Download Glaucoma

Glaucoma
Group of diseases characterized by
increased intraocular pressure resulting in
damage to the optic nerve and retinal
nerve fibers
It is a combination of ocular conditions that result in
damage to the optic nerve head and a loss of the
visual field. Most forms of glaucoma follow the
classic triad of (1) increased intraocular pressure, (2)
optic nerve damage, and (3) a loss of side vision.
It is a symptomatic condition of the eye in which the
I.O.P. exceeds the tolerance the affected eye
resulting in visual dysfunction
Rise in intraocular pressure(IOP)
• Determined by:
1.An increase in formation of the aqueous
2.A decrease in the drainage of the aqueous
Decreased drainage
Plays:
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Improper development of the angle of A.C.
Narrow configuration of the angle of A.C.
Obstruction of the trabecular mesh work (particulate material)
Peripheral anterior synechiae
Plasmoid aqueous
Pupil block (lens/seclusio pupillae)
Classification of Glaucoma
A. Primary Glaucomas
B.Secondary Glaucomas
Primary Glaucomas
1.Primary congenital glaucomas
a.
Early onset congenital glaucoma(Buphthalmos)
b.
Late onset congenital glaucoma (Infantile)
c.
Glaucoma associated with congenital anomalies
2.Primary open angle glaucoma(POAG)
a. Primary open angle glaucoma (High pressure)
b.Primary open angle glaucoma (Low pressure or Normal
pressure)
3.Primary angle closure glaucoma(POAG)
B.Secondary Glaucomas
Primary open glaucoma(POAG)
• Previously known as Chronic simple glaucoma
• Defined as
Chronic progressive neuropathy resulting
- (Cupping of the disc)
- Visual field defects
- Associated with elevated IOP
Pathophysiology
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Interference of outflow
May be due to degenerative changes in:
Trabecular
Schlemm’s canal
Exit channels
Fig. 3.11: Aqueous humor (green) drains through the
trabecular meshwork into Schlemm's canal.
• Increase outflow resistant in trabecular meshwork or in
Schlemm canal
POAG:
Presentations
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More common than angle closure
Age 40yrs and > Much more common
Male more affected ?
Familial tendency More
Associated with diabetes 3 time more
Preferentially in subjects of Vascular sclerosis
Increased prevalence in High myopia
- B/L symptom free chronic condition
- Slow progressive course
- Mild pain in eye/periorbital region
- Frequent change of glass
- Insidious onset (unnoticed till serious field impairment)
- Slow and silent killer of the vision
(Known as Chronic Simple Glaucoma)
Suggestions
• Eye examinations:
-
Before Admission at primary school
Thorough if possible twice in year
If impossible Once in a year
Detail examination advised to begin Presbyopic glass
Screening camps in school or Target Population
Intra Ocular Pressure(IOP)
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Great variation in open angle glaucoma
Careful tonometry is essential
Exaggeration of the normal diurnal variation
Mean of 3.7 mm of Hg
Biphasic rise in some patients may occur.
Asymmetric C.D.R.> 0.2
Nasal displacement of blood vessels
Cupping of the disc
• Physiological cupping
• Pathological cupping
• Cup Disc Ratio
Visual field defect
• Must be determined
- Central field
- Peripheral field
1.Small Central/Para central Scotomas (2 to 4 degree)
- Relative / Absolute
2.Sickle extension of blind spot (above/below)
- Seidel’s Sign
- Bjerrum’s scotoma
-Roenne’s nasal step
- Tubular vision
small central/Para central visual field
(visual acuity may or may not be affected)
Generalized constriction of the peripheral field is considered as
Peripheral
field may be generalized
early glaucoma
constriction
• Primary Normal Tension/Low tension Glaucoma
• Ocular Hypertension
Angles
Normal aqueous out flow
Abnormal aqueous out flow
Diagnosis of POAG
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Early detection(funduscopy)
Observation/follow-up
Recording of IOP different methods
CDR evaluation
Photography of the disc
Visual field central/peripheral recording and
Comparing
Normal or low tension glaucoma
• Glaucoma is usually high pressure inside the eye
that damages the optic nerve and can result in
permanent vision loss.
• Normal-tension glaucoma (also called low-tension
glaucoma) is a unique condition in which optic nerve
damage and vision loss have occurred despite a
normal pressure inside the eye.
NTG/LTG
• Normal tension glaucoma (NTG), also known as low
tension or normal pressure glaucoma
• is a form of glaucoma in which damage occurs to
the optic nerve without eye pressure exceeding the
normal range.
• In general, a “normal” pressure range is between 1020 mm Hg.
• Glaucoma is generally associated with high pressure in the
eyes
• But many cases of glaucoma occur in the absence of high
pressure readings during exams.
Ocular hypertension
• Ocular hypertension is an elevation of the pressure
in the eye above the range considered normal with
no detectable changes in vision or damage to the
structures of the eyes.
Normal disc
Normal disc
Normal disc
Glaucomatous Cupping
Primary optic atrophy
Management of POAG
• Reduce IOP to the level:
-Doesn’t cause damage to optic nerve/fibers of the nerve
-Judged by stabilizing visual field
-Unchanged appearance of optic disc
Visual field defect progressing after normalization of IOP
Indications:
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Medical +Surgical
Combination
Management
• Medical Treatment
• Laser treatment
• Surgical treatment
1.Medical treatment
Cholinergic Drugs(Parasympathomimetics effect
• Pilocarpine
• Carbachol
- Binding cholinesterase
(Anticholinesterase action)
- Resulting constriction of pupil(miosis)
- Contraction of ciliary muscles
- Opening Trabecular meshwork
- Facilitates the aqueous outflow
Adrenergic Antagonist or Beta-Blockers
• Nonselective Beta1 and Beta 2agents:
-Timolol maleate:
Reduces IOP lowering the rate of aqueous production
May result Broncho spasm and Vascular Hypotension
• Selective Beta blocker (B1Blocker)
Carbonic anhydrase inhibitor
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Acetazolamide
Reduces IOP by decreasing:
The carbonic anhydrase depend aqueous production
Decreases the availability of Bicarbonate
2. Laser Trabeculoplasty(LT)
-Argon laser or Diode laser Trabeculoplasty to control IOP
-Alternative of filtration surgery
3.Trabeculectomy
4.Trabeculotomy
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