PhacoTrainer: A Multicenter Study of Deep Learning for Activity Recognition in Cataract Surgical Videos

To build and evaluate deep learning models for recognizing cataract surgical steps from whole-length surgical videos with minimal preprocessing, including identification of routine and complex steps.

We collected 298 cataract surgical videos from 12 resident surgeons across 6 sites and excluded 30 incomplete, duplicated, and combination surgery videos. Videos were downsampled at 1 frame/second. Trained annotators labeled 13 steps of surgery: create wound, injection into the eye, capsulorrhexis, hydrodissection, phacoemulsification, irrigation/aspiration, place lens, remove viscoelastic, close wound, advanced technique/other, stain with trypan blue, manipulating iris, and subconjunctival injection. We trained two deep learning models, one based on the VGG16 architecture (VGG model) and the second using VGG16 followed by a long short-term memory network (convolutional neural network [CNN]- recurrent neural network [RNN] model). Class activation maps were visualized using Grad-CAM.

Overall top 1 prediction accuracy was 76% for VGG model (93% for top 3 accuracy) and 84% for the CNN-RNN model (97% for top 3 accuracy). The microaveraged area under receiver-operating characteristic curves was 0.97 for the VGG model and 0.99 for the CNN-RNN model. The microaveraged average precision score was 0.83 for the VGG model and 0.92 for the CNN-RNN model. Class activation maps revealed the model was appropriately focused on the instrumentation used in each step to identify which step was being performed.

Deep learning models can classify cataract surgical activities on a frame-by-frame basis with remarkably high accuracy, especially routine surgical steps.

An automated system for recognition of cataract surgical steps could provide to residents automated feedback metrics, such as the length of time spent on each step.