Subjective Depth-of-Focus of the Eye
Atchison, David A., Charman, William N., & Woods, Russell L. (1997) Subjective Depth-of-Focus of the Eye. Optometry and Vision Science, 74(5), pp. 511-520.
Abstract: An experiment is described in which the subjective depth-of-focus (DOF) of the eye, defined as the range of focussing errors for which the image of the target appears to have the same clarity, contrast, and form as the optimal in-focus image, was measured as a function of the size of high contrast (99%) Snellen Es for 5 trained subjects under cycloplegia. Mean DOF increased by approximately 60% as the size of the letter detail increased from -0.2 to 0.87 log min arc (Snellen equivalent: 6/3.8 to 6/45), although there were considerable intersubject variations. DOF declined with increasing pupil diameter, the mean total DOFs being 0.86, 0.59, and 0.55 D for 2-, 4-, and 6-mm pupils, respectively. In a second experiment, use of low (21%) contrast letters with a 4-mm pupil and 4 subjects marginally increased the DOF (by 0.08 ± 0.05 D); refraction also shifted in a myopic direction by a mean of 0.15 ± 0.06 D compared with the high contrast letters. A third experiment with four less-experienced subjects demonstrated the importance of instruction and training in any measurement involving judgement of just-perceptible defocus blur. The clinical implications of the results for measurements of refraction and amplitude of accommodation are discussed.
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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. For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: email@example.com|
|Keywords:||amplitude of accommodation, depth, of, focus, pupil size, refraction|
|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 1997 Lippincott Williams & Wilkins|
|Deposited On:||09 Oct 2006|
|Last Modified:||10 Aug 2011 18:25|
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