A Phase 1/2 interventional study of 9-cis beta-Carotene-rich extract of Dunaliella alga and Placebo Corn Oil in Retinitis Pigmentosa, sponsored by Sheba Medical Center. Enrolling by invitation at 1 site in Israel. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-27.
Sponsored by Sheba Medical Center · Phase 1/2, Interventional, and Treatment
The goal of this clinical trial is to learn if a natural supplement called 9-cis beta-carotene (derived from the Dunaliella alga) can improve vision and retinal function in adults with Retinitis Pigmentosa. The study will also monitor the safety of the food supplement and how it affects levels of Vitamin A-related proteins in the blood. The main questions the study aims to answer are: (1) Does taking the supplement improve light sensitivity in the retina (measured by microperimetry)? (2) Does the supplement improve electrical responses in the eye (ERG) or other visual functions like contrast and color vision? (3) How do blood levels of beta-carotene and Vitamin A change during treatment? Researchers will use a crossover design. This means every participant will receive both the active supplement and a placebo (a "dummy" pill with corn oil) at different times during the study to compare the results. Participants will take two soft-gel capsules twice a day for 3 months, undergo a 6-month "washout" period where no study capsules are taken.Then they will take the opposite capsules (either the supplement or the placebo) for another 3 months. The participants will visit the clinic 4 times over the course of 12 months for eye exams, eye imaging (like OCT), and blood tests. Participants will also receive follow-up phone calls every 6 weeks to check on their progress and health.
This study is a randomized, double-masked, crossover, placebo-controlled clinical trial designed to evaluate the efficacy of a 9-cis beta-carotene-rich alga (Dunaliella) supplement in patients with Retinitis Pigmentosa (RP). The study specifically targets individuals with mutations in genes related to the retinoid cycle, a critical process for maintaining vision. Previous research has shown that prolonged treatment (at least 3 months) with 9-cis beta-carotene can lead to significant improvements in retinal function and substential visual field cahnges in a subset of RP patients. Because beta-carotene persists in the body, this study utilizes an extended 6-month washout period between treatment arms to ensure plasma levels return to baseline, allowing for a clear comparison between the active supplement and the placebo.
Participants will be randomized into three blocks based on their baseline electroretinogram (ERG) b-wave responses (low, medium, or high) to ensure balanced groups. As a crossover study, every participant will complete two 3-month treatment periods: one with the active Dunaliella soft-gels and one with a corn oil placebo. The total study duration is 12 months, divided into the following phases: Initial Treatment (Months 0-3): Participants take 2 capsules twice daily of either Dunaliella oil (containing 20 mg of beta-carotene) or a placebo. Washout Period (Months 3-9): A 6-month period with no study medication to allow the supplement to clear from the system. Crossed Treatment (Months 9-12): Participants switch to the opposite treatment for a final 3 months. Participants will visit the clinic at the beginning and end of each treatment phase (Months 0, 3, 9, and 12). At these visits, the following assessments will be performed: Primary Objective: Measuring changes in retinal sensitivity via microperimetry. Secondary Objectives: Evaluating electrical retinal activity (ERG), visual acuity (ETDRS), contrast sensitivity, and retinal structure using Optical Coherence Tomography (OCT) and fundus photography. Blood samples will be analyzed for plasma levels of beta-carotene, retinol, and Retinal Binding Protein 4 (RBP4). Participants will complete the NEI VFQ-25 life quality questionnaire to assess the functional impact of the treatment. Adherence will be monitored through capsule counts at each visit, and safety will be assessed via medical history reviews and phone calls every 6 weeks.
278 studies on the registry are indexed under Retinitis Pigmentosa; 72 are open to participants now.
This study's planned enrollment of 41 is above the median of 27 across 179 interventional studies indexed under Retinitis Pigmentosa.
Browse Retinitis Pigmentosa studies →Sheba Medical Center is the lead sponsor of 678 studies on the registry; 63 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants receive two soft-gel capsules twice daily (total 4 capsules/day). Each capsule contains Dunaliella algae, rich in beta-carotene (70% 9-cis and 30% all-trans isomers)
Dietary Supplement: 9-cis beta-Carotene-rich extract of Dunaliella alga
Participants receive two soft-gel capsules twice daily (total 4 capsules/day). Each capsule contains corn oil, manufactured to match the appearance of the active supplement.
Other: Placebo Corn Oil
Participants will be instructed to take two soft-gel capsules twice daily (total of 4 capsules per day) for a period of 90 days. Each soft-gel capsule contains oil extraction of the alga Dunaliella, which is rich in beta-carotene (composed of approximately 70% 9-cis and 30% all-trans isomers). The capsules are manufactured by Hetchyn Ingredients Biotechnology Co., Ltd.
Also known as: Dunaliella alga
Participants will be instructed to take two soft-gel capsules twice daily (total of 4 capsules per day) for a period of 90 days. The placebo capsules contain corn oil and are manufactured to be identical in appearance (size, color, and texture) to the active Dunaliella soft-gels to maintain masking.
Also known as: Placebo
Change in Retinal Sensitivity via Microperimetry
Microperimetry will be used to measure the mean retinal sensitivity (expressed in decibels, dB) in the central visual field. This test assesses the minimum light intensity a patient can perceive at specific points on the retina. An increase in dB indicates improved retinal function and light sensitivity.
