One of my shelties is on a low fat diet to control cholesterol. It affects his eyes and leaves cholesterol deposits on his cornea. This causes pain and "pits" on his cornea and could eventually cause vision issues. I cannot remember the name of this disease, but it is controlled with a low fat diet.
Most dogs in the US suffer from obesity, however, due to people overfeeding and over-treating their dogs. If the dog in the picture is your dog, it looks to be overweight, and possibly quite overweight. :) Here is a video link to show you quickly how to tell if your dog needs to lose a few pounds.
Being overweight can cause some very serious health issues and will also affect your pocketbook with vet bills. :)