Medicine:Negative relative accommodation
Negative relative accommodation (NRA) was proposed by Joseph Kearney of Oxford University in 1967 as a measure of the maximum ability to relax accommodation while maintaining clear, single binocular vision. It is an indirect measurement of fusional vergence in binocular vision.[1]
This measurement is typically obtained by an orthoptist, ophthalmologist or optometrist during an eye examination using a phoropter. After the patient's distance correction is established, the patient is instructed to view small letters on a card 40 cm from the eyes. The examiner adds convex lenses in +0.25 increments until the patient first reports that they become blurry.[2] The total value of the lenses added to reach this point is the NRA value. High NRA values (above +2.50) might be evidence to over minus, uncorrected hyperopia or latent hyperopia.
See also
References
- ↑ Scheiman, Mitchell; Wick, Bruce (2008) (in en). Clinical Management of Binocular Vision: Heterophoric, Accommodative, and Eye Movement Disorders. Lippincott Williams & Wilkins. pp. 4. ISBN 978-0-7817-7784-1. https://www.google.com/books/edition/Clinical_Management_of_Binocular_Vision/jGGROHBFYt8C?hl=en&gbpv=1&dq=%22negative+relative+accommodation%22+vision&pg=PA4&printsec=frontcover.
- ↑ Millodot, Michel (2017-10-19) (in en). Dictionary of Optometry and Vision Science. Elsevier Health Sciences. pp. 7. ISBN 978-0-7020-7223-9. https://www.google.com/books/edition/Dictionary_of_Optometry_and_Vision_Scien/Wfw6DwAAQBAJ?hl=en&gbpv=1&dq=%22negative+relative+accommodation%22+vision&pg=PA7&printsec=frontcover.
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