Rretrnfl2oclockthicknessoct
A non-invasive eye imaging test that measures the thickness of the retinal nerve fiber layer to detect optic nerve damage.
{"Uses light waves to create detailed cross-sectional images of the retina","Helps detect and monitor glaucoma and other optic nerve conditions","Quick, painless procedure that takes about 10-15 minutes","Results are compared to normal reference values by age group","Regular testing helps track changes in eye health over time"}
Key facts at a glance
- LOINC
- 86306-8
- Short code
- RNFL-2-OCT
- Synonyms
- R ret RNFL 2 o'clock thickness OCT
- Category
- cardiac
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 65
- Ref high
- 95
- Critical range
- 40 N/A – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Optical Coherence Tomography (OCT)
- CPT
- 92134
- SNOMED
- 371632009
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–24 hours
- Order
- routine
What is this test?
Optical Coherence Tomography (OCT) is an advanced imaging test that uses light waves to take cross-sectional pictures of your retina. The retinal nerve fiber layer (RNFL) is a layer of nerve fibers that carries visual information from the retina to the brain. This test specifically measures the thickness of the RNFL at different points around the optic nerve, like a clock face with 12 positions.
How is the test performed?
During the test, you will sit in front of the OCT machine and rest your chin on a support. The technician will align the machine with your eye. You will see a brief flash of light as the scan is taken. The test is completely painless and does not involve any radiation. Your pupils may be dilated with eye drops for better imaging.
How to prepare for the test?
No special preparation is needed. Bring your glasses or contact lenses if you wear them. If your eyes are dilated, you may be sensitive to light for a few hours, so bringing sunglasses is recommended. Avoid wearing eye makeup on the day of the test.
Reference range
Normal Retinal Nerve Fiber Layer (RNFL) thickness for clock hour 2 (temporal-superior) ranges from 65-95 micrometers in healthy adults. Values below 50 micrometers may indicate glaucomatous or optic nerve damage.N/A
No special preparation required. Patient should remove eye makeup and contact lenses before imaging. Pupillary dilation may be performed for better visualization.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Does the test hurt?
How long does the test take?
When will I get my results?
How often should I have this test?
What do the results mean?
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