I never realised Chekhov had a squint. I've always had a soft spot for people with a squint, especially in women. 'What else did she want, that witch with a very slight squint in one eye?' (from Bulgakov's novel The Master and Margarita, tr. by Michael Glenny).
But Chekhov! The great playwright and humourist, the master of short story who is always portrayed with his trademark pince-nez on!
In this portrait of 1903, Serov, a great portraitist (he is famous for the portrait of Shaliapin among others), removes the pince-nez and tucks it inside Chekhov's waistcoat at the bottom of the picture, as though saying, there, he is not a sad narrator of declime, doom and gloom, look, he is a bubbly, fun loving man.
This portrait and a big gallery of Serov's works is here on Wikiart.