Tai Yang is located in the depression about an inch from the midpoint between the lateral end of the eyebrow and the outer canthus of the eye. Or, as the classical texts say, "in the depression behind the eyebrow, at the purple vein of the temple." In the picture below, she is massing the area.
For acupressure, you can be more generous in the area covered than with the much smaller acupuncture needle. Use gentle, broad circles on both sides of the temple to benefit from this point.
This point is used to clear wind and heat, benefitting the head and eyes.
Symptoms include: headache, trigeminal neuraglia, insomnia, and eye redness.