Having a comprehensive eye exam each year is the best way to enjoy good vision throughout your life. Many eye and vision problems have no obvious signs or symptoms. As a result, individuals are often unaware that problems exist.
Early diagnosis and treatment of eye and vision problems
are important for maintaining good vision and eye health, and when possible,
preventing vision loss.
Common Tests Used During Eye Exams
There are many common tests your eye doctor uses
during an eye examination. Some of these are listed below:
Vision testing:
Vision testing involves making a person read
standard sized letters at a specified distance. The doctors record the vision
as a fraction e.g. 6/6 etc. The top number denotes the distance (in feet) at
which the patient has been able to read the particular sized letter while the
bottom number indicates the distance at which a normal person is expected to
read the same letter. Near vision is tested separately in good illumination
using special test charts held at normal reading distance. The testing is done
with each eye separately. The doctors often test the vision using a pinhole.
This gives an estimate of improvement possible with glasses. The patient in
place of glasses cannot use the pinhole.
Refraction
This test uses an instrument referred to as a
phoropter. It looks kind of like a space age eye examination machine with
varying lenses. Your eye doctor will use this instrument to test various lenses
against your eyes, enabling the eye doctor to determine the best power
prescription for your eyeglasses or contacts. The phoropter measure the exact
level of astigmatism, myopia or hyperopia you may have.
Tonometry
This test is important to determine the eye
pressure in the evaluaton for glaucoma. There are various ways to test the
intraocular pressure (IOP) or eye pressure. Non-Contact Tonometry is typically
performed by the technician. Many of you know this test as the “puff of air
test.” Contact Tonometry is performed by your eye doctor by a probe that
touches the eye. But because a numbing drop is used during this test, you won’t
feel a thing. Infact, most patients prefer this method over the puff of air.
Retinoscopy
This is a technique to obtain the objective
measurement of your prescription. It provides a way to estimate what your
vision prescription may be. It can either be performed by an automated machine
or it can be done manually with a Retinoscope. The Retinoscope shines a bright
light into the eye, while the doctor is observing the reflection off your
retina, he or she can determine your estimated prescription.
Cover Test
During this test, your eye doctor will cover one
eye at a time to detect any ocular deviation such as strabismus also known as
an eye turn or lazy eye. Essentially, it measures how well your eye works
together and helps detects problems including poor depth perception.
Slit Lamp
During this test the doctor uses a special high
power microscope to examine the structures of your eye, testing for infections
or ocular diseases. You place your chin on a chin rest, while your eye doctor
reviews your ocular structures through the microscope. This test is beneficial
for detecting conjunctivitis and other common eye diseases as well as more
serious ocular conditions such as cataracts and macular degeneration.
Dilated Fundus Exam
This test requires the doctor place an eye drop in
the eyes in order to dilate the pupil. With the pupils dilated, it creates a
larger window for your doctor to look inside the eyes. The drops typically take
15-20 minutes to take affect. Once dilated your doctor will test your eyes for
various eye diseases. This is an important test for measure the health of the
internal structures of the eye.
A-Scan
biometry by immersion has better reproducibility,
which leads to an overall increase in accuracy. The immersion technique can be
performed rapidly and with greater confidence than the applanation method.
Making the change from the applanation to immersion is well worth the small
learning curve.
Visual Field Screening
This test is usually performed by the eye care
assistant, also known as a technician, with the assistance of a machine to
analyze your visual field. The machine then prints out a detailed reading of
areas of the vision that were or were not seen.
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Source : www.eyecarehospital.org
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