Reading with central field loss: number of letters masked is more important than the size of the mask in degrees

Abstract

When the center of a readers, visual field is blocked from view, reading rates decline and eye movement patterns change. This is true whether the central visual field is blocked artificially (i.e. a mask) or through disease (e.g. a retinal scotoma due to macular degeneration). In past studies, when mask size was defined in terms of the number of letters masked from view, reading rates declined sharply as number of letters masked increased. Patients with larger central scotomas (in degrees of visual angle) also read slower. We sought to determine whether number of letters masked or size of the mask in degrees is the predominant factor affecting reading rates and eye movement behavior. By matching number of letters masked across several mask sizes (and compensating for reduced acuity in the periphery), we found that number of letters masked is the more important factor until mask size is quite large (> or = -7.5 degrees) and number of letters masked from view is more than seven.

Improvement in near visual function after macular translocation surgery with 360-degree peripheral retinectomy

“…), as well as in published studies on near vision testing, central visual field loss is associated with poor reading ability defined by significant decreases in reading speed [8,13]. Many ocular factors affect the reading speed, including print size, contrast, field of view, and size and location of scotoma [8,13,14,21,25]. The scotoma location is a major factor for macular degeneration patients, since reading rates are reduced severely when a scotoma is centered on the fovea.…”

“…A likely explanation for this difference in near visual function relative to distance acuity is the very complex interaction between the density, location, and size of a central scotoma, color vision, and contrast sensitivity and the reading speed. As numerous researchers have shown, each of these factors has an impact on near function and reading ability [3,4,5,8,10,13,14,18,19,21,25]. It is unclear why the improvement in distance acuity is less than that in near acuity after MT360.…”

A behavioral task for the validation of a gaze-contingent simulated scotoma

“…In gaze-contingent paradigms, the gaze location is monitored with an eyetracker and is then used to manipulate the visual information the observer is currently looking at. In one variant of such gaze-contingent paradigms, the moving mask technique (Rayner & Bertera, 1979), foveal information is degraded in order to investigate scene and object perception (Henderson, McClure, Pierce, & Schrock, 1997;Larson & Loschky, 2009;van Diepen, Ruelens, & d'Ydewalle, 1999), eye movement patterns in visual search (Bertera, 1988;Bertera & Rayner, 2000;Cornelissen, Bruin, & Kooijman, 2005) and reading (Fine & Rubin, 1999;Scherlen, Bernard, Calabrese, & Castet, 2008), and highlevel cognitive functioning such as visual context learning (Geringswald, Baumgartner, & Pollmann, 2012) when the observer is faced with a central scotoma.…”

Reading with a filtered fovea: The influence of visual quality at the point of fixation during reading

“…Indeed, a long-standing view is that the rich detail provided by high-quality foveal input is crucially important for word recognition (e.g., McConkie et al, 1988;O'Regan et al, 1984;Stevens & Grainger, 2003), and models of reading emphasize greatly the importance of high-quality visual input from text falling within foveal vision during each fixational pause (e.g., Engbert, Nuthmann, Richter, & Kliegl, 2005;Pollatsek, Reichle, & Rayner, 2006;Reichle, Pollatsek, Fisher, & Rayner, 1998;Reichle, Rayner, & Pollatsek, 2003). Moreover, substantial impairments in reading are known to occur when sections of foveal vision are completely obliterated, either by experimental manipulation (e.g., Fine & Rubin, 1999;Rayner & Bertera, 1979;Rayner, Inhoff, Morrison, Slowiaczek, & Bertera, 1981) or by natural degeneration (e.g., Faye, 1984;Legge, Rubin, Pelli, & Schleske, 1985;Owsley, 2011;Whittaker & Lovie-Kitchin, 1993), and impairments occur even when words in foveal vision are simply made faint (e.g., Drieghe, 2008;Reingold & Rayner, 2006).…”