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negative relative accommodation

Negative relative accommodation (NRA) is the maximum amount of accommodation a patient can relax and still keep clear, single binocular vision.1 The test is done at 40 cm through the subjective prescription, and the target asks for about 2.5 D of accommodation.2 The examiner adds plus lenses binocularly in +0.25 D steps until the patient reports the first sustained blur, meaning the letters are no longer as sharp and clear as they were at the start.3

Convergence demand stays fixed during the test.4 Each step of relaxed accommodation therefore removes some accommodative convergence, by an amount set by the AC/A ratio.4 The patient must use positive fusional vergence to keep the target single, so the NRA depends on positive fusional vergence as well as on the ability to relax accommodation.4 At 40 cm the patient can relax at most about 2.50 D, and an NRA greater than +2.50 suggests that the subjective refraction was overminused.2

More detail

In a prepresbyopic patient the NRA and the positive relative accommodation (PRA) should be roughly balanced, near +2.50 and −2.50, and an NRA higher than the PRA suggests the patient may benefit from a near add.2 To find whether accommodation or positive fusional vergence limits the result, the examiner can cover one eye once the patient reports blur.4 If the target clears under monocular conditions, the fusional vergence system is at fault.4

Sources (7)
  1. American Optometric Association, Care of the Patient with Accommodative and Vergence Dysfunction, glossary
  2. Scheiman and Wick, Clinical Management of Binocular Vision, ch. 1
  3. Carlson and Kurtz, Clinical Procedures for Ocular Examination, ch. 4
  4. Scheiman and Wick, Clinical Management of Binocular Vision, ch. 2
  5. Carlson, N.B. and Kurtz, D. 2004. Clinical procedures for ocular examination. 3rd ed. New York: McGraw-Hill.
  6. Grosvenor, T. 2007. Primary care optometry. 5th ed. St. Louis (MO): Butterworth-Heinemann Elsevier.
  7. Scheiman, M. and Wick, B. 2014. Clinical management of binocular vision: heterophoric, accommodative, and eye movement disorders. 4th ed. Philadelphia: Lippincott Williams & Wilkins.

Reviewed October 2026

Related terms

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← near point of convergenceneutral density filter test →
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