Glaucoma Awareness Month: Cataract vs Glaucoma - What's the difference?

January is Glaucoma Awareness Month, a dedicated time to raise awareness about this often-silent eye condition that can lead to irreversible vision loss. World Health Organization estimates that over 80 million people are suffering from Glaucoma worldwide while 4.5 million people have gone blind due to the eye disease, making it the second leading cause of blindness in the world. In the United States alone, over 3 million people have Glaucoma and according to the National Eye Institute, this number will reach 4.2 million by 2030, projecting a 58 per cent increase.

Amidst the focus on Glaucoma during Glaucoma Awareness Month, it's essential to also shed light on another common eye ailment, i.e. Cataracts, and understand the differences between the two.

Glaucoma: The Silent Thief of Sight

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Glaucoma is a group of eye conditions that damage the optic nerve, leading to progressive vision loss. Often referred to as the "silent thief of sight", Glaucoma typically presents no symptoms in its early stages, making regular eye exams crucial for early detection.

Types of Glaucoma

1. Primary Open-Angle Glaucoma (POAG): This is the most common type and occurs when the drainage channels within the eye become clogged over time, increasing intraocular pressure.
2. Angle-Closure Glaucoma: Less common, this type occurs when the iris blocks the drainage angle of the eye, leading to a sudden increase in intraocular pressure (IOP).
3. Normal-Tension Glaucoma: In this variation, optic nerve damage occurs despite normal intraocular pressure. The reasons behind this phenomenon are still being studied.
4. Secondary Glaucoma: This type of eye condition refers to any case in which another disease causes or contributes to increased eye pressure, resulting in optic nerve damage and vision loss.

There are several other less common types of Glaucoma including Congenial Glaucoma, Exfoliative Glaucoma, Neovascular Glaucoma, Traumatic Glaucoma, and Uveitic Glaucoma.

Risk Factors

• Age
• Family history
• Elevated intraocular pressure
• Ethnicity (African Americans and Hispanics are at higher risk)
• Medical conditions like diabetes and heart disease

Types of Glaucoma Tests

In an exclusive conversation with WION, Dr Deepak Sadarangani (Consultant, Ophthalmology - Jaslok Hospital & Research Centre, Mumbai) shared details of five common tests available to diagnose Glaucoma. He revealed that depending on the symptoms, your healthcare provider may prescribe a combination of the tests mentioned below.

Dilated eye exam (Ophthalmoscope): A dilated eye exam helps view the optic nerve.

Gonioscopy: The purpose of a gonioscopy is to examine the angle where your cornea and iris intersect.

Pachymetry: A pachymetry involves using a pachymeter tool to help measure corneal thickness.

Perimetry: Also called a visual field test, the perimetrytest makes a detailed record of your visual fields.

Tonometry: A tonometry test measures pressure in your eye.

Dr Deepak stressed, "Glaucoma doesn't always cause noticeable symptoms in its early stages, so testing can help detect it before it progresses to a more advanced stage."

Prevention and Treatment

Regular eye check-ups are vital for early detection, especially for those at higher risk. Treatment often involves medication to reduce intraocular pressure, laser therapy, or surgical procedures to improve fluid drainage.

Cataracts: Clouding the Lens

Cataracts, on the other hand, involve the clouding of the eye's natural lens, affecting vision. While Glaucoma is related to increased intraocular pressure, Cataracts have a different mechanism.

Causes of Cataracts

• Ageing (most common cause)
• Diabetes
• Smoking
• Prolonged exposure to sunlight
• Certain medications

Symptoms of Cataracts

• Blurred or hazy vision
• Sensitivity to light
• Difficulty seeing at night
• Fading or yellowing of colours
• Frequent changes in prescription glasses

Prevention and Treatment

Preventing Cataracts involves lifestyle choices such as protecting your eyes from harmful UV rays, maintaining a healthy diet, and managing conditions like diabetes. Surgical removal of the cloudy lens and replacing it with an artificial one is a common and effective treatment for cataracts.

Distinguishing the Differences

1. Affected Structures: While Glaucoma primarily affects the optic nerve due to increased intraocular pressure, Cataracts involve clouding of the eye's natural lens.
2. Symptoms: Glaucoma is often asymptomatic in the early stages and causes peripheral vision loss in later stages. On the other hand, Cataracts cause gradual vision changes, including blurred or hazy vision.
3. Detection: Glaucoma can be detected through regular eye exams, including measurement of intraocular pressure. Meanwhile, Cataracts are detected through a comprehensive eye examination.

Speaking exclusively to WION, Dr Janhvi Mehta (Consultant, Ophthalmology - Jaslok Hospital & Research Centre, Mumbai) explained, "Cataracts are usually painless and progress gradually, while Glaucoma on the other hand can be both slow and subtle or painful and quick. If you have Cataracts, you suffer from a change in the lens. The cloudiness causes the light to not be seen properly. Glaucoma is the damage of the optic nerve, which is an important part of how the brain processes the information you see due to an increase in eye pressure or sometimes not. Glaucoma is more likely to cause blindness and the blindness is irreversible, so treatment is vital."

Understanding the differences between these two eye conditions empowers all of us to take proactive steps to preserve our vision. Whether it's the silent progression of Glaucoma or the gradual clouding of Cataracts, early detection and appropriate management are key to maintaining eye health and preventing permanent vision loss.

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