A Review of Depth of Focus in Measurement of the Amplitude of Accommodation

David H Burns; Peter M Allen; David F Edgar; Bruce J W Evans

doi:10.3390/vision2030037

A Review of Depth of Focus in Measurement of the Amplitude of Accommodation

Vision (Basel). 2018 Sep 6;2(3):37. doi: 10.3390/vision2030037.

Authors

David H Burns^{1

2}, Peter M Allen³, David F Edgar⁴, Bruce J W Evans^{1

2

4}

Affiliations

¹ Institute of Optometry, 56-62 Newington Causeway, London SE1 6DS, UK.
² School of Health and Social Care, London South Bank University, 103 Borough Road, London SE1 0AA, UK.
³ Department of Vision and Hearing Sciences & Vision and Eye Research Unit, Anglia Ruskin University, East Road, Cambridge CB1 1PT, UK.
⁴ Centre for Applied Vision Research, Division of Optometry and Visual Science, City, University of London, Northampton Square, London EC1V 0HB, UK.

Abstract

The aim of this review is to investigate the role of depth of focus (DoF) as a potential confounding variable in the measurement of the amplitude of accommodation (AoA). The role of DoF in human vision is briefly summarised, and it is noted that the prevalent method of measuring AoA is the push-up method. Factors influencing the effect of DoF on the push-up and other methods of measuring AoA are reviewed in detail. DoF is shown to add substantial measurement error in the routine assessment of accommodation when the AoA is measured by methods involving subjective judgement of an object's clarity. Reliable compensation for this source of error is not realistically possible because of the complexity of the aetiology of DoF, and its inter-individual and intra-individual variation. The method of measurement also influences the extent of the error. It is concluded that methods of measurement of AoA that exclude DoF should be preferred.

Keywords: amplitude of accommodation; depth of focus; measurement error; optometry.

Publication types

Review