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 of 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 by trying 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  

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 the instruments 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.

In January 1997, Dr. Weiss performed the first REVS procedure on a patient with CRVO. Since that time we’ve 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 REVS. For 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!  

HOW 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).

Acuity (lines)	RON (n = 111)	REVS alone, < 20/200 (n = 93)	REVS/IVTA (n = 42)	REVS (all) (n = 150)
> 8	Not reported	14%(13)	19%(8)	14%(21)
> 6	13%(14)	24%(22)	42%(18)	27%(41)
> 4	24%(27)	33%(31)	59%(25)	39%(58)
> 3	41%(45)	50%(47)	64%(27)	52%(78)

     
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 RON.

DO YOU WANT TO HELP? Click here.

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.