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Laser Treatment for Wet ARMD
The Laser Controversy
Laser photocoagulation has been shown to prolong visual function by
sealing leaky blood vessels. But in many cases, vision worsens after
treatment or improves only for a short time. As one retina specialist said,
"It gives patients poor vision to keep them from getting terrible
vision." Patients should understand beforehand that in addition to
destroying the unwanted blood vessels, the laser beam also burns out the
photoreceptors lying above them. It creates an area of depressed vision
called a scotoma, Without treatment, some patients central vision is
destroyed almost overnight. Which is the lesser of two evils? Because of the
difficult choices involved, consultation among the patient, the eye
care provider and the retinal specialist needs to be clear and complete.
The decision is a difficult one. The Macular Study Group, made up of 15
centers in the U.S., produced guidelines that predict what the outcome
will be for the first year post-surgery and for the years after that. Their
study concluded that some vision loss always occurs as a result of the
treatment. But for some people, this loss was less than it would have been
had the disease progressed unchecked. In general, after 18 months, vision in
the treated and untreated eyes was about the same. However, in some cases,
the treatment may have reduced or halted the deterioration.
Inhibitors for Macular Degeneration
Angiogenesis is the formation or growth of new blood vessels. In the most
severe form of age-related macular degeneration (known as "wet"
ARMD) abnormal angiogenesis occurs under the retina resulting in
irreversible loss of vision. The loss of vision is due to scarring of the
retina secondary to the bleeding from the new blood vessels. Only 10% of
patients with age-related macular degeneration will grow abnormal blood
vessels under their retinas and thus progress from the "dry" form
to the "wet" form of ARMD.
treatments for "wet" ARMD utilize laser based therapy to destroy
offending blood vessels. However, this treatment is not optimal since the
laser can permanently scar the overlying retina and the offending blood
vessels often regrow. Recently, new trials have begun to investigate if
angiogenesis inhibitors can effectively inhibit the growth of new vessels in
age-related macular degeneration. The following is a list of companies with
angiogenesis inhibitors in clinical trials:
Anecortave acetate given by periocular injection.
2) Agouron: Prinomastat given orally.
3) Genentech: Anti-VEGF antibody given by intravitreal injection.
4) NeXstar/EyeTech: Anti-VEGF aptamer (NX-1838) given by intravitreal
Thermotherapy (TTT) Photocoagulation
thermotherapy (TTT) photocoagulation is a method of delivering heat to the
back of the patient's eye using an 810 nm infrared laser (IRIS Medical
OcuLight SLx). This creates a localized hyperthermia, a natural healing
mechanism, which results in closure of choroidal vessels. TTT is commonly
used worldwide as an effective treatment for ocular tumors such as
retinoblastoma and choroidal melanoma.
Preliminary results of TTT
treatment in subfoveal occult choroidal neovascularization (CNV) in
age-related macular degeneration (AMD), have shown to reduce subretinal
fluid in about 90% of cases and stabilize or improve vision in about 75% of
cases without the substantial side effects of laser photocoagulation
performed at conventional settings.
The study titled
"Transpupillary Thermotherapy (TTT) Of Occult Subfoveal Choroidal
Neovascular Membranes (CNV) In Patients With Age-Related Macular
Degeneration" (shortened to TTT4CNV) is a prospective, randomized,
sham-controlled, multi-center clinical trial intended to ultimately
determine the effectiveness of TTT in the treatment of occult CNV caused by
AMD when compared to no treatment.
is a new surgical technique designed to move the area of the retina
responsible for fine vision (macula) away from the diseased underlying
layers (the retinal pigment epithelium and choroid). The macula is moved to
an area where these underlying tissues are healthier. Consequently, safe
treatment of the sick blood vessels [choroidal neovascularization (CNV)]
with, for example, laser treatment can be performed without harming central
Two Surgical techniques
In the first technique, the entire retina is cut 360 degrees around the
periphery. It remains attached to the optic nerve at the back of the eye.
Then, like an umbrella, the whole retina is rotated around the optic nerve
and the macula becomes repositioned. The abnormal blood vessels once under
the fovea are now outside of the center of vision and can be treated.
In the second technique, no large retinal cuts or rotations are needed.
Instead, the outer part of the eye-wall (the sclera) is shortened with
sutures (stitches). This results in there being more retina than its
underlying eye-wall. That is, when you look into the eye, the retina is
wrinkled and folded. Then the surgeon flattens the retina over the shortened
eye-wall, causing the macular retina to move away from the optic nerve
toward the periphery. As with the first technique, the central macula has
been moved. The abnormal blood vessels once under the fovea are now outside
of the center of vision and can be treated.
