Improved diagnosis for glaucoma, the 'sneak thief of sight'

UNSW researchers have bridged a key knowledge gap in the diagnosis of glaucoma, allowing observable damage to the optic nerve caused by the condition to be accurately linked to vision loss.

Glaucoma is one of the leading causes of irreversible blindness in the world, with damage to the optic nerve resulting in loss of vision. Sometimes referred to as the ‘sneak thief of sight’, it is often asymptomatic in the early stages of the disease, with about half of all cases in the general population estimated to remain undiagnosed.

Clinically, glaucoma is diagnosed through a combination of clinical tests including eye pressure measurement; visual inspection of eye structures, specifically around the optic nerve; and assessment of functional loss using a technique known as standard automated perimetry, which measures a person’s field of vision. More recently, new imaging instruments that allow precise measurements of the optic nerve thickness and integrity have been increasingly used for diagnosis.

For decades, clinicians and scientists have been baffled by a mismatch between structural and functional deficits noticing that, in some cases, there was no detectable loss of vision despite obvious damage to the optic nerve. This mismatch potentially prevents accurate and timely diagnosis of glaucoma and creates a high risk of irreversible vision loss for patients not being treated in time.

Now, researchers at UNSW’s Centre for Eye Health and School of Optometry and Vision Science have established a model that can robustly predict changes in ganglion cells — the neurons making up the optic nerve — that occur with age or with the disease, and correlated them with functional loss. Their study has been published in the journal Investigative Ophthalmology and Visual Science.

“Neither the functional nor structural models that are currently applied in clinical practice adequately reflect our understanding of changes in retinal ganglion cells responsible for glaucomatous damage, and thus may be not be sensitive to early disease detection,” said PhD candidate Nayuta Yoshioka, first author on the study.

“By developing better models to describe both functional and structural changes in the ganglion cell layer of the retina, we were able to consolidate our theoretical understanding of retinal changes occurring with age and with disease,” added Professor Michael Kalloniatis, director of the Centre for Eye Health. “This work has shown how they are directly related.”

Image caption: Study first author Nayuta Yoshioka.