3 weeks ago, I have woke up with a scotoma the length of a mouse-pointer near the center of my right vision. I can't see anything on that spot, and the scotoma has not moved or changed since. Eye exams report nothing wrong, suggesting a neurological cause. I'd like to know what parts of the brain could be responsible for this symptom. Is it possible that it is a lesion on the visual cortex or nearby, or is the problem necessarily at or before from the chiasm? I'm 26 yo, no medical condition, no drug/medication use.