What does photophobia refer to?

Photophobia refers to light sensitivity, which is a condition where bright light triggers discomfort or pain in the eyes. This can occur due to various underlying issues, such as migraines, certain eye conditions, or diseases that affect the nervous system. Individuals with photophobia often need to avoid bright environments or wear sunglasses to relieve their symptoms.

The other choices do not align with the definition of photophobia: muscle weakness pertains to a reduction in muscle strength; bone sensitivity is not a widely recognized medical term; and skin sensitivity refers to an overreaction of the skin to certain stimuli, which is unrelated to light exposure. Hence, the correct understanding of photophobia is specifically tied to sensitivity to light.