my eye power is-7 and I have to use laptop for 8 hrs at least ?What should I do
As you have really high eye power, its recommended that you use your laptop at a proper distance from your eye i.e., you should use the laptop on a table only and keep at least 1 meter distance from you. Now apart from this there are glass protection known as Bluelight filter. You can visit your nearest optic shop and you can make your glasses bluelight filter protected, this will help you to reduce the strain in eyes. Also nowadays in laptop or mobile phone also there are some blue light filter available, you should also keep it on. These you can take as a precautionary measure.
I hope this helps. All the very best for your future endeavors!