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Lretrnflinftempthicknessoct

Published: August 9, 2026Updated: August 16, 2026

This test uses special imaging technology to measure the thickness of the nerve fiber layer in your left retina, helping doctors detect and monitor eye conditions like glaucoma.

Quick summary

{"Uses OCT (Optical Coherence Tomography) to take detailed images of your retina","Measures the thickness of the retinal nerve fiber layer in the left eye","Helps detect early signs of glaucoma and other optic nerve diseases","Non-invasive imaging test that takes only a few minutes","Results help your doctor monitor eye health over time"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
86289-6
Short code
L-RETINA-RNFL-IT-OCT
Synonyms
L ret RNFL inf temp thickness OCT
Category
cardiac
Sample
serum
Container
Not applicable - this is an imaging procedure, not a blood or fluid specimen
Units
N/A
Ref low
71
Ref high
110
Critical range
— – 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
Stability
Not applicable
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
1–24 hours
Order
routine

What is this test?

The Left Retina Retinal Nerve Fiber Layer (RNFL) Thickness test uses Optical Coherence Tomography (OCT), a advanced imaging technology that uses light waves to create detailed cross-sectional images of your retina. Specifically, this test measures the thickness of the retinal nerve fiber layer in the inferior temporal region of your left eye. The retinal nerve fiber layer contains nerve fibers that carry visual information from your retina to your brain.

Why is this test performed?

This test is primarily performed to: 1) Detect early signs of glaucoma, a condition that damages the optic nerve; 2) Monitor the progression of glaucoma or other optic nerve disorders; 3) Evaluate the health of the retinal nerve fiber layer; and 4) Help differentiate between various eye conditions that may affect vision.

What happens during the test?

During the OCT scan, you will sit in front of a special machine called an OCT scanner. You will place your chin on a support and look at a target light. The machine will scan your eye without touching it, using light beams to create detailed images. The test is painless, takes only a few minutes, and requires no special preparation.

Are there any risks?

OCT is a non-invasive and safe procedure. It uses light waves, not radiation, so there is no radiation exposure. Most patients experience no discomfort during the test, though you may need to stay still for a few seconds while the images are being taken.

Reference range

Reference range for Left Retina RNFL Inferior Temporal thickness is approximately 71-110 microns in healthy adult eyes. Values below 71 microns may indicate retinal nerve fiber layer thinning suggestive of glaucomatous or neurological damage. Reference ranges may vary by instrument manufacturer and should be interpreted using device-specific normative databases.N/A

Specimen: serum

No fasting required. Patient should remove contact lenses before imaging. Inform technician of any eye surgery history, glaucoma, or neurological conditions. Pupillary dilation may be performed for optimal image quality but is not always required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Do I need to fast before this test?
No, fasting is not required for this test. You can eat and drink normally before your appointment.
Will the test hurt?
No, the OCT test is completely painless. You may feel slight discomfort from keeping your head still, but there is no pain involved.
How long does the test take?
The actual scanning process takes only about 1-2 minutes per eye. The entire appointment, including preparation, typically takes 10-15 minutes.
When will I get my results?
Your doctor will usually discuss the results with you during the same visit or at a follow-up appointment. The images need to be analyzed, so it may take a short time for your doctor to provide a complete interpretation.
Do I need to stop using eye drops before the test?
Generally, you should continue using your regular eye medications as prescribed. However, always follow your doctor's specific instructions regarding medications before the test.
How often do I need this test?
The frequency depends on your eye condition. For glaucoma patients, OCT RNFL scans are typically repeated annually or as directed by your eye doctor to monitor disease progression.
  1. 1
    American Academy of Ophthalmology - OCT for GlaucomaSource
  2. 2
    National Eye Institute - Glaucoma InformationSource

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 16, 2026. · Read our editorial policy