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The retinal nerve fiber layer, called RNFL, is a layer of nerve fibers that carries visual signals toward the optic nerve. It is made from the long fibers of ganglion cells. Doctors measure RNFL thickness on OCT scans to watch for nerve damage. Changes can be small, so trending across visits matters.
read more about retinal nerve fiber layer ...The RNFL sits near the inner surface of the retina, closer to the vitreous. The fibers run toward the optic nerve, similar to cables carrying signal information. Near the optic nerve, the layer forms a thicker ring pattern. Doctors look for thinning that matches symptoms and visual field tests.
RNFL thickness is used in glaucoma care because glaucoma can damage these fibers. A thinner reading over time can match changes in peripheral vision tests. One scan is a snapshot, so trend lines across visits matter more. Doctors also look at how the two eyes compare.
OCT takes a circular scan around the optic nerve and measures layer thickness. Software compares results with a reference range based on age. The doctor also reviews the raw image to rule out scan errors. A repeat scan is common if the image quality is low.
High myopia can change eye shape and affect readings. Cataracts, dry eyes, or poor fixation can reduce scan quality. A tilted optic disc can also shift the thickness pattern. This is why OCT results are read together with the full eye exam.
No. RNFL can look thinner from high myopia, optic nerve differences, or other nerve conditions. Glaucoma diagnosis uses multiple tests, not one number.
Yes. A longer eye can stretch retinal layers and change the thickness map. Your eye doctor may use extra scans or compare results over time to get a clearer picture.
There is no single normal number for everyone. Readings vary by device, age, and eye anatomy. Your report is best read as a trend across visits.
It depends on risk level and any glaucoma findings. Some people get it yearly, while others need it more frequently during treatment changes.
1. Mahabadi N, et al. Neuroanatomy, Retina. NCBI Bookshelf (StatPearls). https://www.ncbi.nlm.nih.gov/books/NBK545310/. Accessed February 24, 2026.
2. Geevarghese A, Wollstein G. Optical Coherence Tomography and Glaucoma. PubMed Central. https://pmc.ncbi.nlm.nih.gov/articles/PMC9184968/. Accessed February 24, 2026.
3. American Academy of Ophthalmology EyeWiki. Optic Nerve and Retinal Nerve Fiber Imaging. https://eyewiki.org/Optic_Nerve_and_Retinal_Nerve_Fiber_Imaging. Accessed February 24, 2026.
4. American Academy of Ophthalmology EyeWiki. Spectral Domain Optical Coherence Tomography in Glaucoma. https://eyewiki.org/Spectral_Domain_Optical_Coherence_Tomography_in_Glaucoma. Accessed February 24, 2026.
5. American Academy of Ophthalmology EyeWiki. Optical Coherence Tomography in Neuro-Ophthalmology. https://eyewiki.org/Optical_Coherence_Tomography_in_Neuro-Ophthalmology. Accessed February 24, 2026.