Online Survey of Digital Reading by Adults with Low Vision

Near prescribing trends in two low vision rehabilitation clinics over a ten-year period

CLINICAL RELEVANCE

Optical magnification (OM), electronic magnification (EM), and assistive technology (AT) can be prescribed in low vision rehabilitation (LVR) clinics for near vision goals of patients. This study shows the prescription of OM has not decreased with increased availability of EM and AT.

BACKGROUND

Near visual goals are a primary concern for patients with visual impairment. LVR providers can prescribe OM, EM and/or AT to help. With the rapid evolution and availability of EM and AT, we aim to evaluate if there have been changes in the prescription patterns of clinicians with respect to OM over time. We hypothesise that the increased availability of technology may result in declining prescriptions of OM and increasing prescription of EM and AT over time.

METHODS

This retrospective study investigated near prescribing between 2008-2017 for 530 new patients to the LVR clinics. Examinations were performed by optometrists specialising in low vision. Near devices prescribed included OM and EM and AT.

RESULTS

Most patients attending the LVR clinics were female, over 60 years old and had age related macular degeneration. Near visual goals were a primary concern of 97.2% of the patients. OM was most prescribed in the 0-19 and >60-year-old age groups. Within the 20-39-year-old age group there was the greatest number of both EM and AT prescriptions. OM was most prescribed in patients with visual acuity better than 6/60. EM and AT showed a trend of increasing prescription as visual acuity decreased. EM prescription peaked in <6/60 to 6/240 category while AT trended upwards from <6/21 to no light perception and peaked in patients with no light perception. Referral rates for additional rehabilitation services were 75.7%.

CONCLUSIONS

This study shows that the prescription of OM is not declining even as the prescription and the breadth of electronic magnification and assistive technology available is expanding. OM continues to be a viable option for patients, especially in the youngest and oldest cohorts.

Screen Magnification for Readers with Low Vision: A Study on Usability and Performance

We present a study with 20 participants with low vision who operated two types of screen magnification (lens and full) on a laptop computer to read two types of document (text and web page). Our purposes were to comparatively assess the two magnification modalities, and to obtain some insight into how people with low vision use the mouse to control the center of magnification. These observations may inform the design of systems for the automatic control of the center of magnification. Our results show that there were no significant differences in reading performances or in subjective preferences between the two magnification modes. However, when using the lens mode, our participants adopted more consistent and uniform mouse motion patterns, while longer and more frequent pauses and shorter overall path lengths were measured using the full mode. Analysis of the distribution of gaze points (as measured by a gaze tracker) using the full mode shows that, when reading a text document, most participants preferred to move the area of interest to a specific region of the screen.

Impact of Apps as Assistive Devices for Visually Impaired Persons

The pervasiveness of mobile devices and other associated technologies has affected all aspects of our daily lives. People with visual impairments are no exception, as they increasingly tend to rely on mobile apps for assistance with various visual tasks in daily life. Compared to dedicated visual aids, mobile apps offer advantages such as affordability, versatility, portability, and ubiquity. We have surveyed hundreds of mobile apps of potential interest to people with vision impairments, either released as special assistive apps claiming to help in tasks such as text or object recognition (n = 68), digital accessibility (n = 84), navigation (n = 44), and remote sighted service (n = 4), among others, or marketed as general camera magnification apps that can be used for visual assistance (n = 77). While assistive apps as a whole received positive feedback from visually impaired users, as reported in various studies, evaluations of the usability of every app were typically limited to user reviews, which are often not scientifically informative. Rigorous evaluation studies on the effect of vision assistance apps on daily task performance and quality of life are relatively rare. Moreover, evaluation criteria are difficult to establish, given the heterogeneity of the visual tasks and visual needs of the users. In addition to surveying literature on vision assistance apps, this review discusses the feasibility and necessity of conducting scientific research to understand visual needs and methods to evaluate real-world benefits.