Time frame: Baseline (Month 0), End of first treatment (Month 3), End of washout (Month 9), and End of second treatment (Month 12).
Change in Full-Field Electroretinogram (ERG)
Measurement of the electrical response of the retina (b-wave amplitude in microvolts) to light stimuli under scotopic (dark-adapted) and photopic (light-adapted) conditions.
Time frame: Months 0, 3, 9, and 12
Change in Best-Corrected Visual Acuity (BCVA)
Measurement of visual sharpness using the ETDRS letter chart at a standard distance.
Time frame: Months 0, 3, 9, and 12
Change in Full Field Scotopic Threshold (FST)
Measurement of the lowest light intensity perceived by the patient across the entire visual field, measured in decibels (dB).
Time frame: Months 0, 3, 9, 12
Change in Plasma beta-carotene Levels
Laboratory analysis of blood samples to measure the concentration of $\\beta$-carotene (mg/L) to correlate with clinical response and ensure washout efficiency.
Time frame: Months 0, 3, 9, and 12
Change in Pupil Response (Chromatic Pupilloperimetry)
Measurement of pupil constriction in response to focal chromatic light stimuli (red and blue light) to assess rod and cone function.
Time frame: Months 0, 3, 9, 12
Change in Retinal Layer Thickness by SD-OCT
Use of Spectral Domain Optical Coherence Tomography (SD-OCT) imaging to monitor changes in the thickness of retinal layers (in micrometers)
Time frame: Months 0, 3, 9, 12
Change in Ellipsoid Zone (EZ) Area (mm^2) as Measured by SD-OCT En Face Imaging
The Ellipsoid Zone (EZ) area reflects photoreceptor integrity. The total area of preserved EZ will be quantified in square millimeters (mm\^2) using semi-automated segmentation of SD-OCT volume scans. The outcome reported is the mean change in EZ area from baseline to each follow-up time point. A decrease in area represents disease progression.
Time frame: Baseline (Month 0), End of first treatment (Month 3), End of washout (Month 9), and End of second treatment (Month 12).
Change from in Ellipsoid Zone (EZ) Length as Measured by SD-OCT
The Ellipsoid Zone (EZ) length (also known as the EZ width or trans-foveal EZ diameter) represents the horizontal extent of preserved photoreceptor integrity. This measure is quantified in micrometers (µm) or millimeters (mm) using a standardized horizontal B-scan passing through the fovea (Spectral-Domain Optical Coherence Tomography - SD-OCT). A decrease in EZ length reflects the progressive constriction of the visual field typical of Retinitis Pigmentosa. The analysis will compare the rate of change during treatment periods versus the baseline measurement and washout period.
Time frame: Baseline (Month 0), End of first treatment (Month 3), End of washout (Month 9), and End of second treatment (Month 12).
Change in Contrast Sensitivity
Assessment of the patient's ability to distinguish foreground objects from backgrounds of similar luminance
Time frame: Months 0, 3, 9, 12
Dark Adaptation Rate
Measurement of the time required for the retina to recover sensitivity in the dark following a bright light bleach.
Time frame: Months 0, 3, 9, 12
Plasma Levels of Retinol and RBP4
Measurement of plasma concentrations of Vitamin A (retinol) and Retinol Binding Protein 4 (RBP4) in mg/L
Time frame: Months 0, 3, 9, 12
Change from Baseline in Intraocular Pressure (IOP) Measured by Goldmann Applanation Tonometry (mmHg).
IOP is measured in millimeters of mercury (mmHg) using Goldmann Applanation Tonometry. The outcome reported is the mean change in IOP from baseline to assess the physiological effect and safety of the treatment.
Time frame: Months 0, 3, 9, 12
Number of Participants With Clinically Significant Abnormal Findings on Slit Lamp Biomicroscopy.
Slit lamp examination includes evaluation of the eyelids, conjunctiva, cornea, iris, and lens. Anterior chamber cells and flare will be graded according to the Standardization of Uveitis Nomenclature (SUN) criteria (scale 0-4+). A "clinically significant abnormal finding" is defined as any new finding or worsening of an existing condition (e.g., increase in SUN grade or LOCS III cataract score) that the investigator judges to be clinically relevant
Time frame: Baseline (Month 0), Month 3 (End of first treatment), Month 9 (End of washout), and Month 12 (End of second treatment)
Change in Quality of Life (Q25 Questionnaire)
Total score from the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25) to assess the impact of vision on daily activities. Scores range from 0 to 100, where higher scores indicate better health-related quality of life.
Time frame: Months 0, 3, 9, 12
Plan to share: Undecided — The investigators have not yet determined if individual participant data will be shared. This decision will depend on the availability of a secure platform for data hosting and ensuring strict adherence to patient privacy regulations and informed consent agreements regarding genetic data.
Start is estimated for Jul 2026; primary completion for Apr 2028, 21 months later.
Of 28 phase 1/2 interventional studies under Retinitis Pigmentosa, half reached primary completion within 53 months of starting (the median), counting those still running; a quarter within 22 and three quarters within 92. This study's planned 21 months is below that.
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