Corneal lipidosis hasn't to my knowledge been reported from dendrobatids, it appears to be most commonly found in female hylids, and larger bodied ranid type frogs. While obesity can be part of the issue with corneal lipidosis, there appears to be an issue with the feeders commonly used with those frogs. Contrary to a lot of the misinformation on the internet, larger frogs fed rodents are not condemed to corneal lipidosis, as it also documented in occuring in many anurans that were never offered rodents as prey. The issue seems to be in the frequency of the feeding in conjuction with obesity and possibly an issue with fat mobilization (in females) for ovulation.
Frogs (all frogs) are hardwired to eat as much as possible whenever it is possible as there isn't any guarantee that a lot of food will be available the next day, next week or even next month. In addition, dendrobatids in the wild forage for thier food resulting in more activity than that of dendrobatids found in captivity who are not only typically fed lots of melanogaster but are given access to microfauna so they can in effect feed continously with little effort. The frogs are also not subjected to periods of reduced food availability such as that found in the wild.
In dendrobatids, the main fat stores are in the fat pads in the abdomen. If the frogs are fed in excess, not only will these become large but you can also get fat storage in the liver (fatty liver) and in real excess depositions elsewhere in the body (the fat rolls near the eyes mentioned above).
Some of the fall out of this can be seen by the comments about how frequently egg clutches are laid as when the enviromental conditions are correct, fat stores are the next main trigger. If there are ample fat stores, the frogs will continually produce eggs even if there are insufficient nutrients to provision the eggs properly with vitamins or minerals (one of the causes of spindly leg).
The whole fat frog mentality is entrenched enough that frogs whose body conformations approach that of wild frogs are often commented on as being too thin..or looking starved. Having pictures to compare one another to isn't always a help as you can't get a hold of when too fat occurs as typically the frogs only look obese when the situation is getting out of hand.
There are a number of threads in which this has all been hashed over several times. I linked to one of the better ones above and as was noted in that thread, one of the most common ways people over feed is through frequency of feedings....