Development and Validation of the Life for Low Vision Questionnaire (LIFE4LVQ) Using Rasch Analysis: A Questionnaire Evaluating Ability and Independence

Low vision (LV) has a substantial impact on an individual’s daily functionality and patient-reported outcome measures (PROMs) are increasingly incorporated into the evaluation of this problem. The objective of this study was to describe the design of the new “Life for Low Vision Questionnaire (LIFE4LVQ)”, as a measure of daily functionality in LV and to explore its psychometric properties. A total of 294 participants completed the LIFE4LVQ and the data were subjected to Rasch analysis to determine the psychometric properties of the questionnaire, including response category ordering, item fit statistics, principal component analysis, precision, differential item functioning, and targeting. Test–retest reliability was evaluated with an interval of three weeks and intraclass correlation coefficients (ICC) were used. The correlation between the questionnaire score and Best Corrected Visual Acuity (BCVA) was examined using Spearman’s correlation coefficient. Rasch analysis revealed that for most items the infit and outfit mean square fit values were close to 1, both for the whole scale and its subscales (ability and independence). The separation index for person measures was 5.18 with a reliability of 0.96, indicating good discriminant ability and adequate model fit. Five response categories were found for all items. The ICC was 0.96 (p < 0.001; 95% CI, 0.93–0.98), suggesting excellent repeatability of the measure. Poorer BCVA was significantly associated with worse scores (rho = 0.559, p < 0.001), indicating excellent convergent validity. The functional, 40-item LIFE4LVQ proved to be a reliable and valid tool that effectively measures the impact of LV on ability and independence.

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.

Assessing optimal colour and illumination to facilitate reading: an analysis of print size

PURPOSE

This study examined how optimal colour/illumination conditions and the efficacy of the iPad, LuxIQ and Smart Bulb varied as a function of print size in younger, older and visually impaired adults.

METHODS

Participants with visual impairments and simulated low vision (SLV) read the MNRead using the iPad, LuxIQ and Smart Bulb.

RESULTS

In the impairment condition at 1.20 logMAR, the iPad (M = 9.49, 95% CI [3.18, 19.42]) and LuxIQ (M = 15.95, 95% CI [9.54, 24.86]) improved the reading speeds. At 0.80 logMAR (SLV), all devices improved reading speeds of older adults (iPad (M = 28.70, 95% CI [14.65, 42.51]); LuxIQ (M = 49.63, 95% CI [30.04, 69.68]); Smart Bulb (M = 23.11, 95% CI [3.33, 42.11])), but in younger adults only the LuxIQ (M = 13.04, 95% CI [3.21, 21.27]) did so. In the impairment condition, the iPad (M = 5.54, 95% CI [0.31, 12.13]) and LuxIQ (M = 13.90, 95% CI [7.88, 23.49]) improved reading speeds. In the SLV condition, age was a significant predictor of reading speed at 1.20 logMAR (F_3,164  = 10.74, p < 0.001, Adj. R²  = 0.16). At 0.80 logMAR, age and luminance, but not colour, were significant predictors (F_3,164  = 52.52, p < 0.001, Adj. R²  = 0.49). In the impairment condition, both age and lux were significant predictors of reading speed at 1.20 (F_3,85  = 7.14, p < 0.001, Adj. R²  = 0.20) and 0.80 logMAR (F_3,85  = 7.97, p < 0.001, Adj. R²  = 0.22), but colour was not.

CONCLUSIONS

Light source effectiveness and optimal colour/illumination vary as a function of print size. It appears that print size is the most important factor for improving reading speed. As print size decreases, luminance becomes crucial, and only at the smallest print sizes does the effect of colour become useful.

Reconciling print-size and display-size constraints on reading

Two fundamental constraints limit the number of characters in text that can be displayed at one time-print size and display size. These dual constraints conflict in two important situations-when people with normal vision read text on small digital displays, and when people with low vision read magnified text. Here, we describe a unified framework for evaluating the joint impact of these constraints on reading performance. We measured reading speed as a function of print size for three digital formats (laptop, tablet, and cellphone) for 30 normally sighted and 10 low-vision participants. Our results showed that a minimum number of characters per line is required to achieve a criterion of 80% of maximum reading speed: 13 characters for normally sighted and eight characters for low-vision readers. This critical number of characters is nearly constant across font and display format. Possible reasons for this required number of characters are discussed. Combining these character count constraints with the requirements for adequate print size reveals that an individual's use of a small digital display or the need for magnified print can shrink or entirely eliminate the range of print size necessary for achieving maximum reading speed.