The Retina:
The M.D.s at Sierra Eye Associates are trained in
recognizing and treating patients with Diabetic
Retinopathy and Macular Degeneration. We have three fellowship trained vitreo-retinal specialist, Dr's Khanani, Durant and Cecchi. We treat all aspects of retinal diseases including diabetic retinopathy, macular degeneration, retinal detachment, macular holes, macular puckers, uveitis and pediatric retinal surgery. We offer all current treatments for vitreous diseases including intravitreal injection of Lucentis, Avastin, as well as small gauge, suture less retina surgery under local anesthesia. Our office also provides the most advanced imaging equipment including the Heidelberg Spectralis OCT.
DIABETIC RETINOPATHY
Diabetes mellitus is a condition that can have an effect on the
small blood vessels of the body. One location of such small blood vessels
is the retina in the eye. When the retinal blood vessels are affected,
this is a condition called diabetic retinopathy.
Diabetic retinopathy development increases with the duration of
the diabetes. It is unusual to see clinical signs of diabetic retinopathy
prior to ten years after the onset of the disease. Diabetic retinopathy
can progress with time, and has become the leading cause of legal blindness in
working-aged adults. Our knowledge of treatment of diabetic retinopathy
has increased over the last several years and blindness due to diabetes is
becoming less frequent. In addition to treatment of the retina directly,
recent studies have shown that strict blood sugar control can decrease the onset
and progression of diabetic retinopathy.
Clinically, diabetic retinopathy is divided into two broad
categories, non-proliferative and proliferative retinopathy.
Non-proliferative diabetic retinopathy is caused by
damage to the walls of the normally present retinal blood vessels. The
damage to the walls of the vessels results in leakage of blood and fluid from
the small blood vessels. This leakage can result in swelling of the
retina, like a sponge taking up water. If the swelling involves the macula
(center of the vision) then vision is affected. Fatty material (lipid) can
leak from blood vessels and can result in more permanent loss of vision. More
severe damage to the retinal blood vessels can result in closure of vessels and
decreased blood flow to areas of the retina. If this loss of blood flow
and nutrition involves the center of the vision, significant loss of vision can
result.
Proliferative diabetic retinopathy results when there is
the development of abnormal ("neovascular") blood vessels in addition
to the normally present retinal blood vessels. Neovascularization results
from the vascular damage resulting in lack of blood flow and nutrition to large
areas of the retina. The retina becomes "starved" for oxygen,
and a chemical signal is sent from damaged retina to induce the body to grow new
blood vessels. This is the body's response to provide more oxygen to those
areas, but the new blood vessels are fragile and grow from the surface of the
retina into the vitreous "jelly" in the center of the eye. The
movement of the vitreous "jelly" and the new blood vessels can result
in rupture of the fragile vessels, resulting in bleeding into the center of the
eye. With time, the abnormal blood vessels can scar over, contract, and
pull on the surface of the retina. This pulling can cause the retina to
come away from the back of the eye (retinal detachment) and can result in
permanent blindness.
Treatment of diabetic retinopathy consists of in-office laser
photocoagulation and/or a surgical procedure known as vitrectomy. We also offer all current treatments for diabetic retinopathy including intravitreal injection of Avastin, steroid, as well as small gauge, suture less retina surgery under local anesthesia.
Laser photocoagulation can be used to achieve one of two goals.
Laser can either cauterize blood vessels that are leaking to stop leakage or it
can destroy damaged retinal tissue by creating scarring.
In non-proliferative diabetic retinopathy, vision loss can be
caused by leakage from retinal blood vessels. Laser is applied to the
areas of leakage to try to decrease leakage and allow the body to reabsorb
leaked material. The laser is often guided by a photograph test known as fluorescein
angiography. This test is performed in the office by injecting an
intravenous fluorescein dye while photos are taken of the dye circulation
through the retina. The risk of significant visual loss can be reduced by
the use of laser in non-proliferative diabetic retinopathy.
In proliferative diabetic retinopathy, new, abnormal, blood
vessel growth develops due to damaged retina that sends out chemical signals.
Laser in this situation is applied to try to ablate damaged retina by creating
scarring. If damaged retina is destroyed, new blood vessel growth will
regress. This ablation of damaged retina requires the application of many
(often more than 1000) laser burns to the peripheral retina. This may be
done in one or multiple sessions, and can be done with or without anesthetic
injection around the eye.
