Researchers have found evidence that intracranial pressure plays an important role in the development of glaucoma, creating a pathway for new treatments.
A recent study, titled ‘The Relationship between Intracranial Pressure and Visual Field Zones in Normal-Tension Glaucoma Patients,’ has found a link between low intracranial pressure and impaired patient visibility, especially in the nasal area. Increased pressure inside the eye (called intraocular pressure or IOP) is commonly found in glaucoma patients. However, the condition can occur in people with normal IOP.
Glaucoma is an optical nerve condition and is one of the leading causes of blindness in people over the age of 60. Existing research on so-called normal tension glaucoma (NTG) has provided varying reports on the prevalence of the condition. Estimates on the percentage of glaucoma cases caused by NTG range from 30%-90% in the global population.
“Contemporary medicine has methods to treat elevated eye pressure and to slow or even stop the damage to the optic nerve. However, these methods do not work in the case of normal tension glaucoma. There is a growing awareness among the scientific community, that glaucoma is a condition caused by two pressures – inside the eye and the skull,” said Professor Arminas Ragauskas of the Kaunas University of Technology (KTU), Lithuania.
Intracranial pressure can damage the optic nerve
The optic nerve, which is surrounded by the cerebrospinal fluid, is connected to the brain. Pressure inside the skull, known as intracranial pressure, and IOP can affect the optic nerve’s condition. In this study, the researchers examined the balance between the two pressures and their association with glaucoma development.
The study enrolled 80 participants with early-stage NTG. These participants were selected from 300 NTG patients referred to the Eye Clinic at the Lithuanian University of Health Sciences between January and October 2018.
The researchers recorded the intraocular pressure, intracranial pressure, and visual field perimetry of each patient. Using this information, the team calculated a translaminar pressure difference (TPD) score for every participant. The visual field perimetry was divided into five zones: nasal, temporal, peripheral, central, and paracentral.
The study found several significant correlations between intracranial pressure, TPD and visual field changes. The researchers observed that higher TPD scores were associated with more significant damage to the patient’s visual field. The most severe vision loss occurred in the nasal zone.
“Visual field loss means only one thing – a person is becoming blind. That’s why it is so important to understand the causes of this condition and to reverse it. We are all aware of the dire outcome,” explained Professor Ragauskas.
Developing new treatments for glaucoma
The researchers concluded that high TPD scores could be used to calculate the risk of NTG development. The results suggested that lowered intracranial pressure is a possible risk factor for NTG.
“The idea that brain pressure is related to the visual field is not new. Several years ago, we conducted a series of experiments studying the links between visual field and intracranial pressure using the non-invasive technology developed here, at KTU. In the conferences that followed, I saw how our new idea was met with excitement by the international community of ophthalmologists,” said Professor Ragauskas.
The correlation between intracranial pressure and glaucoma has opened new pathways for medical professionals to research new treatments and understand the causes of the condition.
Current methods for relieving intracranial pressure involve the drilling of a small-sized hole into the patient’s skull. Considering this study, researchers at KTU have been developing ways of treating intracranial pressure using non-invasive technology.
“We are not competing with invasive methods but heading towards an entirely new direction. At the moment, I see that ophthalmology is the field where our technology is needed most, and we are using it for research purposes. However, we are constantly developing our invention and have recently patented a couple of new applications,” concluded Professor Ragauskas.
