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Fatigue reduces tonic accommodation

Fatigue reduces tonic accommodation
Fatigue reduces tonic accommodation
Ocular accommodation adopts a mean baseline response level of approximately 1.0 D in the absence of blur feedback (open-loop state). This baseline or tonic accommodation (TA) can be elevated following a sustained monocular accommodative response to a dioptric stimulus (lens adaptation) that exceeds the baseline open-loop level of TA. The accommodative response to the lens persists in the open-loop state (accommodative hysteresis), and eventually decays to a stable end-point. Interestingly, if the baseline TA is high, the monocularly adapted accommodative state can decay to an end-point that is below the initial pre-adapted baseline level of the TA (counter-adaptive response) (McBrien, N.A. and Millodot, M., (1988). Differences in adaptation of TA with refractive state. Invest. Ophthalmol. Vis. Sci., 29, 460–469).
We have investigated the possible contribution of accommodation fatigue to the counter-adaptive change in baseline TA following sustained accommodation. Two fatigue procedures were used while viewing a target at 66 or 33 cm. In a monocular condition, accommodation was stimulated for 3 min with lens values alternating from ?1.5 to +1.5 D at a rate of 0.25 Hz. In the binocular condition, convergence was stimulated with alternating prism values from 9 prism diopters (PD) base-out to 9 PD base-in. Both monocular and binocular tasks resulted in a significant reduction of TA.
These results suggest that previously reported reductions of baseline TA following sustained monocular accommodation or binocular convergence could have resulted from fatigue of the accommodative system. Accommodative fatigue could be responsible for the lower values of TA observed in counter-adaptive responses to sustained accommodative or convergence effort.
0275-5408
151-160
Hasebe, Satoshi
127c40ce-5a1d-4994-93d1-de02e9c0048f
Graf, Erich W.
1a5123e2-8f05-4084-a6e6-837dcfc66209
Schor, Clifton M.
ff1da7c6-b0f3-4199-9908-3f9c90c86e14
Hasebe, Satoshi
127c40ce-5a1d-4994-93d1-de02e9c0048f
Graf, Erich W.
1a5123e2-8f05-4084-a6e6-837dcfc66209
Schor, Clifton M.
ff1da7c6-b0f3-4199-9908-3f9c90c86e14

Hasebe, Satoshi, Graf, Erich W. and Schor, Clifton M. (2001) Fatigue reduces tonic accommodation. Ophthalmic and Physiological Optics, 21 (2), 151-160. (doi:10.1016/S0275-5408(00)00020-X).

Record type: Article

Abstract

Ocular accommodation adopts a mean baseline response level of approximately 1.0 D in the absence of blur feedback (open-loop state). This baseline or tonic accommodation (TA) can be elevated following a sustained monocular accommodative response to a dioptric stimulus (lens adaptation) that exceeds the baseline open-loop level of TA. The accommodative response to the lens persists in the open-loop state (accommodative hysteresis), and eventually decays to a stable end-point. Interestingly, if the baseline TA is high, the monocularly adapted accommodative state can decay to an end-point that is below the initial pre-adapted baseline level of the TA (counter-adaptive response) (McBrien, N.A. and Millodot, M., (1988). Differences in adaptation of TA with refractive state. Invest. Ophthalmol. Vis. Sci., 29, 460–469).
We have investigated the possible contribution of accommodation fatigue to the counter-adaptive change in baseline TA following sustained accommodation. Two fatigue procedures were used while viewing a target at 66 or 33 cm. In a monocular condition, accommodation was stimulated for 3 min with lens values alternating from ?1.5 to +1.5 D at a rate of 0.25 Hz. In the binocular condition, convergence was stimulated with alternating prism values from 9 prism diopters (PD) base-out to 9 PD base-in. Both monocular and binocular tasks resulted in a significant reduction of TA.
These results suggest that previously reported reductions of baseline TA following sustained monocular accommodation or binocular convergence could have resulted from fatigue of the accommodative system. Accommodative fatigue could be responsible for the lower values of TA observed in counter-adaptive responses to sustained accommodative or convergence effort.

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Published date: 2001

Identifiers

Local EPrints ID: 18303
URI: http://eprints.soton.ac.uk/id/eprint/18303
ISSN: 0275-5408
PURE UUID: e23bdb2a-1098-40e3-8da6-590990003076
ORCID for Erich W. Graf: ORCID iD orcid.org/0000-0002-3162-4233

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Date deposited: 17 Jan 2006
Last modified: 16 Mar 2024 03:39

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Contributors

Author: Satoshi Hasebe
Author: Erich W. Graf ORCID iD
Author: Clifton M. Schor

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