Well, quite often entropion - the turning in of the eye margins causing damage to the dogs' eyes.
It is a direct consequence of the wrinkling/skin folds that have become a defining feature of the Westernised version of the breed but was never a feature of the original Shar-pei (see here).
And, indeed, it is is so bad that "tacking" is routine in the breed - a procedure in which the vet places sutures around the eye when the dogs are pups to prevent the eye surface being injured by the inward rolling of eyelashes.
This often does the trick; sometimes, though, Shar-pei need more surgery to correct the entropion when they are older.
Shar-pei breeders are so de-sensitised to this that tacking (and entropion surgery) is not considered a big deal in the breed. In fact, in the twisted logic adopted by some breeders, tacking is actually considered a sign of a responsible breeder. And although the Kennel Club dictated a few years back that dogs that have had their eyes tacked cannot be shown, insiders tell me that an awful lot of show dogs will have had their eyes tacked as pups. It is hard to prove one way or the other.
But there are some breeders taking a stand and one in particular I'd like to praise.
Three years ago, I blogged this photograph, as featured in a book by the photographer Tim Flach. As you can see, this very wrinkled eight-week-old pup is sporting a stitch above her right eye - a "tack".
It turned out that the pup was bred by a UK-based breeder called Ines Alarcao. She took quite a lot of stick at the time and has since withdrawn from showing.
But she's kept breeding Shar-pei and she recently sent me these pix of her current litter of eight pups. Here they are at six weeks old. They all have clear eyes and not a single one has had to be tacked. They also have fewer wrinkles and bigger ears (breeding for very small ears in Shar-pei has led to tiny ear canals prone to ear infections).
Have a look at these photos and then see below for what Ines says about these pups.
It's a big improvement - at least in terms of their conformation.
I asked Ines how she had achieved it:
"I bought two girls from different lines four years ago , with reasonable eyes and not many wrinkles and good ears. I have mated them with guys with the same features. One of them produced a blue boy with excellent eyes, the other produced a girl with good eyes too, and I have now mated these two together and produced this guys. Some people say that good eyes are a matter of luck. Not true! But I had to find it through trial and error. I am keeping two girls from this litter , I bought another one that has got less wrinkles and more traditional features, and I have another 6 mth-old girl that i bred and kept with really good eyes. My new breeding program will be based on them."
Now these pups are still too immoderate for me. And, in my opinion, this breed is too inbred and has too many inherent health problems (notably Familial Shar-pei Fever) to be able to justify breeding it at all.
But I really was pleased to see these pix. A step in the right direction.