As people age, blurred vision is almost inevitable. As presbyopia slowly diminishes the eyes ability to focus clearly, people turn to eye glasses and contact lenses to see clearly. But for people who wear multifocal contact lenses in order to see clearly both up close and at a distance, there may still be moments of blurred vision as the eyes transition from one focal area of the lens to another.
Poor vision is now thought to be a contributing factor to tripping and falling in senior citizens.
This new claim comes from a study in the June 2016 issue of Optometry and Vision Science, official journal of the American Academy of Optometry. Its author, Alex A. Black, BAppSc(Optom), PhD, along with his team at the Queensland University of Technology, Brisbane, Australia postulate that both blurred vision and gaze position play a large role in precision stepping, and can lead to falling accidents in certain challenging environments.
For the purposes of their research, 19 seniors, with an average age of 72 years, were observed as they completed a set of precision stepping tasks. The objective for the participants was to navigate a path with target footprints along the way. They were then instructed to either look directly at the targets while walking, or to aim their gaze 30-60 centimeters ahead of it.
Additionally, the subjects were tested while wearing both normal glasses, as well as ones that caused intentional blurring, similar to that caused by the transition between focal points in bifocal lenses.
Their performance was monitored throughout the experiment, and their gaze position was measured by eye tracking devices.
The results show that their foot placement errors were larger and their step position more varied while gazing ahead of the targets, and worse still while wearing blurring glasses. The most common stepping error was under-stepping, or stepping short of the target.
Dr. Black points out that while the error rate in this study was relatively small, it also took place on flat ground, and in a safe and controlled environment. In less ideal situations, such as dark places, stairs, or slippery surfaces, walking errors can be not just more dangerous, but also more likely.