The negative side effects of concussions have been well-documented, but new research suggests that head trauma can cause lingering changes in the way our eyes focus.

To get a better understanding of how concussive and sub-concussive head trauma affects a person’s vision, researchers examined a small sample of Division 1 football players. 29 players volunteered to wear special mouthgards that tracked the number of hits to the head each player received over the course of four full-contact practices. In total, the 29 players experienced nearly 1,200 sub-concussive head impacts during the practices, and researchers then split the players into two groups based on the number of hits to the head they received. Only seven players were in the low trauma group, as these players only received between 6 and 16 sub-concussive hits to the head. The rest of the players experienced between 41 and 96 sub-concussive hits. Researchers conducted neurological tests at the outset and at the completion of the study.

One takeaway they noticed is that players who experienced more hits to the head exhibited more “near point convergence” of their eyes. Near point convergence is the closest point at which the two eyes can view something clearly before double-vision occurs. The changes eventually plateaued, and returned to their normal point three weeks after practices ended.

Researchers were fascinated by the findings, but they noted that the full effects of short-term changes in eye function are unknown.

“I can’t say that (players) should be concerned at this point, but they should definitely be aware that these changes occur,” said study lead author Dianne Langford. “Anyone who is concerned about these results should speak with their neurologist, ophthalmologist or other physician.”

The last statement by Langford is the takeaway point – if you suffer a head trauma and are concerned about the injury or any symptoms you are experiencing, you should set up a consultation with a neurologist. Some symptoms you should watch for in the days after a head injury include:

• Headaches
• Dizziness
• Blurred vision
• Trouble concentrating/focusing
• Difficulty sleeping/Difficulty staying awake