During an eye appointment several types of eye tests may be
performed. In addition to a complete eye examination, your doctor
may want to order one of the following special tests.
Applanation method: A test that helps doctors diagnose
glaucoma by measuring the amount of pressure needed to flatten a
portion of the cornea. This is done by taking a thin strip of paper
stained with the dye flourescein. This dye stains the front of the
eye and enables a better examination by the doctor. The patient is
then given a local anesthesia in the form of drops and the pressure
is measured using a tonometer.
Corneal topography: During this procedure, a computer is
used create a "map" of the curvature of the cornea. The computer
analysis will show any distortions of the cornea (e.g., scarring)
as well as conditions such as astigmatism. This test is used to
screen patients before they undergo any refractive surgery. It also
can be used before contact fittings and corneal
transplants.
Fluorescein angiography: This is a test used to evaluate
the blood circulation in the retina. It is useful in helping to
diagnose diabetic retinopathy and retinal detachment. During this
test, a special dye called fluorescein is injected into a vein in
the arm. The dye quickly travels to the blood vessels inside the
eye. Once the dye reaches the eye, a specialized camera is used to
photograph the fluorescein as it circulates though the blood
vessels in the back of the eye. This will enable the doctor to
diagnose any circulation problems, swelling, leaking or abnormal
blood vessels.
Pupillary dilation test: During this procedure, the eye
doctor places special drops in the eye, causing the pupil to dilate
(expand). By dilating the pupils, your doctor can examine your
retina for any signs of disease.
Refraction test: This test measures your ability to see
objects at specific distances. It is often done by having the
patient look at a chart at a fixed distance, usually 20 feet away.
The patient tries to read the chart while looking through a
special instrument known as a phoropter. The phoropter moves lenses
of different strengths into place for the patient to look through.
This test is useful in helping to diagnose presbyopia, hyperopia,
myopia, and astigmatism.
Slit-lamp exam: A test that looks at the front of the eye
by shining a beam of light shaped like a small slit on the eye. The
eye doctor may also dilate your pupils while you are undergoing
this exam. The test can be used to help diagnose cataracts, retinal
detachment, macular degeneration, injuries to the cornea and
presbyopia.