Positive relative accommodation
Lua error in package.lua at line 80: module 'strict' not found.Positive relative accommodation (PRA) is a measure of the maximum ability to stimulate accommodation while maintaining clear, single 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, he is instructed to view small letters on a card 40 cm from the eyes. The examiner adds lenses in −0.25 diopter increments until the patient first reports that they become blurry. The total value of the lenses added to reach this point is the PRA value.
High PRA values (> or = 3.50 diopters) are considered to be diagnostic of disorders involving accommodative excess.[2] Those with accommodative insufficiency typically have PRA values below −1.50 diopters.[3]
References
- ↑ www.vision-therapy.com[dead link]
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ http://www.aoa.org/documents/CPG-18.pdf[dead link]
See also
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