Eales disease¹ is a rare eye condition that causes inflammation and blockage of the retinal blood vessels, which can eventually lead to new abnormal vessels and vision loss. It mostly affects young adults and is more common in countries where Tuberculosis (TB) is common.² Eales disease shares many signs with TB-related eye problems, so it can be a challenge to diagnose early. The lack of a single test to confirm the disease, together with limited access to specialist care in many TB-endemic areas, makes early recognition even harder. Since detecting the disease quickly is key to preventing serious vision damage, it is important to understand the challenges faced in making an early diagnosis. 

Clinical Overlap with Tuberculosis (TB)

One of the biggest challenges in the early diagnosis of Eales disease is that symptoms can look similar to eye problems caused by tuberculosis (TB). Both conditions can cause inflammation in the retina, blockage of blood vessels, and even new abnormal vessel growth. Such overlap makes it hard for doctors to know whether a patient has Eales disease, TB-related eye disease, or both.

Tests that are often used to check for TB, such as the tuberculin skin test or interferon-gamma release assays (IGRAs), are not always reliable in countries where TB is common. Many people in these areas may test positive because they were exposed to TB in the past, even if their current eye problem is not caused by it. As a result, patients may be misdiagnosed and either placed on unnecessary TB treatment or miss out on the right treatment for Eales disease.

As there is no single test that clearly separates Eales disease from TB-related eye disease, doctors must rely on a combination of patient history, test results, and eye examinations. This overlap makes early diagnosis difficult and often leads to delays in treatment.

Lack of Definitive Diagnostic Tests

Another major challenge in diagnosing Eales disease early is that there is no single test that can confirm it. Doctors usually make the diagnosis by ruling out other possible causes of retinal inflammation, which takes time and can be uncertain.

The tests that are currently available are helpful but not specific. For example, eye imaging such as fluorescein angiography and optical coherence tomography (OCT) can show areas of inflammation and blocked blood vessels, but these changes are also seen in other diseases. TB tests like the tuberculin skin test and interferon-gamma release assays (IGRAs) are widely used, but in TB-endemic regions, many people will test positive even without active TB. This makes it hard to know if TB is actually responsible for the eye disease. Without a reliable biomarker or specific test, early recognition remains very difficult, especially in regions where TB is widespread.

Geographic and Resource Constraints

In many TB-endemic regions, healthcare systems face resource limitations that make early diagnosis of Eales disease even harder. Advanced eye imaging tools like fluorescein angiography and OCT may only be available in large hospitals or urban centres, leaving patients in rural areas without access to them. This often leads to delays, as patients may need to travel long distances to see a specialist.

There is also a shortage of trained retinal specialists in many of these regions. General doctors or basic eye care providers may not be familiar with the early signs of Eales disease, which can result in misdiagnosis or late referral. In addition, healthcare systems in resource-limited settings may prioritise infectious diseases like TB itself over rarer conditions such as Eales disease, further contributing to delayed recognition.

These geographic and resource challenges mean that patients often present at later stages of the disease, when complications such as bleeding or scarring have already occurred and treatment options are more limited.

Patient-Related Factors

Patients themselves may also face barriers that delay the early diagnosis of Eales disease. In the early stages, symptoms like mild floaters or slight blurring of vision may not seem serious, so many people delay seeking medical help until the disease has progressed. By this time, damage to the retina may already be advanced.

Socioeconomic barriers also play a role. In TB-endemic regions, many patients cannot afford specialist eye care or the costs of traveling to major hospitals. This often results in late presentation or missed follow-up appointments.

Stigma surrounding tuberculosis can add another layer of difficulty. As Eales disease is sometimes linked with TB, patients may be reluctant to share their history of TB infection or exposure, which can make it harder for doctors to reach the right diagnosis.

Together, these patient-related factors contribute to delays in diagnosis and treatment, making it less likely that the disease will be caught at an early, more manageable stage.

Implications of Delayed or Incorrect Diagnosis

If Eales disease is not diagnosed early, the condition can progress to more severe stages. Blocked blood vessels in the retina reduce blood supply, leading to ischemia, which then triggers the growth of abnormal new vessels. These fragile vessels can easily bleed into the eye (vitreous hemorrhage), causing sudden vision loss. In advanced cases, scarring and retinal detachment may occur, which can result in permanent blindness.

Misdiagnosis is another serious issue associated with Eales disease. In TB-endemic regions, patients may endure long courses of anti-tubercular therapy (ATT) if their eye condition is mistaken for TB-related disease. This exposes patients to the side effects of strong medications without addressing the real cause of their symptoms. On the other hand, if Eales disease is overlooked, patients may miss out on timely treatment with corticosteroids, immunosuppressants, or laser therapy that could help preserve their vision.

Therefore, delayed or incorrect diagnosis not only worsens patient outcomes but also increases the overall healthcare burden in regions where resources are already limited.

Potential Strategies to Improve Early Diagnosis

Improving the early detection of Eales disease in TB-endemic regions requires changes at several levels. First, raising awareness among healthcare providers is essential. Training general doctors and basic eye care providers to recognise the early signs, such as retinal vein inflammation or unexplained floaters in young adults, could lead to faster referrals to specialists.

Furthermore, better diagnostic tools are needed. Research into specific biomarkers or clearer diagnostic criteria could help separate Eales disease from TB-related eye problems. Integrating TB screening with eye care services may also reduce confusion, especially in areas where both conditions are common.

Strengthening healthcare systems can also improve treatment. Expanding access to imaging technologies like OCT and fluorescein angiography in regional centers, as well as increasing the number of trained retinal specialists, would help increase earlier diagnosis for patients in rural or underserved areas. 

Finally, educating patients is equally important. Public health campaigns that encourage people to seek medical attention for early eye symptoms could reduce delays in diagnosis and treatment, improving long-term outcomes.

Summary

Early diagnosis of Eales disease in TB-endemic regions is challenging due to overlapping symptoms with TB, lack of specific tests, limited healthcare resources, and patient-related barriers. These challenges often lead to delayed treatment, which increases the risk of serious vision loss. Addressing these issues through improved awareness, better diagnostic tools, strengthened healthcare systems, and patient education is essential. By focusing on these strategies, it is possible to detect Eales disease earlier and provide timely treatment, ultimately reducing preventable blindness in affected populations.

• Eales disease is a retinal vasculitis that can lead to vision loss and is more common in TB-endemic regions, but early diagnosis is difficult
• Its symptoms overlap with TB-related eye disease, making it hard to distinguish between the two conditions
• There is no definitive diagnostic test; diagnosis relies on exclusion, clinical examination, and imaging, which may be limited in low-resource areas
• Delayed or incorrect diagnosis can result in severe complications, including vitreous hemorrhage, retinal detachment, and unnecessary anti-TB treatment
• Improving early detection requires better awareness among healthcare providers, development of specific diagnostic tools, stronger healthcare infrastructure, and patient education