Useful Variations of the Badal Optometer
The simple Badal Optometer consists of a movable target and a fixed positive power lens placed at its focal distance away from the eye. The perceived angular size of the target is independent of target position and the power scale is linear. Limitations of the simple Badal Optometer include restriction of negative (myopic) ocular vergence range, the need for targets to be small, and the problem of "proximal" accommodation. We describe two modifications to the Badal system in which these limitations may be overcome by the use of a movable auxiliary optical system. In one modification, the movable auxiliary system consists of a target and positive lens which together may provide a virtual "target" for the Badal lens and thus increase the negative range. In the second modification, the Badal lens is positioned as it would normally be, but the target is an image of a distant stimulus created by the auxiliary lens. The target position (and hence the ocular vergence) is changed by moving the auxiliary lens. The distant target eliminates the proximal accommodation stimulus and allows spatial detail near the resolution limit to be displayed.
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|Item Type:||Journal Article|
|Additional Information:||The contents of this journal can be freely accessed online via the journal’s web page (see link) 12 months after publication. Self-archiving of the author-version is not yet supported by this publisher.
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|Keywords:||Badal Optometer, proximal accommodation|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 1995 Lippincott Williams & Wilkins|
|Deposited On:||28 Sep 2006 00:00|
|Last Modified:||10 Aug 2011 17:50|
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