Is there an evolutionary explanation for the black spots around a pandas eyes?
As your commenters have suggested, no.

In order for an explanation to be a good evolutionary explanation, it needs to have a testable hypothesis and a mechanism to test it. 

The most common mechanism for testing the crypsis (camouflage) hypothesis is to take a large number of closely-related species, and see if their coloration differences are correlated to a particular habitat. Since pandas have few black-and-white relatives, there is no statistical power in this analysis. 

Another option is to take a large number of pandas, create a treatment and control group and bleach the treatment group (or their eyespots) white, and compare survival or visual acuity. Unsurprisingly, this has not been done. 

Here's a nice article to animal coloration for those that have access: 

Caro, T. I. M. (2005). The adaptive significance of coloration in mammals. Bioscience, 55(2), 125-136.