Laboratory Testing Overview: What This Test Is, How Your Sample Is Collected, and Why It Is Performed
This test measures the number of basophils (a type of white blood cell) in the vitreous fluid of the eye.
{"Basophils are immune cells normally found in blood, not typically in eye fluid","The presence of basophils in vitreous fluid may indicate eye inflammation or infection","This is a specialized test performed by manual microscopic examination","Results help doctors diagnose certain eye conditions","The test uses fluid from inside the eye, collected during a minor procedure"}
Key facts at a glance
- LOINC
- 68397-9
- Short code
- VFBAS
- Synonyms
- Basophils # Vitf Manual
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, preservative-free, leak-proof microcentrifuge tube or cryovial (polypropylene); no anticoagulant required for manual cell counts, though EDTA may be used if concurrent flow cytometry is planned.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- manual-count
- CPT
- 89051 (Cell count, miscellaneous body fluids, with cell count); may also be reported under 87086 (Culture) or 88108 (Cytology) when combined.
- SNOMED
- 416980001 |Basophil count| + 258538003 |Vitreous humor specimen|
- Specimen volume
- 0.2–1.0 mL of vitreous fluid (minimum 0.1 mL for manual hemocytometer counting).
- Stability
- Process within 1 hour of collection for optimal cell morphology. If delayed, refrigerate at 2–8°C for up to 4 hours; do not freeze. Cell viability and differential accuracy decline rapidly.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–4 hours
- Order
- routine
This test is a laboratory analysis performed on a sample from your body, such as blood, urine, or a swab from a specific area, to help your healthcare provider evaluate your health, detect possible medical conditions, and check how well your body is functioning over time.
A basophil count in vitreous fluid is a specialized laboratory test that measures the number of basophils in the vitreous humor—the clear, gel-like substance that fills the space between the lens and the retina in the eye. Basophils are a type of white blood cell (granulocyte) that play a role in the body's immune response and allergic reactions. Under normal conditions, basophils are found primarily in the blood, not in the vitreous fluid of the eye.
Your sample is collected in a way that matches the type of test your provider has ordered. This may involve a routine blood draw from a vein in your arm, providing a urine specimen in a sterile container, or a quick swab of the nose, throat, or affected area. A trained healthcare professional will collect the sample safely, and you will receive clear instructions in advance, such as whether you need to fast or avoid certain medications beforehand.
Vitreous fluid is collected through a procedure called vitreous tap (vitrectomy) or during eye surgery. A thin needle is used to withdraw a small amount of fluid from the vitreous cavity of the eye. This procedure is typically performed by an ophthalmologist (eye specialist) and requires local anesthesia. The sample is then sent to a laboratory where a technician manually counts the basophils under a microscope.
This test is performed to help identify the cause of symptoms you may be having, screen for conditions before symptoms appear, monitor an existing illness, or check how well a treatment is working. The results give your healthcare provider important information to guide diagnosis, plan your care, and decide on any next steps for your health.
This test is not a routine blood test. It is performed when a doctor suspects certain eye conditions that may involve inflammation or infection. The presence of basophils in the vitreous fluid can provide important diagnostic information about inflammatory, infectious, or other pathological conditions affecting the inside of the eye.
Reference range
Vitreous fluid basophils are not normally present in significant numbers. Manual differential cell counts of vitreous fluid are typically reported qualitatively (rare, occasional, many) due to low cellularity and limited clinical reference data.N/A
Vitreous fluid is obtained via pars plana vitrectomy or diagnostic vitreous tap by an ophthalmologist. No fasting or special patient preparation is required prior to specimen collection. Informed consent for the ophthalmic procedure must be obtained.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Detection of basophils in vitreous fluid may indicate: intraocular inflammation (uveitis), infectious processes such as endophthalmitis (infection inside the eye), inflammatory eye diseases, or possibly a reaction to trauma or surgery. Basophils contain histamine and other inflammatory mediators, so their presence in the eye fluid suggests an active inflammatory or immune response. The interpretation of results should be done by an ophthalmologist in conjunction with other clinical findings and test results.
Frequently asked questions
Is this a routine eye test?
Does having basophils in my eye fluid mean I have cancer?
How long does it take to get results?
Is the vitreous tap procedure dangerous?
Sources
- 1
- 2
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy