Contributions of optical and non-optical blur to variation in visual acuity.
Purpose: To determine the relative contributions of optical and non-optical sources of intrinsic blur to variations in visual acuity (VA) among normally sighted subjects.Methods: Best-corrected VA of 16 normally sighted subjects was measured using briefly presented (59 ms) tumbling E optotypes that...
| Publicado en: | Optometry & Vision Science Vol. 88; no. 6; pp. 716 - 724 |
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| Autores principales: | , , , , , , , , , |
| Formato: | research Journal Article |
| Publicado: |
Wiley-Blackwell
2011 Jun
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=104905476&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 104905476 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 10405488 1X24 jtl: Optometry & Vision Science issn: 10405488 maglogo: N pubinfo: dt: 2011 Jun vid: 88 iid: 6 pid: 480 pub: Wiley-Blackwell place: Malden, Massachusetts artinfo: ui: 104905476 104905476 NLM21460756 2011064258 10.1097/OPX.0b013e3182147202 NLM21460756 PMC3100362 104905476 ppf: 716 ppct: 8 formats: tig: atl: Contributions of optical and non-optical blur to variation in visual acuity. aug: au: McAnany JJ Shahidi M Applegate RA Zelkha R Alexander KR McAnany, J Jason Shahidi, Mahnaz Applegate, Raymond A Zelkha, Ruth Alexander, Kenneth R affil: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, USA sug: subj: Astigmatism Physiopathology Visual Acuity Diagnosis, Eye Adult Eyeglasses Female Male Middle Age Physical Stimulation Methods Psychophysics Methods Neural Pathways Physiopathology Young Adult Adult: 19-44 years Middle Aged: 45-64 years Female Male ab: Purpose: To determine the relative contributions of optical and non-optical sources of intrinsic blur to variations in visual acuity (VA) among normally sighted subjects.Methods: Best-corrected VA of 16 normally sighted subjects was measured using briefly presented (59 ms) tumbling E optotypes that were either unblurred or blurred through convolution with Gaussian functions of different widths. A standard model of intrinsic blur was used to estimate each subject's equivalent intrinsic blur (σint) and VA for the unblurred tumbling E (MAR0). For 14 subjects, a radially averaged optical point spread function due to higher-order aberrations was derived by Shack-Hartmann aberrometry and fit with a Gaussian function. The standard deviation of the best-fit Gaussian function defined optical blur (σopt). An index of non-optical blur (η) was defined as 1 - σopt/σint. A control experiment was conducted on five subjects to evaluate the effect of stimulus duration on MAR0 and σint. RESULTS.: The logarithm of the minimum angle of resolution (logMAR₀) for the briefly presented E was correlated significantly with log σint (r = 0.95, p < 0.01), consistent with previous work. However, logMAR₀ was not correlated significantly with log σopt (r = 0.46, p = 0.11). For subjects with logMAR₀ equivalent to ~20/20 or better, logMAR₀ was independent of log η, whereas for subjects with larger logMAR₀ values, logMAR₀ was proportional to log η. The control experiment showed a statistically significant effect of stimulus duration on logMAR₀ (p < 0.01) but a non-significant effect on σint (p = 0.13).Conclusions: The relative contributions of optical and non-optical blur to VA varied among the subjects and were related to the subject's VA. Evaluating optical and non-optical blur may be useful for predicting changes in VA following procedures that improve the optics of the eye in patients with both optical and non-optical sources of VA loss. pubtype: Academic Journal doctype: research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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