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Influence of amplitude and starting point on accommodative dynamics in humans.
Invest Ophthalmol Vis Sci. 2005 Sep; 46(9):3463-72.IO

Abstract

PURPOSE

The effects of amplitude and the starting point of an accommodative response on the dynamics of far-to-near (accommodation) and near-to-far (disaccommodation) focus were studied.

METHODS

Step responses were recorded with a dynamic optometer in nine 22- to 30-year-old subjects, under three conditions: (1) Fixed far: accommodative demands from 1 to 6 D were created by placing the far target at 6 m and the near target at various proximal distances. (2) Fixed near: accommodative demands from 1 to 5 D were created by placing the near target at 16.7 cm and the far target at various distal positions. (3) Fixed amplitude: far and near target positions were changed to create an accommodative demand of 1.5 D from starting positions of 1 to 4.5 D in 0.5-D steps. Each recorded response was fitted with an exponential function to calculate response amplitude, peak velocity, time constant, and starting point.

RESULTS

The relationship between starting point and amplitude of accommodation and disaccommodation was effectively manipulated in the three conditions. For accommodation and disaccommodation, peak velocity increased linearly with response starting point, whereas the peak velocity versus response amplitude relationship differed according to the condition. Similar amplitude responses were associated with a higher peak velocity and a smaller time constant at proximal starting points than at distal starting points. Low-amplitude responses were influenced by both starting point and amplitude.

CONCLUSIONS

The dynamics of accommodation and disaccommodation are strongly influenced by the starting point, but less so by amplitude.

Authors+Show Affiliations

College of Optometry, University of Houston, 4901 Calhoun Road, Houston, TX 77204, USA.No affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

16123453

Citation

Kasthurirangan, Sanjeev, and Adrian Glasser. "Influence of Amplitude and Starting Point On Accommodative Dynamics in Humans." Investigative Ophthalmology & Visual Science, vol. 46, no. 9, 2005, pp. 3463-72.
Kasthurirangan S, Glasser A. Influence of amplitude and starting point on accommodative dynamics in humans. Invest Ophthalmol Vis Sci. 2005;46(9):3463-72.
Kasthurirangan, S., & Glasser, A. (2005). Influence of amplitude and starting point on accommodative dynamics in humans. Investigative Ophthalmology & Visual Science, 46(9), 3463-72.
Kasthurirangan S, Glasser A. Influence of Amplitude and Starting Point On Accommodative Dynamics in Humans. Invest Ophthalmol Vis Sci. 2005;46(9):3463-72. PubMed PMID: 16123453.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Influence of amplitude and starting point on accommodative dynamics in humans. AU - Kasthurirangan,Sanjeev, AU - Glasser,Adrian, PY - 2005/8/27/pubmed PY - 2005/11/3/medline PY - 2005/8/27/entrez SP - 3463 EP - 72 JF - Investigative ophthalmology & visual science JO - Invest. Ophthalmol. Vis. Sci. VL - 46 IS - 9 N2 - PURPOSE: The effects of amplitude and the starting point of an accommodative response on the dynamics of far-to-near (accommodation) and near-to-far (disaccommodation) focus were studied. METHODS: Step responses were recorded with a dynamic optometer in nine 22- to 30-year-old subjects, under three conditions: (1) Fixed far: accommodative demands from 1 to 6 D were created by placing the far target at 6 m and the near target at various proximal distances. (2) Fixed near: accommodative demands from 1 to 5 D were created by placing the near target at 16.7 cm and the far target at various distal positions. (3) Fixed amplitude: far and near target positions were changed to create an accommodative demand of 1.5 D from starting positions of 1 to 4.5 D in 0.5-D steps. Each recorded response was fitted with an exponential function to calculate response amplitude, peak velocity, time constant, and starting point. RESULTS: The relationship between starting point and amplitude of accommodation and disaccommodation was effectively manipulated in the three conditions. For accommodation and disaccommodation, peak velocity increased linearly with response starting point, whereas the peak velocity versus response amplitude relationship differed according to the condition. Similar amplitude responses were associated with a higher peak velocity and a smaller time constant at proximal starting points than at distal starting points. Low-amplitude responses were influenced by both starting point and amplitude. CONCLUSIONS: The dynamics of accommodation and disaccommodation are strongly influenced by the starting point, but less so by amplitude. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/16123453/Influence_of_amplitude_and_starting_point_on_accommodative_dynamics_in_humans_ L2 - https://iovs.arvojournals.org/article.aspx?doi=10.1167/iovs.04-1408 DB - PRIME DP - Unbound Medicine ER -