The
eye condition of glaucoma is a public health issue
of global concern. An estimated 6.7 million people
are affected by this disease. Moreover, blindness
caused by glaucoma is irreversible, unlike loss
of vision from cataracts.
More alarming are the various research reports
suggesting that health services in developed
nations are aware of only 50% of the total count
of people suffering from glaucoma. From this
data, one can conclude that it is highly probable
that the situation is even worse in the developing
parts of the world.
Though a lot more research needs to done about
the core pathogenesis of this disease, there
has been sufficient progress in its therapeutic
concepts. The process of reducing intraocular
pressure (IOP) has proved to be most effective
in checking the disease. Early detection of the
condition is also vital in delaying blindness
in glaucoma patients. Moreover, choosing the
right kind of therapy for a particular case is
also a complicated process, which involves a
variety of factors.
Proper planning of a glaucoma therapy
Any practitioner must chalk out a therapeutic
plan to ensure optimal results and minimum risks
for the patient. Here are a few essential tips
for a safe and successful glaucoma treatment:
- Before a starting on the medication,
a doctor must also be equipped with sound knowledge
of the procedure behind the process to be implemented,
its disadvantages, associated adversities etc.
- Both
the patient and the doctor should involve in
a discussion about the pros and cons of
the therapy according to the case at hand.
- A detailed investigation about the
patient’s
general health, current medication, vulnerability
to side effects and psychosocial factors must
be conducted.
- Every patient’s risk factors
for glaucoma development must be evaluated
vis-à-vis
estimated life span. This assessment must take
into account the patient’s intraocular
pressure, age, ethnicity, family record and
educational background.
The physician should also have some detailed
knowhow about how to recommend medication by
determining a baseline and a target intraocular
pressure. The quality and quantity of medication
must also be cautiously handled.
The intraocular pressure (IOP) control process
The process of lowering IOP with medication
has been practiced for many years now. However,
its effectiveness in the treatment of primary
open-angle glaucoma (POAG) has been reported
only very recently. There have been a number
of studies like the The Early Manifest Glaucoma
Trial (EMGT), Normal
Tension Glaucoma Study, The Ocular Hypertension
Treatment Study (OHTS), the Collaborative Initial
Glaucoma Treatment Study (CIGTS) etc. that
have reported the effectiveness of this therapy.
Intraocular pressure-lowering medication
There are over 25 varieties of glaucoma drugs,
grouped into six board categories. Here is an
overview of the drugs based on their means of
action.
- Prostaglandin analogues like latanoprost,
bimatoprost, travoprost, isopropyl unoprostone
etc.
- Beta-blockers like timolol, betaxolol,
levobunolol, metipranolol and carteolol.
- Carbonic
anhydrase inhibitors like acetazolamide, methazolamide,
dorzolamide and brinzolamide.
- Adrenergic agonists
like epinephrine, dipivefrin, apraclonidine
and brimonidine. Apraclonidine
and brimonidine are more frequently administered
now-a-days.
- Hyperosmotic agents are applicable
only in cases where topical medications and
oral CAIs prove
slow and ineffective in lowering IOP. The oral
drug glycerol and isosorbide and intravenous
drug mannitol are some hyperosmotic agents.
- Parasympathomimetic/Cholinergic
agents: They were the first administered glaucoma
drugs
and include the acetyl choline receptor agonist,
pilocarpine, and the indirectly acting echothiophate
iodide. Currently they are not so popular treatments
due to their drawbacks in prolonged glaucoma therapy,
especially their serious ocular side effects.
- Combination
therapy: A combination of drugs is one of
the most potent ways to treat glaucoma.
Almost 40% of glaucoma cases need to use
more than one IOP-checking drug. In fact, it
is
a common strategy to use these combination drugs
to decrease resistance and help in administration
of the doses. Ideally, it should be for cases
where monotherapy fails. Cosopt, xalacom,
timpilo and extravan are the names of some
of these combination drugs.
Treatment of glaucoma with neuroprotective agents
Reducing IOP cannot work in isolation in order
to check glaucoma and lowering the risk of blindness.
Since, optic nerve cupping (resulting from retinal
ganglion cell death) and loss of axons occur
simultaneously with physical alterations in the
optic nerve, it is necessary to preserve the
optic nerve as well. Though there are still more
conclusive studies required for ascertaining
the role of neuroprotective agents in glaucoma
treatment, it is as of now available only as
a part of research protocols. Some of the neuroprotective
agents are mementine, calcium channel blockers,
alpha-2 adrenergic agonists and beta-blockers.
Apart from a detailed knowledge of the indications
and therapies of glaucoma, one needs to be abreast
with the latest treatments town as well.
