Smartphone-based Anterior Segment Imaging: A Comparative Diagnostic Accuracy Study of a Potential Tool for Blindness Prevalence Surveys

ABSTRACT

Purpose

To determine if smartphone photography could be a useful adjunct to blindness prevalence surveys by providing an accurate diagnosis of corneal opacity.

Methods

A total of 174 patients with infectious keratitis who had undergone corneal culturing over the past 5 years were enrolled in a diagnostic accuracy study at an eye hospital in South India. Both eyes had an ophthalmologist-performed slit lamp examination, followed by anterior segment photography with a handheld digital single lens reflex (SLR) camera and a smartphone camera coupled to an external attachment that provided magnification and illumination. The diagnostic accuracy of photography was assessed relative to slit lamp examination.

Results

In total, 90 of 174 enrolled participants had a corneal opacity in the cultured eye and no opacity in the contralateral eye, and did not have a penetrating keratoplasty or missing photographs. Relative to slit lamp examination, the sensitivity of corneal opacity diagnosis was 68% (95%CI 58–77%) using the smartphone’s default settings and 59% (95%CI 49–69%) using the SLR, and the specificity was 97% (95%CI 93–100%) for the smartphone and 97% (95%CI 92–100%) for the SLR. The sensitivity of smartphone-based corneal opacity diagnosis was higher for larger scars (81% for opacities 2 mm in diameter or larger), more visually significant scars (100% for eyes with visual acuity worse than 20/400), and more recent scars (85% for eyes cultured in the past 12 months).

Conclusion

The diagnostic performance of a smartphone coupled to an external attachment, while somewhat variable, demonstrated high specificity and high sensitivity for all but the smallest opacities.

KEYWORDS:

• Corneal ulcer
• telemedicine
• smartphone
• cornea
• photography
• diagnostic techniques
• ophthalmological

Disclosure statement

Drs Fletcher and Maamari are co-inventors on patents owned by the University of California, Berkeley that pertain to CellScope technology. None of the intellectual property is directly related to the Corneal CellScope used in this study. None of the other authors have financial disclosures.

Previous submission

The article was submitted to the Bulletin of the World Health Organization but not sent out for review.

Supplemental material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This work was supported by the National Institutes of Health [grant U10EY022880], the Harper-Inglis Memorial for Eye Research, The Peierls Foundation, That Man May See, and Research to Prevent Blindness.