Glaucoma

A group of diseases characterized by a particular pattern of optic nerve damage and visual field loss. It is the major cause of irreversible blindness worldwide and it affects more than 2.5 million people in the United States.

Two main forms of glaucoma

  • Open angle glaucoma
  • Angle closure glaucoma
  • There are several subtypes of glaucoma that fall within these categories

Open vs. closed angle glaucoma

  • Open angle glaucoma is generally asymptomatic until advanced stages
  • Acute angle closure glaucoma is associated with severe ocular pain and redness, headache, nausea, and vomiting

Most common form: Primary open angle glaucoma

  • Asymptomatic until advanced stages
  • Over half of these patients are unaware that they have the disease

Primary Risk Factors

  • Increased eye pressure
  • Family History
  • African/African-American race
  • Advanced age

Secondary Risk Factors

  • Steroid use
  • Trauma
  • Ocular inflammation
  • Complicated ocular surgery

Why does glaucoma occur?

  • Increased intraocular pressure (IOP) occurs as a result of defective drainage of aqueous humor
  • Increased intraocular pressure (IOP) and/or poor blood flow to the optic nerve directly damages the optic nerve

What is “normal” eye pressure?

  • Traditionally 8-21 mm Hg
  • However, we now know that glaucoma can occur even in the setting of “normal” intraocular pressure

How do we diagnose glaucoma?

  • Check vision and eye pressure (high eye pressure is a major risk factor for glaucoma)
  • Look for signs of optic nerve damage
  • Test for visual field loss

How can we evaluate the optic nerve?

Biomicroscopic (slit-lamp) examination with auxilliary lenses
Direct Ophthalmoscopy
Optic Nerve Imaging
 - Fundus photography (gold standard)
 - Optical Coherence Tomography (OCT)
 - Heidelberg Retinal Tomography (HRT)
 - Glaucoma Diagnosis Nerve Fiber Analyzer (GDx)

Optic nerve appearance in glaucoma

  • Enlarged “cup”
  • Focal or diffuse thinning of the neuroretinal rim (characteristically begins with thinning of the inferior or superior rim)
  • Splinter hemorrhage(s) on the optic nerve head

How do we test visual fields?

  • Humphrey Visual Field Test (gold standard)
  • Confrontation Visual Fields
  • Goldmann Perimetry
  • Frequency Doubling Technology (screening)

How do we treat glaucoma?

  • Medications
  • Laser
  • Surgery

Goal of glaucoma treatment

Prevent blindness by lowering intraocular pressure and halting progression of optic nerve damage

Treatment

Most treatment modalities lower eye pressure by decreasing aqueous humor production or by increasing aqueous humor outflow

Compliance with medical treatment and follow-up

Glaucoma medications work only when taken as prescribed.  It is important to take the medications regularly.
Frequent visits to your doctor (typically a minimum of 3 – 4 times per year) are necessary to make sure that the medications are effective.

Laser treatment

  • Laser Iridotomy:  A small hole is made in the iris (colored part of the eye) to allow fluid drainage.  This procedure is only performed for narrow or closed angle glaucomas.
  • Laser Trabeculoplasty:  Multiple microscopic holes are created in the angle.  This procedure is only performed in open angle glaucomas.

Surgical treatment

  • Trabeculectomy:  lowers eye pressure by creating a drainage pathway underneath the conjunctiva (membrane surrounding the eye wall)
  • Glaucoma Implant (Tube Shunt):  lowers eye pressure via an artificial device placed under the conjunctiva

Summary

  • Glaucoma is a group of diseases characterized by a particular pattern of optic nerve damage and visual field loss
  • Patients with high eye pressure, family history, African heritage, and advanced age are at highest risk
  • Current treatment for glaucoma is aimed at lowering the intraocular pressure
  • Multiple methods (including eye drops, systemic medications, laser, and surgical procedures) are used to lower eye pressure