Can Our Eye Movements While Watching Television Reveal the Presence of Glaucoma?

photograph of retina showing glaucomatous cupping of the optic disc

New research from City University London indicates that the sequence of specific eye movements an individual uses while watching television or films (called an “eye movement signature”) could offer clues as to whether or not he or she has glaucoma.

According to the research team, these “proof of principle” findings could spur the development of an easy-to-use, non-invasive method of screening for glaucoma and additional eye conditions.

From Frontiers in Aging Neuroscience

The research, entitled What’s on TV? Detecting age-related neurodegenerative eye disease using eye movement scan paths, was published in the November 11, 2014 edition of Frontiers in Aging Neuroscience. The authors are David P. Crabb, Nicholas D. Smith, and Haogang Zhu, from the Department of Optometry and Visual Science, City University London.

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About the Research

Excerpted from Eye movements while watching TV could reveal glaucoma, via Optometry Today:

How a patient watches TV and films could offer clues as to whether or not they have glaucoma. The new findings, which come from a group of London-based researchers, hint at the potential for an easy, non-invasive method of screening for eye conditions in future.

As we watch movies and TV, our eyes make large numbers of small, rapid movements [called saccades] before lingering briefly on each focal spot. Researchers have long been interested in whether neurological impairments, such as damage to the optic nerve or retinal cells, could potentially leave a trace or disease signature on these patterns of eye movements.

To investigate, a team at City University London observed 32 older adult patients with healthy vision and 44 with varying severities of clinically diagnosed glaucoma. Using eye tracking software, the researchers logged the thousands of small eye movements patients made as they watched a series of three film clips. The team generated “saccade maps,” in order to analyze trends in eye movements.

Glaucoma eye movements as charted on a TV screen

Glaucoma eye movements tracked via television and film clips
(Source: Frontiers in Aging Neuroscience. Used in accordance
with the Creative Commons Attribution License)

“What we’ve been able to untangle, from looking at all of these maps, is that there are little departures [from healthy visual patterns] and little features that occur that are different from the [control subjects],” said study author David Crabb. Using statistical techniques normally employed … to sift through large amounts of genetic data … allowed the team to identify those with glaucoma from the control patients with healthy vision.

“There are some interesting ways in which this research could go forward,” said Professor Crabb, explaining that monitoring vision over long periods could allow practitioners to look for signs of deterioration. Such a test could be done remotely in a patient’s home using a tablet or computer. The team is now looking to follow up patients over a longer period to monitor vision using the technique, and there is potential to explore other areas of eye disease.

More about Glaucoma

The term “glaucoma” describes a group of eye diseases that can lead to blindness by damaging the optic nerve. It is one of the leading causes of vision loss and blindness. The human eye continuously produces a fluid, called the aqueous, that must drain from the eye to maintain healthy eye pressure.

Types of Glaucoma

In primary open-angle glaucoma, the most common type of glaucoma, the eye’s drainage canals become blocked, and the fluid accumulation causes pressure to build within the eye. This increasing pressure can cause damage to the optic nerve, which transmits information from the eye to the brain. Vision loss is usually gradual and often there are no early warning signs.

In angle-closure glaucoma, also called “acute” glaucoma, the aqueous cannot drain properly because the entrance to the drainage canal is either too narrow or is closed completely. In this case, eye pressure can rise very quickly and cause an acute glaucoma attack. Symptoms can include sudden eye pain, nausea, headaches, and blurred vision. Acute glaucoma is a true ocular emergency and requires immediate treatment.

In normal-tension glaucoma, also called low-tension/low pressure glaucoma, individuals with the disease experience optic nerve damage and subsequent vision loss, despite having normal intraocular [i.e., within the eye] pressure (IOP).

Most eye care professionals define the range of normal IOP as between 10 and 21 mm Hg [i.e., millimeters of mercury, which is a pressure measurement]. Most persons with glaucoma have an IOP measurement of greater than 21 mm Hg; persons with normal-tension glaucoma, however, have an IOP measurement within the normal range.

Visual Field Loss

Glaucoma results in peripheral (or side) vision loss initially, and the effect as this field loss progresses is like looking through a tube or into a narrow tunnel. This constricted “tunnel vision” effect makes it difficult to walk without bumping into objects that are off to the side, near the head, or at foot level.

A living room viewed through a constricted visual field

A living room viewed through a constricted visual field.
Source: Making Life More Livable. Used with permission.

Glaucoma is an especially dangerous eye condition because most people do not experience any symptoms or early warning signs at the onset. Glaucoma can be treated, but it is not curable. The damage to the optic nerve from glaucoma cannot be reversed.

More about the Study from Frontiers in Aging Neuroscience

From the article abstract:

Purpose: We test the hypothesis that age-related neurodegenerative eye disease can be detected by examining patterns of eye movement recorded whilst a person naturally watches a movie.

Methods: Thirty-two elderly people with healthy vision (median age: 70) and 44 patients with a clinical diagnosis of glaucoma (median age: 69) had standard vision examinations including automated perimetry. Disease severity was measured using a standard clinical measure (visual field mean deviation).

All study participants viewed three unmodified TV and film clips on a computer setup incorporating the Eyelink 1000 eyetracker. Eye movement scanpaths were plotted using novel methods that first filtered the data and then generated saccade density maps. Maps were then subjected to a feature extraction analysis.

Results: Patients had a range of disease severity from early to advanced. Average sensitivity for correctly identifying a glaucoma patient at a fixed specificity of 90% was 79%.

Conclusions: Huge data from scanpaths of eye movements recorded whilst people freely watch TV type films can be processed into maps that contain a signature of vision loss. In this proof of principle study we have demonstrated that a group of patients with age-related neurodegenerative eye disease can be reasonably well separated from a group of healthy peers by considering these eye movement signatures alone.

Additional Information about Glaucoma Studies

Image credit: Copyright © 2014 Crabb, Smith, and Zhu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice.