Digital Reading with Low Vision: Principles for Selecting Display Size

SIGNIFICANCE Digital reading devices have become increasingly popular among people with low vision. Because displays come in many sizes ranging from smart watches to large desktop computer displays, it is important to have principles to guide people with low vision in selecting suitable displays for reading. PURPOSE The selection of effective digital displays for reading by people with low vision focuses attention on the interacting effects of print size, display size, font, visual acuity, and reading distance. This technical report aims to provide principles for identifying the minimum size of digital displays required for fluent reading by people with low vision. METHODS We emphasize two critical factors in selecting an appropriate reading display: angular print size, which should exceed the individual's critical print size, and display size, which should allow at least 13 characters to be presented on each line. Our approach considers a low-vision individual's acuity and preferences for viewing distance and fonts. RESULTS Through an illustrative example, we demonstrate how our approach can be used to determine display size for a low-vision individual with 20/200 acuity and central field loss who wants to read at 30-cm viewing distance with the Times Roman font. We have developed a web application based on our recommended approach to provide easy access to our algorithm. CONCLUSIONS We provide a procedure to guide the selection of appropriate displays for a wide range of acuities. Our approach can help clinicians in making recommendations for their patients, digital product designers in developing more accessible devices, and low-vision individuals in selecting digital displays for reading.