Glaucoma on My Mind

Even though normal tension glaucoma (NTG) affects approximately 50 percent of primary open-angle glaucoma patients, the pathophysiology of the disease remains poorly understood. Now, new research – conducted at the Kaunas University of Technology (KTU), Lithuania – provides additional evidence that intracranial pressure (ICP) and translaminar pressure difference (TPD) play a major role in NTG development (1). The study gathered ICP and visual field perimetry data from 80 early-stage NTG patients referred to the Eye Clinic at the Lithuanian University of Health Sciences between January and October 2018.

Typically, ICP measurements require that a small-sized hole is drilled in the patient’s skull, which limits the use of the metric. In this study, the researchers used a two-depth transcranial doppler, technology invented by Arminas Ragauskas, Head of the Health Telematics Science Institute at KTU (2), to measure ICP non-invasively through the eye using ultrasound. Ragauskas notes that the new technology does not compete with invasive methods, but rather takes us towards “an entirely new direction” for measuring ICP. (Interesting sidenote: Ragauskas also says that his team is constantly developing the invention, with patents for new applications and ambitions to see the technology used in long-term space missions!)

With easier access to ICP,  the team were able to explore several significant correlations between ICP, TPD (gained through the simple formula: TPD = IOP – ICP), and visual field changes. In particular, though lower ICP correlated with lower IOP, higher TPD was associated with significant changes to the patient’s visual field. Out of the five visual zones (nasal, temporal, peripheral, central, and paracentral), the most significant visual field losses occurred in the nasal zone.

The researchers concluded that TPD and lower ICP could be possible risk factors for the development of NTG. Although the relationship between ICP and the visual field has long been acknowledged, the study points to a new avenue of NTG research powered by more accessible ICP measurements.