I would like to let you know about an interesting piece of news I found while searching the web,looking



Download 15.23 Kb.
Date21.06.2018
Size15.23 Kb.
"I would like to let you know about an interesting
piece of news I found while searching the web,looking
for something that could help one of my patients with
macular degeneration (of course, one of the things  I
suggested to him was to put his breathing in order but
the patient was quite sceptical on the subject).
This is what I found at the following link:
www.mdsupport.org/library/carbondioxide.html
"Carbon Dioxide May Improve Vision in AMD Patients
by Dan Roberts
April 2002
AMD patients are benefitting from a new combination
drug therapy being tested at the University of Texas
Health Science Center at San Antonio (UTHSC). The
therapy involves a combination of medicines which
includes carbon dioxide, an element which dilates the
blood vessels in the retina for the maintenance of
proper blood flow. William E. Sponsel, M.D., associate
professor and director of research in the department
of ophthalmology at UTHSC, maintains that it is the
diminished circulation of these vessels that can cause
the photoreceptor cells to deteriorate, leading to
macular degeneration and loss of central vision.
With certain combinations of chemicals called
"carbonic anhydrase inhibitors" (CAI) given as eye
drops, Dr. Sponsel is "tricking" the eye into
maintaining its carbon dioxide while supplying
important nutrients. As a result, he reports that 60
of 65 patients have shown "dramatically" improved
vision, no matter whether their vision loss was a
result of AMD or glaucoma. Dr. Sponsel says that the
results "bode well for treatment of these disorders in
the future."
Of course, I was very interested in this intention of
Dr. Sponsel of "tricking the eye into maintaining its
carbon dioxide" (the first and best way to achieve
this result would appear to be avoiding CO2 loss by
avoiding hyperventilation!); I intensified my search
and I found a few more interesting articles. In the
website of the UT Health Science Center-San Antonio,
where Dr. Sponsel is working, I found this:
"Subjects seeing better after use of CO2-enhancing
drug(2-22-02)
Eye redness was the clue that something was happening
to Celia Ramirez's vision. Although she wasn't having
trouble driving or doing other tasks, her children
urged her to have a checkup. It turned out she was in
the early stages of age-related macular degeneration
(AMD), a disease that attacks a person's central field
of vision..... her central vision continued to
deteriorate. Her specialist is William E. Sponsel,
M.D., associate professor and director of research in
the department of ophthalmology at The University of
Texas Health Science Center at San Antonio (UTHSC).
Dr. Sponsel's research led him to prescribe treatment
with new combinations of medications. "These last two
medicines he's had me on, they have really worked,"
Mrs. Ramirez said. "We've done a lot of praying. This
is somewhat of a miracle."
The miracle involves carbon dioxide, which is crucial
for vision. The healthy eye produces enough carbon
dioxide to dilate blood vessels around the retina and
maintain proper blood flow. The ailing eye does not
produce enough. This holds important implications for
the treatment of patients with blinding eye diseases
such as AMD and glaucoma, which are marked by
diminished circulation of blood in the back of the
eye. Eye pressure also is a conventional barometer of
eye health.
About 60 of 65 patients have seen their vision improve
while receiving treatment at UTHSC's teaching
hospital, University Hospital..........  The miracle
agents are called "carbonic anhydrase inhibitors"
(CAI's). Given as eyedrops, CAI's reach the back of
the eye rapidly and slow the clearance of carbon
dioxide while increasing the supply of nutrients. They
help dilate blood vessels within and behind the
retina, which is the structure that receives,
processes and transmits visual images relayed from the
brain.
Dr. Sponsel pursued this line of research in an
intriguing way — after discovering that adults who
hyperventilated and rapidly blew off their body's
carbon dioxide showed decreased vision, eye pressure
and circulation in the back of the eye. He was
treating subjects one week with a CAI called
dorzolamide and the next week with placebo eyedrops.
During hyperventilation, the subjects on dorzolamide
maintained good light sensitivity in their central
field of vision, while the same subjects during
placebo treatment showed central visual loss....."

