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A novel view on the role of vision in brain injury

Each year tens of thousands of Swedes suffer from concussion. Some of them experience persistent difficulties, such as brain fatigue, sensitivity to light, headache and problems focusing. Optometrist and Research Group Leader Tony Pansell researches the benefits of spectacle treatment and vision therapy in this context.

According to Tony Pansell it is a magical combination to meet patients, do research and teach within the same topic.

Tony Pansell became Sweden's first PhD in optometry in 2003. His thesis elaborated how eye movements can provide an understanding of the brain´s vision and balance functions. Since then he has focused on a closely related research area – within neuro optometry, where knowledge of vision, i.e. not eyes, merge with brain research. Currently, Tony Pansell devotes his time to mild traumatic brain injury. Or, as we all know it, concussion.

The role of vision in this context is twofold. On the one hand, vision is affected by a concussion. On the other hand, a concussion may cause prolonged vision and brain fatigue problems and reduced cognitive abilities, such as poor memory and an inability to concentrate. If you can treat vision problems – well, it also seems positively to affect cognitive abilities and fatigue.

"People with concussion are my most frequent patients, and they are the ones I now devote myself to in my research. In addition, I teach aspiring optometrists, nurses and doctors in vision functions following brain trauma. It is a magical combination to meet patients, do research and teach within the same topic," says Tony Pansell, Optometrist at the Neuro-ophthalmology service at St. Erik Eye Hospital, Associate Professor at Karolinska Institutet and Director of the Marianne Bernadotte Centrum.

Monitoring hockey players before and after a concussion

He is in charge of a research group at Marianne Bernadotte Centrum, located at Karolinska Institutet. There, Tony Pansell conducts research on vision function during the natural course of a concussion, that is, a process where the injury heals by itself. This is done by following hockey players, for example.

The hockey players have been examined with particularly accurate vision tests during the summer break when they were healthy. As the hockey season gets underway, some of them have suffered concussions. In such cases, the tests were repeated on day 3, 10, and 30 after the injury.

As the researcher have healthy data from all study participants, they can monitor the changes in visual function and see how long it usually takes to recover from a concussion.

"On day 3, vision is most affected. It is also the time where the study participants themselves experience most vision problems. So, it is an important finding – that what we measure correlates with subjective complaints," says Tony Pansell.

One in five suffer persistent problems

The hockey players were usually back on the ice after ten days, but they only fully recovered after 30 days. And for the vast majority, a concussion heals. However, up to one in five people suffer persistent problems with vision, memory, or an inability to concentrate. Many also suffer from lack of energy, a need to rest and unplug, so-called brain fatigue.

These are the patients that Tony Pansell sees at St. Erik Eye Hospital. The brain's eyes and visual pathways usually work, and they have no apparent injury or bleeding in the brain. The muscles inside and around the eyes also work normally. All separate visual components work fine, but together, they don’t.

"The patients often describe problems with reading, difficulties working in front of a screen and a sensitivity to light," Tony Pansell says.

He performs measurements that focus on visual function – which reveals subnormal function after all. Common problems are difficulties with adjusting focus (accommodation) and turning the eyes inwards to look at something close to the face (convergence). Many describe a feeling of dizziness related to vision.

"The investigations reveal that both motor function and sensory function work. The problem seems to be at another level – in the very integration between motor and sensory function. The brain is unable to provide a motor response to a visual impression. It seems, in fact, to be the cooperation between different parts of the brain that works more poorly after a concussion," says Tony Pansell.

Delayed reaction time after a concussion

A man with a green shirt and glasses.
Tony Pansell. Photo: Johanna Hanno
The investigations provide more findings to support the reasoning. For example, a person who has suffered a concussion can quickly turn the gaze towards a dot that suddenly appears on a screen. Doing that is a reflex. But moving the gaze away from a suddenly appearing dot is, on the other hand, harder. It is also harder to move the gaze between two dots as quickly as possible.

"These tests require more cooperation between different parts of the brain – they require interaction of will and an ability to suppress reflexes. We observe that concussion patients have a delayed reaction time and more often make mistakes in these tests," Tony Pansell says.

His – and others´ research – points towards all this being linked to the patients’ complaints of tiredness and various cognitive problems. These ideas are supported by a study from his research group where the patients described how they felt when they used relieving spectacles.

"They experienced an improved visual function and reduced brain fatigue. We believe that it is a result of not having to fight and strain to see good enough."

Special spectacles provide relief

When Tony Pansell fit spectacles to this patient group, his goal is to create relief for the brain.

"I only care little about visual acuity. Instead, I ask, 'what is giving you most relief?'. The solutions can be several things, such as using glasses with coloured filters or a cap, shielding the field of vision or inserting relieving prisms in the glasses to reduce the eye strain," says Tony Pansell.

Once the glasses are on, the visual rehabilitation begins, which involves training, training, and more training – Tony Pansell compares himself to a physiotherapist in this context. The exercises trim eye motor skills and visual cooperation functions, i.e., the ability to get two eyes to agree on a single image.

The patients must exercise to improve gaze stability and to move their gaze between different distances alternatively. One exercise involves the patient holding a card with letters in hand while a similar but larger card hangs on the wall a little further away. The patient should then alternate between reading the letters up close and from a distance. This requires the brain to execute a repertoire of sensory and motor functions to interact with very high precision.

"We have noticed that the cognitive abilities improve when the patients get relieving spectacles and visual rehabilitation. We believe that our treatment reduces brain fatigue by putting so much energy into managing all visual functions. Then the brain can then function more normally and direct more energy toward the cognitive functions instead," says Tony Pansell.

Text: Annika Lund

Tony Pansell

Title: Optometrist at the Neuro-ophthalmology service at St. Erik Eye Hospital, Associate Professor at Karolinska Institutet and Director of the Marianne Bernadotte Centrum

Research role: Research Group Leader at Marianne Bernadotte Centrum, located to Karolinska Institutet.

Motto: "My motto is that 'it is always possible to make an improvement'. Many patients often feel very poor when they come to see me, and they wonder if they will be OK. Then I usually reply that 'I can’t answer that, but I promise that we will come up with something that will make it a little better'," Tony Pansell concludes.