The Effect of a Head-mounted Low Vision Device on Visual Function

Abstract

Significance: Head-mounted low vision devices have received considerable attention in recent years owing to rapidly developing technology, facilitating ease of use and functionality. Systematic clinical evaluations of such devices remain rare but are needed to steer future device development.

Purpose: The purpose of this study was to investigate, in a multicenter prospective trial, the short- and medium-term effects of a head-worn vision enhancement device (eSight Eyewear).

Methods: Participants aged 13 to 75 years with stable vision (distance acuity, 20/60 to 20/400; visual field diameter >20°) were recruited across six sites. Data were collected at baseline (no device), at fitting (with device), and after 3 months of everyday use. Outcome measures were visual ability measured by the Veterans Affairs Low Vision Visual Functioning Questionnaire 48, distance acuity (Early Treatment Diabetic Retinopathy Study), reading performance (MNREAD chart), contrast sensitivity (MARS chart), face recognition, and a modified version of the Melbourne Low Vision Activities of Daily Living (ADL) Index.

Results: Among the 51 participants, eSight introduction immediately improved distance acuity (0.74 ± 0.28 logMAR), contrast sensitivity (0.57 ± 0.53 log units), and critical print size (0.52 ± 0.43 logMAR), all P < .001, without any further change after 3 months; reading acuity improved at fitting (0.56 ± 0.35 logMAR) and by one additional line after 3 months, whereas reading speed only slightly increased across all three time points. The Melbourne ADL score and face recognition improved at fitting (P < .01) with trends toward further improvement at 3 months. After 3 months of use, Veterans Affairs Low Vision Visual Functioning Questionnaire 48 person measures (in logits) improved: overall, 0.84, P < .001; reading, 2.75, P < .001; mobility, 0.04, not statistically significant; visual information, 1.08, P < .001; and visual motor, 0.48, P = .02.

Conclusions: eSight introduction yields immediate improvements in visual ability, with face recognition and ADLs showing a tentative benefit of further use. Overall, visual ability, reading, and visual information showed greatest benefit with device use. Further studies need to examine benefits of practice and training and possible differential effects of underlying pathology or baseline vision.

FIGURE 1

eSight Eyewear (glasses and manual controller) in its second generation.

FIGURE 2

Display of the study components and their chronological order, including data on the number of participants who completed in each step.

FIGURE 3

Distance acuity equivalent of print size correctly read on the ETDRS chart at baseline without the device, at fitting with the device, and after 3 months of device use. Mean baseline acuity without device was 20/177 (mean logMAR, 0.95 [SD, 0.25]), which improved to 20/32 (mean, 0.20 [SD, 0.31]) with the device but stayed unchanged after 3 months of device use and training (mean, 0.19 [SD, 0.30]). ID numbers of outlier correspond to participant IDs in Table 3. *Statistically significant differences. ETDRS = Early Treatment Diabetic Retinopathy Study.

FIGURE 4

Reading acuity equivalent of print size read on the MNREAD chart at baseline without the device, at fitting with the device, and after 3 months of device use. Mean baseline reading acuity without device was 20/159 (mean logMAR, 0.90 [SD, 0.34]), which improved to 20/43 (mean, 0.33 [SD, 0.39]) with the device but stayed unchanged after 3 months of device use and training (mean, 0.24 [SD, 0.36]). ID numbers of outlier correspond to participant IDs in Table 3. *Statistically significant differences.

FIGURE 5

Critical print size measured on the MNREAD chart at baseline without the device, at fitting with the device, and after 3 months of device use. Mean baseline critical print size without device was 20/240 (mean logMAR, 1.08 [SD, 0.27]), which improved to 20/78 (mean, 0.59 [SD, 0.40]) with the device but stayed unchanged after 3 months of device use and training (mean, 0.50 [SD, 0.31]). ID numbers of outlier correspond to participant IDs in Table 3. *Statistically significant differences.

FIGURE 6

Reading accessibility index values at baseline without the device, at fitting with the device, and after 3 months of device use. Mean values increased significantly with the device at fitting but did not improve further after 3 months of device use and training. *Statistically significant differences.

FIGURE 7

Reading speed values at baseline without the device, at fitting with the device, and after 3 months of device use. The analysis did not reveal any statistically significant change in reading speed between any of the time points.

FIGURE 8

Contrast sensitivity (CS) measured by the MARS chart at baseline without the device, at fitting with the device, and after 3 months of device use. Mean baseline log CS without device was 0.89 (20/177 [SD, 0.48]), which improved to 1.44 (SD, 0.44) with the device but stayed unchanged after 3 months of device use and training (mean, 1.41 [SD, 0.44]). ID numbers of outlier correspond to participant IDs in Table 3. *Statistically significant differences.

FIGURE 9

Face perception test results at baseline without the device, at fitting with the device, and after 3 months of device use. The mean baseline face perception test score without device was 37.77 (SD, 17.57), which improved to 45.29 (SD, 18.45) with the device but stayed unchanged after 3 months of device use and training (47.08 [SD, 15.41]). The ID number of the outlier corresponds to participant ID in Table 3. *Statistically significant differences.

FIGURE 10

Partial Melbourne Low Vision Activities of Daily Living Index results at baseline without the device, at fitting with the device, and after 3 months of device use. Participant ID numbers are grouped by site (first digit). The mean baseline partial Melbourne score without device was 69.90 (SD, 19.10), which improved to 76.61 (SD, 19.51) with the device but stayed unchanged after 3 months of device use and training (mean, 78.84 [SD, 22.09]). ID numbers of outlier correspond to participant IDs in Table 3. *Statistically significant differences.

FIGURE 11

Results of four domains of the Veterans Affairs Low Vision Visual Functioning Questionnaire at baseline and after 3 months of device use. For the reading items, the mean baseline reading score without device was 1.75 logit units (SD, 1.43), which improved to 4.33 logits (SD, 2.68). For visual information items, the mean score without device was 1.21 logit units (SD, 0.91), which improved to 2.29 logits (SD, 1.19). The mean baseline visual motor score without device was 1.05 logit units (SD, 0.81), which improved to 1.42 logits (SD, 1.30) with the device after 3 months of device use and training. Scores on the mobility items did not demonstrate a significant change after 3 months. ID numbers of outlier correspond to participant IDs in Table 3. *Statistically significant differences.