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Corneal pachymetry allows us to measure the thickness of the cornea using ultrasound. Typically the cornea is
about 0.5mm, but varies from person to person. This is significant when measuring intra-ocular pressure. If the
cornea is unusually thick, it may cause us to over-estimate the pressure within the eye. Conversely, if the cornea
is thin we can under-estimate the pressure. Using this quick method, we can adjust the pressure readings to get a
more accurate measurement of the pressure within the eye. The procedure is similar to the measurement of
In a fluorescein angiogram, a fluorescent dye called fluorescein is injected into a vein of the arm or hand, which
quickly travels through the blood stream. A series of photos of the retina are taken with a fundus camera to
capture the appearance of the blood vessels as the dye travels through the vessels of the eye. Fluorescein
angiography enables the doctor to view details, such as emboli, blockages or abnormal blood vessels. We can
also evaluate tumors or swelling of the retina.
Fundus photography uses a fundus camera to take color photographs of the retina after the eyes have fully
dilated. The photos document retina abnormalities.
Optical Coherence Tomography (OCT) is a computer-assisted precision optical instrument that generates cross
sectional images (tomograms) of the retina with < 6 microns (millionths of a meter) axial resolution. It is used to
facilitate diagnosis and management of retinal diseases and glaucoma. It works by using an optical measurement
technique known as low-coherence interferometry. It is similar to ultrasound, except that it uses light rather than
sound, and does not require contact with the eye.
The ocular ultrasound is an imaging technique that uses the reflection (echo) of high-frequency sound waves to
define the outline of ocular and orbital structures, measure the distance between structures, and identify,
measure , and detect position of abnormal tissues inside or around the eye. You will lie back in the exam chair
and close your eyes. A small amount of gel will be placed on your eyelid and a small probe will be placed over the
eye. The probe sends the utrasound waves to the area of interest. During the test, the physician may ask you to
move your eye to different positions to get different views.
Visual Field Test
Your visual field is the area actually seen by the eye when looking straight ahead. A visual field analyzer
(computer) may be used to automatically measure the area and sensitivity of your field of view. You will sit in front
of a machine that looks like a half circle dome and you will be asked to stare at a center point. A computer is
programmed to flash light at different points around the dome and you will press a button each time you see the
light. Sometimes, this is done with a moving target or using a blue light on a yellow background. The computer can
automatically measure the loss of visual field based on your responses.
|Midwest Retina Associates, Inc.