What is Central Retinal Vein Occlusion (CRVO)?
The retina, which is the tissue that lines the
inside of the eye, is the sensory organ for vision. If the
eye were compared to a camera, the retina would be the "film"
where the picture is formed. Because the retina needs a lot
oxygen to function, significant blood circulation must be
present. Normally, blood flows into the retina through the
Central Retinal Artery (CRA) and leaves through the Central
Retinal Vein (CRV). Both of these blood vessels enter the
eye through the optic nerve.
Central Retinal Vein Occlusion (CRVO) is caused
by a blood clot in the CRV, which slows or stops blood from
leaving the retina. Although at first blood may continue
to enter the retina through the CRA, the blockage ultimately
stops blood circulation. As a result, blood and fluid are
backed up which causes retinal injury and loss of vision.
Over time as the retina becomes "ischemic" (which means
starved for oxygen-containing blood), the eye responds
to make new blood vessels. Unfortunately, these new blood
vessels can lead to severe complications, including retinal
detachment and neovascular glaucoma, both of which may
cause total blindness.
Patients with high blood pressure, diabetes, or
glaucoma are at increased risk for developing CRVO. One researcher
estimates that approximately 60,000 people develop CRVO each
year in the United States, making it one of the most common
vascular diseases of the retina.
Retinal Endovascular Surgery
(REVS) to Treat
CRVO used to be considered an "untreatable" disease
and the "standard of care" management was simple observation
with intervention only for complications (such as development
of neovascular glaucoma). Unfortunately, the majority of
eyes will not recover vision with this type of management,
and in the few eyes that do, the amount of vision recovered
is very small. The Central Vein Occlusion Study (CVOS) was
the largest study of CRVO and was funded by the National
Eye Institute of the National Institutes of Health. This
study showed that only 6% of eyes with CRVO recover at least
3 lines of vision (i.e., a 2-fold improvement, such as starting
at 20/400 and improving to 20/200) within 1 year. Therefore,
if vision is poor following CRVO, it is unlikely to get significantly
better without treatment.
Tissue plasminogen activator (t-PA) is a well-known
"clot busting" medication successfully used for
treating heart attack and stroke patients. Dr. Weiss developed
and the surgical technique that allows t-PA to be injected
directly into the branches of the CRV. The t-PA causes the
clot to dissolve which allows retinal blood circulation to
become more normal. This procedure is called "Retinal Endovascular Surgery" or REVS. REVS is performed in the operating
room on an outpatient basis and takes approximately 40 minutes.
ARE THE RESULTS
In January 1997, Dr. Weiss performed the first
REVS procedure on a patient with CRVO. Since that time
collected data on 150 consecutive patients with CRVO who
have had REVS as part of a clinical study approved by our
Institutional Review Board (which is monitored by the Food
and Drug Administration). Of the 150 eyes, 78 (52%) recovered at least 3 lines of vision, a rate that is over 8
times higher than what occurs with no intervention (6%).
Furthermore, while none
of the 150 eyes in the CVOS recovered at least 8 lines
of vision (such as 20/400 to 20/63) in the first year,
21 eyes (14%) recovered at least 8 lines of vision following
a more detailed description of the results, click here. Dr.
Weiss has performed REVS on over 450 patients. Following
REVS, many eyes made legally blind from CRVO recover enough
vision to read or drive a car!
REVS COMPARES TO OTHER
TREATMENTS FOR CRVO
Other treatments for CRVO include injection of
the steroid triamcinolone acetonide into the eye (intravitreal
triamcinolone acetonide injection, or IVTA) and radial optic
neurotomy (RON) in which a stab incision is made in the optic
nerve of the eye.
We often perform IVTA, which is a short procedure
that is performed in the office (while both REVS and RON
must be performed in the operating room). We have found IVTA
can be very beneficial in CRVOs in which retinal blood circulation
is relatively good, but it often fails when blood circulation
is poor. However, even when IVTA fails, we can usually perform
REVS and get good results.
RON is also employed to treat CRVO, and many eyes
recover vision following the procedure. However, we believe
visual recovery may be better following REVS, IVTA, or a
combination of REVS and IVTA. Visual recovery in CRVO seems
to occur more frequently and to be of larger magnitude following
REVS than following RON (see table below).
(n = 111)
(n = 93)
(n = 42)
(n = 150)
The table shows a higher percentage of eyes recover
vision following REVS compared to following RON. Furthermore,
more eyes experience large magnitude visual recovery following
REVS; nearly twice as many eyes recover at least 6 lines
of vision (such as 20/200 to 20/50) following REVS compared
to following RON. Finally, the results following REVS and
IVTA are achieved without cutting into the optic nerve, a
maneuver whose long-term effects we don’t know. Therefore,
our preference is to offer IVTA, REVS, or REVS/IVTA instead
of central retinal vein occlusion by injection of tissue
plasminogen activator into retinal vein. Am.J. Ophthalmol.126:142-144,1998.
surgery for treatment of central retinal vein occlusion.
Ophthalmic Surgery and Lasers. 31(2):162-165, 2000.
||Weiss JN, Bynoe LA, Injection
of tissue plasminogen activator into a retinal vein in
patients with central retinal vein occlusion. Ophthalmology.
Bynoe LA, Weiss JN, Retinal
endovascular surgery and intravitreal triamcinolone
acetonide for central vein occlusion in young adults.
Am. J. Ophthalmol. 135;382-384, 2001.
Weiss JN, Bynoe LA. Injection
of tissue plasminogen activator into a retinal vein
in patients with central and hemispheric retinal vein
occlusions. Invest Ophthalmol Vis Sci(Supp). 2001;
Weiss JN, Bynoe LA. Central
retinal vein cannulation with retinal vein t-PA injection
for central and hemispheric vein occlusion: our four
year experience. Retina 2001: A Retina Odyssey.
Bynoe LA, Weiss JN. Retinal vascular
tissue plasminogen activator injection for anterior
ischemic optic neuropathy. Invest. Ophthalmol Vis Sci(Supp).
Weiss JN, Bynoe LA. Retinal
endovascular surgery for central and hemispheric retinal
vein occlusion. Contemporary Ophthalmology 2003;2(13):1-8.
Bynoe LA, Lazarus HS, Hutchins RK, Friedberg
MA. Retinal endovascular surgery for central
vein occlusion; Initial experience of 4 surgeons.
Retina 25(5):625-632, July/August 2005.
DO YOU WANT TO HELP? Click
FOR MORE INFORMATION
*Telephone the Retina Associates of South Florida Monday
through Friday from 9AM - 4PM EST, at 954-975-0044 and ask for
Mr. Anthony Lobacz, the CRVO Study Coordinator.
*In order for you to avoid unnecessary travel time and costs,
the Retina Associates of South Florida will review your ophthalmic
records at no charge to determine if you would be a candidate
for the procedure. For those patients traveling from outside
Florida, our office will assist you in making the travel arrangements.