Evaluation of a retinal projection laser eyewear in subjects with visual impairment caused by corneal diseases in a randomized trial

Abstract

Purpose

Patients with incurable corneal diseases experience visual impairment despite having a healthy retina and optic pathway. Low vision aids (LVAs) are prescribed to optimize the use of remaining vision through magnification and contrast enhancement, but do not fully utilize the patient's visual capacity since they rely on the optic media. Therefore, we investigated a novel laser-eyewear (LEW) technology that bypasses the anterior segment of the eye. Images captured by an integrated camera are directly projected onto the retina using a low-energy-class-I-RGB-laser. The patient is able to view a full-color video, realized as augmented-reality. We aimed to evaluate the efficacy of LEW to enhance the vision of individuals with corneal diseases.

Design

A prospective, randomized, cross-over clinical trial.

Subjects

We examined the retinal projection glasses in 21 subjects (aged 25-69 years) with visual impairment (0.7logMAR or worse) due to corneal diseases. Subjects with comorbidities that impact vision, such as retinal disorders, were excluded.

Methods

Standardized measurements of visual acuity for near (NV) and distance vision (DV) were conducted using ETDRS charts with the respective best correction (BC) and then with LEW. In addition reading speed, Vision-related-quality–of-life (QoL) and capacity to carry out daily tasks were assessed at an initial visit and two subsequent visits after a home phase with and without the device. Six weeks after last usage of LEW an ophthalmological exam including SD-OCT or full-field electroretinography was conducted and compared to baseline to evaluate the safety of the device. Four subjects participated and completed a subsequent 12-month follow-up phase.

Main Outcome Measures

Improvement of visual acuity using LEW. Secondary objectives included safety, reading speed, QoL and usability in daily activities.

Results

The mean visual acuity (VA) in subjects with visual impairment was improved by 0.43logMAR in the DV using LEW compared to BC (p<0.0001). Using the 2x magnification mode of LEW resulted in an average improvement of 0.66logMAR compared to BC (p<0.0001). In NV an increase of 0.47logMAR was achieved compared to BC (p<0.0001). While only 4 out of 21 participants were able to read with BC, 17/21 were able to read with LEW. QoL significantly improved in the 17 subjects who completed all visits.

Conclusion

We demonstrated that the retinal projection glasses resulted in enhanced visual acuity for all subjects by directly projecting images onto the intact retina. In the future, LEW could represent a new supply option as a LVA for patients with corneal diseases.