micron
One Millionth of a Meter
Plain-language definition
A unit of measurement (1/1000 of a millimeter) used for retinal layer thickness on OCT. Normal RNFL is roughly 90-110 microns.
Where this term comes up
“Measures corneal thickness (normal: approximately 520-560 microns centrally)”
“RNFL (retinal nerve fiber layer) thickness is the central glaucoma metric - measured around the optic nerve in microns”
Guide · How to Read Your OCT Report
“Typically 100-300 microns across (small fractions of a millimeter)”
Finding · Cotton-Wool Spots
- Category
- Test or diagnostic term
- Also written as
- microns, micrometer, micrometers
Diagnostic terms describe tests, measurements, imaging, or exam techniques used to understand eye and neuro-ophthalmic problems.
Related glossary terms
A note on medical context
A glossary definition can explain a word, but it cannot tell you whether a symptom or test result is serious. If this term came from an article, use the full article and your clinician's guidance for context.