Many were convinced that the overloads were supposed to «press the glasses into the brain» of the astronaut.
In fact, there is nothing strange and unusual here. The thing is that the flight of Crew Dragon Demo-2 received very wide media coverage, and American astronauts were seen by many people who had last seen cosmonauts 40 years ago, and therefore many ordinary things caused bewilderment.
One hundred percent vision has long ceased to be a mandatory requirement for space flight. The first person with glasses to fly into space was American astronaut John Young in April 1981 on the space shuttle Columbia as part of the STS-1 mission.
After that, many «bespectacled» people visited space. In Roskosmos, the requirements for the health of astronauts remained stricter for quite a long time, but for our cosmonauts from about the beginning of the 2000s, wearing glasses has ceased to be an obstacle to flying into space.
In general, the saying «health like an astronaut» is largely outdated. The requirements for the health of astronauts are constantly decreasing, and at present, most people with completely mediocre health, in the absence of chronic diseases, could well undergo a pre-flight medical examination.
As for «pressing» glasses into the head, these claims are simply ridiculous and cannot be explained by anything other than the lack of elementary knowledge of physics.
On average, the weight of the glasses varies from 25 to 50 grams. When alliances, shuttles and Crew Dragon take off, people on board experience G-forces from -0.5 to 4g. Those. at maximum overload, the weight of the glasses will be equivalent to their weight under normal gravity, as if their mass is 100-200 grams. Of course, a human face can withstand such a weight without any problems.
Moreover, during landing, the G-forces are much stronger, but even this does not prevent the astronauts from wearing glasses during landing.