The eye is by far the most complex electrical organ in the body with over a billion highly specialized circuits. These circuits are linked to millions more in the
optic nerve tracts leading to the brain centers that process and interpret the data transmitted, transforming it into the rich sensory tapestry we experience as vision.Most of the eye's electrical complexity is found
in the retina - an extraordinary photosensitive array of cells lining the back of the eye that transforms light into electrical signals. The most concentrated collection of cells including those that enable critical
color and detail vision are found in the bull's eye center zone of the retina in an area known by the geographic term - the macula.
Macular degeneration is the imprecise historical name given to that group of diseases
that cause sight sensing cells in the macular zone of the retina to malfunction or lose function and results in debilitating loss of vital central or detail vision. Because the brain cleverly learns to compensate and
fill in the missing part of the picture in early cases with spotty macular cell damage or dysfunction, most patients only present to their ophthalmologists when disease is fairly advanced. Compared to its huge
prevalence in the population at large, research into its cause and cure are inappropriately small, both by the Federal government, public and private institutions. Despite years of promises the National Eye Institute, a
division of the National Institutes of Health, still allocates less than 5% of its entire eye research budget to macular degeneration despite the fact that it is the most common cause of legal blindness in the US.
It
is in this setting that the challenge has been taken up by the committed all-volunteer Macular Degeneration Foundation (MDF) to lead in formulation, fund raising and management of research for real solutions to this
emerging national epidemic.
Rationale: The Beauty of Going Back to Basics - Realizing the Promise of Electrophysiology Research and Therapy. One of the most promising areas for progress towards solutions is via
exploration of how the eye's electrical function is affected by macular degeneration. Strangely, the Macular Degeneration Foundation has discovered that despite the pivotal role played by electrical events in the
process of enabling our sight, visual electrophysiology - the vital field of direct study of the electrical function and dysfunction of the human visual system, is like a malnourished orphan infant.
Why? First, there
is a de facto shortage of researchers in this area due to a historical lack of direct research support. Second, alternate sources of support such as insurance coverage for diagnostic testing of visual electrical
function or electrophysiology testing is difficult to secure. Specifically, the absence of any efficacious therapeutic intervention for diagnosed dysfunction has allowed most health insurance plans to deny coverage for
electrophysiologic testing of the macula. Their argument: Why test when you can't treat?
As a result, electrophysiologic testing of the macula to map areas of dysfunction is currently restricted to a few major
academic medical centers where it is usually heavily cross-subsidized by other common eye tests and procedures. However, in this era of aggressive managed care scrutiny of all medical care expenses this kind of indirect
support is rapidly evaporating, and along with it the hope and promise of breakthrough developments that could restore central sight to millions of affected Americans and prevent millions from losing it.
The result is
that this potentially key field of research into the cause and potential treatment of macular degeneration has languished.
Why does macular electrophysiology
research hold so much promise?
There is formidable precedent in another field of medicine for significant therapeutic benefit to flow from discoveries in this arena. Consider the heart. Compared to the eye, the heart is a relatively
primitive organ - a pump with an electrical circuit linking its four chambers. The electrical impulses flowing through the circuits tell the chambers when and how hard to pump to ensure that blood flows synchronously in
one direction. When the electrical circuits are faulty, either due to defective genes or acquired disease, the pump can malfunction with potentially fatal consequences. Until the development of the discipline of cardiac
electrophysiology testing, there were only imprecise ways to find and treat the exact location of the faulty circuit.
Today thanks to dedicated funding support the mature discipline of cardiac
electrophysiology provides the means for cardiologists to correct specific faulty circuitry directly by specialized electrical stimulation (pacemakers) or surgery to the circuit itself. Millions of people are alive and
active, thanks to the dedication and perseverance of supported electrophysiologists who developed their discipline into the modality of choice for the diagnosis and then treatment of specific heart electrical
disturbances in a targeted and cost effective way.
The Implications for Visual Electrophysiology
Research - Pursuing the Promise of Progress.
So, what are the visual
electrophysiology tests and how might we use them in the search for real solutions to the puzzle of macular dysfunction and degeneration? The present small pool of visual electrophysiologists use a variety of tests for
retinal and macular function testing. These include:
The electroretinogram (like the electrocardiogram for the heart) which tests overall retinal function.
The multifocal electroretinogram
which is a more specialized variant of the classic electroretinogram that can be used to specifically test macular function.
Other electrophysiological tests that have utility for other eye diseases may,
with further research, development and testing, prove useful for testing for retinal pigment epithelial (RPE) dysfunction. The retinal pigment epithelium is a vital foundation layer of cells that structurally and
functionally supports the delicate macular vision sensing cells.The RPE is the all-important conduit for the transport of oxygen and vital nutrients to hungry macular cells and the removal of waste products from them.
Research has shown that macular cells are among the most metabolically active cells in the human body. Consequently they are also some of the hungriest. They have a constant requirement for high amounts of
oxygen and other nutrients. Understandably they generate large amounts of waste products of metabolism too.
The RPE functions as a sponge-like service station for all macular cells, fueling them with fresh
oxygen and other nutrients while mopping up the considerable wastes emitted by the turbocharged sight sensing engine that is the macular constellation of cells. Today there is a growing body of scientific evidence that
RPE malfunction adversely affects macular cells and could lead to macular degeneration.
However, unlike in cardiac electrophysiology, there have been no potentially efficacious therapies that can be offered
patients once retinal and/or macular dysfunction is discovered using these diagnostic electrophysiology tests. Until now!.
The MDF has determined in preliminary uncontrolled trials by pioneering
ophthalmologist/researchers that a painless form of microcurrent stimulation (MCS) of the eye can improve visual acuity, sharpness and color perception in 68 percent of patients with dry macular degeneration and in 58
percent of those with the wet form. Anecdotal reports from Russia suggest similar benefits.
Microcurrent stimulation is currently administered by ophthalmologists consistent with approved off-label
experimental policy using a variety of modified devices that are FDA approved for the physician-only supervised treatment of chronic back pain, muscular sports injuries and by plastic surgeons to promote certain types
of wound healing.
How might MCS be working?
One of several hypotheses we plan to test using electrophysiological approaches is that MCS may improve RPE efficiency and thereby may
restore and/or improve macular cell function. If our theory is correct this improvement in macular function should be measurable using focal electroretinograms and other electrophysiologic tests under development.
Good science that benefits all dictates that formal confirmatory controlled clinical trials of this phenomenon be performed in independent clinical settings around the US before MCS can be endorsed as
efficacious.
It is critically important that pre-treatment and post-treatment macular electrophysiological studies be performed on each and every patient. This will enable objective documentation of any
improvement in macular function that correlates with clinical improvement measured using standard visual acuity testing. The test panel will include focal electroretinograms (ERG's).
Second, when and if a
therapeutic benefit is confirmed, further studies need to be conducted to establish the optimal dose-effect curve. For patient safety, strict surveillance for any and all side effects of therapy needs to be undertaken.
When and if MCS is confirmed as safe and efficacious a concerted education program has to be implemented to reach and teach the public and professionals alike. So, what do we have to do to rescue the
starving orphan electrophysiology baby and nourish it so that it can rapidly grow to become a David capable of defeating macular degeneration - the ruthless Goliath that destroys most Americans' central vision?
