A system to describe OCT scans

Tim Cole, clinical affairs manager for Heidelberg Engineering, described a method to systematically evaluate optical coherence tomography (OCT) images in an educational session at 100% Optical, held at London’s ExCeL 23–25 April.

Beginning the session titled, Peer review: How to become an OCT expert, Cole outlined the steps involved in becoming an expert of any given field.

Citing a book by Malcolm Gladwell which explored how professionals ranging from athletes to entrepreneurs became experts in their specialities, Cole shared that the author came to the “age old” conclusion: “practice makes perfect.”

In particular, 10,000 hours is the amount of time thought to take to become an expert in a field. Applying this to OCT, Cole worked from an example suggesting that an average working year might include 255 days. Of those days, if a practitioner looked at OCTs for two hours, the practitioner would see 510 hours of OCT.

By that logic, Cole posed, it would take 19.6 years for an optometrist to become an OCT expert. He added that OCT has only been commercially available in the last 20 years.

The key issue for optometrists, Cole suggested, is how to become an expert “without all those hours?”

The answer could be pattern recognition, Cole said. He highlighted that this is one of the reasons that interest and research in artificial intelligence is growing, giving the example of the Moorfields’ DeepMind project.

When working with OCT, Cole advised delegates: “The one big thing to remember is that OCT is just one piece of the investigation.”

Cole outlined two approaches to OCT interpretation: descriptive and diagnosis. Descriptive interpretation means to look at a scan, observe that something is not normal, and be able to consider why it is not normal by describing anything strange on the scan.

Diagnosis represents a side of interpretation seen in ophthalmology, but that, Cole observed, is a step that many practitioners who are new to OCT are inclined to skip to.

“But what do you do when you don’t know the diagnosis?” Cole asked. “That’s why it is so important to have descriptive, systematic methodology to look at OCT.”

Heidelberg Engineering’s Eyeway Code aims to act as a method to evaluate scans, as well as providing the language to discuss the images with other eye care professionals.

Taking inspiration from the Highway Code, with the triangular red sign indicating a ‘hazard,’ the Eyeway Code features 10 hazard signs that can be used to describe shapes and patterns in the scan.

The signs include:

1. Depression
2. Elevation
3. Fragmentation
4. Interruption
5. Irregularity
6. Rupture
7. Thinning
8. Thickening
9. Hyper reflectivity
10. Hypo reflectivity.

Using the Eyeway Code, Cole took delegates through a number of example scans, identifying the different patterns, and explaining the eventual diagnosis in each case.

Cole also noted how the code would be applied differently in a case of glaucoma, because “only one area of the scan is changing.” Cole explained: “Glaucoma is really about systematic, time-based analysis, building up that thickness information over time.”

Delegates also heard about medical terminology and abbreviations that could be used to describe the signs observed in scans when making a referral.

“The point of doing this isn’t to jump to a diagnosis, it’s all about understanding how we get there,” Cole told attendees. “Because if we’re not an OCT expert – and who is – it’s all about explaining what you see in the scan.”

100% Optical 2023 will be held at London’s ExCeL from 25-27 February.