Semantic segmentation of gonio-photographs via adaptive ROI localisation and uncertainty estimation

Andrea Peroni (Lead / Corresponding author), Anna Paviotti, Mauro Campigotto, Luis A. Pinto, Carlo A. Cutolo, Jacintha Gong, Sirjhun Patel, Caroline Cobb, Stewart Gillan, Andrew J. Tatham, Manuel Trucco

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
32 Downloads (Pure)


To develop and test a deep learning (DL) model for semantic segmentation of anatomical layers of the anterior chamber angle (ACA) in digital gonio-photographs. We used a pilot dataset of 274 ACA sector images, annotated by expert ophthalmologists to delineate five anatomical layers: iris root, ciliary body band, scleral spur, trabecular meshwork and cornea. Narrow depth-of-field and peripheral vignetting prevented clinicians from annotating part of each image with sufficient confidence, introducing a degree of subjectivity and features correlation in the ground truth. To overcome these limitations, we present a DL model, designed and trained to perform two tasks simultaneously: (1) maximise the segmentation accuracy within the annotated region of each frame and (2) identify a region of interest (ROI) based on local image informativeness. Moreover, our calibrated model provides results interpretability returning pixel-wise classification uncertainty through Monte Carlo dropout. The model was trained and validated in a 5-fold cross-validation experiment on ~90% of available data, achieving ~91% average segmentation accuracy within the annotated part of each ground truth image of the hold-out test set. An appropriate ROI was successfully identified in all test frames. The uncertainty estimation module located correctly inaccuracies and errors of segmentation outputs. The proposed model improves the only previously published work on gonio-photographs segmentation and may be a valid support for the automatic processing of these images to evaluate local tissue morphology. Uncertainty estimation is expected to facilitate acceptance of this system in clinical settings.

Original languageEnglish
Article numbere000898
Number of pages7
JournalBMJ Open Ophthalmology
Issue number1
Early online date25 Nov 2021
Publication statusPublished - 25 Nov 2021


  • Automated gonioscopy
  • Semantic segmentation
  • Deep learning
  • glaucoma
  • imaging
  • anterior chamber

ASJC Scopus subject areas

  • Ophthalmology


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