If I remeber correctly you are still working on 2d coordinates with Movenet so probably It better to work on 3d landmarks also if you want to try a simpler approach:

  
      

      blog.tensorflow.org
  

  
    

Iris landmark tracking in the browser with MediaPipe and TensorFlow.js 2

  Iris tracking enables a wide range of applications, such as hands-free interfaces for assistive technologies and understanding user behavior beyond