A research team led by the Department of Ophthalmology, School of Clinical Medicine, LKS Faculty of Medicine of The University of Hong Kong (HKUMed), alongside partners from the Faculty of Medicine of The Chinese University of Hong Kong (CU Medicine) and local and international partners, have developed a new technology ROTA (Retinal nerve fibre layer Optical Texture Analysis) to unveil the optical texture and trajectories of the axonal fibre bundles on the retina.
So far, ROTA has outperformed current clinical standards, attaining 15.0% to 28.4% higher sensitivity in detecting early optic nerve damage in glaucoma – the leading cause of irreversible blindness. The research has been published in Nature Biomedical Engineering.
The most common form of neurodegenerative disease is glaucoma. While a clinical diagnosis of the disease is predicated on the measurement of retinal nerve fibre layer (RNFL) thickness which is typically determined via a non-invasive digital imaging device – optical coherence tomography (OCT) – false positives and false negatives are common.
Thus, it is difficult, even for glaucoma specialists, to obtain a clinical interpretation of OCT findings. This is supported by a meta-analysis reporting that the sensitivities of best-performing OCT parameters for detection of RNFL thickness abnormalities were only 65%-75% at specificities of 90%-95%.
ROTA is a patented algorithm (US Patent No. 10,918,275) that integrates RNFL thickness and RNFL reflectance measurements obtained from standard OCT scans to discern the optical texture and trajectories of the axonal fibre bundles and reveal RNFL defects.
The technology can detect focal RNFL defects that are missed by standard clinical tests. Compared with OCT, ROTA can increase the sensitivity of detecting early optic nerve damage in glaucoma by 15-22%. At 95% specificity, the sensitivity of ROTA was 97.3-98.4% for detection of early glaucoma, 15.0% to 28.4% higher than the current clinical standards.
HKUMed is working with the University of California San Diego (UCSD), the United States, to apply ROTA in research and patient care, while patients can find the application of ROTA at HKU Eye Centre and Southern District Hong Kong Eye Survey.
The CUHK Eye Centre of CU Medicine conducted a diagnostic study and examined 177 healthy individuals and 363 glaucoma patients. They found that ROTA attained a significantly higher sensitivity and specificity than conventional OCT RNFL thickness analysis to detect glaucoma1. Furthermore, ROTA was able to identify axonal fibre bundle damage in optic neuritis, ischemic optic neuropathy, and compressive optic neuropathy.
Professor Christopher Leung Kai-shun, Chairperson and Clinical Professor of the Department of Ophthalmology, School of Clinical Medicine, HKUMed stated that the team’s next steps include enrolling patients from Queen Mary Hospital, Grantham Hospital, and Hong Kong Eye Hospital for longitudinal studies to examine the effectiveness of ROTA for detection of glaucoma progression, as well as working with OCT industrial partners to deploy ROTA in clinical care. Furthermore, HKU Eye Centre welcomes patients with a questionable diagnosis of glaucoma for ROTA assessment.
Meanwhile, Professor Clement Tham Chee-yung, Chairman of the Department of Ophthalmology and Visual Sciences and S.H. Ho Professor of Ophthalmology and Visual Sciences, CU Medicine, noted that glaucoma can lead to irreversible loss of vision if it is not diagnosed and treated early. In Hong Kong, about 25% of irreversible blindness is caused by glaucoma, and there are more than 100,000 glaucoma patients suffering from various levels of visual disability.
It was added that achieving an earlier diagnosis of glaucoma and detection of progression through advanced imaging technologies is essential.
Clinical applications
ROTA underpins a highly sensitive and specific technique to advance the diagnosis of glaucoma and optic neuropathies. ROTA will be deployed on the Advanced Nerve and Glaucoma Imaging Network (ANGI Network), which comprises ophthalmologists, neuro-ophthalmologists and clinical researchers around the world.
The committee members of ANGI Network include world-leading institutions in glaucoma research such as HKU, Asan Medical Center (Korea), Beyer Eye Institute at Stanford University (US), Moorfields Eye Hospital (UK), NTU Langone’s Eye Center (US), and University College London (UK).
