What is Glaucoma?
Glaucoma is a progressive optic neuropathy characterized by damage to the optic nerve head and corresponding visual field loss. It is most commonly associated with elevated intraocular pressure (IOP), although it can occur at normal pressure levels (normal-tension glaucoma). The condition arises when intraocular fluid cannot drain properly through the trabecular meshwork, leading to a build-up of pressure. Over time, this elevated pressure damages the retinal ganglion cells and their axons that form the optic nerve, resulting in gradual and irreversible peripheral vision loss. The two main types are open-angle glaucoma (the most common, with slow progression) and angle-closure glaucoma (less common but can present as an acute emergency). Early detection through regular screening is critical because vision lost to glaucoma cannot be restored.
Symptoms
- Gradual loss of peripheral (side) vision, usually in both eyes
- Tunnel vision in advanced stages
- Severe eye pain and headache (acute angle-closure)
- Nausea and vomiting (acute angle-closure)
- Halos around lights
- Sudden blurred vision
- Redness of the eye
Open-angle glaucoma typically progresses without noticeable symptoms until significant vision loss has already occurred. Acute angle-closure glaucoma, by contrast, is a medical emergency with sudden and severe symptoms requiring immediate treatment.
Causes and Risk Factors
Glaucoma results from damage to the optic nerve, most often related to elevated intraocular pressure. The exact mechanism of nerve damage is not fully understood and likely involves both mechanical compression and reduced blood supply to the nerve. Risk factors include:
- Elevated intraocular pressure (above 21 mmHg)
- Age over 60 (risk increases significantly with age)
- Family history of glaucoma
- African, Hispanic, or Asian descent (depending on the type)
- High myopia (nearsightedness)
- Thin central corneal thickness
- Diabetes, hypertension, and cardiovascular disease
- Prolonged corticosteroid use
- History of eye trauma or surgery
Diagnosis
A comprehensive glaucoma evaluation includes several tests. Tonometry measures intraocular pressure. Gonioscopy examines the drainage angle to classify the type of glaucoma. Ophthalmoscopy (fundoscopy) assesses the optic nerve head for cupping, notching, or pallor. Optical coherence tomography (OCT) provides high-resolution imaging of the retinal nerve fiber layer and ganglion cell complex to detect early structural damage. Visual field testing (perimetry) maps the patient's field of vision to identify characteristic patterns of loss. Pachymetry measures corneal thickness, which can influence IOP readings. These tests are often repeated over time to monitor for progression.
Treatment
The goal of glaucoma treatment is to lower intraocular pressure to prevent further optic nerve damage. Treatment options include:
- Topical medications (eye drops) — prostaglandin analogs, beta-blockers, alpha-agonists, carbonic anhydrase inhibitors, and rho-kinase inhibitors
- Laser therapy — selective laser trabeculoplasty (SLT) for open-angle glaucoma or laser peripheral iridotomy (LPI) for angle-closure glaucoma
- Minimally invasive glaucoma surgery (MIGS) — iStent, Hydrus, or XEN gel stent implantation
- Traditional surgical procedures — trabeculectomy or tube shunt implantation for cases unresponsive to other treatments
- Cyclodestructive procedures for refractory glaucoma
Prevention and Recommendations
- Schedule regular comprehensive eye examinations, especially after age 40
- Inform your ophthalmologist about any family history of glaucoma
- Use prescribed eye drops consistently and as directed
- Avoid prolonged use of corticosteroid medications without medical supervision
- Protect your eyes from trauma by wearing appropriate eyewear
- Maintain a healthy lifestyle with regular exercise and balanced nutrition
- Seek immediate medical attention if you experience sudden eye pain, vision loss, or halos around lights