In the following article there is a more recent study


that confirms the favourable effect of carbonic
anhydrase inhibitors on the blood flow in the eye:
"Acta Ophthalmologica Scandinavica. 82(6):730-737,
December 2004.
Januleviciene, I. 1; Harris, A. 2; Kagemann, L. 2;
Siesky, B. 2; McCranor, L. 2
Abstract:
Purpose: To evaluate the effects of
dorzolamide/timolol fixed combination (D/T) compared
to latanoprost on intraocular pressure (IOP) and
pulsatile ocular blood flow (POBF) in primary
open-angle glaucoma (POAG) patients.
Methods: Thirty patients with POAG were randomized in
an open-label, cross-over study. Intraocular pressure
reduction was achieved by 4 weeks medical therapy with
D/T twice daily or latanoprost 0.005% dosed once in
the evening. During a 4-week run-in and a 4-week
wash-out period between study arms, patients ceased
use of all other glaucoma medications and used timolol
maleate 0.5% twice daily. Primary efficacy variables
were IOP and POBF.
Results:...........Repeated measures ANOVA detected
significant changes in POBF with treatment (p =
0.0361). Dorzolamide/timolol fixed combination
statistically significantly increased pulse volume by
0.767 [mu]l (p = 0.0087), while latanoprost therapy
had no significant effect (p = 0.2407).
Conclusions: Both drugs had similar effects in terms
of IOP reduction. Dorzolamide/timolol significantly
increased pulse volume while latanoprost had no
effect......"
And here an Italian study on the benefits of Carbonic
anhydrase inhibitors also for other problems, through
their "physiological function related to respiration
and transport of CO2/HCO3:
 
"Carbonic anhydrase inhibitors and their therapeutic
potential. Claudiu T Supuran​‌, ­Andrea
Scozzafava​‌­
Università degli Studi, Laboratorio di Chimica
Inorganica e Bioinorganica, via Gino Capponi 7,
I-50121, Florence, Italy. cts@bio.chim.unifi.it
Carbonic anhydrases (CAs, EC 4.2.1.1) are wide-spread
zinc enzymes, present in archaeo- and eubacteria,
algae, green plants and animals. Within these
organisms CAs are encoded by three distinct,
evolutionarily unrelated gene families: the α-CA,
the β-CA and the γ-CA families,
respectively. These enzymes are very efficient
catalysts for the reversible hydration of CO2 to
bicarbonate.......
sulphonamide CA inhibitors (CAIs) are useful as
diuretics, or in the treatment and prevention of a
variety of diseases such as glaucoma, epilepsy,
congestive heart failure, mountain sickness, gastric
and duodenal ulcers, neurological disorders and
osteoporosis among others, as well as diagnostic
tools. Their applications are due to the wide
distribution of the different α-CA isozymes (14
are presently known) in higher vertebrates, where they
play important physiological functions related to
respiration and transport of CO2/HCO3 between
metabolising tissues and the lungs, pH and CO2
homeostasis, electrolyte secretion in a variety of
tissues/organs, and biosynthetic reactions, such as
gluconeogenesis and ureagenesis, among others. CA
activators have recently been described and their
mechanism of action at molecular level elucidated.
Such agents might be useful for developing therapies
for the CA deficiency syndrome."
And finally, one more recent study that refers to the
"vasoconstriction during acute
hyperventilation-induced hypocapnia", which can be
avoided by Dorzolamide.
"Topical dorzolamide increases pericentral visual
function in age-related maculopathy: pilot study
findings with short-wavelength automated perimetry.
Acta Ophthalmologica Scandinavica. 83(2):154-160,
April 2005.
Remky, Andreas 1; Weber, Anke 1; Arend, Oliver 1;
Sponsel, William Eric 2
Abstract:
Purpose: Numerous studies have confirmed the
enhancement of ocular circulation by carbonic
anhydrase inhibitors (CAIs). Topical CAI treatment
with dorzolamide averts the significant pericentral
visual function loss accompanying retinal and
choroidal vasoconstriction during acute
hyperventilation-induced hypocapnia. This study was
designed to discern whether dorzolamide might
similarly enhance macular function in patients with
age-related maculopathy (ARM)........
Conclusions: This study demonstrated a significant
increase in short-wavelength sensitivity in ARM with
dorzolamide and the lack thereof with placebo. These
encouraging pilot study data suggest a potential role
for topical CAIs in ARM patients, and establish
objective parameters for prospective studies to
further evaluate the effects of dorzolamide in ARM.
Copyright (C) 2005 Blackwell Publishing Ltd."
Even if Dr.Sponsel and the Scandinavian doctors do
not reach the   conclusion that one of the first
things to do would seem to be to avoid
"hyperventilation-hypocapnia" by cessation of
hyperventilation, I think it is very positive that the
damage done by hyperventilation is once more
confirmed, especially in  a field as important as that
of preventing visual loss."


Share with your friends:


The database is protected by copyright ©dentisty.org 2019
send message

    Main page