Secondary Glaucoma: Causes, Symptoms, and Treatment

Vision loss rarely happens overnight. It creeps in, sometimes unnoticed, until everyday tasks feel harder. Secondary glaucoma is one such silent threat. It damages the optic nerve, often due to increased eye pressure or inflammation from other eye conditions or injuries. Without timely care, it can lead to irreversible blindness.

What is Secondary Glaucoma?

Glaucoma is an eye condition that harms the optic nerve. It is usually linked to high eye pressure. While primary glaucoma develops without a known cause, secondary glaucoma occurs due to another medical issue, eye injury, medication, or abnormal blood vessel growth.

This type of glaucoma can strike at any age. It is not a single disease but a result of underlying problems. Unlike primary glaucoma, this condition does not develop on its own. The increased eye pressure may come from fluid build-up, blocked drainage, abnormal blood vessel growth, or inflammation. Over time, the optic nerve gets damaged, leading to gradual vision loss.

Types of Secondary Glaucoma

Secondary glaucoma is not a single condition. It has different forms. Each secondary glaucoma type is caused by a specific problem in the eye. The symptoms and progression vary based on the underlying issue.

• Neovascular glaucoma: Abnormal blood vessels grow in the eye, blocking fluid drainage. It often occurs in people with diabetes or after a blocked artery in the retina. This type is aggressive and can cause severe pain.
• Exfoliative glaucoma: A fibrillar (thread-like living tissue) material accumulates on the eye’s lens, iris, and drainage structures of the eye, impairing outflow and increasing pressure. It is more common in older adults and progresses gradually.
• Pigmentary glaucoma: Tiny pigment particles from the iris break off and block fluid outflow. It is often seen in younger, near-sighted individuals. Certain activities, such as vigorous exercise, may increase eye pressure by dislodging pigment granules from the iris, leading to temporary blockages.
• Uveitic glaucoma: Eye inflammation, known as uveitis, leads to swelling and scarring. These changes interfere with normal fluid drainage. Some treatments for uveitis, like steroids, may also raise eye pressure.
• Traumatic glaucoma: An eye injury, either from blunt force or penetrating trauma, can damage the drainage system. The effects may appear immediately or develop years later, making monitoring crucial.

Causes of Secondary Glaucoma

Secondary glaucoma develops due to an underlying condition. It is not a standalone disease but a complication of other eye or health issues. Identifying the root causes of secondary glaucoma is essential for effective treatment.

1. Eye injuries
   A direct blow to the eye can damage internal structures. This disrupts fluid drainage, leading to increased pressure. Trauma-related glaucoma may develop immediately or years later.
2. Inflammatory eye diseases
   Conditions like uveitis cause swelling inside the eye. Inflammation blocks the natural drainage pathway, causing fluid build-up. Some treatments for uveitis, such as steroids, may also raise eye pressure.
3. Diabetes and vascular disorders
   High blood sugar levels can damage blood vessels in the eye. This can trigger neovascular glaucoma, where new blood vessels obstruct drainage. Retinal vein blockages can have a similar effect.
4. Cataract or eye surgery complications
   An advanced cataract may contribute to secondary glaucoma by blocking the drainage angle, (phacomorphic glaucoma). Post-surgical swelling or scarring can also interfere with fluid flow, causing secondary glaucoma.
5. Medicines
   Long-term steroid use, whether in eye drops, tablets, or inhalers, may elevate eye pressure. Certain drugs prescribed for other medical conditions can also contribute to glaucoma development.
6. Tumours and abnormal growth
   Rarely, eye tumours or cysts can physically obstruct the drainage system. This leads to fluid build-up and persistent pressure spikes.

Symptoms of Secondary Glaucoma 

Changes in vision often go unnoticed until they disrupt daily life. Secondary glaucoma progresses silently in some cases, while in others, secondary glaucoma symptoms appear suddenly. The warning signs depend on the underlying cause and how quickly eye pressure rises.

Blurry vision is a common early symptom, but its onset varies. Some people notice halos around lights, making night driving difficult. Colours may appear dull, and contrast sensitivity might reduce. A feeling of heaviness or discomfort in the eye can also develop.

As pressure builds up, pain becomes more noticeable. Some experience headaches that do not respond to usual painkillers. Redness in the affected eye is another warning sign, often accompanied by excessive watering or irritation.

Diagnosing Secondary Glaucoma 

An eye pressure test, known as tonometry, measures intraocular pressure. Higher-than-normal readings suggest fluid build-up. However, pressure levels alone are not enough to diagnose glaucoma. A detailed eye examination is necessary.

A slit-lamp test allows doctors to examine the front part of the eye. This helps identify inflammation, pigment deposits, or structural abnormalities that could be causing pressure changes. Gonioscopy and optic nerve evaluation are key tests for assessing drainage pathways and optic nerve health.

Visual field tests assess peripheral vision loss, while optical coherence tomography (OCT) scans provide high-resolution images of the optic nerve. 

Treatment for Secondary Glaucoma

Managing secondary glaucoma requires addressing both the underlying cause and elevated eye pressure. The secondary glaucoma treatment plan varies based on severity, symptoms, and overall eye health.

Eye drops are the first line of defence. They reduce fluid production or improve drainage, helping to lower pressure. In some cases, oral medications may be prescribed to enhance this effect. However, not all cases respond to medication alone.

If pressure remains high, laser procedures can help. Selective laser trabeculoplasty (SLT) is effective in some forms of secondary glaucoma by improving fluid drainage, while laser cyclophotocoagulation is used in severe or refractory cases to reduce fluid production.

Surgery becomes necessary when other secondary glaucoma treatments fail. Trabeculectomy modifies the eye’s drainage pathway to lower pressure, while shunt implants provide an alternative drainage route. In trauma or tumour-related cases, specialised procedures may be required.

Can Secondary Glaucoma Be Prevented? 

Regular eye check-ups play a crucial role. Early detection of conditions like uveitis, diabetes-related eye disease, or cataracts helps prevent complications. Controlling blood sugar levels and maintaining overall health can also protect eye function.

Avoiding prolonged steroid use is another preventive measure. If steroids are necessary, regular monitoring ensures any pressure changes are caught early. People with a history of eye injuries should stay vigilant, as trauma-related glaucoma can develop years later.

Protecting the eyes from injury matters too. Safety goggles during sports or hazardous activities reduce the risk of trauma. Managing inflammation and infections promptly prevents long-term damage that could lead to pressure build-up.