Significant visual loss can be reduced by up to 66% with the use
of laser in proliferative diabetic retinopathy. There can be side effects
of this more intense laser treatment, such as decreased night vision, decreased
peripheral vision, and blurring of central vision.
Vitrectomy surgery is indicated when there is bleeding into the
center of the eye that persists and cannot be treated with laser. At
times, scar tissue formation from abnormal blood vessel growth can cause pulling
on the retina and retinal detachment. Vitrectomy surgery is microscopic
surgery with small instrumentation that is used to remove vitreous, blood, and
certain scar tissue. Damage that results in the need for vitrectomy
surgery is often advanced, and the goals of surgery are often to regain
ambulating vision, but not particularly reading vision.
In summary, vision can often be maintained in diabetes.
Strict blood sugar control and regular examinations for early detection are
critical elements in maintaining as much vision as possible. The incidence
of diabetic retinopathy goes up after 10 years of diabetes, and the frequency of
examination will be determined by your eye specialist. Very close
monitoring of diabetic retinopathy is necessary during pregnancy, as progression
can occur. If changes of diabetic retinopathy threaten visual loss, laser
photocoagulation should be considered. We often can maintain vision at a
certain level, but regaining vision lost is usually not possible.
MACULAR DEGENERATION
Age Related Macular Degeneration (ARMD) is a disease that
affects the retina of the eye. This condition is probably hereditary in
nature, but the only known association is advancing age. The retina is the
inner lining of the back of the eye, like the inside of the wall of a
basketball. The retina works like film in a camera. The central part
of the vision, that part used for reading, is served by a portion of the retina
called the macula. This is the area involved in ARMD.
The earliest sign seen in ARMD is the presence of yellow
deposits below the retina, called drusen. This indicates a
"tendency" toward ARMD, but typically does not cause significant loss
of vision. ARMD may progress in those eyes with drusen, and therefore
regular observation for the signs of ARMD is indicated.
ARMD is clinically divided into two types. These vary in
time course of vision loss, symptoms, and options for treatment.
Dry Macular Degeneration is a type where there is gradual
degeneration of the cells associated with the central vision. The major
symptom is usually gradual onset of increased difficulty with reading and
central vision. This may occur over many years. Loss of vision can
vary from mild to severe central vision loss. No specific treatment for
this condition is known. There has been a lot of "talk" about
the role of vitamins in ARMD, but scientific evidence is lacking. Those
proponents of vitamins feel that vitamin use may help to keep the affected
cells more healthy and slow down the degeneration of those cells.
Wet Macular Degeneration is a type where leakage develops
under the macula. Leakage may be associated with abnormal blood vessels
called Choroidal Neovascularization. If leakage is not associated
with choroidal neovascularization, then typically a blister of fluid develops,
and this may remain the same or slowly become larger. This can cause
distortion and/or blurring of the central vision. If no choroidal
neovascularization is present, then the situation is observed only, and the
blister can collapse over time.
If choroidal neovascularization is present, the abnormal blood
vessels are often fragile and leaky. This can result in fluid leakage or
bleeding. Such changes often cause distortion, "missing areas"
and blurring of the central vision. The onset of these changes can
literally be over a matter of hours. We offer all current treatments for wet age related macular degeneration including intravitreal injection of Lucentis and Avastin.
Fluorescein Angiography is a test performed in the office
to identify if macular degeneration is of the wet or dry type, and to determine
if choroidal neovascularization is present. This involves injection of a
fluorescein dye into a vein and taking pictures of the retina with a special
fluorescein camera to track the flow of fluorescein through the blood vessels.
Management of patients with ARMD varies according to the
type of ARMD, stage of the disease, and the treatment that may have been
indicated. All patients with ARMD should check their own vision every day
for any change such as decreased vision, new distortion or new missing areas.
Patients are typically scheduled for regular follow-up visits to determine if
there is progression, but since dry ARMD can change to wet ARMD at any time it
is important that you let us know if there are new changes so we can evaluate
you sooner than the scheduled follow-up visit.
ARMD is a disease that affects both eyes. One eye may have
much more involvement than the other. In a patient who has had significant
changes in one eye, the other eye is at somewhat more of a risk of having
similar changes. Both eyes are evaluated at follow-up visits, and changes
in either eye may be important.
One concern of many patients is the fear of total blindness.
Fortunately, ARMD does not cause total blindness and even with total loss of
central vision there is still usable peripheral vision.
Please call (775) 329-0286 if you would like
to schedule an appointment.
