Intravitreal Avastin Therapy for Macular Edema Caused by
Diabetic Retinopathy and Other Conditions
Avastin is the parent drug of Lucentis (both
made by Genentech), and both are commonly used to treat wet
age-related macular degeneration (AMD). They work by blocking
potent biochemicals that are part of the inflammatory process. They
slow and often stop the growth and leakage of abnormal blood
vessels.
Avastin can also be used in select
patients to treat macular edema caused by diabetic retinopathy,
cataract removal, inflammation within the eye, and other systemic
and retinal vascular conditions.
The vitreous is the transparent gel between the
lens and the retina that fills two-thirds of the volume of the eye.
The retina is the light-sensitive tissue lining
the back of the eye. The macula is the center of
the retina and provides the sharpest vision. Macular
Edema occurs when excess fluid accumulates within the
macula, causing swelling and decreasing vision.
Since October, 2005 I have used Avastin with much success for a
variety of conditions. Intravitreal Avastin is generally safer than
the intravitreal alternatives that were used previously.
A very small volume (0.05 ml.) of Avastin is injected into the
eye with a very tiny needle (under sterile conditions, using
topical and local anesthetic). Those who have had this injection
usually do not object to another, if needed at a future date. The
injection is minimally uncomfortable, typically with discomfort
lasting for just a few seconds. A series of at least three Avastin
injections may be required to get the desired response. The biggest
risk is failure of the Avastin to do all that is expected.
Complications such as infection, bleeding, cataract or retinal
detachment are fortunately rare.
Avastin use in the eye, like other drugs commonly used, is
presently "off-label", though approved by Medicare and most other
insurance carriers. Avastin is FDA approved to treat patients with
colon cancer, using frequent high-dose intravenous infusions. In
that cancer group there was a two-fold increase in the incidence of
heart attack and stroke, as well as increased rates of
hypertension. However, there have been no similar adverse events
reported attributable to intravitreal Avastin injections. The dose
used in the eye is approximately only 1/400 of the FDA approved
intravenous dose and most of that small dose is limited to the eye
itself. On-going monitoring and more experience may show some
systemic risk but, to date, the systemic risk is hypothetical.
Every treatment modality has its risks, benefits and
limitations. Extensive discussion with patients and their families
will be critical in selecting the most appropriate treatment for
each patient. If and when new and better therapies become
available, I will reassess each patient for the most beneficial
treatment option. Providing the best care possible for all of our
patients, and keeping them and their referring physicians informed
of new treatment options, is of the utmost importance to me.
David V. Poer, MD, FACS