Health
Problems
Glaucoma
What is Glaucoma?
Glaucoma is a condition where there is a build up of pressure
within the eyeball, due to the presence of excess fluid. As a consequence, the eyeball
becomes hard instead of its normal soft and resilient state and this leads to vision
disturbance and, even blindness.
return to top
Known Causes
There three major classes of glaucoma:
1. Open Angle Glaucoma,
2. Angle Closure Glaucoma, and
3. Congenital or Infantile Glaucoma.
Each of these has many subtypes and can occur in
association with other eye or generalized diseases. Open Angle Glaucoma simply means that
the drainage angle is open, but the fluid reaching it is not able to percolate through.
The "plumbing" in the eye is not working properly.
Angle Closure Glaucoma is different; in this case, the
angle structures in the eye are blocked and this prevents fluid in the eye from reaching
the drainage channels.
Congenital Glaucoma is an inborn deficiency of the drainage
structures in the eye and may be brought about by abnormally developed structures and
tissues that prevent the drainage of fluid from the eye.
return to top
Symptoms
Estimates suggest that approximately one percent of the
population of the UK over the age of 40 suffer from glaucoma. Primary Open Angle Glaucoma,
comprises the largest majority, accounting for 60 - 70 % of the cases and is said to be
the cause of about 10 - 20 % of all blindness in the U.S.A.
Unfortunately, the initial symptoms are often minimal
making early detection (other than through regular visits to an optometrist) difficult.
Glaucoma is a chronic, insidious, bilateral disease, gradually destroying the optic nerve
and constricting the sufferer's field of vision ("tunnel vision") as well as
creating "holes" in one's visual field, a condition known as scotoma . Lastly,
central or reading vision is affected, but by this time, the glaucoma is far advanced.
In contrast, Angle Closure or Narrow Angle Glacoma is much
less common. It usually presents as an acute or sudden event. The drainage angle is
obstructed, usually by iris, and the pressure in the eyeball rapidly rises. This produces
pain, blurred vision, haloes around light, redness, and pupil abnormalities. Acute angle
closure attacks tend to occur in smaller, far-sighted eyes.
Congenital Glaucoma is so rare that a typical eye surgeon
will see only one or two cases in his entire career. About 60% present before six months
of age, at least 80% before one year of age. The early signs are tearing, light
sensitivity, and tight lid closing. In nearly all cases, the cornea becomes cloudy or
hazy, and enlarges abnormally.
return to top
Diagnosis
Glaucoma is easily diagnosed during a standard opthalmological
examination through the measurement of intraocular pressure. It is a painless, quick, and
simple method of determining intraocular pressure. All individuals over age 40 should have
regular annual glaucoma checks. Those especially at risk are people of
colour, diabetics,
highly near-sighted individuals, older people, and relatives of glaucoma patients.
It should be noted that Angle Closure Glaucoma cannot be
detected prior to an attack, but the 'tendency' for this disease may be seen during a
complete ophthalmologic exam.
Congenital Glaucoma, being so rare and very different from
adult glaucoma, is difficult to diagnose. It requires a thorough examination under
anesthesia by a pediatric ophthalmologist.
return to top
Conventional Treatment
Medical treatment involves a variety of means: medical,
surgical, and now, Laser. Drug therapy includes topical or drop medications, and
occasionally pills. Drugs either help by reducing the production of fluid in the eye
(typical drugs include timolol, epinephrine, and oral carbonic anhydrase inhibitors) or by
increasing the drainage of fluid (eg. pilocarpine and similar drugs). Sometimes the drugs
are used in combination. as with all drugs, side effects are known and documented and
include headache, temporarily blurred vision, depression, loss of appetite and drowsiness.
Incredibly some medications may even cause cataract(1)
If drug therapy fails, then either surgery or Laser therapy
is considered. Their success rates are variable depending on the severity and subtype of
glaucoma and there are associated risks. In general, drug therapy is usually reserved for
Open Angle Glaucoma, while Angle Closure Glaucoma and especially Congenital Glaucoma are
surgically treated.
(1) British National Formulary
return to top
|
