Ocular Hypertension

Ocular hypertension is a prevalent eye condition that affects millions of people worldwide. It is characterised by increased pressure within the eye, which can potentially lead to glaucoma if left unmanaged. Understanding the causes, symptoms, and available treatment options for ocular hypertension is crucial for maintaining healthy vision and preventing vision loss.

What is Ocular Hypertension?

Ocular hypertension refers to a condition where the pressure inside the eye, known as intraocular pressure (IOP), is higher than the normal range. The normal IOP range is typically between 10 and 21 mmHg. In ocular hypertension, the IOP consistently measures above 21 mmHg. This increased pressure occurs when the fluid in the eye, called aqueous humour, does not drain properly, leading to a buildup of pressure.

Ocular hypertension can affect one eye (unilateral) or both eyes (bilateral). It is essential to note that having elevated IOP does not necessarily mean that a person has glaucoma. However, ocular hypertension is a significant risk factor for developing glaucoma. Glaucoma is a serious eye condition that can cause irreversible damage to the optic nerve and lead to vision loss.

Unlike many other eye conditions, ocular hypertension does not present specific early signs that patients would typically notice. Since the condition is usually asymptomatic, it is often discovered during routine eye exams when the intraocular pressure (IOP) is measured. An IOP of 21 mmHg or higher is considered elevated and may indicate the presence of ocular hypertension. Regular eye examinations are the most reliable way to detect ocular hypertension in its early stages, allowing for timely intervention and management to preserve eye health.

Ocular hypertension, a condition characterised by elevated intraocular pressure (IOP), is often asymptomatic.

• Most people with ocular hypertension do not experience any noticeable symptoms, which is why regular eye examinations are essential for early detection.

• In rare cases, some individuals might experience occasional eye pain when moving or touching their eyes.

• However, these symptoms are not typical and can also be associated with other eye problems.

• The absence of apparent symptoms makes it crucial to attend routine eye check-ups to identify ocular hypertension and prevent potential complications.

While there are no distinct stages of ocular hypertension, eye doctors categorise the condition based on the level of risk for developing glaucoma. The ocular hypertension treatment study (OHTS) identifies patients with OHT who are at moderate risk for developing primary open-angle glaucoma (POAG). The management of ocular hypertension is tailored according to the patient's risk level:

• Low-Risk Patients: Regular monitoring and follow-up appointments with an eye doctor to assess the condition and adjust treatment as needed.

• Moderate-Risk Patients: Treatment with eye drops or other medications to lower IOP and reduce the risk of glaucoma.

• High-Risk Patients: More aggressive treatment, including surgery or laser therapy, to lower IOP and prevent glaucoma.

Ocular hypertension occurs when there is an imbalance between the production and drainage of aqueous humour. This imbalance can result from either an overproduction of aqueous humour or a blockage or malfunction in the eye's drainage system. Several factors can contribute to the development of ocular hypertension:

• Increased Fluid Production: In some cases, the eye may produce an excessive amount of aqueous humour. This leads to a buildup of pressure within the eye.

• Drainage Issues: A blockage or malfunction of the trabecular meshwork can prevent the aqueous humour from draining out of the eye effectively. This results in increased intraocular pressure.

• Age: The risk of ocular hypertension increases with age, particularly in individuals over 40 years old.

• Family History: Having a family member with ocular hypertension or glaucoma increases the likelihood of developing the condition.

• Medical Conditions: Certain health issues, such as diabetes and high blood pressure, can increase the risk of ocular hypertension.

• Medications: Long-term use of corticosteroids, either in the form of eye drops or oral medications, can lead to elevated intraocular pressure.

• Eye Trauma or Surgery: Previous injuries to the eye or certain eye surgeries can disrupt the balance of fluid production and drainage, potentially causing ocular hypertension.

Several factors can increase the risk of developing ocular hypertension, which may lead to glaucoma if left untreated. Some of the key risk factors include:

• Age: Individuals over 40 years old have a higher risk of developing ocular hypertension and glaucoma.

• Family History: If you have a family member with glaucoma or ocular hypertension, your risk is increased.

• Ethnicity: African Americans are more likely to develop glaucoma, possibly due to having thinner corneas, which can affect intraocular pressure (IOP) measurements.

• Intraocular Pressure: Higher IOP levels (e.g., 21-25 mmHg, 26-30 mmHg, or above 30 mmHg) are associated with an increased risk of glaucoma.

• Corneal Thickness: People with thinner central corneal measurements have a higher risk of developing glaucoma.

• Optic Disc Appearance: A larger vertical or horizontal cup-disc ratio may indicate an increased risk of glaucoma.

• Systemic Health Conditions: High blood pressure, diabetes, and obesity are linked to elevated IOP.

• Myopia: Axial myopia, or nearsightedness, is a risk factor for developing glaucoma.

• Previous Eye Conditions or Injuries: Uveitis, pigment dispersion syndrome, pseudoexfoliation syndrome, tumours, large cataracts, and previous eye injuries or surgeries can increase the risk of ocular hypertension.

While it may not be possible to completely prevent ocular hypertension, there are steps you can take to manage the condition. These measures can help reduce the risk of complications.

• Schedule Regular Eye Exams: Routine eye check-ups are essential for early detection and management of ocular hypertension, especially if you are over 40 or have other risk factors.

