Amplitude of accommodation
Encyclopedia
Amplitude of accommodation (AA) is a measurement of the eye
’s ability to focus clearly on objects at near distances (i.e. accommodation
). This eye focusing range for a child is usually about 5–7.5 cm (2–3 inches). For a young adult, it is 10–15 cm (4–6 inches). The focus range for a 45-year-old adult is about 50 cm (20 inches). For an 80-year-old adult, it is 1.5 m (60 inches).
The average amplitude of accommodation, in diopters, for a patient of a given age may be estimated by Hofstetter's formula: 18.5 minus one third of the patient's age in years.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
’s ability to focus clearly on objects at near distances (i.e. accommodation
Accommodation (eye)
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image on an object as its distance changes....
). This eye focusing range for a child is usually about 5–7.5 cm (2–3 inches). For a young adult, it is 10–15 cm (4–6 inches). The focus range for a 45-year-old adult is about 50 cm (20 inches). For an 80-year-old adult, it is 1.5 m (60 inches).
The average amplitude of accommodation, in diopters, for a patient of a given age may be estimated by Hofstetter's formula: 18.5 minus one third of the patient's age in years.
See also
- Convergence insufficiencyConvergence insufficiencyConvergence insufficiency or Convergence Disorder is a sensory and neuromuscular anomaly of the binocular vision system, characterized by an inability of the eyes to turn towards each other, or sustain convergence.-Symptoms:...
- Eye examinationEye examinationAn eye examination is a battery of tests performed by an ophthalmologist, optometrist, or orthoptist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes....
- Negative relative accommodationNegative relative accommodationNegative relative accommodation was proposed by Prof. Joseph Kearney of Oxford University in 1967, is a measure of the maximum ability to relax accommodation while maintaining clear, single binocular vision. This measurement is typically obtained by an orthoptist, ophthalmologist or optometrist...
- Positive relative accommodationPositive relative accommodationPositive relative accommodation is a measure of the maximum ability to stimulate accommodation while maintaining clear, single binocular vision. This measurement is typically obtained by an orthoptist, ophthalmologist or optometrist during an eye examination using a phoropter...
- PresbyopiaPresbyopiaPresbyopia is a condition where the eye exhibits a progressively diminished ability to focus on near objects with age. Presbyopia’s exact mechanisms are not known with certainty; the research evidence most strongly supports a loss of elasticity of the crystalline lens, although changes in the...
External links
- http://www.ijo.in/article.asp?issn=0301-4738;year=2005;volume=53;issue=2;spage=105;epage=108;aulast=Abraham