Brief Answer:
Possible ocular migraine.

Detailed Answer:
Hello dear, welcome to Ask a doctor service.
I read your query and here is my advice.

I think you may be having ocular migraine which is the main cause of causing kaleidoscopic vision and flashing lights.
It is good that your blood pressure and heart rate are within normal range because it excludes that stroke may have caused it.
If it just happened once no treatment is needed. Stress may be a trigger
Just eat healthy and stay hydrated,
avoid the things that may trigger it.
get plenty of sleep
avoid stressful situations and reduce every day stress.
If you experience it often you may need to visit a neurologist and start migraine medications.

Hope I have answered the question.
Let me know if I can assist you further.

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