Different Types of Glaucoma | Eye & Retina Surgeons

Glaucoma is one of the leading causes of permanent blindness globally and in Singapore. Its prevalence increases with age, and genetics play a significant role, with individuals who have a family history being at a higher risk.

While elevated intraocular pressure (IOP) is a major risk factor that can damage the optic nerve (making IOP-lowering a key treatment), some glaucoma cases involve normal eye pressure. Though incurable, glaucoma is manageable and timely treatment can often prevent further vision loss.

Primary Glaucoma

Primary glaucoma develops independently, without underlying eye diseases or systemic conditions triggering their onset.

Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) or chronic glaucoma is the most common form of glaucoma and a major cause of irreversible blindness. Unlike other eye diseases, it progresses silently. There are no warning signs until significant, often irreversible damage has occurred. Peripheral vision typically deteriorates first, narrowing sight over time.

Normal-Tension Glaucoma

Normal-tension glaucoma, also known as low tension or normal pressure glaucoma, is a form of open-angle glaucoma in which damage occurs to the optic nerve without eye pressure exceeding the normal range. The condition is associated with diseases such as high blood pressure, diabetes, and sleep apnoea.

Angle-Closure Glaucoma

Closed-angle or narrow-angle glaucoma occurs when the angle between the cornea and the iris is very narrow, or even closed. Unlike POAG's open drainage system, angle-closure involves physical blockage of the drainage pathway.

Secondary Glaucomas

Secondary glaucomas develop as a consequence of other eye diseases, systemic conditions, or external factors. They are usually caused by eye injuries, eye surgeries, and other eye conditions.

Uveitic Glaucoma

This condition arises from inflammation within the eye (uveitis), which can both damage and obstruct the eye's natural fluid drainage pathway, leading to elevated intraocular pressure (IOP). Specifically, the inflammation itself can directly harm the drainage structures, while the accumulation of inflammatory cells and debris can clog the drainage system, impeding fluid outflow.

Neovascular Glaucoma

Noted as one of the most severe forms of glaucoma, neovascular glaucoma occurs when new blood vessels grow in areas where they should not, such as the drainage area of the eye. It is often caused by other serious health problems, such as diabetic retinopathy, retinal vein blockages, or carotid artery disease.

Traumatic Glaucoma

Eye injuries can lead to traumatic glaucoma, which may develop suddenly or gradually, making it hard to detect in the early stages. Blunt trauma is a common cause, often resulting from sports like boxing, basketball, or baseball. Penetrating injuries from sharp objects or debris can also trigger this condition.

Childhood Glaucoma

Although paediatric glaucoma is uncommon, it is a serious condition. Unlike adults, children may not be able to express vision problems, and symptoms may be overlooked.

Congenital Glaucoma

Congenital glaucoma is a rare condition. It happens when the eye's drainage system does not develop properly before birth, causing high eye pressure. This often shows up in babies around 3 to 9 months old. Common signs include cloudy eyes or sensitivity to light.

Juvenile Open-Angle Glaucoma

Juvenile glaucoma manifests between the ages of 4 and 40, bridging childhood and adult-onset types. It frequently exhibits a stronger genetic link compared to the more common primary open-angle glaucoma (POAG). This condition leads to progressive optic nerve damage, which can ultimately result in vision loss.

Treatments for Different Types of Glaucoma

Treatment approaches for glaucoma vary significantly, depending on the type of glaucoma, its severity, and individual patient factors. The primary goal of treatment is to lower intraocular pressure (IOP) to a target level, thereby preventing further optic nerve damage and preserving vision.

Eye Drops to Lower IOP

Topical medications are a common first-line treatment for most types of glaucoma. Various drug classes work through different mechanisms to lower intraocular pressure.

These include:

Prostaglandins – These medications work by increasing the outflow of fluid from the eye.
Beta-blockers – These medications primarily reduce the production of fluid within the eye.
Alpha-agonists – These medications typically decrease fluid production and can also increase fluid outflow from the eye.

Glaucoma Surgery

When medications prove insufficient, glaucoma surgery may be the best option. Common surgical procedures for glaucoma include:

Laser Therapy – In this procedure, the surgeon utilises a tiny laser to treat the area where the iris and cornea meet – the eye's natural drainage angle. The laser helps improve fluid outflow, allowing the intraocular pressure to decrease.
Trabeculectomy – This glaucoma surgery creates a new drainage pathway (sclera), allowing the fluid to bypass the eye's natural drainage system.
Drainage Implants – Glaucoma drainage devices (tubes or shunts) provide controlled outflow when conventional surgery fails or carries high risk.

Why Early Detection Is Important

Glaucoma's silent progression makes early detection critical, particularly in its initial stages. Once optic nerve damage occurs, the resulting vision loss is irreversible.

If you believe you are at risk of developing glaucoma, we invite you to visit our eye clinic for a comprehensive and personalised assessment. Eye & Retina Surgeons (ERS) is here to guide you through every step, from diagnosis and treatment to post-treatment care. Contact us today to schedule an appointment.