The aim of this study is to determine whether 9-cis-beta Caroten rich D. Brdawiil extract is effective in the treatment of retinitis pigmentosa in adolescent patients.

Retinitis pigmentosa is a genetically disease consisting of progressive retinal degeneration starting in the rods. Its prevalence is 1:4000 people and is the fourth most common blinding disease in Israel in 2004 [7% of all blindness]. The investigators treated a non-progressive form of the disease [Fundus Albipunctatus] by oral therapy of the food supplement made from alga Dunaliella Bardawil composed of approximately 50% 9-cis β-carotene.

The 9-cis β -carotene has been shown to be a precursor of 9-cis retinoic acid both in-vitro in human intestinal mucosa and in-vivo in a ferret, perfused with 9-cis b-carotene. The night vision, as measured objectively by electroretinography (ERG) more than doubled in six patients tested following treatment. The visual field was also improved significantly. In a more recent study the investigators treated 29 retinitis pigmentosa patients with the 9-cis b Carotene algae Dunaliella Bardawil in a double masked placebo control cross over trial. Significant improvement in retinal function was recorded in 34% of the patients.

As a natural extension of this study we will perform a double-masked, randomized, crossover, placebo-controlled study for adolescent patients. Longer treatment duration will be tested: a 24 week treatment with either the 9-cis β-carotene-rich capsules or placebo followed by an additional a 24 week treatment with the other capsules and a wash-out period of 24 weeks between this two type of treatments. We predict that with this study design a maximal/increased therapeutic effect as well as efficient washout will be achieved.

Inclusion Criteria:

• Written informed consent to participate in the study.
• Adolescent 12-18 years old.
• Electroretinogram (ERG) responses compatible with the diagnosis of Retinitis Pigmentosa

Exclusion Criteria:

• Currently a smoker
• Current use of vitamin A/ β-carotene supplements
• Active arterial disease within 3 months prior to enrolment in the study, e.g. unstable angina, myocardial infarction, transient ischemic attack, stroke, coronary artery bypass graft surgery
• History of malignancy, excepting basal or squamous cell skin carcinoma
• Females who are pregnant, or breast feeding, or are premenopausal but not using chemical or mechanical contraception
• Uncontrolled hypertension, defined either as resting diastolic blood pressure >95 mmHg (taken from the mean of 3 readings) or as resting systolic blood pressure >180 mmHg
• History of alcohol abuse or drug abuse or both
• Intention to engage in vigorous exercise or an aggressive diet regimen
• Uncontrolled endocrine or metabolic disease
• Participation in another investigational drug study within 4 weeks prior to enrolment
• Serious or unstable medical or psychological condition which, in the opinion of the PI, would compromise the subject's safety or successful participation in the study
• Initiation of hormone replacement therapy or oral contraceptive therapy within 3 months prior to enrolment