Could Blood Tests One Day Help Diagnose Eye Diseases?
Blood can contain proteins, antibodies, metabolites and genetic material associated with conditions affecting the eyes. Researchers are investigating whether combinations of these biomarkers could eventually support earlier detection, monitoring and treatment selection.
Blood tests already have established roles in selected areas of eye care, including investigating inflammation, infection, thyroid disease and inherited retinal conditions. However, no single blood test can currently diagnose most common retinal, optic-nerve or macular diseases without an eye examination and appropriate imaging.
What Is a Blood Biomarker?
A blood biomarker is a measurable biological feature associated with a disease process, physiological change or treatment response. Examples include proteins, antibodies, metabolites, hormones, microRNAs and specific genetic variants.
A measurable association does not automatically make a biomarker suitable for diagnosis. It must be reproducible, sufficiently accurate and shown to improve patient care when compared with established tests.
Are Blood Tests Already Used in Eye Care?
Blood tests already help your clinician investigate the causes of certain eye problems. They can provide useful information about underlying conditions that may affect your eyes.
These tests may support the assessment of inflammation, infection, autoimmune disease, diabetes, thyroid disease or inherited conditions. However, they usually complement rather than replace a detailed eye examination.
Why Could Blood Testing Be Useful?
Blood samples are relatively simple to collect and can be repeated more easily than samples taken from inside your eye. This makes them a practical option for tracking changes over time.
In the future, this could support screening, monitoring how your condition progresses and assessing how well your treatment is working, alongside your regular eye examinations.
Diabetic Retinopathy
Blood tests such as HbA1c already help assess your diabetes control and your risk of developing complications. However, they cannot show whether diabetic retinopathy is actually present in your eyes.
Researchers are studying additional blood biomarkers, including inflammatory proteins, growth factors and microRNAs, to see whether they could provide more eye-specific information in the future.
How Promising Are Circulating MicroRNAs?
A 2025 meta-analysis included 16 studies and 1,849 participants. In the nine studies comparing diabetic retinopathy with type 2 diabetes without retinopathy, circulating microRNAs produced a pooled sensitivity of 81%, specificity of 80% and AUC of 0.88.
Performance varied according to the blood component tested, laboratory methods, normalisation techniques and individual microRNA. Prospective validation and standardised testing are required before circulating microRNAs can support routine diabetic eye screening.
Multi-Biomarker Tests for Retinal Disease
A single blood marker may not capture all the processes involved in retinal damage. Your eye disease can involve inflammation, vascular changes and metabolic factors.
Researchers are combining proteins, microRNAs and gene-expression data with machine learning to create broader risk profiles. These approaches may improve prediction and monitoring, but they are not yet used routinely.
Age-Related Macular Degeneration
A multicentre, multiphase study published in a 2025 journal issue included 547 participants with AMD, other eye diseases or no identified eye disease. Researchers developed a serum panel containing hypoxanthine, 2-furoylglycine and a phospholipid known as 1-hexadecyl-2-azelaoyl-sn-glycero-3-phosphocholine.
The panel performed strongly within the study’s discovery and external-validation datasets. However, this does not establish a routine diagnostic or monitoring blood test for AMD. Prospective studies must determine whether it performs reliably across different populations and whether repeated measurements reflect disease development, progression or treatment response.
Key Points About Metabolomics in AMD
| Aspect | Explanation | Current Status |
| Blood metabolomics | Studies small molecules in your blood to identify disease-related patterns | Being researched as a potential diagnostic tool |
| Disease markers | Includes signals linked to inflammation, oxidative stress and lipid metabolism | May reflect processes affecting the retina |
| Three-metabolite panels | Specific combinations of metabolites have shown promising results | Need confirmation in larger studies |
| Early detection potential | The panel classified AMD and comparison groups within the study datasets | It has not been validated for screening people without diagnosed AMD |
| Research limitations | Findings need validation across different populations | Further studies are required before clinical use |
Glaucoma
A 2025 single-centre case-control study included 110 people with glaucoma and 113 controls without glaucoma who were undergoing planned eye surgery. It measured neurofilament light in blood and in aqueous humour, the fluid inside the front of the eye.
