Smartphone Slit Lamp Imaging-Usability and Quality Assessment

Abstract

Purpose: To assess the usability and image quality of a smartphone adapter for direct slit lamp imaging.

Methods: A single-center, prospective, clinical study conducted in the Department of Ophthalmology at the University Hospital Zurich, Switzerland. The smartphone group consisted of 26 medical staff (consultants, residents, and students). The control group consisted of one ophthalmic photographer. Both groups took images of the anterior and the posterior eye segment of the same proband. The control group used professional photography equipment. The participant group used an Apple iPhone 11 mounted on a slit lamp via a removable SlitREC smartphone adapter (Custom Surgical GmbH, Munich, Germany). The image quality was graded independently by two blinded ophthalmologists on a scale from 0 (low) to 10 (high quality). Images with a score ≥ 7.0/10 were considered as good as the reference images. The acquisition time was measured. A questionnaire on usability and experience in smartphone and slit lamp use was taken by all of the participants.

Results: Each participant had three attempts at the same task. The overall smartphone quality was 7.2/10 for the anterior and 6.4/10 for the posterior segment. The subjectively perceived difficulty decreased significantly over the course of three attempts (Kendall's W). Image quality increased as well but did not improve significantly from take 1 to take 3. However, the image quality of the posterior segment was significantly, positively correlated (Spearman's Rho) with work experience. The mean acquisition time for anterior segment imaging was faster in the smartphone group compared to the control group (156 vs. 206 s). It was vice versa for the posterior segment (180 vs. 151 s).

Conclusion: Slit lamp imaging with the presented smartphone adapter provides high-quality imaging of the anterior segment. Posterior segment imaging remains challenging in terms of image quality. The adapter constitutes a cost-effective, portable, easy-to-use solution for recording ophthalmic photos and videos. It can facilitate clinical documentation and communication among colleagues and with the patient especially outside normal consultation hours. Direct slit lamp imaging allows for time to be saved and increases the independence of ophthalmologists in terms of patient mobility and the availability of photographic staff.

Keywords: Custom Surgical; imaging; photography; slit REC; slit lamp; smartphone adapter.

Figure 1

Custom Surgical SlitREC adapter: (A) smartphone adapter (left) and eyepiece adapter (right). (B) Eyepiece adapter mounted on a slit lamp via two hex socket screws (Allen/Inbus screws). The other two screws can be used optionally to hold the smartphone adapter. In our setting, the magnetic ring alone proved to be strong enough. (C) Eyepiece adapter flipped up to allow binocular use of the slit lamp.

Figure 2

Smartphone mounted on a slit lamp via Custom Surgical SlitREC adapters: (A) adapter flipped down (capture mode), side view; (B) adapter flipped down (capture mode), front view; and (C) adapter flipped up (clinical mode) with a smartphone (held by magnets only), front view.

Figure 3

Comparison of smartphone images with photo studio images: (A) Anterior segment picture taken by smartphone; (B) Anterior segment picture taken by photo studio; (C) Posterior segment picture taken by smartphone. (D) Posterior segment picture taken by photo studio.