Small Effect of Interline Spacing on Maximal Reading Speed in Low-Vision Patients with Central Field Loss Irrespective of Scotoma Size

Calabrèse, Aurélie; Bernard, Jean Baptiste; Hoffart, L.; Faure, Géraldine; Barouch, Fatiha; Conrath, J.; Castet, Éric

doi:10.1167/iovs.09-3682

Cited by 40 publications

(34 citation statements)

References 39 publications

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“…On the other hand, unlike RSVP reading, the role of visual crowding in ordinary text reading (eye-mediated reading) is still unclear, as studies have reported little effect of reduced crowding on ordinary reading speed (Bernard et al, 2007; Calabrese et al, 2010; Chung, Jarvis, Woo, Hanson, & Jose, 2008). As reading is a complex cognitive process involving various perceptual and cognitive components (e.g., sensory and perceptual encoding of text, oculomotor control, and linguistic influences), the outcome is likely to be changed depending on its interaction with other components.…”

Section: Discussionmentioning

confidence: 99%

Integrating oculomotor and perceptual training to induce a pseudofovea: A model system for studying central vision loss

Liu¹,

Kwon²

2016

Journal of Vision

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People with a central scotoma often adopt an eccentric retinal location (Preferred Retinal Locus, PRL) for fixation. Here, we proposed a novel training paradigm as a model system to study the nature of the PRL formation and its impacts on visual function. The training paradigm was designed to effectively induce a PRL at any intended retinal location by integrating oculomotor control and pattern recognition. Using a gaze-contingent display, a simulated central scotoma was induced in eight normally sighted subjects. A subject's entire peripheral visual field was blurred, except for a small circular aperture with location randomly assigned to each subject (to the left, right, above, or below the scotoma). Under this viewing condition, subjects performed a demanding oculomotor and visual recognition task. Various visual functions were tested before and after training at both PRL and nonPRL locations. After 6–10 hr of the training, all subjects formed their PRL within the clear window. Both oculomotor control and visual recognition performance significantly improved. Moreover, there was considerable improvement at PRL location in high-level function, such as trigram letter-recognition, reading, and spatial attention, but not in low-level function, such as acuity and contrast sensitivity. Our results demonstrated that within a relatively short time, a PRL could be induced at any intended retinal location in normally-sighted subjects with a simulated scotoma. Our training paradigm might not only hold promise as a model system to study the dynamic nature of the PRL formation, but also serve as a rehabilitation regimen for individuals with central vision loss.

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Section: Discussionmentioning

confidence: 99%

Integrating oculomotor and perceptual training to induce a pseudofovea: A model system for studying central vision loss

Liu¹,

Kwon²

2016

Journal of Vision

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“…Recent psychophysical evidence shows that when the disorder has been present for a long time, many people with AMD exhibit characteristics that are more similar to those usually found in the normal fovea, and different from those usually observed in the normal periphery. Such evidence includes the lack of a benefit of reading text with line spacing greater than the standard (Chung et al, 2008; Calabrèse et al, 2010), 4 and that the crowding zone measured at the PRL used by people with AMD is isotropic as in the normal fovea (Toet & Levi, 1992); instead of anisotropic in shape (Chung, 2013b). The changes observed in some spatial properties at the PRL of people with AMD have been attributed to the plasticity of the visual system.…”

Section: Discussionmentioning

confidence: 99%

Size or spacing: Which limits letter recognition in people with age-related macular degeneration?

Chung

2014

Vision Research

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Recent evidence suggests a double dissociation of size and spacing limit on letter recognition — it is limited by size in the fovea and critical spacing in the normal periphery. Here, we evaluated whether size or spacing limits letter recognition in people with age-related macular degeneration (AMD) who must use their peripheral vision. We measured the size threshold for recognizing lowercase letters presented alone, or flanked by two letters at various center-to-center nominal letter spacings (multiples of letter size) for 11 observers with AMD. For comparison, similar measurements were obtained at 5 and 10° eccentricity in the nasal and lower visual fields in three older adults with normal vision. Single-letter size thresholds were worse for observers with AMD than at comparable retinal locations in the normal periphery. For flanked letters, size threshold improved with larger nominal spacing up to the critical spacing, beyond which size threshold was unaffected by the flankers. Seven AMD observers had a nominal critical spacing between 1.25× and 1.80×, values close to those in the normal fovea, suggesting that their letter recognition is size-limited; two had a nominal critical spacing of 3–4×, values close to those in the normal periphery, implying that their letter recognition is limited by spacing; and another two had a nominal critical spacing of ~2.3×, implying that their letter recognition is limited by both size and spacing. The wide range of nominal critical spacings observed in our AMD observers may reflect the degree of completeness of their adaptation process to vision loss.

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“…This seems to contradict some of the evidence showing that there is less crowding at the PRL in observers with AMD than in the normal periphery. 60–63 Note however that in the present study, we only determined the size of the integration field along the horizontal meridian. It remains possible that the integration field could shrink in its dimensions along other meridians for people with central vision loss, as shown in Chung and Lin.…”

Section: Discussionmentioning

confidence: 99%

Dependence of Reading Speed on Letter Spacing in Central Vision Loss

Chung¹

2012

Optometry and Vision Science

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Purpose Crowding, the difficulty in recognizing a letter in close proximity with other letters, has been suggested as an explanation for slow reading in people with central vision loss. The goals of this study were (1) to examine whether increased letter spacing in words, which presumably reduces crowding among letters, would benefit reading for people with central vision loss; and (2) to relate our finding to the current account of faulty feature integration of crowding. Methods Fourteen observers with central vision loss read aloud single sentences, one word at a time, using rapid serial visual presentation (RSVP). Reading speeds were calculated based on the RSVP exposure durations yielding 80% accuracy. Letters were rendered in Courier, a fixed-width font. Observers were tested at 1.4× the critical print size (CPS), three were also tested at 0.8× CPS. Reading speed was measured for five center-to-center letter spacings (range: 0.5–2× the standard spacing). The preferred retinal locus (PRL) for fixation was determined for nine of the observers, from which we calculated the horizontal dimension of the integration field for crowding. Results All observers showed increased reading speed with letter spacing for small spacings, until an optimal spacing, beyond which reading speed either showed a plateau, or dropped as letter spacing further increased. The optimal spacing averaged 0.95±0.06× [±95%CI] the standard spacing for 1.4× CPS (similar for 0.8× CPS), which was not different from the standard. When converted to angular size, the measured values of the optimal letter spacing for reading show a good relationship with the calculated horizontal dimension of the integration field. Conclusions Increased letter spacing beyond the standard size, which presumably reduces crowding among letters in text, does not improve reading speed for people with central vision loss. The optimal letter spacing for reading can be predicted based on the PRL.

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Small Effect of Interline Spacing on Maximal Reading Speed in Low-Vision Patients with Central Field Loss Irrespective of Scotoma Size

Abstract: Increasing interline spacing is advisable only for very slow readers (<20 words/min) who want to read a few words (spot reading). Vertical crowding does not seem to be a major determinant of maximal reading speed for patients with central scotomas.

Cited by 40 publications

References 39 publications

Integrating oculomotor and perceptual training to induce a pseudofovea: A model system for studying central vision loss

Integrating oculomotor and perceptual training to induce a pseudofovea: A model system for studying central vision loss

Size or spacing: Which limits letter recognition in people with age-related macular degeneration?

Dependence of Reading Speed on Letter Spacing in Central Vision Loss

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