Pannus is believed to be an immune mediated eye disease that unfortunately can result in blindness if it is not treated.  It is common in retired police dogs. 

Pannus is more common and more severe at high altitudes and in areas with significant air pollution. Military working dogs in Afghanistan for example were seen to have higher rates of pannus. 

Other factors may be a response to exposure to ultraviolet light or other irritants which might be risk factors for your retired dogs. German Shepherds as a breed are genetically predisposed.  

Middle aged dogs (4 to 7 years) are at highest risk for developing pannus. In German Shepherds if a dog is diagnosed younger than this, the condition will be severe and harder to treat. 

Both eyes are affected, although commonly one may look worse than the other. Usually a pinkish discolouration starts at the outer aspect of the eye and spreads towards the center. As the discolouration spreads it can become more opaque and blindness can be the outcome. 

Having your dog examined by your veterinarian or by a veterinary ophthalmologist can help identify this problem early. With early intervention remission can be attained which is the good news.  The photo below shows an area on the lower part of the eye that is cloudy and very irritated which is Pannus.