My last job for 6 years was fixing hydraulics and electrical systems under water, among other things. I am now 51, and at that time, my presbyopia, or farsightedness increased. I wear +1.50 reading glasses topside. Just old age, and the len's inability to accommodate as much as when you are younger. I could open my eyes, maskless in fresh or salt water. And it is not chlorine that burns your eyes in most cases. If you think you smell chlorine, you're mistaken; chlorine is odorless. It is the byproducts of free chlorine that eat abundant organic matter that creates chloramines that you are smelling. A sure indicator they did not maintain a minimum level of free chlorine to begin with. In any case, I was able to improve my work underwater over those six years. If you discount feeling with my hands, what augmented my ability was not pupil dilation or lens accommodation, but the brain's processing. It has been proven if you concentrate while reading without your reading glasses, you can train your years of reading to recognize the letter shapes in their new blurry appearance. Not magic here, hard work. What I would be interested in is did she change it from merely horizontal and vertical lines? I can easily see the brain also augmenting their ability to accommodate their lens and pupil dilation to make their ability even more impressive. This would explain how the European children may have 'thought' they saw clearer, but it was the brain clarifying their perception and not any lens or pupil dilation in their short study.