Omar Mahroo

Omar Mahroo is Consultant Ophthalmologist at Moorfields Eye Hospital NHS Foundation Trust, Wellcome Clinician Scientist and Associate Professor, UCL Institute of Ophthalmology and is Honorary Clinical Senior Lecturer in Ophthalmology at King's College London.

What was your journey to ophthalmology?

"I became fascinated with vision whilst at medical school in Cambridge. I was taught by the late Roger Carpenter, an outstanding neurophysiologist and expert in eye movements, and I found his scientific approach inspiring. I was inspired further by lectures on photoreceptors (the cells in our eyes which detect light) by Trevor Lamb FRS, under whose supervision I went on to conduct a research project and then a PhD, investigating human photoreceptor function using electrophysiological recordings. I was amazed that we could record electrical responses to light from the cells in the retina of a living human eye (and I was frequently the subject in those experiments). These recordings are called the electroretinogram (ERG). We made novel discoveries about the processes by which our rod and cone photoreceptors adapt to different light levels.

Ophthalmology attracted me as I already developed a scientific interest in the retina and as it was a specialty combining medicine and precise surgery to restore vision, which I have found hugely fulfilling. After my medical degree, I did post-doctoral research at the Australian National University, and then general medical and surgical jobs back in Cambridge, before commencing ophthalmology training in London. "

Can you talk about your current research?

"My main area of research is still in the field of retinal electrophysiology that I entered over 20 years ago. Now I’m not just investigating how the retina works in healthy people, but also what goes wrong in disease, particularly inherited retinal diseases, which are a major cause of blindness in working age people. Over the past couple of decades our ability to image the structures of the eye has advanced tremendously, allowing us to see the layers of the retina. However, this does not always tell us about whether or not the cells are functioning properly, and electrophysiology allows us to directly assess this. Part of my research involves developing newer ways of isolating these responses and using mathematical modelling techniques to analyse them. Through this work, we hope to better understand, not only inherited retinal diseases, but mechanisms driving myopia development and also retinal impairment in neurological conditions.

I am using the ERG to understand how the retina adapts to light and dark, rapidly changing sensitivity in ways superior to many cameras. Difficultly adapting to different light levels is a feature of many retinal diseases and is not easy to quantify objectively. We are measuring how human retinal responses change in light and dark environments in healthy volunteers and in patients with retinal disease. We used this ERG technique to show that the “transient blindness” experienced by some people after viewing a smartphone with one eye in the dark was simply related to retinal adaptation and completely benign; our article (in the New England Journal of Medicine in 2016) received much media attention.

Another area of my research focuses on the use of a portable ERG device in clinics. Usually, in eye departments across the country, patients who require ERG testing have to be booked for a separate visit often at another hospital weeks or months later. Portable devices have been developed that can be used within minutes in an eye clinic, and can give some of the information needed. ERG testing could then be incorporated more widely into routine clinical care. We have used this device in more than 1500 healthy volunteers and in over 100 patients with retinal disease."

Has the NIHR played a role in your work? If so, in what way?

"The NIHR has significantly enabled my research. Much of my work investigating normal retinal responses has come from healthy volunteers from the TwinsUK cohort, which is supported by the NIHR Biomedical Research Centre (BRC) at Guys and St Thomas’ Foundation Trust and King’s College London. I have also received significant support from the NIHR Moorfields BRC, which has provided infrastructure for my research in patients with retinal disease, funded time to conduct this research and enabled me to successfully apply for a major Wellcome Trust Clinical Research Career Development Fellowship Award."

What do you think the future holds in the field?

"The future is exciting as techniques to assess retinal structure and function continue to improve, yielding more information and becoming more accessible, even remotely. Inherited retinal diseases have been largely untreatable to date, but we are now seeing the emergence of new gene-based and other therapies that have shown promising results. Machine learning techniques are likely to not only assist with clinical decision-making, but yield novel mechanistic insights from existing and future large datasets that will improve our understanding of disease and help us explore new avenues for treatment. I think we will also learn more of how retinal signalling drives myopia, which will help us understand what is driving the huge increase in prevalence worldwide."