the care provider sees an inverted view of the back of the eye and can take note of what is seen there. Indirect ophthalmoscopy is usually used to check the retina and vitreous humor in the eye.
During an examination with an indirect ophthalmoscope the care provider will usually ask the patient to move the eye and change focal points several times. This allows for different views of the eye. In addition, the eye may be gently pressured through the eyelid with the assistance of a blunt instrument. This can sometimes be uncomfortable and patients should speak up if it becomes painful.
Both binocular and monocular versions of the indirect ophthalmoscope are available. They are usually sold through medical supply catalogs, along with accessories like lens cleaners, replacement head bands, and light bulbs. Many manufacturers provide servicing within a set time period for devices which need adjustment or become damaged. Outside this period, the indirect ophthalmoscope can be sent to the manufacturer or a technician can service it in an office, but there will usually be a fee.
The eyes are usually dilated for an indirect ophthalmoscopy so that a better view is available. As a result, the bright light can be very painful. Patients should also be aware that they will have obscured vision after the test and will need to wear eye protection before going outside. The dilation will fade within a few hours so that the patient can see normally again. It is advisable to have an escort or ride home after the test because the sensitivity to light can become disorienting.