Possible complications of these techniques are retinal tears, retinal
detachment, intraocular bleeding, infection and cataract formation. After
surgery the abnormal vessels can re-grow and new subretinal
neovascularization can develop. Most patients do not develop these
Macular translocation has been shown beneficial in a few series of patients
(phase-I studies), showing improvement of visual acuity in 30-40%, and
stabilization of visual acuity in 15-30%. Controlled studies comparing this
surgery to the natural course of the disease or to laser and photodynamic
treatments are needed.
Macular translocation is a new and possibly helpful method in treating
patients with subfoveal CNV with a unique potential to improve visual
acuity. Randomized controlled (statistically significant) clinical studies
are needed to evaluate the effectiveness and safety of macular translocation
for treating visual loss from AMD and to compare it to other techniques.
Retinal Transplants and Implants
this office has received a number of inquiries from people who listened to a
brief broadcast news report about retinal transplants. Apparently , the
newscast gave many people the impression that a new way to restore lost or
impaired vision was about to become available. The purpose of this report is
to respond to those inquiries.
Some researchers do indeed think that it may one day be possible to restore
some degree of vision to people with damaged or malfunctioning retinas, by
placing in their eyes either retinal transplants or retinal implants.
What is a retinal transplant?
A retinal transplant is a graft of "good" retina tissue onto a
non-working retina. The retinal transplant tissue might originate from
another human, perhaps just deceased, or an aborted fetus. Less likely
origins of the tissue to be transplanted are human retina tissue which has
proliferated in culture; or retina tissue from another animal species.
In order for a retinal transplant to work, several technologies which do not
yet exist have to be developed:
1.The cells in the transplant must stay alive for a long time, preferably
for the life of the recipient.
2.Those cells must have, and maintain, the light-sensing activities of
normal, healthy retina cells.
3.Those cells must transmit electric or electrochemical signals to the
brain, which the brain can interpret as the experience of vision.
A handful of laboratories are currently trying to develop retinal transplant
technology, or are doing the research on which such technology might
eventually be based (see links at the end of this page). Ophthalmic surgeons
are still at the stage of testing techniques for placing transplants in the
retina. Methods for getting retinal transplants to stay healthy will most
likely get worked out first in an animal species other than humans. Some
neuroscientists are trying to find conditions under which retinal tissue
such as what might be used in a transplant, will produce an electrical
signal. The hope of some researchers is that if the transplant produces a
2-dimensional pattern of electrical signals in response to light, e.g. in
the shape of an alphabetical character projected onto the transplant, the
underlying retina which is not light-responsive will still be able to pick
up the signal pattern from the transplant and transmit it to the brain.
This research and development path is "high risk", meaning that it
is full of pitfalls, with a high probability that the goal may not be
What is a retinal implant?
A retinal implant is a
prosthetic retina, i.e. a manmade device designed to approximately do the
job of the retina.
The concept currently being explored, principally in an overly publicized
joint project of MIT & Harvard, but also in a project in Germany, is to
develop a light-sensitive diode array which can be mounted on the retina.
The person with the implant would wear on the head a miniature electronic
camera mounted in a unit resembling glasses. The image formed in the camera
would be transferred to the diode array implanted on the retina. The diode
array would produce a two-dimensional pattern of electrical signals, which
it is again hoped would be picked up by the underlying malfunctioning
retina, and transmitted to the brain for interpretation as vision.
This type of research is at an early stage: learning
how to get electric signals from implants in an animal model, the eye of the
There is a related field called computer vision, which is concerned with
developing electronic devices which approximate the light-responsive
behavior of a retina. These silicon retinas can be used to give robots the
ability to see. It is likely that much of prosthetic retina technology will
come from that field. However, the major uncertainty again is: how to
transmit a signal from the prosthetic retina to the brain which the brain
can interpret as vision?
The path to a successful retinal implant device is high risk, like the path
to a successful retinal transplant technique. It will be many years before
we know if either path has been traversed successfully to its goal.
Regeneration of Retinal Cells
Up untill now, macular degeneration has stubbornly
resisted attempts to reverse its inexorable course. Sufferers are routinely
told that nothing can be done and that they should resign themselves to a
life restricted by fading central vision and low vision aids.
All that has now changed. Fascinating new research
reported May 4, 2000 at the Annual Meeting of the Association for Research
in Vision and Ophthalmology revealed remarkable progress made towards
detecting and deploying resting omnipotent cells in the eye and other
The hope: to harvest resting omnipotent cells hiding
in various sites in your body and inject them into diseased macular sites.
These cells are then woken up, allowing them to grow and replace defective,
dying or dead cells with new, vital and healthy ones.
A slew of papers were presented documenting the
discovery of so-called totipotential cells - cells that have the ability to
turn themselves into any other specialized cell that they choose to.
Specifically, scientists discussed the use of neural
stem cells that proceed fully developed nerves and brain tissue. They
injected these into the space beneath rat retinas and were able to stimulate
them to grow into macular light sensing cells or photoreceptors after
stressing these cells by reducing the blood supply to the retina and then
Rat visual acuity was not assessed before or after,
so its unclear if these new photoreceptors were able to connect up the rest
of the light sensing and transmission system.
