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LIST OF SERVICES & PROCEDURES
Retina & Vitreous Surgery
What is the Retina?
The eye is a ball that works like camera. As the camera has film in the back, so does the eye. The film in the eye is
called the retina, and it is a thin tissue that lines the inside of the eyeball like wallpaper. In the camera, light enters
through the lens in the front and it is focused on the film. The same occurs in the eye. Light enters the eye through the
cornea, which serves as a clear windshield, goes through the lens of the eye, and is also focused on the film of the eye -
the retina.
The word retina comes from Latin and it means network. This is a very appropriate term since the retina is actually
a network of very specialized nerve cells. These nerve cells are called the photoreceptors and are made up of the rods
and cones. When light hits the rods and cones, the energy of the light is changed to electrical impulses that are sent to
the brain by nerve fibers. There are approximately 1,000,000 nerve fibers that transmit this information from the retina
to the brain. The nerve fibers are bundled together and form the optic nerve. The optic nerve travels from the back of
the eye to the vision center in the back of the brain. The vision center of the brain interprets the signals from the retina
and gives us a picture.
What is the Macula?
Remember, the retina is a wallpaper that lines almost the entire inside of the eyeball. The macula is a very special
area of the retina that is located exactly in the center. As a Bull's eye is the center of a target and is equal to 100 points,
the macula is the center of the retina and is responsible for our best, 20/20 vision. The macula is the area of our most
precise vision, concerned with such functions as recognizing faces, reading, and driving. If the macula is damaged,
then one will still have good ambulatory or "walk-a-round" vision. People with severe macular disease are still able to
see steps, and avoid walking into doors and walls. Some people with macular problems are not able to drive or read.
There are a number of low vision aids available such as special magnifying glasses and lenses that may be very
useful in improving the quality of life for a person with macular disease.
What is the Vitreous ?
The inside of the eyeball is filled with a jelly-like substance that has the consistency of egg white, and is crystal
clear. The vitreous is important during the fetal development of the eye. After birth, there is no obvious role or function
of the vitreous, and it can be removed surgically without harming the eye. The vitreous gel is normally adherent or
"stuck" to the retina.
What is a Posterior Vitreous Detachment or Separation?
At some point in life, the vitreous gel may become more "watery", or undergo a process known as syneresis.
When the vitreous gel liquefies, its structure collapses, and it separates or pulls away from the retina. This event is
known as a posterior vitreous detachment, and it is quite common. It occurs in most people by the age of 60 years.
This vitreous separation may be may be induced by severe trauma, such as a direct punch to the eye. They also tend to
occur in very nearsighted individuals at a younger age.
When the vitreous separates, or pulls away from the retina, it can be like pulling a piece of "scotch tape" from
wallpaper. Several things can happen when the vitreous separates from the retina.
Floaters: When tape is pulled from wallpaper, pieces or paper, or flecks of paint may come away with the tape.
Floaters occur when the vitreous pulls a few fine flecks from the surface of the retina, the eye's wallpaper. These flecks
float around in the vitreous and may appear as black dots, flies, blobs, or cobwebs. When bright light enters the eye,
these flecks cast a shadow on the retina. Therefore, they are most noticeable when looking at brightly-lit backgrounds,
such as a white wall, the sky, or the newspaper. They are usually invisible in dim light. Floaters almost never go
away, but with time they may shrink and people tend to adjust to their presence.
Flashes of Light: The retina does not contain the special nerve fibers that are required to feel pain. Thus, when the
vitreous pulls on the retina, it is completely painless. However, when the vitreous pulls on the retina, it triggers the rods
and cones. They become stimulated and show their "discomfort" by sending out flashes of white light. Flashes of light
indicate that the vitreous is actively pulling on the retina. While floaters never go away, light flashes will diminish as the
vitreous pulling subsides. This usually occurs over a period of 4 to 6 weeks. These light flashes are like small, brief
lightning bolts, and are usually seen in the side vision. These flashes are so weak, that are seen only in very dim light.
Occasionally, migraines, with or without headaches, are associated with flashing lights. Ocular migraines produce
stronger, longer lasting flashes of light. They are seen in daylight, and are usually organized into geometric patterns
that change shape, and can be different colors.
Vitreous Hemorrhage: There are many fine blood vessels within the retina. These blood vessels bring nutrition to
the retina. When the vitreous pulls on the retina, it may rupture or break a blood vessel. This will result in bleeding into
the center of the eye, and is called a vitreous hemorrhage. It usually has the appearance of reddish or black cigarette
smoke, and it may seriously affect the vision. This blood almost always clears spontaneously within 1 to 3 months,
and surgical removal is rarely necessary. When a vitreous hemorrhage occurs as a result of a posterior vitreous
detachment, there is a higher risk of a retinal tear, and these eyes are evaluated very carefully until the blood clears. An
ultrasound test of the eye is performed, if the hemorrhage is too dense to permit examination of the retina.
Retinal Tear: When the vitreous separates or pulls away from the retina, there may be a small area where the
vitreous gel is particularly adherent to the retina. If the adhesion or stickiness between the retina and gel is very strong,
then something must give. In this case, it is always the retina since it is a delicate wallpaper. When the retina tears from
the vitreous traction, this can lead to a serious problem. The retina usually tears on the side of the eyeball, so vision is
not immediately affected. However, once the retina is torn, some of the liquefied vitreous may seep through the retinal
tear. Once this occurs and the vitreous fluid goes beneath the retina, a retinal detachment develops.
How Do We Treat a Posterior Vitreous Detachment?
Since a vitreous separation can create a retinal tear, followed by a retinal detachment, we take these very seriously.
It is the process of the vitreous separation that carries the risk of inducing a retinal tear. Once the vitreous has
completely separated, there is very little reason for concern. The process of vitreous separation usually occurs over a
period of 4 to 6 weeks, (although there are always exceptions where it may take months to years). Therefore, it is very
important to carefully evaluate the retina when the vitreous separation begins, and again, about a month later. The
examination technique requires the use of a headlight worn by your ophthalmologist, and the use of scleral depression.
Gentle pressure is applied to the eyelids so that the peripheral or side retina can be visualized. This is the area where
retinal tears are most frequently located. Occasionally, a special type of examination contact lens may be temporarily
applied to the eye after it is numbed with eyedrops.
As a rule-of-thumb, a retinal tear usually occurs within a month after the vitreous begins to separate. During this
time, it is very important for the patient to be aware of worsening floaters, increasing light flashes or a shadow or a
curtain in the vision. These are all signs that the retina may be detaching, and an emergency visit is essential. In most
cases, a vitreous separation is nothing more than a nuisance. Most people who are plagued by floaters will tell you that
they drive them crazy. They are only of medical importance during the first month after they are first noted. After a
period of time, the floaters usually shrink, and are less noticeable. Although floaters can be removed surgically, the risk
of such an operation certainly outweighs the benefits, and surgery would never be advised.
How Do You Treat a Retinal Tear?
A retinal tear is usually treated in the office with a laser. The laser is used to produce small "welds" around the
retinal tear. The entire procedure takes about 10 minutes. After a retinal tear has been sealed, retinal detachments can
usually be prevented. Alternatively, a freezing treatment (cryotherapy) of the retina can be performed. The outside of
the eye is numbed with medication. The tip of a small freezing pencil is applied to the surface of the eye for a few
seconds. The freezing treatment "irritates" the retina and makes it sticky, thereby sealing the retina.
Reference: University of Pittsburgh, Department of Ophthalmology (9/99)
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