Researchers from the University College London's (UCL) Institute of Ophthalmology have developed a quick test to identify which people with glaucoma are at risk of rapid progression to blindness.

The test, called DARC (Detection of Apoptosing Retinal Cells), can detect glaucoma progression 18 months earlier than the current gold standard method, said the study published in the journal Expert Review of Molecular Diagnostics.

It involves injecting a fluorescent dye, that attaches to retinal cells, into the bloodstream (via the arm) and illuminates the retinal cells that are in the process of apoptosis, a form of programmed cell death. The damaged cells appear bright white when viewed in eye examinations — the more damaged cells detected, the higher the DARC count.

“Being able to diagnose glaucoma at an earlier stage, and predict its course of progression, could help people to maintain their sight, as treatment is most successful if provided at an early stage of the disease,” said study first author Eduardo Normando from Imperial College London.

One challenge with evaluating eye diseases is that specialists often disagree when viewing the same scans, so the researchers have incorporated an AI algorithm into their method.

In phase II clinical trial of DARC, the AI was used to assess 60 of the study participants — 20 with glaucoma and 40 healthy control subjects.

The AI was initially trained by analysing the retinal scans (after injection of the dye) of the healthy control participants and then tested on the glaucoma patients.

A follow-up after18 months revealed that the researchers were able to accurately predict progressive glaucomatous damage 18 months before that seen with the current gold standard OCT retinal imaging technology, as every patient with a DARC count over a certain threshold was found to have progressive glaucoma at follow-up.

“These results are very promising as they show DARC could be used as a biomarker when combined with the AI-aided algorithm,” said lead researcher Francesca Cordeiro from University College London (UCL) Institute of Ophthalmology.

Glaucoma, the leading global cause of irreversible blindness, affects over 60 million people, which is predicted to double by 2040 as the global population ages. In India, the estimated number of cases of glaucoma is 12 million, around one-fifth of the global burden of glaucoma.