However, the demonstration that one can grow new
photoreceptors in the adult eye is quite extraordinary, and was received
with great enthusiasm at the conference.
Other scientists injected neural stem cells into the
vitreous, the gel-like substance bathing the retina that fills the globe of
the eye and responsible for retaining its normal oval shape. Under
controlled circumstances, the neural stem cells were able to find their way
to the retina and change into photoreceptors.
Other researchers demonstrated similar findings
using even more primitive omni-potent cells – those called embryonic stems
cells. First, they were cultured into embryonic bodies. These embryonic
bodies were then transplanted into the sub-retinal space. Here, under the
influence of retinoic acid (Vitamin A) and intermittent high and low blood
flow stimulation they developed into photoreceptors.
What are the implications of this research for
patients with macular degeneration?
First, this work explodes the myth that macular
degeneration is irreversible. As the MDF has long held, it clearly is not.
These landmark studies demonstrate that, in adult eyes, one can resurrect
vision-related cells like photoreceptors and induce production of critical
visual process dependent chemicals such as rhodopsin.
Second it emphasizes the critical importance of more
funding for omni-potent cell related research as the best hope yet for a
cure for this disease. The MDF is redoubling its efforts to fund additional
studies to broaden our understanding of these remarkable cells and develop
the best ways to accelerate application of this new knowledge for humans.
You can help us to help you or someone you love by
contributing to the MDF Cells for Sight Initiative. Together we can help
better fund the existing small group of researchers, enabling them to
accelerate their work and add new talent and resources to the development of
human therapies based upon this exciting discovery.
From the pilot study conducted at the
University of Utah last year, it has been learned that certain patients with
non exudative (Dry) AMD have elevated levels of some undesirable lipids
(fats) and heavy proteins, like cholesterol and fibrinogen, in their blood.
Furthermore, the data from this study suggested that if these patients were
treated with the RheofilterTM MDF system, some of these patients
obtained improved vision. The treatment involved the use of an apheresis
blood filtering procedure used to deplete fats and heavy proteins from the
blood. From the patient's perspective, the process is similar to
donating blood. The idea is to use the blood filtering system to deplete
heavy fats and proteins from the blood by obtaining several treatments
spaced over a period of about 2 1/2-months. Theoretically, the sustained
depletion of these unwanted fats and heavy proteins improves blood vessel
function in the retina, and improves the blood flow to the macula, which may
result in the patient obtaining better vision.
Patients chosen to be included in this
study, before beginning, will be required to undergo a qualifying
examination that includes vital signs (heart rate, blood pressure,
respirations and temperature), blood tests, a medical and ocular (eye)
history, a complete physical and complete eye examination including eye
photographs, and written questionnaires. If the patient qualifies, he
or she will be asked to return for a visit within 3 weeks of the
beginning of treatment.
About 200 patients will be participating
in the study at up to 10 centers across the country and the study will
last approximately 12 months. Patients will be randomly assigned to one of
two study treatment groups (either the Rheopheresis treatment group or the
placebo treatment group). During the study, patients will not know which
group they are assigned to, however there will be an approximate 2:1 chance
of being in the apheresis treatment group. At the completion of the study,
pending favorable study results, the patients who received the placebo
treatment will be offered the Rheopheresis treatment free of charge.
In either of these groups, patients will
undergo 8 treatments over a period of about 2 1/2-months. Patients in the
Rheopheresis treatment group will have their blood pumped through the filter
system being investigated. Patients in the placebo treatment group will not
have their blood filtered. At each visit, patients' vital signs will be
recorded, and they will be asked to give blood samples for complete testing
prior to and immediately after each treatment, which takes about 3
hours to complete. Between the 4th and 5th treatments and two weeks after
the 8th treatment, patients will come back to the clinic for a visit
where they will receive many of the same tests taken at the initial
qualifying visit. There will be three more evaluations at approximately 6
months, 9 months, and 12 months. At those evaluations, the patients' blood
will be tested and another complete set of ocular examinations will be
Macular Surgery with Tissue
Plasminogen Activator (TPA).
surgery has been used in several ways to treat macular degeneration.
It was first used to wash out blood from beneath the retina when
large hemorrhages occur.
Tissue Plasminogen Activator (TPA) has been used with the surgery to
help dissolve the clot.
More recently, submacular surgery has been used to operate beneath
the retina and remove the abnormal blood vessels ("membranes")
that have grown.
While excellent results have been found for macular degeneration
associated with Presumed Ocular Histoplasmosis Syndrome (POHS), Multifocal
Choroiditis with Panuveitits (MPC) and Punctate Inner Chorioditis (PIC), the
results with age-related macular degeneration have been less impressive.
Careful patient selection may improve success rates in age-related
A randomized, controlled, multi-center clinical trial of submacular
surgery is currently underway.