Breakthrough could make OCT images clearer

For a quarter of a century, researchers have tried to reduce “noise” in OCT images. Now an inventive solution may hold the answer

Optometrist using OCT

Scientists believe they have developed a relatively simple, low-cost solution that could increase the resolution of optical coherence tomography (OCT) by several-fold. 

In a study published in Nature Communications, Stanford University researchers detail how they tackled the problem of the inherent noise in OCT images – called ‘speckle noise.’

This conundrum has puzzled researchers since the inception of OCT technology 25 years ago. 

A new technique used in the study, speckle-modulating OCT (SM-OCT), was found to clarify and reveal structures that were previously undetectable. 

Lead author, Orly Liba, told OT that removing speckle noise allowed clinicians to see the structure of the tissue much better. 

“We were able to see the inner stromal structure of a live mouse cornea and see improved definition of the mouse retinal layers,” Ms Liba explained. 

“We also tested SM-OCT on people and saw reduced speckle noise,” she added. 

The research has the potential to give clinicians the tools for improved diagnosis of eye conditions and better follow-up treatments, Ms Liba elaborated. 

The latest study involved using a pair of lenses, a piece of ground glass and some software changes to create a holograph-like image that was moved in location between each scan. 

Averaging the successive images created a noise-free image that was free of speckles. 

Scientists have previously attempted to solve the problem of speckle noise by taking a series of images with non-correlated speckle patterns. However, this technique reduced the resolution of the image. 

Another technique involved image processing techniques – but this only reduced the appearance of speckle noise without capturing the lost information.

Image credit: National Eye Institute