Understanding Glaucoma: Early Detection and Effective Management - Dr Prerna Ojha
Glaucoma comprises a range of eye conditions that result in damaged optic nerve, which connects the eye to the brain. If left untreated, it can lead to irreversible vision loss and blindness. This damage occurs because the fluid inside the eye, known as aqueous humour, doesn't drain properly, causing an increase in intraocular pressure (eye pressure) that harms the optic nerve. However, when identified early and managed effectively, the advancement of the disease can often be slowed or halted, thus averting blindness in most cases.
Prevalence
Glaucoma stands as the second leading cause of irreversible blindness globally, affecting around 11 million individuals, with an alarming statistic that 1 million of those afflicted are unaware and untreated. In India, the prevalence is significant, with nearly one in every eight individuals aged 40 or above either suffering from glaucoma or at risk of developing it. Glaucoma manifests in various forms, primarily as primary glaucoma, where no specific cause is discernible, or as secondary glaucoma, triggered by other eye conditions like trauma, inflammation, or surgical procedures.
While elevated intraocular pressure (IOP) is a recognized risk factor for glaucoma, the condition can also arise in individuals with normal IOP levels, impacting their vision and contrast sensitivity. Glaucoma is broadly categorized into two types: open-angle glaucoma, characterized by a wide-open angle for fluid drainage, and closed-angle glaucoma, where the drainage angle is closed. Notably, closed-angle glaucoma prevails more commonly in India, especially among women. Although the precise reasons remain elusive, women, often noted for having smaller eyes, face a twofold increased risk compared to open-angle glaucoma.
Although glaucoma typically affects individuals beyond their fourth decade, it can also manifest in newborns, infants, and young children. Some newborns are born predisposed to glaucoma, exhibiting enlarged eyes and excessive tearing, known as congenital glaucoma, while others develop the condition later in life.
Types of Glaucoma
Primary glaucoma can be further divided into two main types: open-angle and angle-closure.
- Primary Open-Angle Glaucoma (POAG): This is the most common type of glaucoma. It develops slowly over time as the drainage canals in the eye become clogged, leading to a gradual increase in IOP. POAG is often called the "silent thief of sight" because it progresses with few symptoms until significant vision loss occurs. Symptoms include Gradual loss of peripheral vision and Tunnel vision in the advanced stages.
- Primary Angle-Closure Glaucoma (PACG): This type occurs when the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris. This blockage can cause a rapid increase in IOP, leading to an acute angle-closure glaucoma attack, which is a medical emergency. Symptoms include Sudden, severe eye pain, Nausea and vomiting, Blurred vision, Halos around lights, and Reddening of the eye.
2. Congenital Glaucoma
Congenital Glaucoma is a rare form that occurs in infants and young children. It is usually diagnosed within the first year of life. This type of glaucoma is often the result of an abnormal development of the eye’s drainage system before birth, leading to an increase in intraocular pressure.
Symptoms include Enlarged eyes, Excessive tearing, Sensitivity to light (photophobia) and Cloudy cornea.
3. Secondary Glaucoma
Secondary Glaucoma results from an underlying condition or factor that increases IOP and damages the optic nerve. It can be associated with eye injuries, inflammation, tumours, or advanced cases of cataracts or diabetes. It can also result from the use of certain medications, such as corticosteroids.
Types of Secondary Glaucoma:
- Steroid-Induced Glaucoma: Prolonged use of corticosteroids can lead to increased IOP. This type of glaucoma is preventable by monitoring and managing steroid use.
- Traumatic Glaucoma: Eye injuries can damage the eye’s drainage system, leading to elevated IOP. Trauma can cause immediate or delayed onset of glaucoma.
- Neovascular Glaucoma: Abnormal blood vessel growth blocks the eye's drainage channels, commonly associated with conditions like diabetes or retinal vein occlusion.
Symptoms vary depending on the underlying cause. Although, common signs include eye pain, redness, blurred vision, and halos around lights.
Who are at risk of developing primary glaucoma? Who needs to be evaluated to pick up or rule out glaucoma?
While glaucoma poses a risk to anyone, individuals with a family history face a heightened susceptibility. Specific types of glaucoma are more prevalent among different racial or ethnic groups, as well as individuals with high myopia (short-sightedness) and older adults. Those with a family history of glaucoma are at a tenfold increased risk of developing the condition. Therefore, it's crucial for all blood relatives, including parents and siblings, to undergo early screening for the detection of glaucoma.
Who are at risk of secondary glaucoma?
One out of every four patients diagnosed with secondary glaucoma in clinics is typically suffering from steroid-induced glaucoma. This condition occurs when the use of steroids, whether for treating red eyes, eye allergies, or other non-eye-related ailments, leads to increased intraocular pressure (IOP). Such instances are entirely preventable. Another preventable cause of secondary glaucoma is eye trauma, commonly resulting from accidents involving balls, road incidents, or injuries sustained during festive events like Diwali. Even seemingly minor injuries caused by hand or fist can potentially alter internal eye structures, predisposing individuals to glaucoma, either immediately or later on. Additionally, any intraocular surgery, particularly those involving corneal transplants, retinal procedures, or cataract surgeries, can elevate the risk of glaucoma development.
Detection
The most effective method for detecting glaucoma, particularly in those with a family history or risk factors, is through comprehensive eye examinations. Individuals aged 40 and above, as well as those with a history of diabetes or high blood pressure, should undergo regular comprehensive eye check-ups with a glaucoma specialist to facilitate early detection or ruling out of glaucoma. Early identification and intervention are paramount in preventing the progression to blindness.
Comprehensive eye testing encompasses various assessments, including vision testing, intraocular pressure (IOP) measurement, gonioscopy to evaluate the drainage angle of the eye, and dilated eye examinations to assess the optic nerve. Glaucoma typically impacts peripheral vision initially, progressing to affect central vision in advanced stages. This subtle onset often leads patients to mistakenly believe their eye health is unaffected, highlighting the necessity of perimetry to map the field of vision and detect any glaucomatous changes. Even in the absence of visual field abnormalities, glaucoma may still be present and necessitates repeated testing to monitor progression.
Treatment
Antiglaucoma medications aim to reduce elevated IOP, thereby preserving vision and preventing blindness. Surgical interventions may be recommended if medication fails to adequately control glaucoma. Regular eye examinations, IOP monitoring, and visual field testing are imperative for treatment compliance and tracking disease progression.
Avoiding over-the-counter steroid use, especially in children and individuals with a family history or risk factors, is crucial. Protecting the eyes from injury, particularly for those wearing high-powered glasses or engaging in contact sports, is essential. Any individual with a history of recent or previous eye trauma should undergo a thorough examination for glaucoma risk assessment.
Children exhibiting symptoms such as light sensitivity, reduced vision, or enlarged eyes should undergo evaluation by a glaucoma specialist. Additionally, individuals experiencing symptoms like redness, pain, watering, rainbow-coloured halos around lights, headache, or nausea should be promptly examined for glaucoma, especially the closed-angle variety.
Given the increasing lifespan and the rising incidence of glaucoma alongside other age-related conditions, timely diagnosis and appropriate management are critical in preventing blindness. Since glaucoma typically progresses without symptoms, early detection and treatment are essential for preserving vision. Although the disease is incurable, effective treatment, whether medical or surgical, can help manage it and prevent further vision loss.