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Lretrnfltempsupthicknessoct

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

This test uses optical coherence tomography (OCT) to measure the thickness of the retinal nerve fiber layer in the upper temporal area of the left eye, helping doctors detect and monitor eye diseases like glaucoma.

Quick summary

{"Uses light waves to take cross-sectional images of your retina","Measures the thickness of nerve fiber layer to detect glaucoma damage","A quick, non-invasive scan that takes about 5-10 minutes","No eye drops or radiation involved","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
86275-5
Short code
RNFL-TS-LT-OCT
Synonyms
L ret RNFL temp 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
150
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 18 years
Method
Optical Coherence Tomography (OCT)
CPT
92134
SNOMED
415334002
Specimen volume
Not applicable - imaging test
Stability
Not applicable - imaging test
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) Temporal Superior Thickness test is an imaging procedure that uses Optical Coherence Tomography (OCT) to measure the thickness of the retinal nerve fiber layer in the upper temporal area of your left eye. The retinal nerve fiber layer is made up of nerve fibers that carry visual information from the retina to the brain.

How is the test performed?

During the test, you will sit in front of an OCT machine. Your chin will rest on a support while the technician aligns your eye with the scanning device. The machine uses light waves to create detailed cross-sectional images of your retina. You will need to stare at a fixed point for a few seconds while the scan is taken. The procedure is completely painless and takes only a few minutes.

Why is this test important?

This test is primarily used to detect and monitor glaucoma, a condition that damages the optic nerve. By measuring the RNFL thickness, doctors can identify early signs of nerve damage before you notice any vision loss. The test is also useful for tracking disease progression and evaluating treatment effectiveness over time.

How to prepare for the test?

No special preparation is needed. You can eat and drink normally before the test. If you wear glasses or contact lenses, you may need to remove them for the scan. The test does not require eye drops or any injections. It's helpful to arrive with clean eyes and avoid wearing eye makeup on the day of the test.

Reference range

Normal temporal superior retinal nerve fiber layer (RNFL) thickness ranges from 100-150 micrometers (μm) in healthy adults. Reference ranges may vary by instrument manufacturer and population normative database.N/A

Specimen: serum

Patient should remove contact lenses before imaging if applicable. Pupil dilation may be performed for better visualization but is not always required. Inform patient that the test involves bright light and requires them to remain still for brief periods.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Does the test hurt?
No, the OCT scan is completely painless. You may feel slight discomfort from keeping your eye open, but there is no pain involved. Some people may experience brief dizziness from the light, but this is rare.
How long does the test take?
The actual scanning process takes only a few seconds, but including preparation and positioning, the entire visit typically takes about 5-10 minutes.
Do I need someone to drive me home?
No, the test does not affect your vision or require any sedation. You can drive home normally after the procedure.
How often should I have this test?
Your doctor will determine how often you need this test based on your condition. For glaucoma patients, it may be done annually or more frequently to monitor disease progression.
What do the results mean?
Your doctor will compare your RNFL thickness measurements to normal values based on age and ethnicity. Thinner than average measurements may indicate glaucoma or risk of developing glaucoma, while thicker measurements may require further investigation for other conditions.
  1. 1
    American Academy of Ophthalmology - OCT for GlaucomaSource
  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 16, 2026. · Read our editorial policy