Aqueous-humour levels were higher in the glaucoma group, but serum neurofilament light was not elevated after adjustment for relevant factors including age and body mass index. The study therefore did not establish serum neurofilament light as a useful circulating biomarker for glaucoma.
Retinal Neurodegeneration
Highly sensitive laboratory methods can detect proteins such as neurofilament light and GFAP in blood. These proteins reflect neural or glial injury but are not specific to the retina and may also be influenced by neurological disease, ageing, kidney function and other health conditions.
A 2025 exploratory, cross-sectional study measured neurofilament light, GFAP and CXCL13 in 151 adults with diabetes, diabetic retinopathy, glaucoma, inherited retinal degeneration or no identified retinal disease. Neurofilament light was higher in some diabetic-retinopathy groups, particularly those with proliferative retinopathy or diabetic macular oedema, but the study did not validate a diagnostic test for retinal neurodegeneration or show how the markers change over time.
Thyroid Eye Disease
Blood tests can assess thyroid function and detect antibodies associated with Graves’ disease. TSH-receptor antibodies may support the underlying diagnosis and provide information about the likelihood of thyroid eye disease in the appropriate clinical context.
Blood results cannot determine the activity or severity of the eye disease on their own. Eyelid changes, eye movement, double vision, corneal exposure, optic-nerve function and imaging findings require direct specialist assessment.
Uveitis
Blood tests may help investigate infection or systemic inflammatory disease when the history and examination suggest a particular cause of uveitis. Tests may include syphilis serology, tuberculosis assessment, HLA-B27 typing or investigations for selected autoimmune conditions.
A broad panel of tests is not appropriate for every patient and may produce misleading incidental results. Investigations should be targeted according to the type of uveitis, symptoms, examination findings and relevant medical history.
Giant Cell Arteritis
Blood tests including C-reactive protein, erythrocyte sedimentation rate and a full blood count can support the assessment of suspected giant cell arteritis. Normal inflammatory markers reduce the likelihood of the condition but do not exclude it, so the clinical symptoms remain important.
Giant cell arteritis is a medical emergency because delayed treatment can cause permanent sight loss. Seek immediate emergency eye or hospital assessment if you develop new visual loss, temporary darkening of vision or double vision, especially if these occur with a new headache, scalp tenderness or jaw pain when chewing. Treatment should not be delayed while waiting for blood tests, ultrasound or biopsy results.
Inherited Retinal Diseases
A blood or saliva sample can be used for genomic testing when an inherited retinal disorder is suspected. Identifying a disease-causing variant may provide a molecular diagnosis, clarify inheritance and determine eligibility for selected treatments, research studies or clinical trials.
Testing does not always identify the cause, and some results are classified as variants of uncertain significance. Results should be interpreted through an appropriate ophthalmic genetics or clinical genetics service, with counselling about possible implications for relatives.
Autoimmune and Infectious Eye Conditions
Blood testing may detect antibodies, immune markers or signs of infection linked to eye inflammation. This can help identify possible underlying causes behind certain eye conditions.
- Immune markers: Blood tests can identify antibodies or other markers that may suggest an autoimmune process
- Infection detection: Testing may provide evidence of infections that could contribute to eye inflammation
- Underlying causes: Results can help your doctor investigate possible reasons for your symptoms
- Diagnostic support: Blood tests provide additional information but are usually combined with other assessments
- Clinical evaluation: Eye examinations are still needed to understand the type and severity of any damage
Blood tests can be a useful part of investigating inflammatory or infectious eye conditions, but they do not provide the complete picture on their own. Your eye specialist will consider your symptoms, examination findings and test results together when planning your care.
Ocular Melanoma
Liquid-biopsy studies are investigating circulating tumour DNA, circulating tumour cells and microRNAs in uveal melanoma. Most clinically relevant evidence currently concerns prognosis or treatment monitoring in metastatic uveal melanoma.
