The condition when you don’t have pupils(iris) is called aniridia which literally means “without iris”.
Technically you can close your eyes a bit and you will stop the amount of light that enters the eye a bit.
You can also get some artificial iris to reduce the amount of light entering the eye.
The job of pupils is to reduce the light entering the eye so you should be able to see fine in the dark but you will have some extreme light sensitivity during the day.
With this light sensitivity during the day software like Iris may help to reduce the light emitted from the screen or lowering the brightness of your screen.
However, if you lower the brightness via the monitor buttons you may get more eye strain because of pulse-width modulation but I’m actually not sure if this will cause more eye strain if you don’t have pupil to adapt to the light around you.
Lowering and filtering blue light may also help since blue light often causes the biggest amount of light sensitivity because it’s the highest energy visible light.
That being said looking directly at the Sun without pupils will probably make you blind for a bit or permanently if you stare too much into the Sun.
Your photoreceptors will be overstimulated and continuous exposure may damage or burn them.
One of the best ways to deal with not having pupils will probably be wearing Sunglasses all the time.
You will probably have different sunglasses for the different kinds of the day to reduce the light entering the light more or less depending on how much light there is around you and how much light sensitivity you have.