Glaucoma is primarily caused by increased intraocular pressure (IOP) due to a build-up of fluid (aqueous humor) within the eye. This fluid usually flows out of the eye through a mesh-like channel. If this channel becomes blocked or if the eye produces too much fluid, the liquid cannot drain properly, leading to a rise in IOP. Elevated IOP puts pressure on the optic nerve, eventually damaging it and causing vision loss. Other causes may include poor blood flow to the optic nerve, physical trauma to the eye, and certain genetic predispositions.

Types of Glaucoma

There are several types of glaucoma, each with distinct characteristics:

1. Primary Open-Angle Glaucoma (POAG): This is the most common form, where the drainage angle formed by the cornea and iris remains open, but the trabecular meshwork is partially blocked, causing a gradual increase in eye pressure. POAG develops slowly and painlessly, making early detection challenging.
2. Angle-Closure Glaucoma: Also known as acute or narrow-angle glaucoma, this type occurs when the iris bulges forward, narrowing or blocking the drainage angle formed by the cornea and iris. This blockage can cause a sudden increase in eye pressure, leading to a rapid onset of symptoms such as severe eye pain, nausea, and blurred vision. Angle-closure glaucoma is a medical emergency that requires immediate treatment.
3. Normal-Tension Glaucoma: In this type, optic nerve damage occurs despite normal eye pressure. The exact cause is unknown, but it may be related to a sensitive optic nerve or reduced blood flow to the nerve.
4. Congenital Glaucoma: This rare form occurs in infants and young children due to developmental defects in the eye's drainage system. It is usually diagnosed within the first year of life and requires prompt treatment to prevent vision loss.
5. Secondary Glaucoma: This type results from another medical condition, such as eye injuries, inflammation, tumors, or advanced cases of cataracts or diabetes.

Symptoms of Glaucoma

The symptoms of glaucoma vary depending on the type and stage of the disease:

• Primary Open-Angle Glaucoma: Often asymptomatic in the early stages, symptoms may include gradual loss of peripheral vision, tunnel vision in advanced stages, and difficulty adjusting to low light.
• Angle-Closure Glaucoma: Symptoms include severe eye pain, headaches, blurred vision, halos around lights, redness in the eye, and nausea or vomiting.
• Normal-Tension Glaucoma: Symptoms are similar to POAG but without elevated eye pressure.
• Congenital Glaucoma: Symptoms in infants may include cloudy eyes, excessive tearing, light sensitivity, and a larger-than-normal eye size.

Diagnosis of Glaucoma

Early detection is critical in preventing vision loss from glaucoma. Routine eye exams are the best way to diagnose glaucoma before significant damage occurs. During a comprehensive eye exam, an optometrist or ophthalmologist may perform the following tests:

• Tonometry: Measures the pressure inside the eye.
• Ophthalmoscopy: Examines the optic nerve for damage.
• Perimetry: Tests the field of vision to detect any vision loss.
• Gonioscopy: Inspects the drainage angle to see if it's open or closed.
• Pachymetry: Measures the thickness of the cornea, which can influence eye pressure readings.

Treatment of Glaucoma

While there is no cure for glaucoma, treatments are available to manage the condition and prevent further vision loss. The main goals of treatment are to lower intraocular pressure and protect the optic nerve. Treatment options include:

1. Medications: Prescription eye drops are the most common treatment for glaucoma. They work by reducing the production of fluid in the eye or improving fluid drainage. In some cases, oral medications may be prescribed.
2. Laser Therapy: Laser trabeculoplasty is a procedure used to increase the drainage of fluid from the eye in open-angle glaucoma. Laser iridotomy and cyclophotocoagulation are other laser treatments used for angle-closure and refractory glaucoma.
3. Surgery: If medications and laser therapy are not effective, surgical procedures such as trabeculectomy, drainage implants, or minimally invasive glaucoma surgeries (MIGS) may be performed to create new drainage channels or reduce fluid production.
4. Lifestyle Changes: Patients with glaucoma are encouraged to maintain a healthy lifestyle, including regular exercise, a balanced diet, and avoiding activities that may increase eye pressure, such as heavy lifting or straining.

Conclusion

Glaucoma is a serious eye condition that can lead to irreversible vision loss if not detected and treated early. Regular eye examinations, especially for those at higher risk, are crucial in catching the disease in its early stages. While glaucoma cannot be cured, appropriate treatment can effectively manage the condition and preserve vision. Awareness, early detection, and adherence to treatment plans are the keys to preventing the devastating effects of this "silent thief of sight"