lnu.sePublikationer
Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Retina Artery to Vein Intensity Ratio as a Function of Wavelength and Dark-Field Offset With Low Cost Ophthalmoscope
Indiana University, USA.
Indiana University, USA;Aeon Imaging, USA.
Indiana University, USA.ORCID-id: 0000-0002-3745-0035
Indiana University, USA.
Visa övriga samt affilieringar
2014 (Engelska)Konferensbidrag, Poster (med eller utan abstract) (Refereegranskat)
Abstract [en]

 PurposeTo quantify light return from retinal vessels for oxygenation status. To use a low-cost Digital Light Ophthalmoscope (DLO) based on a novel structured light pattern Digital Light Projector for quantitative retinal imaging.  MethodsFive normal subjects of ages 27-63 and various eye colors were imaged without mydriasis. The DLO produced a progressively scanning 6 pixel wide stripe, 96 stripe illumination pattern (85 μm stripe width at retina) with LEDs at 635 +/- 25nm (Red) and 535 +/- 70nm (Green) with a constant fixation target location across tests. The illumination was synchronized to a 13.2 Hz rolling shutter CMOS sensor (11 μm resolution at retina). To collect the light return from the retina at varying light multiply scattered levels, aperture offset was varied in position with respect to the illumination centerline: dark-field mode was obtained with large offsets and confocal mode had small offsets, where offset was varied from -517 μm (row start 30) to 1353 μm (row start 200). Multiple images of 12 bit dynamic range were captured in sequence, aligned with translational cross correlation, then time averaged to reduce noise. The artery and vein gray scale intensity level was measured at vessel centers for: 1) both vessels over background retina and 2) artery over the optic disc and vein over background. Mean-to-mean intensity ratios were then compared.  ResultsWith an aperture width of 704 μm, intensity varied by 2.60 bits (a factor of 4.5) for each subject per condition: red, green, artery, and vein, 3.39 bits if same subject and condition (2.3% Red A/V ratio CoV σ/μ), and by 5.07 bits over all tests. Yet, the ratio (Red/Green Artery)/(Red/Green Vein) was close to unity across offsets and linear fits had an R^2 regression of, for case 1: 0.72, 0.06, 0.25, 0.18, and 0.49, and case 2: 0.0005, 0.89, 0.75, 0.50, and 0.18. The Artery/Vein ratio trend slopes, intercept points, and inversions varied between subjects, i.e. contrast reversals were observed.  ConclusionsThe DLO can be utilized electronically to effectively perform quantitative fundus imaging at both Red and Green wavelengths, which is a step towards performing oximetry. 77 is zero offset

Ort, förlag, år, upplaga, sidor
2014.
Nationell ämneskategori
Oftalmologi
Forskningsämne
Naturvetenskap, Optometri
Identifikatorer
URN: urn:nbn:se:lnu:diva-74457OAI: oai:DiVA.org:lnu-74457DiVA, id: diva2:1209210
Konferens
ARVO Annual Meeting 2014, Orlando, Florida, USA
Tillgänglig från: 2018-05-22 Skapad: 2018-05-22 Senast uppdaterad: 2018-12-07Bibliografiskt granskad

Open Access i DiVA

Fulltext saknas i DiVA

Övriga länkar

Abstract

Personposter BETA

Baskaran, Karthikeyan

Sök vidare i DiVA

Av författaren/redaktören
Baskaran, Karthikeyan
Oftalmologi

Sök vidare utanför DiVA

GoogleGoogle Scholar

urn-nbn

Altmetricpoäng

urn-nbn
Totalt: 17 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf