Glaucoma is a group of eye diseases that arises due to increase of intraocular pressure in the eye leading to damage to the optic nerve.
It can lead to complete blindness.
CLASSIFICATION OF GLAUCOMA
- Open-angle: Although the drainage angle in the eye remains open, an ocular blockage or obstruction can lead to retention of fluid in the eye.
- Closed-angle: The drainage angle partially closes and this leads to retention of fluid in the eye.
SIGNS & SYMPTOMS OF GLAUCOMA
In open angle glaucoma
- Progressive visual field loss
- Optic nerve changes
- Patchy blind spots in the peripheral or central vision, frequently in both eyes
- Tunnel vision in the advanced stages
In closed angle glaucoma
- Sudden ocular pain
- Severe Headache
- Seeing halos around lights,
- Red eye
- Very high intraocular pressure (>30 mmHg)
- Nausea and vomiting
- Suddenly decreased vision
- Fixed, mid-dilated pupil.
- Oval pupil (rare)
- Opaque specks may occur in the lens in glaucoma.
COMPLICATIONS ARISING FROM GLAUCOMA
- Formation of scars
- Swelling of the iris
- Severe redness of the eye
- Blurred vision
- Complete loss of vision/blindness.
- Elevated ocular pressure i.e. intraocular pressure above the threshold of 21 mm Hg or even above 24 mm Hg
- Damage to optic nerve
- Prolonged use of steroids
- Conditions that severely restrict blood flow to the eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma)
- Ocular trauma (angle-recession glaucoma)
- Inflammation of the middle layer of the pigmented vascular eye structure (uveitis), known as uveitic glaucoma.
- Glaucoma at birth due to structural defects.
- Geriatrics are more prone to this disease (over age of 60)
- Having severe myopia or hyperopia
- Family history
- African, American or Asian ethnicity
- Intraocular tumors
- Having corneas that are thin in the center
- An eye injury or certain types of eye surgery.
- Flammer Syndrome
- Taking corticosteroid medications, especially eye drops, for a large period of time.
- Screening for glaucoma is usually performed as part of a standard eye examination.
- Imaging techniques that are used for assessment of retinal nerve damage are:
a) Optical coherence tomography
b) Scanning laser polarimetry
c) Scanning laser ophthalmoscopy
- Various other tests done for diagnosis & assessment of damage caused by glaucoma are:
a) Tonometry for examination of inner eye pressure.
b) Ophthalmoscopy for examination of shape & size of the optic nerve.
c) Perimetry, done for visual field test.
d) Gonioscopy for measurement of the angle in the eye where the cornea meets the iris.
e) Pachymetry for the measurement of thickness of the cornea
f) Nerve fiber analysis for the determination of the thickness of the nerve fiber.
TYPES OF GLAUCOMA
Glaucoma can be classified and sub-classified in various types on the basis of diagnosis:
- Primary Glaucoma
a) Pigmentary glaucoma
b) Exfoliatory glaucoma
c) Primary juvenile glaucoma
- Developmental Glaucoma
a) Congenital glaucoma
b) Infantile glaucoma
c) Genetic glaucoma
- Secondary Glaucoma
a) Inflammatory glaucoma
b) Phacogenic glaucoma
c) Traumatic glaucoma
d) Neurovascular glaucoma
e) Drug Induced glaucoma
- Absolute Glaucoma
TREATMENT OF GLAUCOMA
Several kinds of medications are used:
- Prostaglandin analogs like latanoprost increases flow of aqueous humor.
- Topical beta blockers reduce the production of aqueous humor.
- Alpha agonists work in dual action with beta blockers.
- Miotic agents, such as pilocarpine work by contraction of the ciliary muscle allowing increased outflow of the aqueous humour.
- Echothiophate an AchE inhibitor, is used in chronic glaucoma.
- Adrenergic agents-this has better penetration and lowers IOP both by increasing aqueous outflow and decreasing humour formation
- Carbonic anhydrase inhibitors, lower secretion of aqueous humor by inhibiting carbonic anhydrase in the ciliary body.
- Cannabis has shown to decrease intraocular pressure.
Surgeries performed for management & correction of glaucoma
- Laser surgery
- Glaucoma drainage implants
- Laser-assisted nonpenetrating deep sclerectomy.