Feasibility Tests for Various Prism Configurations for Visual Field Loss

Visual Field Expansion Through Innovative Multi-Periscopic Prism Design

Status

Recruiting

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT04424979

Enrollment

Registered

2020-06-11

Start date

2020-11-06

Completion date

2026-12-31

Last updated

2025-09-23

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Hemianopia, Homonymous, Tunnel Vision, Visual Field Constriction Bilateral, Visual Field Defect Homonymous Bilateral, Visual Field Defect, Peripheral

Keywords

Visual field expansion, Prisms, Hemianopsia, Tunnel vision, Visual field loss

Brief summary

The investigators will develop and test different configurations of high-power prisms to expand the field of vision of patients with visual field loss to assist them with obstacle detection when walking. The study will involve multiple visits (typically four) to Schepens Eye Research Institute for fitting and testing with the prism glasses. The overall objective is to determine best designs and fitting parameters for implementation in prism devices for future clinical trials.

Interventions

DEVICEHigh power prisms

High power prisms designed to shift images from blind areas into portions of the wearer's remaining, seeing, field of vision

Study design

Allocation

Intervention model

SINGLE_GROUP

Primary purpose

DEVICE_FEASIBILITY

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

7 Years to 80 Years

Healthy volunteers

Inclusion criteria

* Visual field loss, either peripheral field loss or hemianopic field loss * Visual acuity of at least 20/50 in the better eye * In sufficiently good health to be able to complete sessions lasting 2-4 hours * Able to independently walk short distances * Able to give voluntary, informed consent * Able to speak English

Exclusion criteria

* Any physical or mental impairments, including cognitive dysfunction, balance problems or other deficits that could impair the ability to walk or use the prism spectacles * A history of seizures in the last 6 months * Hemispatial neglect (subjects with hemianopic field loss only)

Design outcomes

Primary

Measure	Time frame	Description
Field of view expansion	Through study completion, an average of four months	Horizontal and vertical extent of the expansion (in degrees) of the field of view

Secondary

Measure	Time frame	Description
Pedestrian detection rate	Through study completion, an average of four months	Proportion of pedestrians detected (in simulated walking or simulated driving)

Countries

United States

Contacts

Primary ContactAlex Bowers

alex_bowers@meei.harvard.edu617 912 2512

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026