Feasibility Study of a Novel Automated Slit Lamp Camera (Lightfield Medical Ophthalmic Camera Model Vscan001)

The standard ophthalmic slit lamp has remained largely unchanged for over 75 years. Anterior segment photography using conventional slit lamp cameras is limited in practice because it requires a highly trained physician or specialized ophthalmic photographer, captures only a small portion of the exam, and is hindered by difficulty with focus, lighting, and glare artifacts. The Lightfield Medical Vscan001 was developed to address these limitations through automation.

The Vscan001 is a semi-portable, joystick-mounted device with a form factor similar to a conventional slit lamp. It incorporates a 5-megapixel primary camera sensor coupled to a high-speed liquid lens capable of refocusing every 4 milliseconds, enabling automated focus control across the z-axis of the eye. A wide-angle 5-megapixel auxiliary camera provides overview imaging and assists with focus. An LED-based slit projector mounted on a rotating arm illuminates the eye from multiple angles; the projector incorporates a synchronized liquid lens to maintain a focused slit image on ocular structures throughout image acquisition. A microprocessor controls slit movement, slit width, and illumination parameters. Images are stored as Raw and JPEG files on an encrypted hard drive connected via USB to a Windows computer. The device's light energy output meets Group 1 radiant exposure limits as defined by ANSI Z80.36-2016 and qualifies as an FDA Class II exempt device under the PJZ slit lamp camera classification (21 CFR 886.1120). It meets FDA criteria for a non-significant risk (NSR) device under 21 CFR 812.3(m).

The study was conducted in two sequential phases. The Optimization/Calibration Phase involved 5-10 subjects, primarily study personnel and clinic staff volunteers, who underwent longer imaging sessions (5-20 minutes) to optimize camera parameters including shutter speed, aperture, sensor gain, illumination angle, and slit width. The General Recruitment Phase enrolled a larger cohort of adult patients (target 50-200) from Northwest Eye Clinic and its affiliate Minnesota Eye Consultants (Unifeye Vision Partners), Golden Valley, Minnesota. Patients with a range of anterior segment pathology and normal eyes were included to assess feasibility across a broad clinical population.

The primary endpoint was the proportion of enrolled patients who could be successfully imaged with the Vscan001 compared to those who could not - expressed as a simple percentage. A stopping rule was pre-specified: the study would be halted if fewer than 50% of patients could be adequately imaged. Exploratory endpoints included subjective assessment of image quality across varying photographic parameter combinations, with the intent of informing optimal settings for a subsequent pivotal study. No diagnostic or treatment decisions were made based on device output; the device was used solely for photographic documentation.

No randomization, blinding, or control group was employed. Statistical analysis was limited to computation of the primary feasibility proportion. The study was conducted under IRB review by Salus IRB (Austin, TX) and complied with FDA regulations governing non-significant risk device investigations under 21 CFR Part 812.2(b).

Inclusion criteria

• Adults 18 years of age or older
• Ability to position at the device (i.e., ability to rest chin on chinrest and forehead against forehead rest)
• Willingness to provide informed consent
• Patients with or without ocular pathology are eligible

Exclusion criteria

• Age younger than 18 years
• Physical inability to position at the device
• Movement disorders that would preclude stable positioning at the device
• Significant photophobia