What is the difference between accommodation and refraction

Judith Flanagan Institute for Eye Research for her helpful suggestions on the manuscript. Commercial relationships: none. Corresponding author: Arthur Ho.

Email: a. Atchison, D. Comparison of peripheral refractions determined by different instruments. Optometry and Vision Science, 80, — Pritchard, N. Schmid, K. Peripheral refraction along the horizontal and vertical visual fields in myopia.

Vision Research, 46, — Scott, D. Jones, C. Pope, J. Shape of the retinal surface in emmetropia and myopia. Berntsen, D. Mutti, D. Zadnik, K. Validation of aberrometry-based relative peripheral refraction measurements. Calver, R. Radhakrishnan, H. Osuobeni, E. O'Leary, D. Peripheral refraction for distance and near vision in emmetropes and myopes. Charman, W. Optimal spherical focus in the peripheral retina.

Mountford, J. Markwell, E. Peripheral refraction in orthokeratology patients. Optometry and Vision Science, 83, — Cohn, H. The hygiene of the eye in schools. Conrady, A. Discussion of the oblique aberrations. Applied optics and optical design: Part one. London: Oxford University Press. Davies, L. Mallen, E. Wolffsohn, J. Gilmartin, B. Ferree, C. Rand, G. Hardy, C. Refractive asymmetry in the temporal and nasal halves of the visual field.

American Journal of Ophthalmology, 15, — Graham, B. Judge, S. The effects of spectacle wear in infancy on eye growth and refractive error in the marmoset Callithrix jacchus. Vision Research, 39, — Greene, P. Mechanical considerations in myopia: Relative effects of accommodation, convergence, intraocular pressure, and the extraocular muscles. American Journal of Optometry and Physiological Optics, 57, — Gwiazda, J. Hyman, L. Hussein, M. Everett, D. Norton, T. Kurtz, D. A randomized clinical trial of progressive addition lenses versus single vision lenses on the progression of myopia in children.

Thorn, F. Bauer, J. Held, R. Myopic children show insufficient accommodative response to blur. Hung, L. Crawford, M. Smith, E. Spectacle lenses alter eye growth and the refractive status of young monkeys.

Nature Medicine, 1, — Ip, J. Saw, S. Rose, K. Morgan, I. Kifley, A. Wang, J. Role of near work in myopia: Findings in a sample of Australian school children. Kee, C. Qiao-Grider, Y. Roorda, A. Effects of optically imposed astigmatism on emmetropization in infant monkeys.

Konstantopoulos, A. Yadegarfar, G. Elgohary, M. Near work, education, family history, and myopia in Greek conscripts. Eye, 22, — Manny, R.

Dong, L. Wang, Y. Role of parental myopia in the progression of myopia and its interaction with treatment in COMET children. Ma, L. Off-axis refraction and aberrations following conventional laser in situ keratomileusis. Journal of Cataract and Refractive Surgery, 31, — McBrien, N. Millodot, M. The effect of refractive error on the accommodative response gradient. McLean, R. Wallman, J. Severe astigmatic blur does not interfere with spectacle lens compensation. Effect of ametropia on peripheral refraction.

American Journal of Optometry and Physiological Optics, 58, — Hayes, J. This depends mainly on stimulus characteristics but also on any anticipation of the changes in accommodation Figure 7.

On top of this, there is a response time of about to 1, ms, during which the accommodation changes before stabilizing at its new level. Response times depend on the amount of accommodative but not disaccommodative demand. This can be appreciated more readily if one of the relative step responses is inverted for direct comparison Figure 8. Although studies suggest that, within the amplitude of accommodation, the dynamic characteristics decline only modestly with age, 22 as Figure 8 suggests, the FN is faster in young patients and more sluggish in older , while the NF response is faster in older patients.

The youthful accommodation system allows the eye to vary its focus to obtain reasonably clear retinal images of objects at different distances. Nevertheless, such focus is rarely exact with lags and leads of accommodation , nor is it stable with microfluctuations. Plainis may be reached at e-mail: plainis med.

Ioannis G. Search for:. CRST Europe. End of Issue. SUMMARY The youthful accommodation system allows the eye to vary its focus to obtain reasonably clear retinal images of objects at different distances.

Weale RA. The Senescence of Human Vision. Oxford: Oxford University Press; Atchison DA. Depth of focus of the human eye. Presbyopia: Origins, Effects, and Treatment. Thorofare NJ: Slack Incorporated; Why we need reading-glasses before a zimmer-frame. Vision Res. Duane A. Studies in monocular and binocular accommodation, with their clinical application.

Trans Am Ophthalmol Soc. Plainis S, Wolffsohn JS. Presbyopia correction: evaluating success using behavioural methods. Descartes R. Cambridge: Harvard University Press; Young T. Property Law. Real Estate Law. Texas Bar Exam. Alternative Medicine. Health Class. Health Science. Human Development. Mental Health. Public Health. ACE Health Coach. Real Estate. Computer Programming. Computer Science. Graphic Design.

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Sports Trivia. Most of the refractive power in the eye comes from the cornea, due to the differences in the indices of refraction between the air refractive index of about 1. Pupil and Iris. Once the light passes through the cornea it goes through the pupil. This is the aperture of the eye, so it is essentially a hole that regulates light intensity by changing the pupil's diameter. So when its dark, the pupils dilate , up to about 8mm, so that more light can enter the eye.