This work by American Eastman Johnson caught my attention. The painting was done circa 1874, pre-dating the introduction of the sun visor by a couple decades. The hat however is functioning almost exclusievly as a sun visors-note the shadow on the woman's face. The hat is clearly important, even central (am I biased?) in the work. Note the lack of vibrant colors in the artist's palatte save the red border of the braided straw. Also, I believe she has changed the hat on her head from its intended position so that it serves as an aid to her reading. Form follows function.
Sun Visors, can be seen at The Village Hat Shop.