Effect of defocus on visual field measurement
Atchison, David A. (1987) Effect of defocus on visual field measurement. Ophthalmic and Physiological Optics, 7(3), pp. 259-265.
Defocus increased visual field contrast thresholds for stimuli equal to or smaller than Goldmann perimeter target III (26 min arc diameter). Beyond 30 degrees - 40 degrees from the centre of the visual field, defocus had little effect on contrast thresholds. For accurate clinical perimetry, ametropia and presbyopia should be corrected for small targets (≤ target III) within 30 degrees - 40 degrees of fixation with either a spectacle lens (if required power less than ± 10 D) or a contact lens. Larger stimuli are little affected by defocus. Outside this central 30 degrees - 40 degrees field, correction with contact lenses should be provided if fixation is poor due to ametropia. Scotomata for which no cause is evident should be further investigated to find whether they have a refractive basis.
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|Item Type:||Journal Article|
|Additional Information:||For more information or for a copy of this article contact: firstname.lastname@example.org|
|Keywords:||visual field, defocus, contrast threshold, perimetry, ametropia|
|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 1987 Blackwell Publishing|
|Copyright Statement:||The definitive version is available at www.blackwell-synergy.com|
|Deposited On:||17 Aug 2006|
|Last Modified:||15 Jan 2009 17:08|
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