 Additional findings include metabolic bone disease and an inability to properly digest food due to a lack of digestive enzymes normally produced by the pancreas pancreatic exocrine insufficiency. Adults with cystinosis may also develop abnormalities affecting the eyes including spasms of the eyelids blepharospasm, band keratopathy and pigmentary retinopathy. Band keratopathy refers to the accumulation of calcium deposits in a band across the central surface of the cornea, which can cause pain and decreased clarity of vision visual acuity. Pigmentary retinopathy is characterized by progressive degeneration of the retina, the thin layer of nerve cells that line the inner surface of the back of the eyes. The retina senses light and converts it to nerve signals, which are then relayed to the brain through the optic nerve. Pigmentary retinopathy can impair night and color vision and, eventually, can contribute to overall reduced clarity of vision. 