After the vitamin B6 study, patients will start a nearly protein-free diet to lower ornithine blood levels. More than 2,000 calories are carbohydrate and fat. Some special low-protein foods and limited fruit is included, plus amino acid supplements. Patients who have carefully adhered to this diet have lowered their ornithine levels and slowed disease progression. Patients will be hospitalized for the first 1 to 3 weeks for close monitoring with frequent urine and blood tests. When the blood ornithine level is normalized, a less restricted low protein diet will be prescribed. Participants will have monthly blood tests and a complete eye examination every 6 months to 1 year to evaluate disease progression.