Comparative effectiveness between two types of head-mounted magnification modes using a smartphone-based virtual display

Abstract

Significance: This work shows the benefits of using two different magnification strategies to improve the reading ability of low-vision patients using a head-mounted technology.

Purpose: The aim of this study was to conduct a comparative clinical trial evaluating the effectiveness of two magnification strategies in a head-mounted virtual reality display.

Methods: Eighty-eight eligible low-vision subjects were randomized into two arms: (1) the full-field magnification display or (2) the virtual bioptic telescope mode. Subjects completed baseline testing and received training on how to use the device properly and then took the device home for a 2- to 4-week intervention period. An adaptive rating scale questionnaire (Activity Inventory) was administered before and after the intervention (home trial) period to measure the effect of the system. A Simulator Sickness Questionnaire was also administered. Baseline and follow-up results were analyzed using Rasch analysis to assess overall effectiveness of each magnification mode for various functional domain categories.

Results: Both magnification modes showed a positive effect for reading, visual information, and the overall goals functional domain categories, with only reading reaching statistical significance after correction for multiple comparisons. However, there were no significant between-group differences between the two modes. The results of the Simulator Sickness Questionnaire showed that the magnification modes of the head-mounted display device were overall well tolerated among low-vision users.

Conclusions: Both the full-field and virtual bioptic magnification strategies were effective in significantly improving functional vision outcomes for self-reported reading ability.

Trial registration: ClinicalTrials.gov NCT03728660.

Figure 1.

Consort flow diagram outlining the research protocol.

Figure 2.

Flow diagram of research protocol. ETDRS = Early Treatment Diabetic Retinopathy Study; AI = Activity Inventory; TICS = Telephone Interview for Cognitive Status; VA = visual acuity; VF = visual field; h = horizontal; v = vertical; SSQ = Simulator Sickness Questionnaire.

Figure 3.

Samsung Gear HMD (head-mounted display) device front view (left) and side view (right).

Figure 4.

Comparison of virtual bioptic telescope mode using the embedded magnification bubble (left) and Full-field magnification mode (right).

Figure 5.

Wright map histograms of Simulator Sickness Questionnaire (SSQ) person measures for each group and anchored item measures. Higher values on the interval SSQ symptom severity scale indicate more severe symptoms. There was a small percentage of patients whose person measure scores fell within the item measure distribution, indicating that the majority of individuals fell on the end of the scale with minor to no symptoms.