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Accommodation responses and ageing.
Invest Ophthalmol Vis Sci. 1999 Nov; 40(12):2872-83.IO

Abstract

PURPOSE

To study the impact of age on accommodation dynamics.

METHODS

Monocular accommodation responses were measured continuously using a modified Canon Auto Ref R1 infrared optometer. The stimulus was a single letter oscillating sinusoidally between 2.38 and 1.33 D providing a stimulus amplitude of 0.52 D, about a mean level of 1.86 D. Response characteristics were used to quantify gain and phase. Step responses were also recorded between these stimulus vergence levels for calibration purposes and to measure reaction and response times. Nineteen visually normal subjects 18 to 49 years of age participated, and 11 frequencies were used in the range 0.05 to 1.0 Hz. A key feature of the experimental design was to use a stimulus vergence range that lay within the amplitude of accommodation of all the observers.

RESULTS

Accommodation gain reduced and phase lag increased with age, particularly at the higher frequencies used. No strongly significant change with age was found for reaction and response times or accommodation velocity, and results were similar for both far-to-near and near-to-far responses. Response amplitude for the step change in target vergence declined with age, and substantial differences were found between the measured and predicted (from reaction time) phase lags at 1.0 Hz as a function of age. Young observers showed a phase lag that was shorter than predicted, whereas older observers' measured phase lags were considerably larger than predicted.

CONCLUSIONS

Results show that for a target oscillating sinusoidally in a predictable manner at a modest amplitude, the main ageing effects occur in phase lag, which is appreciably longer than predicted from reaction times in the older observers. The effects of ageing on gain were not as marked. Although responses to small step changes do reduce with age, there is no evidence of increased response times with ageing. In general, accommodation function in the middle-aged eye is quite robust despite a dwindling amplitude of accommodation. These results provide evidence of accommodative vigor in youth and a slowing of accommodation with ageing.

Authors+Show Affiliations

Department of Vision Sciences, Glasgow Caledonian University, Scotland, United Kingdom. ghe@gcal.ac.ukNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10549647

Citation

Heron, G, et al. "Accommodation Responses and Ageing." Investigative Ophthalmology & Visual Science, vol. 40, no. 12, 1999, pp. 2872-83.
Heron G, Charman WN, Gray LS. Accommodation responses and ageing. Invest Ophthalmol Vis Sci. 1999;40(12):2872-83.
Heron, G., Charman, W. N., & Gray, L. S. (1999). Accommodation responses and ageing. Investigative Ophthalmology & Visual Science, 40(12), 2872-83.
Heron G, Charman WN, Gray LS. Accommodation Responses and Ageing. Invest Ophthalmol Vis Sci. 1999;40(12):2872-83. PubMed PMID: 10549647.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Accommodation responses and ageing. AU - Heron,G, AU - Charman,W N, AU - Gray,L S, PY - 1999/11/5/pubmed PY - 1999/11/5/medline PY - 1999/11/5/entrez SP - 2872 EP - 83 JF - Investigative ophthalmology & visual science JO - Invest. Ophthalmol. Vis. Sci. VL - 40 IS - 12 N2 - PURPOSE: To study the impact of age on accommodation dynamics. METHODS: Monocular accommodation responses were measured continuously using a modified Canon Auto Ref R1 infrared optometer. The stimulus was a single letter oscillating sinusoidally between 2.38 and 1.33 D providing a stimulus amplitude of 0.52 D, about a mean level of 1.86 D. Response characteristics were used to quantify gain and phase. Step responses were also recorded between these stimulus vergence levels for calibration purposes and to measure reaction and response times. Nineteen visually normal subjects 18 to 49 years of age participated, and 11 frequencies were used in the range 0.05 to 1.0 Hz. A key feature of the experimental design was to use a stimulus vergence range that lay within the amplitude of accommodation of all the observers. RESULTS: Accommodation gain reduced and phase lag increased with age, particularly at the higher frequencies used. No strongly significant change with age was found for reaction and response times or accommodation velocity, and results were similar for both far-to-near and near-to-far responses. Response amplitude for the step change in target vergence declined with age, and substantial differences were found between the measured and predicted (from reaction time) phase lags at 1.0 Hz as a function of age. Young observers showed a phase lag that was shorter than predicted, whereas older observers' measured phase lags were considerably larger than predicted. CONCLUSIONS: Results show that for a target oscillating sinusoidally in a predictable manner at a modest amplitude, the main ageing effects occur in phase lag, which is appreciably longer than predicted from reaction times in the older observers. The effects of ageing on gain were not as marked. Although responses to small step changes do reduce with age, there is no evidence of increased response times with ageing. In general, accommodation function in the middle-aged eye is quite robust despite a dwindling amplitude of accommodation. These results provide evidence of accommodative vigor in youth and a slowing of accommodation with ageing. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/10549647/Accommodation_responses_and_ageing_ L2 - https://iovs.arvojournals.org/article.aspx?volume=40&issue=12&page=2872 DB - PRIME DP - Unbound Medicine ER -