VARIATION OF THE VISUAL THRESHOLD WITH RETINAL LOCATION. PART 1 THE CENTRAL 20 DEGREES OF VISUAL FIELD. PART 2 THE FOVEA

THRESHOLD MEASUREMENTS HAE BEEN CARRIED OUT ACROSS THE CENTRAL 20 DEGREES OF THE VISUAL FIELD USING WHITE, RED, GREEN AND BLUE STIMULI OF 2'S AND 32'S ANGULAR SUBTENSE AND OF SHORT AND LONG DURATION UNDER CONDITIONS OF SCOTOPIC, MESOPIC AND PHOTOPIC ADAPTATION. WHEREAS THE DEGREE OF SPATIAL SUMMATION INCREASES IN THE PERIPHERY UNDER ALL CONDITIONS OF ADAPTATION, THE DEGREE OF TEMPORAL SUMMATION IS UNIFORM TO A FIRST APPROXIMATION OVER THE REGION INVESTIGATED. SOME OF THE RESULTS INDICATE THAT A GROUP OF RETINAL LOCATIONS GIVING THE SAME THRESHOLD UNDER ONE SET OF OBSERVING CONDITIONS CONTINUE TO HAVE ESSENTIALLY EQUAL THRESHOLDS UNDER OTHER QUITE DIFFERENT CONDITIONS OF OBSERVATION. A METHOD IS DESCRIBED WHEREBY THOSE REGIONS OF THE RETINA WHERE BLOOD VESSELS MAY INTERFERE WITH LVISUAL MEASUREMENTS MAY BE AVOIDED. MEASUREMENTS WITH A SMALL TEST FIELD WITHIN 2 DEGREES FROM THE VISUAL AXIS INDICATE THAT THE CENTRAL REGION OF THE FOVEA, ABOUT 30' DIAMETER MAY HAVE VERY DIFFERENT PROPERTIES FROM THE REST AND SHOWS A REDUCED SENSITIVITY AT ALL WAVELENGTHS IN THE DARK-ADPATED STATE. /RRL(A)/

  • Availability:
  • Supplemental Notes:
    • Vol 10, pp 745-767, 16 FIG, 1 TAB, REFS
  • Authors:
    • Kishto, B N
    • Saunders, R
  • Publication Date: 1970

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Filing Info

  • Accession Number: 00220206
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Oct 3 1971 12:00AM