Glaucoma: a group of eye disorders characterized by increased IOP. Increased IOP damages
optic nerve and optic fibers = optic nerve atrophy and peripheral visual field loss. Second
leading cause of blindness in US. PATIENT LOSE PERIPHERAL VISION IN GLAUCOMA.
RISK FACTORS:
1. African American x6
2. Cardiovascular disease
3. Diabetes
4. Family history
5. Nearsightedness (MYOPIA)
6. Old age
7. Previous eye trauma
8. Prolonged use of corticosteroids
THEORIES:
- Direct Mechanical Theory: High IOP damages the retinal layer
- Indirect Ischemia: High IOP compresses the circulation in the optic nerve = cell
injury/death.
-
Normal IOP is 10 to 21.
IOP is regulated by inflow and outflow. If inflow and outflow is not equal = problems
with IOP.
Inflow: production of aqueous fluid
Outflow: the rate of reabsorption of aqueous fluid
- Aqueous fluid flows between iris and lens. It nourishes the cornea and the lens.
Whatever is in the body is in the aqueous fluid.
- Fluid flows from 1.) anterior chamber then 2.) drains through the trabecular meshwork,
3.) into canal of Schelmm and the Epi-scleral veins.
- If Inflow > Outflow = increase in IOP. The eye is producing the aqueous fluid, but not
draining it.
WIDE ANGLE/OPEN GLAUCOMA: outflow of the aqueous humor is decreased in the
trabecular meshwork. The drainage channels become blocked = optic nerve damage.
- Happens over time; may develop slowly w/o symptoms.
- Most common type
- Tunnel vision
- IOP is 22-32
NARROW ANGLE/CLOSED GLAUCOMA: obstruction in aqueous humor outflow due to
complete or partial closure of the angle from the forward shift of the peripheral Iris to the
trabecula = Reduction of outflow = increase IOP.
- ACUTE: Eye is dilated and will not constrict back. When dilated = closure of angle
(Mydriasis: eye dilation)
o Causes: 1.) DRUGS 2.) EMOTIONAL EXCITEMENT (ex: crying for long period of
time) 3.) DARKNESS
o S/SX: 1.) sudden, excruciating pain in/around eye, 2.) N/V, 3.) IOP of >50mmHg,
4.) colored halos around lights, 5.) blurred vision, 6.) ocular redness, 7.) brow
pain
o Assessment: H&P, visual acuity, Ophthalmoscopy, slit lamp microscopy, visual
field perimetry. KEY TESTS: tonometry (measures IOP) and Gonioscopy (visualizes
anterior chamber angle) ***Test is looking for PRESSURE, ANGLE, and CUPPING.