Zookeepers noticed something was amiss shortly after the otherwise healthy cubs were born in June.
After the first surgeries were performed two weeks ago, zookeepers noticed one cub still had an irritated eye. University of Pennsylvania veterinary ophthalmologists will perform the second surgery this week.
The zoo says the condition occurs in animals and humans but is more common in snow leopards than other species.
The cubs will make their public debut next month.
