Re: Why do humans have vision problems?
Hi there! I don't think you have such a bad vision if all you have is -6.50 and -6.00 myopia!!! Most people with *serious* vision issues have really high myopia (> -9.00). So I'm not sure if myopia is your only problem.
As for genetics, maybe your parents' eyes were fine but how about your grandparents'? Sometimes, genes skip a generation.
Above all, you can help your eye with good nutrition (omega3 helps a lot) and a healthy lifestyle. You must protect your eyes from the sun and visit your eye doctor for regular check-ups.
The most worrying thing IMO is your prescription changing a lot/fast. What is your age? If you're still a teenager, this may explain it.
At some point, myopia gets stabilized.
Always get fitted for the right glasses for your eyes, never use somebody else's glasses or contacts, always follow your prescription from a reputable ophthalmologist and optometrist.