Glaucoma is an optic neuropathy characterized by progressive loss of retinal ganglion cells and their axons and a characteristic visual field defect.
It is the 2nd leading cause of blindness worldwide, often diagnosed late. For the foreseeable future, the best hope for glaucoma therefore is early diagnosis and monitoring.
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combating glaucoma, the green water
1. Dr.Usman Abubakar Bosso, MD, DO, MSc.
Authors information
Ophthalmologist at the eye centre,General hospital
Minna, Nigeria; Postgraduate student at Department
of Ophthalmology, Belarus State Medical University,
Minsk, Republic of Belarus.
E-mail: bossodr@yahoo.com, drbossoau@gmail.com
Tel:+2348036785253; +375295115990
Combating Glaucoma, the green water.
The word glaucoma is from the ancient Greek word âglausâ which means âgreen waterâ or âcolour
of the seaâ. It described the typical picture of the blind eye from glaucoma - a dilated non-reactive pupil
with a greenish- blue tent (G.F. Malinowski, 2014).
Glaucoma is the second commonest cause of blindness in the world (WHO,2015). Presently there
are 60.6 million people with glaucoma in the world with a prospective increase to over 90 million in 2020
(H.A.Quigley, 2006). In Nigeria glaucoma is among the first three causes of visual disability (NBS 2005)
with over 180,000 Nigerian adults who are blind from glaucoma (F.Kyari, 2015)
Glaucoma referred to groups of diseases that lead to optic nerve atrophy with blindness as the end
points. It is a disease that usually occurs in people who are 40 years and over, but can be seen in younger
age and even neonate. In many cases, glaucoma is compulsorily associated with raised intraocular pressure
(IOP),a specific excavation of the optic nerve head and typical defects in the central and peripheral visual
field.
IOP is however individualized. Statistically, the normal IOP is between 11 to 22 mm Hg and about
80% population have IOP at about 20 mm Hg (G.F. Malinowski, 2014). In situations where IOP fallwithin
statistically normal, the doctor and the patient may be comfortable. However, in the current concept,raised
IOP is not a most criteria in the diagnosis and treatment of glaucoma. It has been confirmed that even with
achievement of âstatistically normal IOPâ,the disease may still develop or progress, hence a âtolerant IOPâ
is now a preferred term. The eye ball is a spherical organ filled with structures that cannot be easily
compressed. The enclosed internal contents are the aqueous humor, lens, and the vitreous humor, all with
a defined volume.
2. Aqueous humor is produce by the epithelium of the cilliary body. The fluid first fill the posterior
chamber and through the pupil on to the anterior chamber and 80% get drained out via the trabecular
meshwork of the anterior chamber angle, while 20% is drained through the uveal- sclera route. This is the
hydrodynamic system of the eye. Disruption of this mechanism especially resistance to the free flow or
drainage of the aqueous humor always leads to a rise in IOP. The raised IOP will mechanically compress
the nerve fibers passing through the lamina cribose around the optic nerve head. This is the mechanical
theory in the pathogenesis of glaucoma. The other theories are the vascular or circulatory disorder of the
optic disk, which lead to hypoxia and ischemia with a subsequent death of the nerve fibers. The metabolic
theory is based on oxidative stress and reduction in the concentration of neurotrophic factors in the brain
cells. The last theory therefore placed glaucoma among the neurodegenerative disease (N. Gupta 2007)
which then mean that the neurologists are now been involve in the management of glaucoma.
Classification of glaucoma.
Glaucoma is broadly classified in to congenital and acquired.
Congenital Glaucoma is due to hereditary or inborn error, or a defect of the drainage system of the eye.
There is obstruction of the drainage of the aqueous humor which leads to pathological rise in IOP.
Early signs of congenital glaucoma include increase in the diameter of the cornea associated with
mild degree of cornea opacification, a very deep anterior chamber and dilated pupil. Sometimes
immediately after birth, the IOP is already very high with associated enlargement of the eye ball (the Bull
eye). The optic nerve in that case is already suffering. However the functionality of the eye may be define
or become obvious only after 2 months of life when the child is expected to show some reaction to the
mother, instrument or light.
Early diagnose of a congenital glaucoma is possible in the labour room especially following a
careful examination of the eyeball of the neonate (recommended) by birth attendants (doctors, nurses,
community health workers, others) or back at home by the parent(s). Redness of the eye ball, increase size
of the cornea with associated mild opacification, increase size of the eye ball (especially as compared to the
2nd
eye), dilated pupil and a bluish - green tent of the iris should alert the birth attendants or the parent(s)
for an URGENT consultation with an eye specialist. This may be impending âglausâ - green water in the
neonate.
