GLAUCOMA


Definition

  • Normal IOP= 12-22mmHg
  • In glaucoma= more than 25mmHg
  • It is a condition that damage the eyes optic nerve. It gets worsen overtime, its often linked to a build up pressure inside the eye.
  • Increased IOP can damage optic nerve, due to which it can cause permanent vision loss or total blindness within few years.

Characteristics

  • Increased IOP
  • Optic nerve damage
  • Peripheral or tunnel vision loss

Risk factors

  • Age more than 40
  • Family history, genetic
  • Poor vision
  • Diabetes
  • Eye injury
  • High B.P., heart disease
  • Steroid medications (prednisone)

Pathophysiology

  • Aqueous humor produced by ciliary body and flows into the posterior chamber behind the iris.
  • It exit the eye by flowing between iris and lens around pupil edge and into anterior chamber.
  • The trabecular meshwork filter the aqueous humor into schlemma’s canal where fluid is picked by episcleral vessels and mixed with blood.
  • Open angle glaucoma caused by degenerative changed into trabecular meshwork.
  • Angle closer glaucoma due to anatomical narrowing of Iris.

Classification

  • True congenital glaucoma :
  • IOP raised during intra uterine life & child born with occular enlargement.
  • Infantile congenital glaucoma :
  • The disease manifest prior to 3rd birthday of child.
  • Juvenile congenital glaucoma:
  • It occur between 10-16 yrs. of age.

Acquired

1⁰ open angle glaucoma: most common type and occur bilateral.

  • Its onset is insidious without discomfort and pain.
  • Due to overproduction or obstruction of the outflow of aqueous humor through trabecular meshwork or schlemma’s canal causing increased IOP and optic nerve damage.
  • Sign and symptoms:
  • Mild aching in eyes
  • Mild headache
  • Increased IOP
  • Loss of peripheral or tunnel vision
  • Decreased visual acuity
  • Halos sign
  • Failure to detect color change

1⁰ angle closure glaucoma/ Narrow angle glaucoma: onset is rapid, if not treated causes blindness in 3 or 5 days.

  • It occur due to abnormality of structure in front of eye.
  • Anatomically narrow angle between the anterior iris and posterior cornea surface due to thickened iris or pupil dilation.
  • If the flow of aqueous humor becomes completely blocked , IOP increases sharply cause sudden angle closure attack.
  • Sign and symptoms:
  • Pain and redness in eyes
  • Increased IOP(40-70mmHg)
  • Blurred vision
  • Halos sign
  • Headache
  • Nausea/ vomiting
  • Photophobia

2⁰ Acquired glaucoma:

It is caused by disease conditions.Diabetes, medications such as steroids, tumors, previous surgery, trauma, inflammation etc..

Diagnostic evaluations

  • Medical history
  • Tonometry
  • Ophthalmoscopy
  • Visual field test
  • Slit lamp examination

Management

  • Medical:
  • Beta-adrenergic blockers (betaxolol)
  • Cholinergics (pilocarpine, carbacol)
  • Carbonic anhydrase inhibitors (acetazolamide)
  • Adrenergic agonist (epinephrine)
  • PGs analogs (latanoprost)
  • Osmotic agents (mannitol, oral glycerine)
  • Surgical:
  • Argon laser trabeculoplasty: it is performed for open angle glaucoma. Thermal argon laser burns are applied to the inner surface of trabecular meshwork to open intratubercular space and widen schlemma’s canal.
  • Laser Iridotomy: laser beam in iris to eliminate the pupillary block to relieve pressure and preserve vision.
  • Cyclocryotherapy: liquid carbon-dioxide is used to freeze. Freezing probe to the sclera over the ciliary body that destroy some of ciliary body to decrease aqueous humor production.