Are there people with epicanthal folds in eyes, but not mentally challenged?

Yes. Epicanthal folds occur commonly in developmentally normal infants and children. They are also common in those of Asian descent as well as certain native peoples. The vast majority of those with epicentral folds are of normal (or perhaps well above average intelligence). A few rare developmental disorders exhibit mental delay in the context of epicentral folds.
Epicanthal Fold OK. An epicanthal fold refers to skin fold from your upper eyelid that covers part of the inside corner of your eye. It is most common in asians. And not related to mental ability.

Related Questions

People with epicanthal folds in eyes (seen in down's syndrome), but not mentally challenged?

Can be normal. Epicanthic folds can be found in people who do not have genetic disorders.
Can be normal. This is a common finding in infants & reflects the growth pattern of the mid face. Infants are rather flat faced while the nose and mid face begins to grow forward with age changing the folds over time. Any kid (normal or not)whose growth pattern produces less mid facial growth is likely to retain them. Down Syndrome patients usually retains a flatter mid face throughout life as a common feature.