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For US Audiences Only

Cystinosis is an autosomal recessive lysosomal storage disease caused by mutations in the CTNS gene.1

CTNS encodes a cystine-specific transporter, cystinosin, which normally transports the amino acid cystine out of lysosomes.2,3

CTNS mutations result in absent or defective cystinosin, which prevents the normal transport of cystine out of the lysosomes. This, in turn, results in cystine crystal accumulation within lysosomes.1,3

Cystine crystal formation negatively impacts many organs throughout the body and leads to significant health complications. One of the organs impacted is the eye.4,5 In the eye, cystine crystals appear most often in the cornea and conjunctiva.9

Cystinosis ocular symptoms

Although ocular symptoms may appear later in life than many other symptoms of cystinosis, ocular symptoms can impair quality of life in untreated patients, especially as cystine crystals accumulate over time.5,6,10

Cystine crystal deposition begins in the peripheral cornea, and then progresses more centrally and more deeply into the stroma with age.8 Corneal crystals typically appear as pointed and needle-shaped, resembling shards of glass.7,9

Images produced using in vivo confocal microscopy (IVCM)11

Cystinosis ocular symptoms

*Reproduced by permission from Labbe 2014

Corneal cystine crystals are not detectable at birth, but they can generally be observed via slit-lamp examination by the age of 12-16 months.12,14 As the disease progresses, by approximately 7 years of age, the entire peripheral stroma and endothelium accumulate crystals. By approximately 20 years of age, crystals can be seen in the entire corneal stroma.14


(WITHOUT TREATMENT) 5,6,10,13,14,15,16

Cystinosis ocular symptoms


Cysteamine eye drops may effectively deplete corneal cystine crystals and, as a result, decrease or lessen the risk of developing uncomfortable or debilitating symptoms.8,14,18 Due to the cornea’s avascularity, systemic cysteamine does not affect corneal cystine crystal accumulation.12,18,19

  • IVCM provides high resolution images of cystine crystals by corneal layer at the cellular level.
  • An IVCM score quantifies cystine crystal deposition in each layer of the central cornea, the sum of which results in the IVCM total score.
  • Higher scores designate larger amounts of cystine crystal deposits; a decrease in IVCM total score indicates a reduction in corneal cystine crystals.

Quantifies: Corneal cystine crystal density at the cellular level in 7 layers of the cornea

IVCM Scoring: 0-4 in each layer

  • 0 = no crystals
  • 1 = <25% deposits in images
  • 2 = 25% to 50% deposits in images
  • 3 = 50% to 75% deposits in images
  • 4 = 75% to 100% deposits in images

Total score: Sum of each layer’s mean score (0-28)

Layers of the cornea


Important Safety Information

  • To minimize the risk of contamination, do not touch the dropper tip to any surface. Keep bottle tightly closed when not in use.


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