Lretrnfl2oclockthicknessoct
This test uses advanced imaging technology to measure the thickness of the retinal nerve fiber layer in a specific area of your left eye.
{"Uses OCT imaging to measure retinal nerve fiber layer thickness","Helps detect and monitor eye conditions like glaucoma","A quick, non-invasive eye scan","No blood sample or eye drops required","Results help your doctor assess your optic nerve health"}
Key facts at a glance
- LOINC
- 86294-6
- Short code
- RNFL-OCT-L-2
- Synonyms
- L ret RNFL 2 o'clock thickness OCT
- Category
- cardiac
- Sample
- serum
- Container
- Not applicable (imaging study)
- Units
- N/A
- Ref low
- 75
- Ref high
- 140
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Optical Coherence Tomography (OCT)
- CPT
- 92133
- SNOMED
- 399550006
- Specimen volume
- Not applicable (imaging study)
- Stability
- Not applicable (imaging study)
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 1–24 hours
- Order
- routine
What is this test?
This test uses Optical Coherence Tomography (OCT), a special imaging technique, to measure the thickness of the retinal nerve fiber layer (RNFL) in your left eye. The 'clock hour 2' refers to a specific position on your retina, similar to how a clock face is divided. This particular area is being measured to check the health of your optic nerve.
Why is it performed?
This test is primarily used to: 1) Detect and monitor glaucoma, a condition that damages the optic nerve; 2) Evaluate the health of your optic nerve; 3) Track changes in retinal nerve fiber layer thickness over time; and 4) Help diagnose other neurological or eye conditions that may affect the optic nerve.
How is the test done?
During the test, you will sit in front of the OCT machine and rest your chin on a support. The machine will scan your eye using light waves to create detailed cross-sectional images of your retina. The test is quick, painless, and does not involve any radiation or blood collection. You may need to stay still for a few seconds while the images are captured.
How to prepare
No special preparation is needed. You can eat and drink normally before the test. If you wear glasses or contact lenses, bring them with you. Avoid wearing eye makeup on the day of the test as it may interfere with the imaging.
Reference range
Normal retinal nerve fiber layer (RNFL) thickness typically ranges from 70 to 140 micrometers depending on the clock hour sector. For clock hour 2 (temporal superior quadrant), normal thickness is generally between 75 and 140 micrometers in adults.N/A
Patient should remove contact lenses prior to imaging. Pupil dilation may be performed to enhance image quality, though undilated imaging is possible with modern OCT devices. Patient should avoid eye rubbing or pressure on eyes before the procedure.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Does this test hurt?
How long does the test take?
Will I need my pupils dilated?
When will I get my results?
How often do I need this test?
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