Is it feared to look at lightning? And has there been a prohibition reported concerning that?

First: Eyesight may be affected by intense, sudden lightning, especially on a dark night, due to the light's power and suddenness. Eyesight may be temporarily lost, or medical complications may occur. Scientists say that lightning weakens eyesight.

Second: There is no prohibition from the Prophet (PBUH) against looking at lightning; rather, some of the Tabi'in disliked it, such as Urwah ibn al-Zubayr, who said: "If one of you sees lightning or rain, he should not point to it; rather, he should describe it and narrate about it." This means not pointing with one's gaze or anything else. The pious predecessors disliked pointing to thunder and lightning.

In summary: There is no authentic, marfu' hadith (definition) that prohibits looking at lightning. Rather, it was narrated from some of the predecessors and adopted by a group of scholars. Whoever follows this, it is permissible for him, but one should not assert that it is haram (definition) or makruh (definition).