Back in the day, when most courts and backgrounds were green,
Bolle Competivision Sunglasses were used by many pro and amateur tennis players as well as by lines-persons and chair umpires. Martina Hingis and others endorsed Competivision sunglasses. The teal-colored lens in these glasses muted most colors expect for optic yellow (the greenish-yellow color of most modern tennis balls). This made the ball color "pop" against the green (or red) background -- improved color contrast made the ball easier to see/track.
Now that many courts are blue rather than green, the need for the teal Competivision lenses has waned somewhat. The optic yellow ball color stands out very well against a blue court color -- no need for special lenses to provide the color contrast. However, many public courts with blue courts still use green windscreens. For these courts as well as other courts that are still green, the Bolle teal lenses can still be useful.
Both Janko Tipsarevic and
Sam Stosur use Oakley sunglasses. Sam uses Oakley Enduring frames with Positive Red Iridium lenses according to her website. I believe that the lenses are
polarized (for glare reduction),
photochromic (light level adaptive) and use
Oakley's High Definition Optics technology. It is possible that the HD technology used by Oakley and other manufacturers could, possibly, improve vision to better than 20/20. I have heard that quite a few baseball players uses clear lens glasses or sunglasses with technology such as this.
http://www.allaboutvision.com/lenses/wavefront-lenses.htm
Janko uses Oakley Fast Jacket XL frames which, I believe, makes it easy for him to quickly swap out different lenses for changing light (or background) conditions. His are prescription lenses that are also photochromic. Do not know if they are polarized. According to the follow article, Janko uses True Digital™ corrective lenses with Dual-Peripheral Technology™.
http://www.prnewswire.com/news-releases/tennis-pro-janko-tipsarevic-relies-on-oakley-true-digital-corrective-lenses-in-key-us-open-victory-102169124.html
http://www.selectspecs.com/blog/wimbledon-2012-janko-tipsarevic-in-oakley-fast-jacket-xl/
Maui Jim sunglasses also have found their way into pro tennis. Their glasses are endorsed and/or used by Monfils, Lisicki, Fish and Hingis (no longer with Bolle, I assume). Nike sunglasses are used by Tomic and Misty May. Other Oakley users include: the Bryan brothers, Almagro, Flipkens, Vemic and Rodionova. These links might provide more details:
https://www.sunglasses-shop.co.uk/sport/tennis/athletes/gael-monfils.aspx
http://www.examiner.com/list/maui-jim-sunglasses-get-a-major-sponsorship-the-world-of-tennis
.