• Maintain a Healthy Lifestyle: Adopting a balanced diet, exercising regularly, and maintaining a healthy weight can help manage systemic health conditions that may contribute to elevated IOP.

• Protect Your Eyes: Wear protective eyewear when engaging in activities that may cause eye injuries, such as sports or certain occupations like construction, welding, carpentry, or laboratory work.

• Manage Underlying Health Conditions: If you have diabetes, high blood pressure, or other health conditions linked to ocular hypertension, it's important to manage them properly. Work closely with your doctor to keep these conditions under control.

• Follow Your Treatment Plan: If you are prescribed eye drops or other medications for ocular hypertension, use them consistently as your eye doctor directs.

• Quit Smoking: Smoking can increase the risk of developing eye conditions, so quitting may help protect your eye health.

If you notice symptoms like eye pain, headaches, or blurred vision or have risk factors for ocular hypertension, see your eye doctor. They may perform various tests to diagnose the condition:

• Tonometry: This test measures the pressure inside your eye (intraocular pressure or IOP). The most common method is applanation tonometry, where a small probe gently flattens a portion of the cornea. Another method is non-contact tonometry, which uses a puff of air to flatten the cornea.

• Ophthalmoscopy: Your eye doctor will use a special magnifying lens to examine the optic nerve for signs of damage or abnormalities.

• Gonioscopy: This test assesses the drainage angle between the iris and the cornea, where the aqueous humour normally drains from the eye.

• Pachymetry: This test measures the thickness of your cornea, which can affect IOP readings and help determine your risk of developing glaucoma.

• Visual Field Test: Also known as perimetry, this test evaluates your peripheral vision to detect any blind spots or areas of reduced sensitivity. It can indicate glaucomatous damage.

• Optical Coherence Tomography (OCT): This non-invasive imaging test uses light waves to create detailed images of the retina and optic nerve, helping to detect subtle changes that may indicate early glaucoma.

The treatment of ocular hypertension focuses on reducing intraocular pressure (IOP) to prevent glaucoma and vision loss.

1. Medical Treatment

• The primary goal of medical treatment for ocular hypertension is to reduce IOP to prevent or delay the onset of POAG.
• Topical ocular hypotensive medications aim to achieve an IOP of 24 mm Hg or lower, with at least a 20% reduction from baseline.
• Medications such as Prostaglandin analogues (e.g., latanoprost), Beta-blockers (e.g., timolol), and Alpha2 adrenergic agonists (e.g., brimonidine) are often prescribed.
• The choice of medication depends on the patient's specific needs, including the level of IOP, corneal thickness, family history, and life expectancy.
• Eye drops for ocular hypertension are a common treatment option, helping to reduce the risk of developing glaucoma.
• In addition to medical treatment, laser therapy may also be considered for managing ocular hypertension.

2. Laser Treatment

• Selective laser trabeculoplasty (SLT) is a clinically effective and cost-effective alternative to ocular hypotensive drops.
• It is recommended for patients with newly diagnosed ocular hypertension and an IOP of 24 mm Hg or higher. This is especially true for those at risk of visual impairment within their lifetime.
• Laser treatment can help lower IOP and reduce the need for daily eye drops in some patients.

3. Monitoring and Follow-Up

• Patients with ocular hypertension should be monitored regularly by a trained healthcare professional with a specialist qualification in glaucoma.
• This includes periodic evaluation of IOP, visual field tests, and assessment of the optic disc.
• The frequency of follow-up visits is determined based on the risk of conversion to POAG and the risk of sight loss.
• Regular monitoring is essential to detect any signs of ocular hypertension progressing to glaucoma and to adjust treatment as needed.

4. Risk Assessment

• Several factors are used to predict the risk of developing POAG in patients with ocular hypertension. These factors include age, IOP level, central corneal thickness, cup-disc ratio, and family history of glaucoma.
• These factors help clinicians decide on the appropriateness of initiating, continuing, or discontinuing treatment.
• Understanding the individual's risk profile is crucial for developing a personalised treatment plan and minimising the chances of vision loss due to glaucoma.

Living with ocular hypertension involves a proactive approach to maintain eye health and prevent the progression to glaucoma. Compliance with prescribed medications is crucial, as non-adherence can lead to increased IOP, optic nerve damage, and permanent vision loss. Patients must properly apply eye drops and follow their doctor's instructions regarding dosage and frequency.

Regular monitoring is essential for individuals with ocular hypertension. Patients should attend scheduled check-ups to monitor IOP, visual fields, and the appearance of the optic disc. These examinations help in the early detection of any changes that may indicate the development of glaucoma, allowing for prompt intervention.

While there is no specific diet proven to cure ocular hypertension, maintaining a healthy lifestyle is important. A balanced diet rich in nutrients like zinc and antioxidants may support overall eye health. Engaging in regular exercise, managing stress, and protecting the eyes from UV radiation are also beneficial practices.

Individuals with ocular hypertension should be aware of the potential signs and symptoms of glaucoma. These may include gradual vision loss, eye pain, headaches, and seeing halos around lights. Promptly reporting any changes in vision or ocular discomfort to an eye care professional is crucial for timely diagnosis and management.

Individuals with ocular hypertension should maintain regular follow-up appointments with their eye care provider as advised. However, certain situations warrant prompt medical attention:

• Sudden or severe eye pain

• Rapid vision loss or changes in vision

• Persistent eye redness or irritation

• Seeing halos around lights

• Headaches accompanied by nausea or vomiting