This study will continue to evaluate the long term safety and effectiveness of cysteamine
eye drops for treating cystine crystals in the corneas of patients with cystinosis. These
drops are not sold commercially and are available only through this study. New patients may
enroll in the study to obtain them.
Cystinosis is an inherited disease that results in poor growth and kidney disease, among
other things. The damage to the kidneys and other organs is thought to be due to
accumulation of cystine inside the cells of various body tissues. This chemical also
accumulates in the cornea-the covering of the eye over the pupil and iris. After 10 to 20
years, the corneas of some patients become so packed with crystals that the surfaces may
become irregular, occasionally causing small, painful breaks.
Patients enrolled in a NIH study on cystinosis are receiving the drug cysteamine. Taken by
mouth, this drug reduces cystine in some tissues, but not in the cornea, perhaps because it
does not reach the corneal cells. The current study was begun to test whether cysteamine
eye drops could prevent or reduce corneal cystine crystals in these patients. The drops
have been very effective in removing crystals and reducing pain in patients who take the
medication as directed. Patients who do not take the medication as prescribed do not
New patients in this study will undergo an eye examination that includes tests of retinal
function and evaluation of visual acuity, night vision and color vision, age permitting.
They will take cysteamine eye drops in both eyes every hour during waking hours. For the
first week of treatment, patients will be followed daily for possible side effects.
Thereafter, eye examinations will be done every 12 months, and photographs will be taken of
the eyes to assess the effects of treatment.
OBJECTIVE: The free thiol cysteamine depletes cystinotic leukocytes and other cells of
cystine, whose accumulation is considered the cause of organ damage in cystinosis. This
organ damage involves most tissues of the body. Cysteamine therapy improved growth and
stabilized renal function in pre-renal transplant cystinotics, without substantial toxicity
but there was no noticeable effect on cystine crystal accumulation in the cornea, most
likely because of inadequate local cysteamine concentration in the cornea. Previous studies
have shown the safety of cysteamine 0.5% topical solution in benzalkonium chloride and its
efficacy in resolving the cystine corneal crystals. The main purpose of this protocol is to
maintain topical cysteamine treatment in patients with nephropathic cystinosis until the
drops are approved by the FDA. When the NDA for the Sigma-Tau standard formulation is
granted, the present protocol (86-EI-0062) will be terminated.
STUDY POPULATION: Up to 300 adults and children over two years, who have confirmed
diagnosis of cystinosis will be enrolled.
DESIGN: This is an open label treatment protocol. Eligible subjects will receive drops of
cysteamine 0.5% topical solution in benzalkonium chloride hourly while awake in both eyes.
The patients will be examined once a year for safety and efficacy considerations.
OUTCOME MEASURES: The main outcome measure will be the reduction of cystine corneal
- INCLUSION CRITERIA:
Patients must have a documented clinical diagnosis of cystinosis.
Patients should be 2 years old or older.
1. Inability to travel to NIH for a baseline examination and yearly thereafter for
2. Inability to cooperate for slit-lamp exminations.