Novel tool reliably measures horizontal strabismus in photographs

This paper reports the validity and reliability of a new app for calculating the gaze angle in patients with strabismus.

Study design

The authors used data from more than 1,000 eye photographs of 15 orthophoric patients to develop a smartphone app, and then tested this app in 72 patients with strabismus.

Outcomes

The photographic smartphone app achieved a high correlation between real and estimated gaze angles (r=0.990, P<0.001). High reliability was achieved between real and estimated imaging distances (r=0.997, P<0.001) as well as when the app’s measurements were compared with those made by a strabismus specialist (r=0.966, P<0.001).

Limitations

The cost and availability of the smartphone app is not yet known.

Clinical significance

This new method of quantitatively measuring horizontal strabismus with a smartphone app may prove useful to ophthalmologists and other eyecare providers.