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Age‐related changes in central and peripheral contrast sensitivity
Author(s) -
Latham Keziah,
Ferguson Ian,
Pacey Ian
Publication year - 1997
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.1997.97807594.x
Subject(s) - foveal , contrast (vision) , spatial frequency , visual field , peripheral vision , eccentricity (behavior) , sensitivity (control systems) , optics , mathematics , orientation (vector space) , statistics , audiology , physics , psychology , medicine , ophthalmology , geometry , retinal , social psychology , electronic engineering , engineering
Purpose: Loss of foveal contrast sensitivity at mid‐high spatial frequencies with increasing age is well documented. The effects of increasing age on peripheral vision are less clear. This study examines the relative effects of age on contrast sensitivity at the fovea and in the periphery, using scaled 2D Gabor patches. Methods: Five young (age 23.4 ± 2.4 yrs) and five elderly (age 71.9 ± 3.4 yrs) visually normal subjects participated. Stimuli were a series of size‐scaled Gabor patches, each consisting of a constant 0.8 grating cycles per envelope standard deviation. To achieve this, Gaussian envelope size varied inversely with the spatial frequency of the carrier grating. Stimuli were presented at 0° and 10° eccentricity in nasal visual field. Contrast sensitivity was measured using a staircase procedure which converged to a performance level of 79% correct. The subject's task was to correctly identify grating orientation as vertical or horizontal. Results: For both the young and elderly subjects, contrast sensitivity functions at the two eccentricities are displaced from one another simply by a change in size scale. E 2 values, describing the rate of scale change with eccentricity, are 5.8° for young and 8.1° for elderly observers. At the fovea, the elderly show a 0.29 log unit sensitivity loss relative to the young, independent of spatial frequency. At 10° eccentricity, the age‐related loss is 0.19 log units. Inclusion of a 0.5 log unit neutral density filter reduces the sensitivity of young observers by 0.09 log units at the fovea and 0.07 log units at 10°. Conclusion: Age‐related contrast sensitivity loss occurs predominantly at the fovea. Only part of the loss observed can be attributed to optical factors. Contrast sensitivity is qualitatively the same in the fovea and periphery of young and elderly observers. The only variables affecting the quantitative variations are a scale change dependent on both eccentricity and age, and an age‐related sensitivity loss.