Lretrnfltempthicknessoct
A non-invasive eye imaging test that measures the thickness of the nerve fiber layer in the retina to detect and monitor glaucoma and other optic nerve diseases.
{"Uses light waves to create detailed images of the retina's nerve fiber layer","Helps detect early signs of glaucoma before vision loss occurs","The test is quick, painless, and requires no blood samples or eye drops"}
Key facts at a glance
- LOINC
- 86278-9
- Short code
- OCT-LT-RNFL-TEMP
- Synonyms
- L ret RNFL temp thickness OCT
- Category
- cardiac
- Sample
- serum
- Container
- Not applicable - imaging test
- Units
- N/A
- Ref low
- 50
- Ref high
- 100
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Optical Coherence Tomography (OCT)
- CPT
- 92134
- SNOMED
- 397141007
- Specimen volume
- Not applicable - imaging test
- Stability
- Not applicable - imaging test
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–24 hours
- Order
- routine
What is this test?
The Retinal Nerve Fiber Layer (RNFL) thickness test uses Optical Coherence Tomography (OCT), a advanced imaging technology that uses light waves to take cross-sectional pictures of your retina. This test specifically measures the thickness of the temporal portion of the retinal nerve fiber layer in your left eye. The retinal nerve fiber layer consists of nerve fibers that carry visual information from the retina to the brain.
How is the test performed?
During the test, you will sit in front of the OCT machine and rest your chin on a support. You will be asked to look at a fixed target while the device scans your eye. The process is completely painless and takes only a few minutes. No blood draw is required for this test, and your eyes may or may not need to be dilated depending on your doctor's preference.
Why is it important?
Measuring the RNFL thickness is crucial for detecting and monitoring glaucoma, a condition that damages the optic nerve and can lead to permanent vision loss if untreated. This test can identify thinning of the nerve fiber layer even before noticeable vision changes occur, allowing for early intervention and treatment.
Reference range
Normal temporal retinal nerve fiber layer thickness ranges from approximately 50 to 100 micrometers (μm). Reference ranges may vary by instrument manufacturer and population. Typical normal range: 55-85 μm for temporal quadrant.N/A
Patient should remove eyeglasses or contact lenses before imaging. No dilation drops typically required for spectral-domain OCT, but pupil dilation may improve image quality. Inform technician of any eye surgery history, trauma, or current eye medications.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings2
Frequently asked questions
Does the test hurt?
How long does the test take?
Do I need to fast before the test?
When will I get my results?
How often should I have this test?
Sources
- 1
- 2
- 3
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 16, 2026. · Read our editorial policy