Treatment of congenital glaucoma is by surgery. The earlier the surgery, the higher the chance of
saving the vision of the child.
Acquired glaucoma in its own part, is divided into primary and secondary. Primary glaucoma has
no known causes (often hereditary), while the secondary glaucoma could be due to inflammation,
degenerative diseases of the eye, trauma, following operation in the eye, pathology of the lens
3. (phacomorphic, phacolitic, phacotopic), neovascularization due to diabetes, post thrombotic, endocrine
pathologies, etc.
Primary glaucoma CAN NOT be prevented, therefore most important aspect is the prophylaxis or
prevention of blindness from it via early diagnosis and periodic but adequate follow up of the patient for
the rest of his/her life.
With reference to the condition of the anterior chamber angle, primary glaucoma is divided into
open angle, closed angle or combined.
Primary open angle glaucoma (POAG) is the most widespread, accounting for 90% of all casesofglaucoma
(A.P. Nesterov,2008). It has insignificant symptoms in the early stage for diagnosis, only for the patient to
present to the eye specialist later in life blind. The following symptoms should be given some attention as
they could be a pointer to POAG: eye discomfort, easy fatigability in vision, early use of or request for
spectacle for an unexplained refractive error but with no improvement in comfort ability. Also with detailed
eye examination and investigations including standard automated perimetry, early diagnosis of glaucoma
is possible.
For the angle closure glaucoma, the symptoms are more obvious: pain in the eyeball after few
general exercise or activity that demand long visual attention, blurring of vision, seeing rainbow round a
source of light, etc. In these cases, the attentions of the eye specialist are usually sorted early enough.
Glaucoma is a diagnosis for life. Once identified, the patient, for the rest of his/her life must be
under the care of an eye specialist preferably an ophthalmologist with a clear â cut instructions, regime of
treatments and monitoring of the IOP and signs of progressive optic neuropathy!
Treatment of glaucoma.
The current concept of glaucoma treatment is directed toward the reduction of IOP,protection of
the optic nerve and improvement of microcirculation of the brain. The main criteria for effective treatment
of glaucoma are stable structural and functional changes in the eye and compensation in IOP. At present,3
methods are employed: medical, laser and surgery; often combined.
The medical treatments include use of eye drops for the lowering of IOP either by increasing the
drainage of the aqueous humor or reducing the rate of it production. The choice of anti - glaucoma treatment
is individualized with consideration of associated diseases. The choose regime MUST be followed strictly.
Following uncompensated IOP control on medical treatment alone, laser treatment is often added.
The main aim is to improve the drainage functionality of the trabecular meshwork. Therefore laser
treatments are more effective in angle closure glaucoma and less effective in open angle glaucoma, patients
with very high IOP, secondary glaucoma, or in advanced cases.
Patients with secondary glaucoma, uncompensated IOP, progression in optic nerve damage, and
advances glaucoma are candidates for surgical treatment immediately identified. The aim of surgery IS
NOTto correctthe glaucoma, BUT ratherto stabilized visual function via the reduction in IOP and increase
4. the resistance of the optic nerve fibers to such level of the IOP. Therefore the best is to operate the patient
when there is still some vision to salvage.
In addition to the above mode of treatment, current opinions about glaucoma management advocate
the use of antioxidants, neuroprotectors and drugs that improves perfusions of circulation of both peripheral
and central nervous system circulation as part of treatment regime of patients with glaucoma.
In the treatment of acute angle closure attack, topical and systemic anti glaucoma drugs are
combined with drugs meant for the reliving of pain, suppression of inflammation and constriction of the
pupil to free the anterior chamber.Once one is able to arrestthe attack,the patient must have laseriridotomy
to the index eye and prophylactic iridotomy to the healthy eye.
For the secondary glaucoma, treatment of the main cause of the glaucoma is part of the entire
treatment package.
Summary.
To save visual lost from glaucoma, early diagnosis and adequate follow up of patients is the key.
Attentions of the neurologists, physicians, O&G specialists, staff of the labour ward, parents of new born
babies, etc are to be involved in the search of the disease. Everybody above 40 years in the country should
be made compulsory or at least be informed and be aware of the need to have his/her eye check for
glaucoma. This should include IOP and visual field testing. Special attention and regime of follow up should
be given to people with high risk factor of developing glaucoma. They are:- very close relatives of a patient
with glaucoma, diabetics, hypertensive, hypotensive, people with progressive high myopia and past history
of trauma or inflammation of the eye. Glaucoma therefore is everybodyâs business including policy makers
in ensuring the integration of the glaucoma program in to the health system.