Navigating diagnostic challenges in glaucoma

Aston University lecturer, Dr Sayantan Biswas, treated delegates to a deep dive on glaucoma identification and management during his talk at 100% Optical (2 March, Excel London).

Biswas highlighted that glaucoma remains a leading cause of irreversible blindness – and can be challenging to diagnose, despite advancements in technology.

“There’s no single diagnostic test that can diagnose glaucoma,” he said.

“It is missed, misdiagnosed and over-diagnosed all the time,” Biswas added.

During his presentation, Biswas outlined diagnostic challenges in identifying glaucoma among patients with myopia.

He noted that visual field defects can develop in highly myopic eyes that are unrelated to glaucoma.

Biswas shared that in these patients using optical coherence tomography to identify glaucomatous change can be useful, in combination with perimetry to identify a corresponding visual field loss.

“In myopic eyes, we see damage and change, but none of this is progressive,” he said.

He emphasised the importance of looking for progression over time rather than making a diagnosis on the basis of a single test.

“A single test showing a visual field defect doesn’t mean a thing. It has to be progressive,” Biswas said.

“When you have a patient with a visual field defect, repeat the test and confirm that it’s a true defect – not just due to a tilted disc,” he said.

He encouraged practitioners to use contact lenses rather than trial lenses when performing visual field tests in patients with myopia.

“Trial lenses are very thick for myopic eyes and can create artefacts,” he said.

Biswas added intraocular pressure measurements should also be conducted over time.

“You have to have a longitudinal pressure measurement, not just a snapshot,” he said.

Addressing a misconception in practice, Biswas shared that myopic eyes can have closed angle glaucoma – the condition is not exclusive to hyperopes.

“It’s good to check their angle using gonioscopy or anterior segment OCT,” he said.

Emerging technology in glaucoma care

Biswas discussed Retinal nerve fiber layer Optical Texture Analysis (ROTA).

“OCT measures thickness within the optic nerve, but ROTA measures the texture of the retinal nerve fiber layer,” he explained.

Biswas highlighted that glaucoma causes axonal degeneration with damage to the retinal ganglion cells.

“That can appear as a texture change before thickness loss,” he said.

The lecturer noted that ROTA could potentially identify patients with early glaucoma at a stage that would not be detected through OCT scans.

Biswas shared that artificial intelligence (AI) is now being trained to identify glaucomatous change from fundus images and OCT scans.

He added that the technology has shown high sensitivity in detecting glaucoma, with some challenges around specificity.

“That means there is a high chance you will detect the abnormality but there is also a high chance of false positives,” Biswas said.

He noted that while there have been promising results with AI, there is a lack of clarity about the process the technology uses to make decisions.

“The clinician is completely in the dark. That’s why it is called a black box decision,” Biswas highlighted.