Photophobia, also known as having light sensitivity, is when your eyes are delicate to certain light. It can be sunlight, fluorescent light or incandescent light. Both fluorescent and incandescent lights are common in most buildings. The difference is fluorescent light is made from mixtures of gases creating light and incandescent is from electricity where electricity runs through the wire inside the bulb. Needing to squint often and headaches becoming more frequent may be an indication of light sensitivity.
Photophobia may be a signal of inflammation within the eye, dry eye or some other pathology related to the cornea (the clear tissue at the front of your eye). Certain other systemic conditions such as migraines may cause photophobia.
Being naturally sensitive to light is simple to avoid by limiting time in bright places or wearing sunglasses with UV protection outside. Always check with your eye doctor to find the underlying cause of light sensitivity in order to treat it as necessary.