SmartKC: Smartphone-based Corneal Topographer for Keratoconus Detection

TL;DR

SmartKC is a low-cost, smartphone-based system that uses a 3D-printed attachment and image analysis to detect keratoconus with high accuracy, making early diagnosis more accessible in low-resource settings.

Contribution

This paper introduces SmartKC, a novel portable keratoconus detection system utilizing smartphone imaging and custom hardware, enabling affordable screening.

Findings

Achieved 94.1% sensitivity and 100% specificity in clinical tests.

Strong correlation (0.78) between SmartKC's curvature estimates and standard devices.

Demonstrated potential for use as a screening tool in real-world settings.

Abstract

Keratoconus is a severe eye disease affecting the cornea (the clear, dome-shaped outer surface of the eye), causing it to become thin and develop a conical bulge. The diagnosis of keratoconus requires sophisticated ophthalmic devices which are non-portable and very expensive. This makes early detection of keratoconus inaccessible to large populations in low- and middle-income countries, making it a leading cause for partial/complete blindness among such populations. We propose SmartKC, a low-cost, smartphone-based keratoconus diagnosis system comprising of a 3D-printed placido's disc attachment, an LED light strip, and an intelligent smartphone app to capture the reflection of the placido rings on the cornea. An image processing pipeline analyzes the corneal image and uses the smartphone's camera parameters, the placido rings' 3D location, the pixel location of the reflected placido rings and the setup's working distance to construct the corneal surface, via the Arc-Step method and Zernike polynomials based surface fitting. In a clinical study with 101 distinct eyes, we found that SmartKC achieves a sensitivity of 94.1% and a specificity of 100.0%. Moreover, the quantitative curvature estimates (sim-K) strongly correlate with a gold-standard medical device (Pearson correlation coefficient =0.78). Our results indicate that SmartKC has the potential to be used as a keratoconus screening tool under real-world medical settings.