Glaucoma Medications
Chat Highlights
August 2, 2006
Norma Devine, Editor
On Wednesday, Augsut 2, 2006, Dr.
Rick Wilson, a glaucoma specialist at Wills, and the glaucoma
chat group discussed "Glaucoma Medications."
Moderator:
Good evening, Dr. Wilson. Tonight's
topic, "Glaucoma Medications," is always a popular one.
Dr.
Rick Wilson: Good evening,
everyone. Hope you are all staying cool during this heat
wave.
P:
Dr. Wilson, I suffer
from allergic reactions to Alphagan, Timoptic, Cosopt, etc. Are
there any phytotherapic medications for treating glaucoma? The
active ingredient in phytotherapic medications is extracted from
plants.
Dr. Rick Wilson:
There is a medication extracted from cannabis, but its duration
is not long enough to be effective. The least allergenic
medication I've found is the beta-blocker cartelol 1%. If
patients are allergic to many medications, it often means they
are allergic to the preservative in the medications. Merck
makes a preservative-free timolol. It is expensive because it
comes in daily-disposable vials.
P: What progress has been made in using THC (tetrahydrocannabinol)
as a topical treatment to help prevent damage to the optic nerve?
Dr. Rick Wilson:
THC is from the cannabis I just mentioned. If taken internally,
it can cause a drop of blood pressure that can hurt blood flow
to the eye. Also, the effect on the IOP (intraocular pressure)
is too short lived to be practical.
P: Why do
glaucoma eyedrops, such as Lumigan, Xalatan, etc., still contain
benzalkonium chloride? That preservative has been shown
to cause serious irritation and corneal disease and has been removed
from most artificial tears.
Dr. Rick Wilson:
Whenever a drug manufacturer changes a medication, there is an
extensive and expensive process in which the maker has to prove
that the medicine is equivalent to the standard and has no additional
side effects. If only a small percentage of patients is
allergic to the medication, there’s no financial incentive
for change. On the other hand, the greater the allergenic
rate is, the greater the incentive is to make the change.
For example, the maker of Alphagan has changed the percentage
of the preservative twice and the preservative, itself, once.
P: Is Alphagan fairly new?
Dr. Rick Wilson: Alphagan has been around for quite some time,
but the manufacturer keeps trying to reduce the side effects.
P: Worse
reactions than local irritation and corneal disease have been
attributed to the use of the preservative, benzalkonium chloride.
How do we patients get the message to the drug companies
that there might be enough interest in preservative-free versions
of their medications to make them financially feasible?
Dr. Rick Wilson:
The drug companies often use focus groups to get opinions from
patients or the public. They do, however, pay attention
to letters they receive and often follow up on them. I would try
that course first, though a larger patients' advocacy group might
be necessary to prompt a change because of the financial considerations
I mentioned.
P: What progress
has been made with Copaxone as a vaccination to prevent the release
of glutamate? Will that help to prevent glaucoma?
Dr. Rick Wilson:
The Israelis are still working on that novel approach. They
have had decent results in animals. I don't know of a study involving
human beings with a significant number of them involved.
We have always tried to treat glaucoma by lowering IOP to a level
the eye can tolerate. Newer approaches, such as vaccination
and neuroprotection, aim to increase the tolerance of the optic
nerve to withstand higher IOP. Combining both approaches
should be twice as effective when effective neuroprotective drugs
have been identified and proven.
P: I have
mid-stage glaucoma and have had three surgeries on my eyes, two
in my left eye and one in my right eye. Will medication
reverse some of the vision loss that occurred after the surgery?
Dr. Rick Wilson:
That depends upon why the vision has changed. Often it is because of changes in the lens of the eye, such as cataract. Medication will not help vision loss caused by cataract. Medication also
will not change wrinkling in the retina from too low an IOP. Medication
usually has no effect on blurry vision. We hope that will
change.
P: How do you think advertisement and the probability of non-compliance
affect eye doctors' prescription behavior?
Dr. Rick Wilson: In all honesty, with declining reimbursement
rates and managed care, eye doctors have to see many more patients
than they used to in order to stay profitable.
Unfortunately, with less time for family, sleep, and reading,
some general ophthalmologists and optometrists may get too much
of their information about drugs from manufacturing representatives
and lecture-dinners. Non-compliance is such a huge problem
that doctors need to try to make it easier on patients to take
their medication by keeping the number of times it is needed to
twice a day and the number of medications to a minimum.
Moderator: Dr. Wilson, thanks for your time and great answers.
Dr. Rick Wilson:
Have a good week, everyone. Stay cool.
On August 9, Dr. Wilson discussed "Childhood vs. Adult Glaucoma"
in the Chat room. Click here for highlights
of that meeting.
Click here for the most recent
glaucoma chat highlights and links to the chat archives.
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upcoming glaucoma chat events.
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