Differential effects of aging on spatial contrast sensitivity to linear and polar sine-wave gratings

Abstract

Changes in visual function beyond high-contrast acuity are known to take place during normal aging. We determined whether sensitivity to linear sine-wave gratings and to an elementary stimulus preferentially processed in extrastriate areas could be distinctively affected by aging. We measured spatial contrast sensitivity twice for concentric polar (Bessel) and vertical linear gratings of 0.6, 2.5, 5, and 20 cycles per degree (cpd) in two age groups (20-30 and 60-70 years). All participants were free of identifiable ocular disease and had normal or corrected-to-normal visual acuity. Participants were more sensitive to Cartesian than to polar gratings in all frequencies tested, and the younger adult group was more sensitive to all stimuli tested. Significant differences between sensitivities of the two groups were found for linear (only 20 cpd; P<0.01) and polar gratings (all frequencies tested; P<0.01). The young adult group was significantly more sensitive to linear than to circular gratings in the 20 cpd frequency. The older adult group was significantly more sensitive to linear than to circular gratings in all spatial frequencies, except in the 20 cpd frequency. The results suggest that sensitivity to the two kinds of stimuli is affected differently by aging. We suggest that neural changes in the aging brain are important determinants of this difference and discuss the results according to current models of human aging.

Visual acuity measured with luminance-modulated and contrast-modulated noise letter stimuli in young adults and adults above 50 years old

“…A decrease in binocular summation ratio with ageing for CM letters in older adults may reflect an early decline in higher visual areas, most likely higher than V1. This speculation is supported by the study of Costa et al (2013) which suggested that ageing might have a more pronounced effect in higher visual areas than in the primary striate cortex. It is vital to know what biological (e.g.…”

Mobile app Aston contrast sensitivity test

“…Dorr et al found a similar shape to these app results for the CSF determined using a 2‐AFC procedure on both the iPad and a traditional CRT laboratory setup, with no ‘peaks’ seen but with a maximum contrast sensitivity around 1.0 cpd. Also previous studies using research laboratory grade CRT setups found maximum contrast sensitivities to occur between 2.0 to 5.0 cpd . Artefacts or visual cues present within the CSV‐1000 printed chart may bias patient responses and explain why peak contrast sensitivity appears to be shifted towards the higher frequencies.…”

“…Also previous studies using research laboratory grade CRT setups found maximum contrast sensitivities to occur between 2.0 to 5.0 cpd. [24][25][26] Artefacts or visual cues present within the CSV-1000 printed chart may bias patient responses and explain why peak contrast sensitivity appears to be shifted towards the higher frequencies. The difference in sensitivity between the apps and the Pelli-Robson chart is unsurprising as the apps are specified in 27,28 and none of these used a chart of similar design allowing comparison of the thresholds across the range of spatial frequencies.…”

Efeitos do envelhecimento no contraste visual de grades senoidais

“…Esses resultados corroboram com outros dados da literatura, mesmo apresentando métodos diferenciados (Burton et al, 1993;Costa et al, 2013;Costa et al, 2009;McGrath & Morrison, 1981;Skalka, 1980). Burton et al (1993) verificou monocularmente a SC de adultos jovens (17-29 anos) e idosos (60-80 anos) por meio do paradigma dos estímulos constantes e percebeu uma diminuição no contraste visual para frequências de 2, 4, 8, 12, 16, 24, 28 e 32 cpg.…”

“…Pesquisas relacionadas a percepção visual mostram que curvas de SC podem ser bastante úteis na detecção de simples padrões visuais em forma de ondas senoidais espaciais com orientação vertical e horizontal (Kalia et al, 2012;Jia, Yan, Hou, Lu & Huang, 2014;Lesmes, Jackson, Wallis, Bex, 2013;Scialfa, Kline & Wood, 2002;Skalka, 1980;Pelli & Bex, 2013). Esses diferentes padrões comportamentais distinguem maneiras dos mecanismos neurais processarem a informação (Costa et al, 2013;Ellemberg, Lewis, Hong Liu, & Maurer, 1999;Santos, Oliveira, Nogueira, Cruz, & Simas, 2006). Neste sentido, este estudo teve por objetivo avaliar a curva de SC de adultos e idosos saudáveis para estímulos de grades senoidais verticais utilizando frequências de 0,6; 2,5; 5 e 20 cpg em condições de luminância fotópica.…”