Lretrnflmeanthicknessoct
A non-invasive eye imaging test that measures the thickness of the retinal nerve fiber layer in the left eye using optical coherence tomography (OCT).
{"Uses OCT technology to capture detailed cross-sectional images of the retina","Measures the thickness of the retinal nerve fiber layer (RNFL) around the optic nerve","Helps detect and monitor glaucoma and other optic nerve diseases","The test is quick, painless, and requires no blood sample","Results are compared with age-matched normal values to assess eye health"}
Key facts at a glance
- LOINC
- 86290-4
- Short code
- RNFL-L-OCT
- Synonyms
- L ret RNFL mean thickness OCT
- Category
- cardiac
- Sample
- serum
- Container
- Not applicable - imaging procedure, not blood collection
- Units
- N/A
- Ref low
- 90
- Ref high
- 120
- Critical range
- 50 N/A – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Optical Coherence Tomography (OCT)
- CPT
- 92134
- SNOMED
- 399550004
- Specimen volume
- Not applicable - imaging procedure
- Stability
- Not applicable - imaging procedure
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The Left Retina Retinal Nerve Fiber Layer (RNFL) Thickness Test is an advanced eye imaging examination that uses Optical Coherence Tomography (OCT) to measure the thickness of the retinal nerve fiber layer in your left eye. OCT is a non-invasive imaging technology that uses light waves to create detailed cross-sectional images of the retina, similar to how ultrasound uses sound waves.
How is the test performed?
During the test, you will sit in front of an OCT machine and rest your chin on a support. The machine will scan your left eye without touching it. You will need to look at a specific target while the scanner captures images. The entire procedure takes about 5-10 minutes and is completely painless. No eye drops or blood samples are required.
Why is RNFL thickness important?
The retinal nerve fiber layer consists of nerve fibers that carry visual information from the retina to the brain. Measuring its thickness helps doctors assess the health of your optic nerve. Thinning of the RNFL can indicate damage to the optic nerve, which is often associated with conditions like glaucoma.
Reference range
Normal Retinal Nerve Fiber Layer (RNFL) thickness ranges from 90-120 μm for mean thickness. Values below 80 μm may indicate early glaucomatous damage. Thickness varies by quadrant: superior (110-140 μm), nasal (60-80 μm), inferior (110-140 μm), temporal (50-70 μm).N/A
Patient should remove contact lenses prior to imaging. Pupils should be dilated for optimal imaging quality. Inform technician of any eye surgery history, glaucoma, or neurological conditions. Avoid caffeine and stimulants before the test as they may affect retinal blood flow.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings2
Frequently asked questions
Do I need to prepare for the test?
Is the test painful?
How long does it take to get results?
Will I need this test repeatedly?
Does the test involve radiation?
Sources
- 1
- 2
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
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 17, 2026. · Read our editorial policy