Introduction

Eales' disease is a retinal condition most commonly observed in young people assigned male at birth (AMAB)  from South Asia.¹ It is characterised by inflammation of the retinal blood vessel walls, often leading to vessel blockage.¹ The exact cause of the disease remains unknown. Early diagnosis and careful monitoring are essential to prevent serious vision loss. Recent advances in medical imaging, particularly Optical Coherence Tomography (OCT), have significantly improved the diagnosis and management of Eales disease. As a non-invasive imaging technique, OCT provides high-resolution, cross-sectional images of retinal tissues, allowing clinicians to detect structural changes and guide treatment decisions effectively.

What is eales' disease?

Eales' disease is an inflammatory occlusive disorder characterised by inflammation of the retinal blood vessels.¹ Retinal changes associated with the condition include perivascular inflammation, areas of the retina with reduced or absent blood flow (nonperfusion), and the growth of abnormal new blood vessels (neovascularisation).³ In severe cases, the disease can lead to vision loss due to recurrent vitreous haemorrhage.³ It was first described in 1880 by Sir Henry Eales, who noted it as an idiopathic (cause unknown) blood vessel disease of the retina that often presented with recurrent vitreous haemorrhage, along with symptoms such as headaches, constipation, and nosebleeds.¹ Eales initially thought it was a vasomotor neurosis, but later Wardsworth identified it as retinal inflammation.³ The cause of the condition is unknown, but some associate the condition with tuberculosis and hypersensitivity to tuberculoprotein. Additionally, there were observations of high positive tuberculosis tests in patients with Eales disease. Diagnosing the disease is essential for guiding further research and informing clinical evaluation.⁴

Demographic factors

Eales disease is most commonly observed in young people AMAB, with the highest prevalence reported in Asia, particularly the Indian subcontinent.¹ Historically, cases were also documented in countries such as the United Kingdom, the United States, and Canada during the late nineteenth and early twentieth centuries. Today, the disease is rare in developed nations and is predominantly seen in South Asia. In India, approximately one in every 200 to 250 patients visiting eye clinics is diagnosed with Eales disease. Men between the ages of 20 and 40 are most frequently affected. The condition is bilateral in about 90 per cent of cases, although around 10 per cent of patients have only one eye affected, and asymmetric involvement of both eyes is relatively common.³ While paediatric cases can occur, they are very rare.¹

Symptoms 

The symptoms of Eales disease include:

• Vitreous Haemorrhage
• Reduction in visual acuity 
• Headache 
• Constipation
• Nosebleeds (Epistaxis)
• Blurry vision 
• Vision loss 

Stages of the disease

Inflammatory stage (periphlebitis)

The inflammation stage is characterised by periphlebitis, meaning inflammation of the veins in the retina. Veins are mostly affected, though small arteries can sometimes be involved. Inflammation can occur in multiple areas of the retina at the same time. Signs of inflammation include fuzzy deposits around blood vessels, venous dilation and small bleeding spots in the retina. It mostly occurs in the peripheral and foveal (middle) retina.¹

Occlusive stage (ischemia)

The main feature is capillary ischemia, meaning tiny blood vessels are blocked and the retina isn’t getting enough oxygen. Signs include venovenous shunts and venous beadings. Ischemia causes the eye to produce vascular endothelial growth factor (VEGF), which can lead to acular oedema and abnormal growth of blood vessels.¹

Proliferative stage (neovascularisation, retinal haemorrhage):

The main feature of this stage is neovascularisation, which is the growth of blood vessels occurring at the boundary of the retina. These new vessels lead to bleeding in the vitreous humour of the eye. New vessels may also form in the iris.¹

Overview of OCT technology

Optical Coherence Tomography (OCT) is a non-invasive imaging technique that uses light waves to generate high-resolution, cross-sectional images of tissues. Often described as an “optical biopsy,” OCT allows clinicians to visualise retinal structures layer by layer.²

OCT comes in several different types, including:

• Time domain is an early form of OCT that uses a low-coherence interferometer to detect the time delay and intensity of light reflected from various tissue layers, creating two-dimensional images ⁹
• Spectral-domain OCT (SD-OCT) is a second-generation OCT technology that offers much faster image capture, improved tissue penetration, and higher-resolution images.
• SS-OCT is an advanced noninvasive imaging technique that uses a wavelength-sweeping laser with a single dual-balanced photodetector to capture high-resolution images of the anterior segment, retina, optic nerve, and choroid ⁹
• OCT angiography (OCTA) is a noninvasive imaging method that provides three-dimensional images of blood vessels at different tissue levels within the retina and choroid ⁹

OCT uses visible and infrared light, making it safe and non-invasive. It provides detailed cross-sectional views and high-resolution images, which makes it superior to many traditional imaging techniques.⁹

