Thanks to the Captain of our snorkeling trip in Hawaii for allowing these photos of his congenital condition called Nevus of Ota. (Originally described by Ota and Tanino in 1939). As you can see, there is a gray or blueish patch on the skin around the eye and hyperpigmentation on his sclera. This is in the distribution of the opthalmic and maxillary branches of the trigeminal nerve and consists of increased pigment producing melanocytes. Because he works in the sun, the pigmentation is probably more noticeable.
This condition causes no problems. Ninety percent are unilateral (one side only) as is his. There is a slightly higher incidence of developing melanoma, but that is rare and it does not affect his vision. Another condition called ocular melanosis looks the same but does not involve the skin. BTW...the snorkeling and whale watching were just great.