Parafoveal letter recognition at reduced contrast in normal aging and in patients with risk factors for AMD

Hahn, Gesa Astrid; Messias, André; MacKeben, Manfred; Dietz, Klaus; Horwath, Karin; Hyvärinen, Lea; Leinonen, Marja; Trauzettel‐Klosinski, Susanne

doi:10.1007/s00417-008-0919-z

Cited by 17 publications

(20 citation statements)

References 43 publications

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“…These include high-pass resolution perimetry (Frisén, 1993(Frisén, , 1995, component perimetry (Bachmann & Fahle, 2000), frequency doubling perimetry (e.g., Chauhan & Johnson, 1999;Spry, Johnson, McKendrick, & Turpin, 2001;Wall, Neahring, & Woodward, 2002), flicker perimetric methods (cf. Rota-Bartelink, 1999 for review), methods that include a recognition task like MacKeben's Macular Mapping Test (Hahn et al, 2009), microperimetry, and the scanning laser ophthalmoscope (SLO; Mainster, Timberlake, Webb, & Hughes, 1982;Rohrschneider, Springer, Bültmann, & Völcker, 2005), as well as objective techniques like the multifocal electroretinogram (Sutter & Tran, 1992). Some of the techniques and implemented test algorithms are briefly reviewed by McKendrick (2005).…”

Section: Perimetrymentioning

confidence: 99%

Peripheral vision and pattern recognition: A review

2011

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We summarize the various strands of research on peripheral vision and relate them to theories of form perception. After a historical overview, we describe quantifications of the cortical magnification hypothesis, including an extension of Schwartz's cortical mapping function. The merits of this concept are considered across a wide range of psychophysical tasks, followed by a discussion of its limitations and the need for non-spatial scaling. We also review the eccentricity dependence of other low-level functions including reaction time, temporal resolution, and spatial summation, as well as perimetric methods. A central topic is then the recognition of characters in peripheral vision, both at low and high levels of contrast, and the impact of surrounding contours known as crowding. We demonstrate how Bouma's law, specifying the critical distance for the onset of crowding, can be stated in terms of the retinocortical mapping. The recognition of more complex stimuli, like textures, faces, and scenes, reveals a substantial impact of mid-level vision and cognitive factors. We further consider eccentricity-dependent limitations of learning, both at the level of perceptual learning and pattern category learning. Generic limitations of extrafoveal vision are observed for the latter in categorization tasks involving multiple stimulus classes. Finally, models of peripheral form vision are discussed. We report that peripheral vision is limited with regard to pattern categorization by a distinctly lower representational complexity and processing speed. Taken together, the limitations of cognitive processing in peripheral vision appear to be as significant as those imposed on low-level functions and by way of crowding.

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Section: Perimetrymentioning

confidence: 99%

Peripheral vision and pattern recognition: A review

2011

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“…A macular mapping test using a similar but more elaborate paradigm was developed with the aim of more accurately plotting a patient's residual functional vision. 21 This test uses a large spoke-like target that is assumed to stimulate foveal fixation; the sizes of the surrounding letter targets are scaled with eccentricity based on this assumption. The results of this test and the clock-dial test become less interpretable when the retinal location of fixation is unknown.…”

Section: Discussionmentioning

confidence: 99%

Fixation Locus in Patients with Bilateral Central Scotomas for Targets that Perceptually Fill In

Pratt

Ohara²,

Woo³

et al. 2014

Optometry and Vision Science

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Purpose In this experiment we investigated whether target type affects the retinal fixation location and stability in patients with bilateral central scotomas, and specifically whether targets expected to perceptually fill in are imaged at or near the vestigial fovea. Methods The retinal location and stability of fixation were measured using the Nidek MP-1 microperimeter in twelve patients with bilateral central scotomas for six types of fixation target, three expected to fill in and three that included letters. The approximate position of the vestigial fovea was delineated in 10 of the patients either by using residual retinal landmarks or by locating the residual foveal pit in a dense macular scan, obtained with a Spectralis Optical Coherence Tomographer. Fixation location and stability were compared for the different target types and referenced to the position of the vestigial fovea. Results All of the subjects except one fixated consistently on targets that included a letter using peripheral retinal locations outside of the central scotoma. Eleven of the twelve subjects used a retinal location closer to the vestigial fovea to fixate targets expected to fill in, compared to letters. Although four of the subjects imaged the fill-in targets at or within a half degree of the vestigial fovea, six other subjects imaged the fill-in targets at a retinal locus removed from the vestigial fovea. Target type produced no overall significant difference in fixation stability, specified in terms of bivariate contour ellipse area (BCEA). However, in some individual subjects, fixation tended to be more stable on letter targets than on fill-in targets. Conclusions In patients with central field loss, letter targets generate more consistent fixation behavior than fill-in targets and should be used for eccentric viewing training and perimetry.

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“…These include changes to contrast sensitivity [9][10][11], colour vision [12][13], flicker sensitivity [13][14], temporal thresholds [15][16][17], microperimetry [11,[18][19], photostress or glare recovery [11,[20][21][22] and dark adaptation [12][13][14][23][24][25][26]. When measured alongside these other visual functions, dark adaptation abnormalities have emerged as the most sensitive markers for early AMD [12][13][14]23].…”

Section: Introductionmentioning

confidence: 99%

The effect of pre-adapting light intensity on dark adaptation in early age-related macular degeneration

2013

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Parafoveal letter recognition at reduced contrast in normal aging and in patients with risk factors for AMD

Abstract: Using parafoveal test locations, a recognition task and diminished contrast increases the chance of early detection of functional defects due to eARM or nfAMD and can differentiate them from those due to aging alone.

Cited by 17 publications

References 43 publications

Peripheral vision and pattern recognition: A review

Peripheral vision and pattern recognition: A review

Fixation Locus in Patients with Bilateral Central Scotomas for Targets that Perceptually Fill In

The effect of pre-adapting light intensity on dark adaptation in early age-related macular degeneration

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