Circulating tumour material may be difficult to detect in localised eye tumours. Blood-based liquid biopsy cannot currently replace ocular imaging, specialist examination, tumour assessment or established surveillance.
Could Blood Tests Predict Treatment Response?
Blood biomarkers may eventually help identify groups more likely to respond to a particular treatment or develop adverse effects. This is being investigated in retinal disease, inflammatory eye conditions and ocular cancer.
Most proposed predictive biomarkers have not yet been validated sufficiently to select treatment for an individual patient. Results would need to provide useful information beyond clinical examination, imaging and existing risk factors.
How Could Artificial Intelligence Help?
Machine-learning systems can analyse combinations of proteins, metabolites and genetic markers and may find patterns that individual measurements do not reveal. These methods are mainly being used to develop and test research models.
High performance within a development dataset does not prove that a model will work in routine care. External validation, representative populations, transparent reporting and comparison with established diagnostic pathways are required.
What Are the Main Limitations?
Blood-biomarker results may be influenced by age, kidney and liver function, diabetes, inflammation, neurological disease, medicines and other health conditions. A protein or metabolite associated with an eye condition may therefore reflect a wider systemic process rather than damage arising specifically within the eye.
Results may also vary according to whether serum, plasma or whole blood is tested and how the sample is collected, processed, stored and analysed. Biomarkers released inside the eye may be present at very low concentrations in the circulation, and studies need standardised methods, representative populations and prospective validation before proposed tests can enter routine care.
Can Blood Tests Replace Eye Scans?
Blood tests are unlikely to replace retinal photography, OCT, visual-field testing or specialist examination. These tools directly assess the structure and function of your eye.
Instead, blood tests may help identify risk, support diagnosis or guide when you need detailed imaging. They are more likely to complement, not replace, eye scans.
Myth vs Fact
| Myth | Fact |
| A normal blood test means your eyes are healthy. | Many eye conditions produce no abnormal blood result. |
| HbA1c can diagnose diabetic retinopathy. | It reflects glucose control, while retinal examination is needed to identify retinopathy. |
| A biomarker associated with disease is automatically a diagnostic test. | It requires validation for accuracy, reproducibility and clinical benefit. |
| Serum neurofilament light can diagnose glaucoma. | In a 2025 case-control study, serum neurofilament light was not elevated after adjustment and was not validated as a glaucoma blood test. |
| Normal inflammatory markers rule out giant cell arteritis. | Normal results do not completely exclude the condition. |
| Blood tests can replace OCT or retinal photography. | They are more likely to provide complementary information. |
| Every inherited retinal disease is found through genetic testing. | Some tests are negative or identify variants whose significance is uncertain. |
| Liquid biopsy can diagnose an ocular melanoma. | This remains investigational and cannot replace specialist tumour assessment. |
Key Takeaways
- Blood tests already support the investigation of selected eye conditions.
- They can identify systemic inflammation, infection, thyroid abnormalities and genetic variants.
- HbA1c indicates diabetes control but cannot show whether diabetic retinopathy is present.
- Circulating microRNAs for diabetic retinopathy remain experimental.
- Blood metabolomics for AMD requires further independent validation.
- Serum neurofilament light is not currently established as a biomarker for diagnosing or monitoring glaucoma.
- Blood tests must not delay urgent assessment for suspected giant cell arteritis.
- Genetic testing for inherited retinal disease is an established specialist application.
- Liquid biopsy for uveal melanoma remains investigational.
- Blood tests are more likely to complement eye imaging than replace it.
Frequently Asked Questions
- Can a blood test diagnose an eye disease?
Blood tests can support the diagnosis of selected conditions affecting the eyes, including infections, inflammatory disease, thyroid disorders and inherited retinal conditions. They cannot currently diagnose most common retinal, macular or optic-nerve diseases independently. - Are blood tests already used in eye care?
Yes. Blood tests are already used to support the assessment of some eye conditions. They may help investigate causes of eye inflammation, autoimmune disease, infections, thyroid-related eye problems, diabetes-related complications and inherited retinal conditions. - Could blood tests detect eye disease earlier in the future?
