A Smartphone Ocular Alignment Measurement App in School Screening for Strabismus

Abstract

Background: Strabismus is the leading risk factor for amblyopia, which should be early detected for minimized visual impairment. However, traditional school screening for strabismus can be challenged due to several factors, most notably training, mobility and cost. The purpose of our study is to evaluate the feasibility of using a smartphone application in school vision screening for detection of strabismus.Methods: The beta smartphone application, EyeTurn, can measure ocular misalignment by computerized Hirschberg test. The application was used by a school nurse in a routine vision screening for 133 elementary school children. All app measurements were reviewed by an ophthalmologist to assess the rate of successful measurement and were flagged for in-person verification with prism alternating cover test (PACT) using a 2.4Δ threshold (root mean squared error of the app). A receiver operating characteristic (ROC) curve was used to determine the best sensitivity and specificity for an 8Δ threshold (recommended by AAPOS) with the PACT measurement as ground truth.Results: The nurse obtained at least one successful app measurement for 93% of children (125/133). 40 were flagged for PACT, of which 6 were confirmed to have strabismus, including 4 exotropia (10△, 10△, 14△ and 18△), 1 constant esotropia (25△) and 1 accommodative esotropia (14△). Based on the ROC curve, the optimum threshold for the app to detect strabismus was determined to be 3.0△, with the best sensitivity (83.0%), specificity (76.5%). With this threshold the app would have missed one child with accommodative esotriopia, whereas conventional screening missed 3 cases of intermittent extropia.Conclusions: Results support feasibility of use of the app by personnel without professional training in routine school screenings to improve detection of strabismus.

Evaluation of the Usability of the Innovative Strabiscan Device for Automatic Strabismus Angle Measurement

“…Researchers around the world are working to develop new devices for more accurate and prompt diagnosis of strabismic disease (7,(22)(23)(24)(25)(26)(27)(28)(29). Numerous scientific articles report methods for estimating strabismus angles based on analysis of reflections on the pupil area, reflections from the cornea and deeper layers, and those based on the shape of the pupil in camera images.…”