Linked Life Data

9293519

Source:http://linkedlifedata.com/resource/pubmed/id/9293519

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1997-10-21
pubmed:abstractText
An experiment is described in which the subjective depth-of-focus (DOF) of the eye, defined as the range of focusing 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 judgment of just-perceptible defocus blur. The clinical implications of the results for measurements of refraction and amplitude of accommodation are discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
1040-5488
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
511-20
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Subjective depth-of-focus of the eye.
pubmed:affiliation
Centre for Eye Research, School of Optometry, Queensland University of Technology, Brisbane, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't