Glaucoma is a group of eye diseases that gradually damage the optic nerve. In many cases, damage occurs silently for years—so understanding how glaucoma works is an important first step in protecting vision.
The Anatomy of the Disease
To understand glaucoma, you have to understand how the eye “breathes.” Your eye constantly produces a clear fluid called aqueous humor, which nourishes the tissues and helps maintain the eye’s shape.
Normally, this fluid drains out through an area called the drainage angle (where the iris and cornea meet).
When this drainage system becomes inefficient or blocked, the fluid has nowhere to go. Internal eye pressure (intraocular pressure) rises, physically compressing and damaging the optic nerve at the back of the eye. As the millions of tiny nerve fibers die, blind spots develop.
The Main Types of Glaucoma
Glaucoma is not a single disease, but a spectrum. Understanding which type you have is the first step in effective management.
Angle-Closure Glaucoma (Acute)
A medical emergency. This occurs when the iris bulges forward and blocks the drainage angle—like a piece of paper sliding over a sink drain. Eye pressure can spike rapidly.
Common symptoms may include:
- Severe eye pain
- Nausea or vomiting
- Blurred vision
- Rainbow-colored halos around lights
If you experience these symptoms, seek immediate emergency medical care.
Normal-Tension Glaucoma
A variation where the optic nerve becomes damaged even though eye pressure remains within a “normal” range.
Secondary Glaucoma
Glaucoma that develops as a direct result of another condition, such as advanced diabetes, an eye injury, or the prolonged use of steroid medications.