Trainer eye burns, it turns out, were not uncommon. Hargrove, who left SeaWorld in 2012 and worked at both SeaWorld California and SeaWorld Texas, explains in an email:
"There are dozens of documented reports of serious eye burns to trainers because there was an over-injection of chlorine in the pool, and as the whale underwater foot-pushed us through this cloud of intense chlorine, we had eye burns so severe we often couldn't even open our eyes. I was treated at least half a dozen times where I was I was sent off site for treatment, and could barely open my eyes because of the pain and wasn't allowed to do waterwork again for 2-3 days until they healed [enough] to swim again."
"That was just from our brief exposure," Hargrove says. "Imagine the whales always having to swim through it."
The mucus secreted by the eyes of the killer whales -- whether it's triggered by chlorine, more frequent exposure to the air, or other factors of captivity, like looking up into the sun more often, or even all of the above -- appears to offer some protection. There is no obvious trend (according to the trainers I have spoken with) of older killer whales predictably developing sight problems in captivity.