Glaucoma is a group of eye conditions that can cause damage to the optic nerve, which is responsible for transmitting visual information from the eye to the brain. This damage is often associated with increased intraocular pressure (pressure within the eye), but it can also occur with normal or even lower-than-normal intraocular pressure.
There are several types of glaucoma, with the most common ones being:
- Primary Open-Angle Glaucoma: This is the most common type of glaucoma. It develops slowly over time and is usually painless. The drainage angle where the iris meets the cornea remains open, but the trabecular meshwork, which is responsible for draining the aqueous humor (fluid within the eye), becomes less efficient. This leads to a gradual increase in intraocular pressure, causing damage to the optic nerve.
- Angle-Closure Glaucoma: This type occurs when the drainage angle between the iris and the cornea becomes blocked or closed, preventing the normal outflow of aqueous humor. This can lead to a sudden increase in intraocular pressure, causing symptoms such as severe eye pain, headache, blurred vision, and even nausea and vomiting. Angle-closure glaucoma is considered a medical emergency.
- Normal-Tension Glaucoma: Also known as low-tension or normal-pressure glaucoma, this type of glaucoma occurs when there is optic nerve damage despite intraocular pressure remaining within the normal range. The exact cause of this type is not well understood.
- Secondary Glaucoma: This type of glaucoma develops as a result of another eye condition, such as trauma, inflammation, diabetes, or prolonged use of certain medications. The increased pressure in the eye is a secondary effect of the underlying condition.
Early stages of glaucoma often do not present any noticeable symptoms, which is why regular eye examinations are crucial for early detection and treatment. If left untreated, glaucoma can lead to gradual vision loss and eventually blindness.