Foldscope: A smartphone based diagnostic tool for fungal keratitis

Abstract

Purpose: Smartphone-based microscopy tool like foldscope (FS) may serve the purpose of a low-cost diagnostic alternative to the compound light microscope especially in areas with limited resources. The purpose of this study was to detect fungal pathogens causing keratitis on direct smear by smartphone-mounted FS and to evaluate the efficacy of FS against routine compound light microscope (CLM). Methods: The prospective study was conducted at a tertiary eye care center from September 2019 to March 2020. The study included 60 smear examinations (Gram stain [GM] n = 30, Lactophenol Cotton Blue [LCB] n = 30) to detect fungal pathogens from corneal scraping material of clinically suspected fungal keratitis (FK) cases. The diagnostic utility of FS was compared with CLM for both GM and LCB wet mount. Data collected were used to quantify the agreement using Cohen’s kappa between CLM and FS imaging. Results: Forty-six samples out of 60 were positive for fungi using CLM. GM stain and LCB showed 22/30 (73.33%) and 24/30 (80%) positive results with CLM, respectively. Moderate agreement (0.49) was observed between CLM and FS with the smartphone method. LCB mount showed high specificity of 1.00 over 0.87 of GM stain for FS with the smartphone. Conclusion: Direct smear can be an early and sensitive measure to diagnose FK other than clinical suspicion. The smartphone-mounted FS has limited sensitivity as an alternative to CLM, but excellent specificity in the present study for FK. The FS as a smartphone-based diagnostic tool is simple, portable, and inexpensive in resource-constrained rural or remote clinical and public health settings in the absence of CLM and other higher diagnostic modalities.

The Case for Fungal Keratitis to Be Accepted as a Neglected Tropical Disease

“…The tool has previously been explored for diagnosis of parasitic helminth infections and cervical smear cytology with high sensitivity. A small study comparing smartphone-mounted Foldscope to conventional light microscopy on 60 corneal scrapings found reasonable sensitivity (0.72) and high specificity (0.92) [ 30 ]. Importantly, the performance of novel tools such as Foldscope relies on experienced and skilled operators, who may be confined to major cities.…”

Igniting children’s enthusiasm for microbes with an origami paper microscope

“…Since, besides its use against a source of light, the Foldscope can be attached to a smartphone, participants were also encouraged to submit their acquired images, to an ad hoc created e-mail address for prizes. We and others have previously evaluated the performance of the Foldscope using clinical samples, showing the comparable quality of the images ( 11 , 12 ). A smartphone app is also available to process, record, and share images.…”

Smart scientific instruments based on smartphones: a brief review

“…The developments of smartphone-based microscopes until 2016 were summarized by Contreras-Naranjo et al [68], and Ayardulabi et al [69] focused on their applications in point-of-care systems. The detection of specific cells, molecules, and microorganisms shown in [69]- [71] could be implemented in practical operations. The image storage and analysis then enable facile and costeffective telemedicine diagnosis in rural or remote areas.…”