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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session D

Poster W11 - A Novel Diagnostic Technique for Intermittent Exotropia

Friday, October 25, 2024
3:30 PM - 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Intermittent Exotropia (IXT) is characterized by an inconsistent outward rotation of one eye and presents a significant diagnostic challenge to clinicians due to its variable nature. IXT affects approximately 1% of the population with greater prevalence in Asia. Common reported visual symptoms include diplopia and eye strain, however severe psychosocial ramifications are also common. Strabismus decreases social interactions, reduces an individual's ability to obtain employment, increases alcohol use, and has been linked to a 2.7x increase in incidences of psychiatric illnesses. Current diagnostic standards include the office control score and prism and alternate cover test, which provide valuable information, but are less accessible and can only be measured at a single instance. This introduces vulnerability to the temporal variability of IXT. Remediation methods are invasive, either utilizing surgery to physically adjust the extraocular muscles, or non-surgical, by strengthening the coordination of the extraocular muscles. Beyond the initial challenges faced in conclusive diagnosis, treatment outcomes are not sufficient, with success rates between 28%-59% dependent on the modality. Interviews and literature suggest a gap in quantitative standards to evaluate the presentation of IXT at-home to limit the effects of in-office stressors and accessibility. This work proposes a portable novel device to detect the presence of IXT in the home-environment.

Materials and

Methods:  The Binocular Eye Alignment Monitor (BEAM) utilizes a Raspberry Pi 4 integrated with a Pupil Labs Core headset and custom C++ software to establish a portable, intuitive, and robust eye tracking platform. Figure 1 A-B presents the components of BEAM. Figure 1C displays the BEAM operator’s point of view. BEAM utilizes infrared (IR) cameras to capture images which are converted to black and white using an operator-specified threshold. The tracked position of each eye is visualized by a circle positioned using circle Hough Transform over the pupil with the midpoint of the circle being recorded. Following study protocol approved by the New Jersey Institute of Technology Institutional Review board (Protocol #: 2401039696), to assess the feasibility of BEAM, IXT patients (N=20) and binocularly normal controls (N=20) are being recruited. Each participant undergoes an optometric evaluation followed by two 1.5 hour recording sessions. For recording, a television is positioned 6m away and participants watch selected media. Ability to detect a deviation will be assessed via a between groups unpaired t-test and reliability will be assessed via the intraclass correlation coefficient.

Results, Conclusions, and Discussions: While data collection is ongoing, preliminary results show distinct behavioral differences between patient and control recording data. Figure 2 depicts the alignment of angular eye position from two binocularly normal controls and two clinically-diagnosed IXT patients. Table 1 contains deviation metrics for each of the individuals. The threshold for a deviation is set at 10 prism diopters, shown as dashed red lines. The behavioral differences between both groups demonstrates that BEAM is able to detect angular deviations, however more testing is required. Preliminary data collected has improved the experimental configuration for the user, as well as provided feedback for clinicians interacting with the BEAM interface. Following validation testing, expanding enrollment of the patient cohort will provide more powered correlations between clinical tests and metrics assessed via BEAM. Areas of focus include 1) total time of deviation and 2) magnitude of deviation. Future implementations of BEAM explore becoming an outcome assessment metric for randomized clinical trials and continuing development of a novel therapeutic method utilizing auditory biofeedback.

Acknowledgements (Optional):  This study was supported by the National Eye Institute of the National Institutes of Health as a part of the CINAPS (NEI R01EY023261) to T.L.A.