{"id":18091,"date":"2026-08-06T11:07:20","date_gmt":"2026-08-06T11:07:20","guid":{"rendered":"https:\/\/www.eyecliniclondon.com\/blog\/?p=18091"},"modified":"2026-08-06T11:07:20","modified_gmt":"2026-08-06T11:07:20","slug":"liquid-biopsy-eye-disease","status":"publish","type":"post","link":"https:\/\/www.eyecliniclondon.com\/blog\/liquid-biopsy-eye-disease\/","title":{"rendered":"Why Liquid Biopsies Could Become Important in Eye Disease Research"},"content":{"rendered":"

A liquid biopsy analyses biological material found in a fluid such as your blood, tears, aqueous humour or vitreous fluid. Researchers are investigating whether these samples can provide molecular information about your eye condition without requiring a conventional tissue biopsy.<\/p>\n

The technology is most developed in specialist ocular cancer research and selected investigations for intraocular lymphoma. Most applications cannot currently diagnose your condition, predict your outcome or guide your treatment without your eye examination, imaging and other established tests.<\/p>\n

What Is a Liquid Biopsy?<\/h2>\n

A liquid biopsy analyses disease-associated material in one of your body fluids rather than relying solely on a conventional tissue sample. Depending on your condition, the test may examine cell-free DNA, tumour DNA, RNA, proteins, metabolites, inflammatory molecules or extracellular vesicles.<\/p>\n

The term covers tests with very different levels of invasiveness and clinical evidence. Your blood or tears can be collected relatively simply, while obtaining aqueous or vitreous fluid requires a procedure that enters your eye.<\/p>\n

Which Fluids Can Be Tested?<\/h2>\n

Researchers may analyse your blood, tears, aqueous humour or vitreous fluid. Each sample provides different information and involves different collection methods and risks.<\/p>\n

Your blood and tears are easier to collect repeatedly, but disease signals originating within your eye may be weak or diluted in these samples. Your aqueous or vitreous fluid may contain material closer to the affected tissue, but collecting it requires specialist clinical justification.<\/p>\n

What Is Cell-Free DNA?<\/h2>\n

Cell-free DNA consists of small fragments released into your body fluids as cells die, become damaged or undergo normal turnover. Your blood contains cell-free DNA from many tissues, which can make a small signal from your eye difficult to detect.<\/p>\n

When DNA fragments originate from tumour cells, they may be described as circulating or cell-free tumour DNA. Detecting these fragments may provide genetic information, but your result does not automatically confirm your diagnosis or determine your treatment.<\/p>\n

Why Are Liquid Biopsies Useful in Eye Research?<\/h2>\n

Obtaining tissue from structures inside your eye may be difficult or may expose you to risks such as bleeding, infection, retinal detachment or loss of vision. If your child has suspected retinoblastoma, directly biopsying the tumour is normally avoided because entering the tumour could allow cancer cells to spread outside the eye.<\/p>\n

A liquid sample may provide molecular information without directly cutting into the tumour. However, collecting your aqueous or vitreous fluid still requires an invasive eye procedure and should be performed only when your specialist believes that the possible information justifies the risks.<\/p>\n

Are All Liquid Biopsies Non-Invasive?<\/h2>\n

No. Your blood and tears can usually be collected without entering your eye. An aqueous tap, vitreous aspiration or vitreous biopsy requires an invasive procedure performed by an appropriately trained specialist.<\/p>\n

The level of risk differs according to the sample, your condition and the technique used. You should receive an explanation of why the procedure is needed, what information it may provide and which complications are possible.<\/p>\n

Types of Liquid Biopsy Sampling<\/h2>\n\n\n\n\n\n\n\n\n
Sample used for your test<\/strong><\/td>\nHow your sample is collected<\/strong><\/td>\nLevel of invasiveness<\/strong><\/td>\nWhat you should understand<\/strong><\/td>\n<\/tr>\n<\/thead>\n
Your blood<\/td>\nYour blood is taken from a vein using a needle<\/td>\nMinimally invasive<\/td>\nIt is relatively simple to repeat, but an eye-derived signal may be very diluted<\/td>\n<\/tr>\n
Your tears<\/td>\nYour tears are collected from the surface of your eye<\/td>\nNon-invasive<\/td>\nYour result can be affected by the collection method, dry eye, medicines and environmental exposure<\/td>\n<\/tr>\n
Your aqueous humour<\/td>\nFluid is removed from the front chamber of your eye using a fine needle<\/td>\nInvasive intraocular procedure<\/td>\nYour sample must be collected by an appropriately trained specialist for a justified clinical purpose<\/td>\n<\/tr>\n
Your vitreous fluid<\/td>\nFluid is taken from the gel inside your eye through aspiration or vitrectomy<\/td>\nInvasive intraocular procedure<\/td>\nYour collection normally takes place during a specialist surgical procedure<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Your specialist should assess whether sampling is clinically justified and explain the possible benefits, risks and alternatives. Samples taken from inside your eye require sterile technique and an appropriately experienced clinical setting.<\/p>\n