The Role of OCT in the diagnosis and monitoring of eales disease

OCT plays a crucial role in the early diagnosis and ongoing management of Eales disease. By providing high-resolution, cross-sectional images of the retina, OCT can detect changes such as macular oedema, thinning, or other retinal alterations even before patients experience noticeable vision problems.⁹ According to the scientific literature, some eyes develop macular changes, with macular oedema being the most common finding.¹⁰

OCT is also valuable in assessing retinochoroidal vascular changes without the need for intravenous dye. Unlike fluorescein angiography, which requires temporary chemical staining, OCT captures repeated cross-sectional images to map blood flow noninvasively. This makes it more sensitive than clinical examination alone in identifying early retinal involvement.¹¹

In addition to diagnosis, OCT is essential for monitoring disease progression and treatment response in Eales disease. Sequential OCT scans allow clinicians to track changes in retinal anatomy, thickness, and fluid accumulation over time. This real-time assessment helps determine the effectiveness of medical therapies, guides the timing of surgical interventions, and ensures the integrity of critical retinal layers, including the photoreceptors.⁹

For patients undergoing treatment, OCT can be used to observe macular changes, guide follow-up intervals, and detect early signs of neovascularisation, thereby reducing the risk of complications such as retinal detachment.

Advanced OCT techniques, such as EDI-OCT, SS-OCT, and OCTA (see above), can provide further insights into vascular changes associated with Eales disease. Among these, OCTA is particularly valuable as it allows noninvasive visualisation of retinal and choroidal vasculature.⁹

OCT angiography (OCTA) in eales disease

OCTA is a noninvasive imaging technique that creates three-dimensional images of blood vessels in the retina and choroid. Unlike traditional angiography (fluorescein or indocyanine green), OCTA does not require the injection of dye/contrast into the bloodstream, making it safer and quicker. The technology works by detecting tiny changes in the OCT signal caused by the movement of red blood cells compared to the surrounding static tissues. This allows OCTA to produce highly detailed maps of blood vessels across different layers of the retina and choroid in a single scan. In addition to being safer, OCTA is particularly valuable for identifying early microvascular changes. As such, OCTA has become an essential tool for diagnosing and monitoring vascular retinal diseases like Eales disease.^9.

Limitations of OCT in eales disease

OCT is widely recognised as a valuable diagnostic tool and has no absolute contraindications. However, because OCT depends on light passing through the eye and reflecting from the retina, any opacity in the ocular media can reduce image quality. Therefore, OCT may be less effective in patients with congenital or acquired corneal opacities, cataracts, or vitreous haemorrhage.⁹

Although OCT provides detailed structural information, it cannot replace the need for a thorough medical history and comprehensive ophthalmoscopic examination.⁹ Moreover, OCT is unable to measure vascular leakage directly, limiting its usefulness in assessing such conditions as macular oedema and retinal vein occlusion.¹²

OCTA, while offering noninvasive vascular imaging, also has certain limitations. Image artefacts may occur due to eye movements, errors in image processing, or display distortions. Additionally, specific ocular features can contribute to artefacts. For example, in patients with high myopia (short sight), the refractive error may cause OCTA light beams to strike the retina at an angle, resulting in a distorted image.¹²

Future work 

While OCT and OCTA have already enhanced the diagnosis and monitoring of Eales disease, there remains considerable scope for further development. Future work might explore whether multimodal OCT imaging can provide a more reliable alternative to fluorescein angiography in detecting ischemic and proliferative changes, especially in patients where dye-based angiography is not recommended. Moreover, integrating OCT with machine learning and artificial intelligence may allow automated detection of disease stages, prediction of progression, and personalised treatment planning. Lastly, improving accessibility and developing cost-effective OCT could help in early diagnosis and detection of Eales disease.⁹

Summary 

• Eales disease is an inflammatory disease, most commonly observed in young people assigned male at birth (South Asia). It often leads to vascular blockage, neovascularisation, and vitreous haemorrhage. In serious cases, it causes vision loss
• Symptoms include vitreous haemorrhage, blurred vision, reduced visual acuity, and, in some cases, headaches or systemic symptoms. Optical Coherence Tomography (OCT) is a non-invasive imaging tool that produces high-resolution cross-sectional retinal images
• OCT detects structural changes such as macular oedema and retinal thinning. It monitors treatment response and disease progression with sequential scans and offers an alternative to fluorescein angiography for assessing vascular changes without dye injection
• OCTA visualises retinal and choroidal microvasculature in 3D, enabling detection of ischemia and neovascularisation without the risks of dye
• Image quality can be reduced by media opacities (cataracts, corneal changes, vitreous haemorrhage)
• OCT cannot measure vascular leakage directly, limiting its role in macular oedema or vein occlusion
• OCTA may show artefacts from eye movement, processing errors, or myopia
• Integration of OCT with AI and machine learning for automated detection and prediction
• Multimodal imaging to reduce reliance on invasive angiography
• Efforts to improve accessibility and affordability to support early diagnosis in high-risk populations