One in a million

A pioneering scanning technique is so precise that it can pick out one retinal nerve cell of the approximately 1.2 million present in the retina – a clarity that researchers hope will enable ocular diseases to be picked up earlier than ever before.

A research team, led by Dr Ethan Rossi and Dr David Williams, at New York state’s University of Rochester pioneered the technique, which they have named ‘multi-offset detection.’

Light is scattered by the retina across a combination of scans, and is collected by the imaging system, according to the paper in the Proceedings of the National Academy of Sciences journal.

The method was used to scan the eyes of animals and patients with age-related macular degeneration (AMD).

The new scans have been able to capture an individual retinal nerve cell – one notoriously hard to image being nearly transparent – as well as the structures inside one.

Dr Rossi told OT that in glaucoma, nerve cells likely go through substantial – and hopefully, now observable – changes before they die.

He explained: “The cells are expected to shrink up before they die.  Structures within the cell also undergo substantial changes that we may be able to detect if we are able to achieve the level of resolution in humans that we previously obtained in monkeys.”

Such scans would be a vast improvement over the current technique of measuring the changing thickness of the nerve fibre layer to monitor glaucoma.

Dr Williams emphasised that by the time there is a detectable change in this layer, tens of thousands of nerve cells may have been lost.

“The sooner we can catch the loss, the better our chances of halting disease and preventing vision loss,” he added.

Currently, it is difficult to monitor the health of cone photoreceptors in areas of the retina that are damaged or where drusen is present. However, the new technique has overcome these challenges, a boost for AMD screening.

Dr Rossi, a new assistant professor at the University of Pittsburgh, explained that the team observed that certain photoreceptors – presumed either unhealthy or lost – scattered less light than their healthy, fully functional counterparts.

The team is now working to improve the image quality and robustness of the technique, and plan to launch a small study scanning the retinae of glaucoma patients in the near future.

Image credit: University of Rochester