Tears as a Liquid Biopsy<\/h2>\n

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Your tears contain proteins, RNA, DNA fragments, metabolites and extracellular vesicles. They are particularly relevant to research involving your ocular surface, including your cornea, conjunctiva and tear film.<\/p>\n

It is less certain whether your tears reliably represent conditions affecting deeper structures such as your retina or optic nerve. Your small sample volume, collection technique, dry eye, medicines and environmental exposure may all influence your result.<\/p>\n

What Are Extracellular Vesicles?<\/h2>\n

Extracellular vesicles are small membrane-bound particles released by your cells. They can carry proteins, lipids and genetic material and may be detected in your blood, tears or intraocular fluid.<\/p>\n

Their membrane can help protect some of their contents, but this does not guarantee that your sample will remain stable. Your collection method, storage conditions, processing and laboratory technique can all affect the result.<\/p>\n

Aqueous Humour Testing<\/h2>\n

Your aqueous humour may contain cell-free DNA, proteins and inflammatory molecules released from tissues within your eye. Researchers are studying whether these markers can support the assessment of retinoblastoma, uveal melanoma and primary vitreoretinal lymphoma.<\/p>\n

Sampling your aqueous humour requires a specialist procedure and is not a routine test for most eye conditions. Whether it is appropriate for you or your child depends on the suspected diagnosis, the clinical purpose and the experience of the treating centre.<\/p>\n

Vitreous Fluid Testing<\/h2>\n

Your vitreous fluid may be examined when your specialist suspects infection, inflammation or primary vitreoretinal lymphoma. Testing can include cytology, microbiology, molecular analysis and measurement of inflammatory molecules.<\/p>\n

Not every vitreous investigation is described clinically as a liquid biopsy. Your results must be interpreted together because a single negative molecular, cytokine or cellular test may not exclude your condition.<\/p>\n

Retinoblastoma Research<\/h2>\n

A conventional biopsy of suspected retinoblastoma is normally avoided because disturbing the tumour could spread cancer cells outside your child\u2019s eye. Your child\u2019s diagnosis is therefore primarily based on specialist examination and imaging.<\/p>\n

Aqueous humour testing is being developed as a way to analyse tumour-related DNA without directly sampling the retinal tumour. It must be performed only through a highly specialised retinoblastoma service and does not replace your child\u2019s full clinical assessment.<\/p>\n

What Did a 2026 Study Find?<\/h2>\n

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A prospective 2026 study assessed aqueous-humour samples from 60 people referred to one ocular-oncology centre, including 41 people with retinoblastoma. At diagnosis, copy-number alterations were detected in 34 of 36 evaluable retinoblastoma eyes, while the targeted sequencing analysis detected pathogenic variants in 83% of the baseline samples tested.<\/p>\n

Tumour DNA was detected in all four evaluable recurrence cases and was not detected in the remission samples studied. These findings are promising, but the recurrence group was small, the study came from one centre and the timing of testing was not standardised in every case. Your child\u2019s result would still need to be interpreted alongside specialist examination, imaging, treatment history and continuing surveillance.<\/p>\n

Is Aqueous Humour Sampling Safe?<\/h2>\n

A multicentre retrospective study reviewed 1,203 aqueous-sampling procedures involving 484 eyes from 425 children. The researchers recorded one mild complication, giving a reported procedure-related complication rate of 0.08%. No moderate or severe procedure-related complications were recorded during a median follow-up of 16 months.<\/p>\n

These findings came from seven specialist centres where trained ocular surgeons collected your child\u2019s sample using a fine needle during an examination under general anaesthesia. The results are reassuring within this highly specialised setting, but they cannot guarantee that your child will experience no complication or justify sampling outside an appropriately experienced retinoblastoma service.<\/p>\n

Uveal Melanoma<\/h2>\n

Liquid biopsy may help identify genetic changes linked to uveal melanoma and estimate your risk of future spread. Researchers are studying samples from your blood and eye fluids to better understand these patterns.<\/p>\n