Researchers are investigating whether blood biomarkers can identify biological changes before symptoms or visible eye damage develop. This has not yet been demonstrated sufficiently for routine screening of most eye diseases. - What types of biomarkers are researchers studying for eye diseases?
Researchers are studying different types of biomarkers, including proteins, genetic material, microRNAs, metabolites, antibodies and inflammatory markers. These may provide information about processes affecting your retina, optic nerve or other eye structures. - Can blood tests detect diabetic eye disease?
HbA1c and other blood tests provide information about diabetes and the risk of complications, but they cannot confirm diabetic retinopathy. Retinal photography or specialist retinal examination is still required. - Could blood tests help diagnose age-related macular degeneration?
A 2025 study identified a promising three-metabolite serum panel for AMD, but the result requires broader independent validation. Blood metabolomics cannot currently replace retinal examination or imaging. - Can blood tests detect glaucoma?
There is no routine blood test for glaucoma. A 2025 case-control study did not find elevated serum neurofilament light after adjustment for age and body mass index, so it did not validate serum neurofilament light as a glaucoma biomarker. - Are genetic blood tests used for inherited retinal diseases?
Blood or saliva may be used for genomic testing when an inherited retinal condition is suspected. A confirmed disease-causing variant can clarify diagnosis and inheritance, but testing does not identify a cause in every patient. - Will blood tests replace eye scans in the future?
It is unlikely that blood tests will replace eye scans such as optical coherence tomography, retinal photography or visual field testing. Instead, they are more likely to complement these assessments by helping identify risk, support diagnosis and guide further investigations. - What are the limitations of blood tests for eye diseases?
Blood biomarkers may be affected by age, kidney function, diabetes, inflammation, medication and neurological disease. Signals produced inside the eye may also be present at very low concentrations in the circulation.
Final Thoughts: Could Blood Tests Shape the Future of Eye Diagnosis?
Blood tests already support selected areas of eye care, including investigations for inflammation, infection, thyroid disease and inherited retinal disorders. Research into proteins, microRNAs, metabolites and tumour-derived material may eventually provide additional information about disease risk, progression or treatment response, but most proposed biomarkers remain investigational.
Blood tests cannot currently replace retinal photography, OCT, visual-field testing or specialist examination for most common eye diseases. To discuss concerns about your vision or eye health, contact Eye Clinic London to arrange an appropriate assessment.
References
- Mustafi, D., Hisama, F.M., Huey, J. and Chao, J.R. (2022) ‘The current state of genetic testing platforms for inherited retinal diseases’, Ophthalmology Retina, 6(8), pp. 702–710. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC9356993/
- NHS England (2025) Your guide to diabetic eye screening. Updated 29 August 2025. Available at: https://www.gov.uk/government/publications/diabetic-eye-screening-description-in-brief/your-guide-to-diabetic-eye-screening
- Sève, P., Cacoub, P., Bodaghi, B., Trad, S., Sellam, J., Bellocq, D. et al. (2017) ‘Uveitis: diagnostic work-up. A literature review and recommendations from an expert committee’, Autoimmunity Reviews, 16(12), pp. 1254–1264. Available at: https://www.sciencedirect.com/science/article/pii/S1568997217302604
- Ueland, H.O., Neset, M.T., Methlie, P., Ueland, G.Å., Pakdel, F. and Rødahl, E. (2023) ‘Molecular biomarkers in thyroid eye disease: a literature review’, Ophthalmic Plastic and Reconstructive Surgery, 39(6 Suppl), pp. S19–S28. Available at: https://pubmed.ncbi.nlm.nih.gov/38054982/
- Li, S., Qiu, Y., Li, Y., Wu, J., Yin, N., Ren, J. et al. (2025) ‘Serum metabolite biomarkers for the early diagnosis and monitoring of age-related macular degeneration’, Journal of Advanced Research, 74, pp. 443–454. Available at: https://www.sciencedirect.com/science/article/pii/S209012322400434X