Senescent changes in photopic spatial summation

Malania, Maka; Devinck, Frédéric; Knoblauch, Kenneth; Delahunt, Peter B.; Hardy, Joseph L.; Werner, John S.

doi:10.1167/11.10.15

Cited by 5 publications

(4 citation statements)

References 87 publications

(107 reference statements)

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“…The higher thresholds in our older population may therefore reflect differences in spatial or temporal summation. Thus far, there is no evidence for a significant age-related change in foveal spatial summation under photopic conditions (Malania et al, 2009; Zele, O'Loughlin, Guymer, & Vingrys, 2005), but evidence against age-related changes in temporal summation is less clear.…”

Section: Discussionmentioning

confidence: 98%

Age-related changes in contrast gain related to the M and P pathways

Elliott¹

2010

JOV

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Neural contributions to the age-related reduction in spatial vision are incontrovertible. Whether there are differential age-related changes in the magnocellular (M) and parvocellular (P) pathways across the life span has not been tested extensively. We studied psychophysically the contrast gain signature of the M and P pathways for 13 younger and 13 older observers. Two separate paradigms thought to separate the M and P pathways based on their contrast gain signature were used. A four-square array was presented as an increment or decrement on a background of 115 Td for 35 ms, with one test square presented at a slightly higher or lower retinal illumination. Using a four-alternative forced-choice procedure, the observer's task was to choose the unique square. The two paradigms differed only in the pretrial adaptation and inter-stimulus array. Data were fitted with models of contrast discrimination derived from the unique contrast gain signatures. The fitted models indicate a change in the discrimination functions with age for both the M and P pathways, revealing a shift in the contrast gain slope. Results indicate that both M and P pathways undergo age-related changes, but functional losses appear greater for the P pathway under the conditions tested.

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Section: Discussionmentioning

confidence: 98%

Age-related changes in contrast gain related to the M and P pathways

Elliott¹

2010

JOV

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“…6,11,13,14,19,20 Furthermore, changes in D CRIT during development [10][11][12] and aging 20,21 are interpreted as indicative of alterations of neural retinal organization. [10][11][12]20,21 Electrophysiology has demonstrated the receptive field characteristics of retinal ganglion cells and of receptive fields in the central visual system. [22][23][24] We suspect that changes in D CRIT in our ROP subjects are due to altered organization of the post receptor neural retina.…”

Section: Discussionmentioning

confidence: 99%

Effect of Retinopathy of Prematurity on Scotopic Spatial Summation

Hansen¹,

Tavormina²,

Moskowitz³

et al. 2014

Invest. Ophthalmol. Vis. Sci.

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“…As age has been shown to be a significant factor in threshold measurements, we used age-correction factors to adjust all subjects' thresholds to a 50 year-old equivalent, as performed by previous studies. 7,9,14,21,28 As Ac does not change significantly with age, 14,18,29 we used the same correction factors for GI, GII, GIV and GV conversions (i.e. also the spatially equated thresholdssee below).…”

Section: Age-corrected Normative Distributionsmentioning

confidence: 99%

A comparison of Goldmann III, V and spatially equated test stimuli in visual field testing: the importance of complete and partial spatial summation

Phu

Khuu

Zangerl

et al. 2017

Ophthalmic Physiologic Optic

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PurposeGoldmann size V (GV) test stimuli are less variable with a greater dynamic range and have been proposed for measuring contrast sensitivity instead of size III (GIII). Since GIII and GV operate within partial summation, we hypothesise that actual GV (aGV) thresholds could predict GIII (pGIII) thresholds, facilitating comparisons between actual GIII (aGIII) thresholds with pGIII thresholds derived from smaller GV variances. We test the suitability of GV for detecting visual field (VF) loss in patients with early glaucoma, and examine eccentricity‐dependent effects of number and depth of defects. We also hypothesise that stimuli operating within complete spatial summation (‘spatially equated stimuli’) would detect more and deeper defects.MethodsSixty normal subjects and 20 glaucoma patients underwent VF testing on the Humphrey Field Analyzer using GI‐V sized stimuli on the 30‐2 test grid in full threshold mode. Point‐wise partial summation slope values were generated from GI‐V thresholds, and we subsequently derived pGIII thresholds using aGV. Difference plots between actual GIII (aGIII) and pGIII thresholds were used to compare the amount of discordance. In glaucoma patients, the number of ‘events’ (points below the 95% lower limit of normal), defect depth and global indices were compared between stimuli.Results90.5% of pGIII and aGIII points were within ±3 dB of each other in normal subjects. In the glaucoma cohort, there was less concordance (63.2% within ±3 dB), decreasing with increasing eccentricity. GIII found more defects compared to GV‐derived thresholds, but only at outermost test locations. Greater defect depth was found using aGIII compared to aGV and pGIII, which increased with eccentricity. Global indices revealed more severe loss when using GIII compared to GV. Spatially equated stimuli detected the greatest number of ‘events’ and largest defect depth.ConclusionsWhilst GV may be used to reliably predict GIII values in normal subjects, there was less concordance in glaucoma patients. Similarities in ‘event’ detection and defect depth in the central VF were consistent with the fact that GIII and GV operate within partial summation in this region. Eccentricity‐dependent effects in ‘events’ and defect depth were congruent with changes in spatial summation across the VF and the increase in critical area with disease. The spatially equated test stimuli showed the greatest number of defective locations and larger sensitivity loss.

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Senescent changes in photopic spatial summation

Cited by 5 publications

References 87 publications

Age-related changes in contrast gain related to the M and P pathways

Age-related changes in contrast gain related to the M and P pathways

Effect of Retinopathy of Prematurity on Scotopic Spatial Summation

A comparison of Goldmann III, V and spatially equated test stimuli in visual field testing: the importance of complete and partial spatial summation

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