Information Services Office   4.1.2013


(From left) Prof. Benny Zee, Dr. Jack Lee and Prof. Vincent Mok with the automatic retinal image analysis system
Normal retina (left) and diabetic retinopathy
Diabetic retinopathy screening process: taking retina image (left), screening (centre) and producing analysis report (right)
Newsletter No. 410 > In Plain View > A Clearer Window to Health Hazards

A Clearer Window to Health Hazards


Richard Dawkins thinks that Darwin is the greatest mind that ever lived. He also admits that he feels the same sense of reverential hush towards R.A. Fisher, founder of modern statistics. The marriage of statistical theories and methods and the biological sciences have brought us the modern discipline of biostatistics. However, neither the impact of Fisher nor that of biostatistics is always duly recognized.

According to Prof. Benny Zee of the Jockey Club School of Public Health and Primary Care, CUHK, biostatistics encompasses the design of biological experiments, especially in medicine and agriculture, on the collection, summarization, and analysis of data from those studies, and their interpretation and inference of the results. Biostatisticians are men of two trades, one in numbers and the other in the field of application. They use statistical reasonings, models and methods to re-formulate the problems into quantifiable functions and optimize the results for solutions and decisions. It is because of their ability to straddle and expand the boundary of a larger terrain of enquiry that they are often in a better position to act as problem-solvers and play a policy and advisory role.

Common applications of biostatistical methods include quality control in industrial engineering, genetics in biology, clinical research methods in medicine, and actuarial and life tables in healthcare. The British statistician, Sir David Cox, has made many important contributions, of which the best known is perhaps the proportional hazards model, which is widely used in the analysis of survival data. An example is survival times in medical research that can be related to information about the patients such as age, diet or exposure to certain substances.

Professor Zee had extensive experience in clinical trial methodology for drug development in North America before he came back to Hong Kong in 2001 to help build the discipline of biostatistics at CUHK. He would apply statistical reasonings to the testing and performance of new drugs to determine the optimal conditions under which a new drug was effective or otherwise, with the aim to enhancing the screening efficiency of new drugs. Such work obviously has immense impact on the pharmaceutical industry and the welfare of patients.

His most recent innovation is in developing an algorithm for an automatic diagnostic system for cerebral vessel conditions and evaluation of the risk of stroke. This grew out of a collaboration with Dr. Jack Lee, a biostatistician with expertise in finance and bioinformatics, and Dr. Li Qing, an ophthalmologist and a PhD student of his who set out to identify vascular diseases before stroke happens.

Up to 80% of all diabetics of over 10 years would develop diabetic retinopathy (DR) which is damage to the retina caused by diabetes mellitus, with a concomitant higher chance of suffering stroke at a later stage. DR screening has become a standard procedure in diabetic care but its effectiveness is hampered by several factors: not enough specialists to administer the screening, human variability in diagnosis, long waiting time for the result, and high cost.

To address these issues, the team had to find a methodology to turn the analogue images of the retina into quantifiable and analyzable data. The finding of a pattern out of seemingly chaotic information was what Professor Zee had learned from his teacher at the University of Pittsburgh, Prof. C.R. Rao. According to Professor Zee, the first difficulty encountered in the process was the location of the optic disc (the spot where the light-sensitive ganglion cell axons leave the eye to form the optic nerve to the brain, also known as the physiological blind spot). Although methods of locating it already existed, his team developed a new method that best fit their purpose. A greater hurdle, however, laid in the detection of new vessels in the eye whose growth is a sure sign of havoc to come. As new blood vessels are short, irregular and squiggly, the determination of their existence and state of growth eluded all existent automatized technology. Applying the skills of a biostatistician in pattern recognition and quantification, the team was able to devise an algorithm which reads pixel by pixel the retinal images and analyze such pixels to come up with measurements on exudates, haemorrhages, new vessels and finally achieve the overall evaluation of retinopathy.

Standard retinal images can be transmitted through the Internet to a server installed with the algorithm and the result or report is available within a short period of time. The new method is non-invasive and will substantially reduce bias due to human perception as well as cost and time. Initial tests have confirmed its dependability and high accuracy rates. Next, Professor Zee intends to expand the technology and apply it to both diabetes and non-diabetes patients for the early detection of strokes.

The eye is the window to the soul, and so is it to sickness. Usually another human eye is required to judge if any hazard is forthcoming—that is the role of the traditional physician. Professor Zee and his team have devised an algorithm that does the job of the expert eye, so that the tool can benefit a wider population of individuals and make bigger impact on health care in general.

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