Treatment for Proliferative Diabetic Retinopathy

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Treatment for Proliferative Diabetic Retinopathy

VEGF causes proliferative diabetic retinopathyPatients with proliferative diabetic retinopathy can be treated with laser photocoagulation and/or Avastin.  Proliferative diabetic retinopathy, or PDR, is  a specific stage of diabetic retinopathy which may lead to blindness if left untreated.

While most patients (if not all) develop some degree of diabetic retinopathy, most patients will not progress to the proliferative stage.

“Proliferative” Means Growth of Abnormal Blood Vessels

Diabetes is a disease which affects blood vessels.  The retina may lose blood supply resulting in “retinal ischemia,” a condition where insufficient oxygen gets to the tissues (“angina” is another ischemic condition, chest pain develops due to lack of oxygen).

In response to chronic ischemia (poor oxygenation), the eye secretes VEGF (vascular endothelial growth factor).  VEGF acts as a fertilizer to grow abnormal vessels somewhere in the eye.  These abnormal vessels are called neovascularization.

Neovascular tissue may cause a diabetic retinal detachment or neovascular glaucoma.  Either can blind.

Treatments Neutralize VEGF

Avastin, a common anti-VEGF, when used in the eye, can treat wet macular degeneration and macular edema.  Over the last few years, Avastin has also been used to chemically treat PDR.

Avastin works by chemically neutralizing VEGF circulating in the eye.

Laser treatment, called pan-retinal photocoagulation (PRP), indirectly reduces VEGF by killing retinal cells.  By reducing the number of retinal cells (we don’t really need them for vision by the way), the overall demand for oxygen is reduced.  At some point, the reduced oxygen supply becomes adequate and VEGF is no longer produced.

Avastin is Only Temporary Treatment

Avastin, in my opinion and experience, is a quick and immediate treatment for PDR.  It needs to be repeated as it does not fix the actual problem…the ischemia.

I have found that repeating the injections every 90 days or so can keep the neovascularization under control.

PRP, the laser photocoagulation, is a more permanent therapy as it remedies the actual problem…it cures the relative ischemia.  Ischemia is inadequate supply of blood flow/oxygen.  While the laser does not improve supply, it reduces demand and cures the oxygen problem.

What Does this Mean?

I don’t really know how long laser treatment takes to work on patients.  There are several reasons why PRP is not immediately effective; severity of disease, amount of laser, etc.

Avastin works almost immediately and usually within 24-48 hours.  It gives me a great clue as to the likely success of the eventual PRP.

I can often “stop” the disease with the Avastin and perform the more curative treatment at a later date.

 

6 Comments

  1. Ankit Gupta says:

    Sir, I have complemetry problem multiple spots on retina in my eyes, i am getting my treatment from AIIMS, New Delhi but there is no improve in my eyes. that means i am going to towords blindness.as i read from your site. please sir tell me advice what should i do

    Date 9/10/2012 Mob no 08899564416
    place moradabad
    country India
    state uttar pradesh

  2. Sawsan says:

    Dear Dr,
    If we need to supply the retina with blood, than why we need anti- VEGF? As far as I know Anti VEGF can inhibit the blood formation.
    What if we can find some compound with pro angiogenesis properties so that to supply the retina with oxygen through the formation of blood vessel?

  3. C.M. Krauss says:

    Dr Wong: I have been receiving treatment for PDR for two years. In that time I have had several laser sessions in both eyes, one vitrectomy to clean out a vitreous hemorrhage, and shots of Avastin every 90 days for two years. One eye has been deemed stable, but that’s because the retina specialist I see lasered away pretty much all of my peripheral vision. I only have central vision in my left eye. My right eye still has pretty much full vision. My doctor says he is reluctant to do much more lasering because he doesn’t want to take away any more of my vision. It’s in my right eye that I have been having all the Avastin shots. I have two questions. First, can Avastin be given every 90 days indefinitely? Is there any long-term risk associated with it? The second question is, my doctor believes he will get my right eye stabliized at some point, can this happen with Avastin or is the laser the only way to do it Again, my left eye is considered to be stable but I only have central vision. I would hate to lose all my peripheral vision in the other eye too. I am still trying to work, drive and live a normal life. I feel like only having central vision in both eyes would be the end of all that.

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