The effect of relative distance enlargement on visual acuity in the visually impaired

Development and Validation of a Smartphone-Based Visual Acuity Test (Vision at Home)

Purpose

To describe the development and validation of a smartphone-based visual acuity (VA) test called Vision at home (V@home).

Methods

Three study populations (elderly Chinese, adolescent Chinese, and Australian groups) underwent distance and near VA testing using standard Early Treatment Diabetic Retinopathy Study (ETDRS) charts and the V@home device; all VA tests used tumbling E optotypes. VA tests were repeated with one eye, selected randomly. Distance VA was measured monocularly at 2 m, and near VA was measured binocularly at 40 cm. Participants also completed a questionnaire about their satisfaction with the device. V@home VA (logMAR) was compared to VA for ETDRS charts at distance and near and test-retest reliability.

Results

The mean difference between V@home and ETDRS distance VA across all groups ranged from -0.010 to -0.100 logMAR. Tolerant weighted kappa (TWK) agreement ranged from substantial (0.742) in the Australian group to almost perfect (0.950) in the adolescent Chinese group. There was high agreement of V@home with near ETDRS VA across all groups, with a mean difference of -0.092 to -0.042 logMAR and a TWK of 0.736 to 0.837. Test-retest reliability was also high (difference: -0.018 to 0.026) for both distance and near VA tests (95% limits of agreement: -0.289 to 0.258 for distance and -0.235 to 0.199 for near). The majority of participants were satisfied with V@home.

Conclusions

V@home could accurately and reliably measure both distance and near VA and is well accepted by participants.

Translational Relevance

The V@home system could potentially serve as a useful tool to improve eye care accessibility, especially in underdeveloped areas with limited eye care personnel and resources.

Measurement of distance objective visual acuity with the computerized optokinetic nystagmus test in patients with ocular diseases

BACKGROUNDS

To evaluate the efficacy of a computerized optokinetic nystagmus (OKN) test for determination of objective visual acuity (VA) at distance in patients with various ocular diseases.

METHODS

This is a prospective, non-interventional study that included 85 eyes of 71 patients with one or more ocular pathologies. Study patients were classified into group C (39 eyes of 30 patients with central visual damage), group P (24 eyes of 20 patients with peripheral visual defect) and group M (22 eyes of 21 patients with media opacity). Objective distance VA was measured with OKN induction and suppression methods, and the correlation between the objective and subjective VA at distance was evaluated using linear regression analysis. Mean subjective VAs were compared among each objective VA step and among the three groups.

RESULTS

Significant correlation was found between subjective distance VA and objective VA determined by both OKN induction and suppression methods in all three groups and in overall patients. In overall patients, the mean subjective VA was significantly different in several objective VA steps (Welch's ANOVA, p < 0.001 for induction and suppression methods). No significant difference in subjective VA among the three groups was found in any objective VA step.

CONCLUSIONS

Our objective VA test using OKN induction and suppression methods can be useful in estimating distance VA in patients with various ocular diseases.

New evidence that vision rehabilitation is a key component in the management of patients with macular degeneration

PURPOSE OF REVIEW

Vision rehabilitation has been considered as an adjunct support option or just the dispensing of magnifiers in the management of macular degeneration.

RECENT FINDINGS

New research suggests that vision rehabilitation can cause physical changes in the brain that help patients adjust to permanent vision loss.

SUMMARY

Vision rehabilitation is related to physical changes that occur in the brain. Its use in conjunction with clinical low-vision programs may pave the way for developing better rehabilitation techniques for patients with macular blindness.