Skip to content

Rretrnflmeanthicknessoct

Published: August 9, 2026Updated: August 17, 2026

This test uses optical coherence tomography (OCT) to measure the thickness of the retinal nerve fiber layer in your right eye, helping doctors assess optic nerve health.

Quick summary

{"A non-invasive imaging test that measures the retinal nerve fiber layer thickness","Helps detect and monitor glaucoma and other optic nerve disorders","Results are compared to age-matched normal values","Thin RNFL may indicate nerve damage","Regular testing tracks disease progression over time"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
86301-9
Short code
RNFL OCT Right
Synonyms
R ret RNFL mean thickness OCT
Category
cardiac
Sample
serum
Container
Not applicable - this is an imaging procedure, not a blood collection
Units
N/A
Ref low
83
Ref high
120
Critical range
70 N/A – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
Optical Coherence Tomography (OCT)
CPT
92133
SNOMED
399171006
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 Right Retina Retinal Nerve Fiber Layer (RNFL) Mean Thickness test uses Optical Coherence Tomography (OCT), a non-invasive imaging technique that uses light waves to take cross-sectional pictures of your retina. The retinal nerve fiber layer (RNFL) is a thin layer of nerve tissue at the back of your eye that carries visual information from the retina to the brain. This test measures the average thickness of this layer in your right eye.

During the test, you will sit in front of an OCT machine and rest your chin on a support while the device scans your eye. The process is quick, painless, and takes only a few minutes. No eye drops or injections are required.

Reference range

Normal retinal nerve fiber layer (RNFL) thickness varies by quadrant. Typical mean thickness reference ranges: Superior: 120-140 μm, Nasal: 60-80 μm, Inferior: 120-140 μm, Temporal: 50-70 μm, Global/Average: 100-110 μm. Reference ranges may vary by instrument manufacturer and population.N/A

Specimen: serum

No fasting required. Patient should remove contact lenses if applicable. Pupillary dilation may be performed for better imaging. Inform technician of any eye surgery history, glaucoma, or optic nerve conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

The RNFL thickness measurement is primarily used to detect and monitor glaucoma, a condition that damages the optic nerve. Thinning of the RNFL may indicate early glaucomatous damage even before vision loss occurs. The test also helps differentiate glaucoma from other optic nerve diseases and monitors disease progression or treatment effectiveness over time.

Abnormally thin RNFL may also be associated with other conditions including optic neuritis, ischemic optic neuropathy, and certain neurological disorders. Your doctor will compare your results with a database of normal eyes matched for age to determine if your RNFL thickness falls within normal range.

Frequently asked questions

Does this test hurt?
No, OCT is completely painless and non-invasive. You will simply look at a fixed target while the scanner takes images of your eye.
How long does the test take?
The actual scanning takes only a few seconds, and the entire appointment is typically completed within 10-15 minutes.
Do I need to prepare for the test?
No special preparation is needed. You may continue with your normal activities before and after the test.
What do the results mean?
Your results will show your RNFL thickness compared to normal values. Thinner than average RNFL may indicate optic nerve damage, while normal thickness suggests healthy nerve tissue. Your eye doctor will interpret the results in context with your overall eye health.
How often should I have this test?
The frequency depends on your eye condition. For glaucoma patients, testing is typically done annually or as recommended by your doctor to monitor disease progression.
  1. 1
    American Academy of Ophthalmology - Understanding OCTSource
  2. 2
    National Eye Institute - GlaucomaSource

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.

Medical Disclaimer

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