2. This painless imaging test uses optical coherence tomography (OCT) to measure the thickness of the upper portion of the retinal nerve fiber layer in your left eye, helping your doctor detect and monitor glaucoma and other optic nerve conditions before vision loss occurs.
This painless imaging test uses optical coherence tomography (OCT) to measure the thickness of the upper portion of the retinal nerve fiber layer in your left eye, helping your doctor detect and monitor glaucoma and other optic nerve conditions before vision loss occurs.
{"Uses OCT technology to measure retinal nerve fiber layer thickness","Helps detect early signs of glaucoma and optic nerve damage","Non-invasive imaging test that takes about 5-10 minutes","Results are compared to age-matched normal databases","Thinning of RNFL may indicate glaucoma progression"}
Key facts at a glance
- LOINC
- 86277-1
- Short code
- RNFL-L-SUP-OCT
- Synonyms
- L ret RNFL sup thickness OCT
- Category
- cardiac
- Sample
- serum
- Container
- Not applicable - This is an imaging test, not a blood collection
- Units
- N/A
- Ref low
- 100
- Ref high
- 140
- Critical range
- 70 N/A – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Optical Coherence Tomography (OCT)
- CPT
- 92134
- SNOMED
- 371632002
- 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) Superior Thickness test is an imaging procedure that uses Optical Coherence Tomography (OCT) to measure the thickness of the superior (upper) portion of the retinal nerve fiber layer in your left eye. OCT is a non-invasive imaging technique that uses light waves to create detailed cross-sectional images of the retina.
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 technician will align your left eye with the scanning beam. You will need to focus on a target light while the device scans your eye. The test is quick, painless, and takes about 5-10 minutes. No eye drops or special preparation are typically required.
Why is this test important?
The retinal nerve fiber layer consists of nerve fibers that carry visual information from the retina to the brain. Measuring RNFL thickness helps doctors detect changes in the optic nerve, which can occur in conditions like glaucoma, multiple sclerosis, and other optic nerve disorders. Early detection of RNFL thinning allows for timely treatment to prevent vision loss.
Reference range
Retinal nerve fiber layer (RNFL) superior quadrant thickness: 100-140 microns (µm) for normal adult eyes. Values below 100 µm may indicate early glaucomatous changes. Reference ranges vary by instrument manufacturer and patient demographics.N/A
Patient should remove contact lenses prior to testing if applicable. Pupil dilation with mydriatic drops may be performed for better visualization. No fasting required. Inform technician of any eye surgery history, glaucoma, or neurological conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The superior RNFL thickness measurement is clinically significant for glaucoma diagnosis and management. Thinning of the RNFL, particularly in the superior region, is often an early indicator of glaucomatous damage. This test helps ophthalmologists track disease progression over time, evaluate treatment effectiveness, and make informed decisions about managing eye health. Results are compared against normative databases adjusted for age and ethnicity.
Frequently asked questions
Does this test require any special preparation?
Is the test painful?
How long does it take to get results?
What do abnormal results mean?
How often should this test be repeated?
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 16, 2026. · Read our editorial policy