STUDIES ON THE SHRINKAGE OF THE VISUAL FIELD WITH AGE

THE LOSS OF VISUAL SENSITIVITY WITH AGE IS ACCOUNTED FOR BY PHYSICAL CHANGES OCCURRING AT ABOUT AGE 35-45 YEARS AND CONSISTS IN REDUCED POWER OF ACCOMMODATION OF THE LENS AND GREATER SENSITIVITY TO SCOTOMATIC GLARE. AT AGE 60 A CONSIDERABLE DECREASE IN THE CAPACITY TO ADAPT TO DARKNESS AND TO PERCEIVE INTERMITTENT STIMULI OCCURS. ALSO AT THIS AGE A MEASURABLE SHRINKAGE OF THE VISUAL FIELD IS OBSERVED. IT IS THOUGHT THAT THESE LATER CHANGES ARE ASSOCIATED WITH CHANGES OF RETINAL METABOLISM. BY MEANS OF PERIMETRIC AND TACHISTOSCOPIC FIELD TEST: CARRIED OUT ON A LARGE NUMBER OF INDIVIDUALS RANGING IN AGE FROM 15 TO 91 YEARS, IT WAS POSSIBLE TO MEASURE CHANGES IN PERIPHERAL SENSITIVITY AND TO RECOGNIZE THE NATURE OF THE CHANGES. A SHRINKAGE OF SEVERAL DEGREES IN EACH DECADE ABOVE AGE 45 YEARS WAS OBSERVED WITH A GREATER SHRINKAGE ABOVE AGE 65. THE LOSS IN THE EXTENT OF PERIPHERAL VISION APPEARS SIMILAR TO THAT PRODUCED BY REDUCTION OF OXYGEN TENSION OF THE BREATHING AIR. IT WAS POSSIBLE TO SHOW THAT BY REDUCING THE PERCENTAGE OF OXYGEN FOR YOUNG OBSERVERS, THEIR SENSITIVITY COULD BE LOWERED TO THE SAME DEGREE AS THAT ATTAINED IN THE NORMAL PROCESS OF AGING IN THE 66-75 YEAR OLD. SUCH RESULTS SUPPORT THE ASSUMPTION THAT THE CHANGES IN PERIPHERAL VISUAL SENSITIVITY IN THE AGED ARE DUE TO REDUCED RETINAL METABOLISM. IT IS POINTED OUT THAT FOR NIGHT VISION AND ROAD SAFETY OF THE AGING POPULATION, REDUCED SENSITIVITY SHOULD BE TAKEN INTO CONSIDERATION BY SUPPLYING ADEQUATE INFORMATION WITHIN THEIR RANGE OF VISUAL PERCEPTION. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-7
  • Monograph Title: Night visibility
  • Serial:

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Filing Info

  • Accession Number: 00219904
  • Record Type: Publication
  • Report/Paper Numbers: HS-000 708
  • Files: TRIS, TRB
  • Created Date: Apr 20 1994 12:00AM