Methods study for the relocation of visual information in central scotoma cases

Abstract

In this study we test the benefit on the reading performance of different ways to relocating the visual information present under the scotoma. The relocation (or unmasking) allows to compensate the loss of information and avoid the patient developing driving strategies not adapted for the reading. Eighty healthy subjects were tested on a reading task, on each a central scotoma of various sizes was simulated. We then evaluate the reading speed (words/min) during three visual information relocation methods: all masked information is relocated -on both side of scotoma, -on the right of scotoma, -and only essentials letters for the word recognition too on the right of scotoma. We compare these reading speeds versus the pathological condition, ie without relocating visual information. Our results show that unmasking strategy improve the reading speed when all the visual information is unmask to the right of scotoma, this only for large scotoma. Taking account the word morphology, the perception of only certain letters outside the scotoma can be sufficient to improve the reading speed. A deepening of reading processes in the presence of a scotoma will then allows a new perspective for visual information unmasking. Multidisciplinary competences brought by engineers, ophtalmologists, linguists, clinicians would allow to optimize the reading benefit brought by the unmasking.

A new concept for visual aids: "ViSAR" Visual Signal Adaptive Restitution

“…The image deformation disrupts low and high level of recognition processes reducing visual performance. Our first experiment have shown that visual performance obtained with this new system is very sensitive to the way masked signal is make visible [18]. Our best condition is observed when displayed signal translates human optimal cognitive processes.…”

“…When patient fixates zone of interest in the text, all visual signal masked under the scotoma is visible outside the scotoma. This new visual signal display limits visual signal search and improve signal location and comprehension [18].…”

High Tech Aids Low Vision: A Review of Image Processing for the Visually Impaired

“…The majority of participants trialing this technique were normally sighted with simulated central scotomas, but two had central field loss (CFL). [58][59][60][61] A modest improvement in reading rate was found in both groups. This may encourage others to update this work with the advances in technology made since its publication, perhaps allowing time for perceptual adaptation.…”