The treatment of wet age-related macular degeneration (AMD) has – by all accounts – been revolutionized by the successful use of the injectable drugs Eylea, Lucentis, and Avastin.
Yet, despite this treatment revolution, significant questions remain about the most effective dosing schedule for these medications: Is it monthly injections, a pro re nata [i.e., “as needed”] (PRN) regimen, or a combination approach that includes monthly controls and injections for recurrent or persistent macular bleeding?
At the 2014 Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO), researchers attempted to answer this critically important question. They concluded that eyes treated with Lucentis with a “treat and extend” regimen (described below) had (a) a better visual outcome and (b) fewer fluctuations between best and worst visual acuity, compared with an “as needed” (PRN) treatment regimen.
ARVO is an international organization that encourages and assists research, training, publication, and dissemination of knowledge in vision and ophthalmology, including low vision.
About the Research
The poster presentation at the ARVO annual meeting, entitled Treat and Extend regimen versus Pro Re Nata regimen in a comparative study of ranibizumab [i.e., Lucentis] in exudative [i.e., wet] age-related macular degeneration: 12 months results was authored by Katja B. Hatz and Christian Pruente from VISTA Klinik, Binningen, Switzerland and Kantonsspital, Liestal, Switzerland.
About Wet Age-Related Macular Degeneration (AMD)
In wet, or exudative, macular degeneration (AMD), the choroid (a part of the eye containing blood vessels that nourish the retina) begins to sprout abnormal new blood vessels that develop into a cluster under the macula, called choroidal neovascularization or CNV (neo = new; vascular = blood vessels).
The macula is the part of the retina that provides the clearest central vision. Because these new blood vessels are abnormal, they tend to break, bleed, and leak fluid under the macula, causing it to lift up and pull away from its base. This damages the fragile photoreceptor cells, which sense and receive light, resulting in a rapid and severe loss of central vision.
Anti-Angiogenic Drugs and Anti-VEGF Treatments
Angiogenesis is a term used to describe the growth of new blood vessels and plays a crucial role in the normal development of body organs and tissue. Sometimes, however, excessive and abnormal blood vessel development can occur in diseases such as cancer (tumor growth) and AMD (retinal and macular bleeding).
Substances that stop the growth of these excessive blood vessels are called anti-angiogenic (anti=against; angio=vessel; genic=development), and anti-neovascular (anti=against; neo=new; vascular=blood vessels).
The focus of current anti-angiogenic drug treatments for wet AMD is to reduce the level of a particular protein (vascular endothelial growth factor, or VEGF) that stimulates abnormal blood vessel growth in the retina and macula; thus, these drugs are classified as anti-VEGF treatments and include Lucentis, Eylea, and Avastin. They are administered by injection directly into the eye after the surface has been numbed.
More about the Research
The purpose of the study was to compare the Pro Re Nata (PRN) regimen and the Treat and Extend (TE) regimen in Lucentis treatment of wet AMD:
- The Pro Re Nata (PRN or “as needed”) regimen was based on monthly optical coherence tomography (OCT) evaluation; retreatment was applied in case of reoccurrence of retinal bleeding or fluid accumulation. OCT is a newer, non-invasive technique that produces a high-resolution image of the layers of the retina.
- The Treat and Extend (TE) regimen was based on treatment intervals that were sequentially lengthened by two weeks, starting at four weeks, until signs of abnormal new blood vessel growth (choroidal neovascularization or CNV) recurred.
From the presentation abstract:
Methods: Data of 140 eyes with treatment-naïve wet AMD were analyzed retrospectively: Two groups of 70 consecutive patients each were treated with [Lucentis] following either the TE or the PRN regimen. [Note: A person is considered to be treatment naïve if he or she has never undergone treatment for a particular illness or disorder.]
We compared the mean gains in best-corrected visual acuity (VA) as well as the mean oscillation in VA [i.e., fluctuations between best and worst VA] and the mean numbers of injections and [doctor] visits.
Results: Both groups were well balanced for baseline characteristics like mean age (79 vs. 79 years) and baseline VA.
At 12 months, the mean gain in VA was significantly greater in the Treat and Extend (TE) group than in the Pro Re Nata (PRN or “as needed”) group and VA [fluctuation] was significantly lower for the TE eyes within the intervals 0-6 months and 6-12 months.
The eyes in the TE group received significantly more injections during the 12 months follow-up, while the number of follow-up visits attended was higher in the PRN group. At 12 months, the mean maximum recurrence-free interval in the TE group was 8.8 weeks plus or minus 2.9 weeks.
Conclusions: Eyes treated according to the TE regimen had a better visual outcome and fewer VA fluctuations compared to PRN treated eyes. They received more injections but with fewer follow-up visits.
VisionAware will provide updates on this important research as they become available.
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