For US Audiences Only
For US Audiences Only

HOW DOES CYSTINOSIS IMPACT YOUR EYES?

Cystinosis is a rare genetic disorder caused by mutations in the CTNS gene.

The job of the CTNS gene is to make cystinosin. Cystinosin transports, or carries, the amino acid cystine out of the lysosomes.

If you or your child has cystinosis, either your body does not make cystinosin, or the cystinosin that your body makes does not work well. As a result, cystine builds up inside lysosomes. Over time, the cystine forms into crystals.

Cystine crystals may build up in cells in every organ of your body, including your eyes. The cornea is the part of the eye that may be affected the most. In the cornea, these crystals are usually pointed and needle-shaped, and look like shards of glass. Cystine crystals may also build up in your conjunctiva, retina, and iris.

The cornea has very important functions:

  • It bends light entering your eye to help your eye focus
  • It protects against infection and damage to inner parts of your eye

WHAT EYE SYMPTOMS ARE CAUSED
BY CORNEAL CYSTINE CRYSTALS?

At first, as cystine crystals begin to build up in your cornea, you may not notice any eye symptoms. But gradually you may begin to feel some discomfort.

PHOTOPHOBIA

Photophobia is sensitivity to light that results in discomfort. It is the first and most common eye symptom noticed by people with cystinosis. It is thought that photophobia is mainly due to the presence of corneal cystine crystals that cause light entering the eye to scatter. Most people with cystinosis develop photophobia by age 10.

OTHER EYE SYMPTOMS

The build-up of corneal cystine crystals may cause other eye symptoms to develop over time. These symptoms may include:

  • Squinting
  • Spasms or contractions of your eyelid muscles (blepharospasm)
  • A feeling like there’s something in your eyes
  • Difficulty seeing the difference between similar shades
  • Increased glare

Photophobia and other symptoms can be uncomfortable and even painful. The symptoms can also affect your ability to carry out daily activities.

Some people use a small notebook to keep track of symptoms over time. This can be helpful when you talk to your doctor.

TALK WITH YOUR DOCTOR ABOUT YOUR OR YOUR CHILD'S EYE SYMPTOMS AND HOW THESE SYMPTOMS AFFECT DAILY ACTIVITIES

HOW ARE CORNEAL CYSTINE CRYSTALS MEASURED?

To measure the amount of cystine crystals in your cornea, your eye doctor can use a machine called a slit-lamp microscope. This microscope directs a high-intensity beam of light onto your cornea, which allows your doctor to score the amount of cystine crystals that have built up and to monitor changes over time. Your eye doctor can also use a different imaging machine to evaluate the corneal cystine crystals.

The slit-lamp microscope can also be used to assess photophobia. Your doctor may also ask questions about how photophobia may be affecting your daily life.

IN MOST PEOPLE WITH CYSTINOSIS, CORNEAL CYSTINE CRYSTALS CAN BE SEEN AS EARLY AS 12 TO 18 MONTHS OF AGE.
THE BUILD-UP OF THESE CRYSTALS INCREASES WITH AGE.

HOW ARE CORNEAL CYSTINE CRYSTALS TREATED?

It’s important to know that cystine-depleting oral medicines do not reduce the build-up of cystine crystals in your cornea. These medicines are delivered to organs in your body through your bloodstream. But these medicines cannot reach your cornea since it does not have blood vessels. Without proper treatment, more and more crystals will form in your cornea.

TREATMENT WITH CYSTEAMINE EYE DROPS IS THE ONLY WAY TO DEPLETE THE BUILD-UP OF CORNEAL CYSTINE CRYSTALS AND REDUCE EYE SYMPTOMS CAUSED BY CYSTINOSIS.

INDICATIONS AND IMPORTANT SAFETY INFORMATION

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.