Cone Rescue in Retinitis Pigmentosa by the Treatment of Lycium Barbarum

Overview

Objectives: To study the immediate effect and the persistent effect of Lycium barbarum (LB) treatment on retinal functions, especially the cone function, and retinal structure in patients with retinitis pigmentosa (RP) Design: Randomised controlled double-masked trial

Setting: Primary Care clinical trial

Participants: 120 RP subjects will be recruited from Ophthalmology department at The University of Hong Kong and the Retina Hong Kong. Interventions: Subjects will be randomly allocated to LB (treated with LB granules) or control (treated with placebo) groups for 1 year. After the 1st year, both groups will stop the treatment and all subjects will also have the same eye exam in 6-month period for the 2nd year.

Main outcome measures: The primary outcome is the total sensitivity scores of 30-2 & 60-4 programmes of Humphrey Visual Field Analysis (HVFA). The secondary outcomes are the b-wave amplitudes of Full-field Electroretinogram (ffERG) responses, the amplitudes of direct component and induced component of Multifocal Electroretinogram (mfERG), and the ETDRS visual acuity.

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Double (Participant, Investigator)
  • Study Primary Completion Date: April 2016

Detailed Description

The study was a randomized controlled trial with a double-masked, placebo-controlled design. All the subjects were randomly allocated into either LB (treatment) group or placebo (control) group.

All the eligible subjects had the eye examination, including VA using the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart, refractions, tonometry, external and internal ocular health assessments, and fundus photo-documentation. Three additional tests were conducted to investigate the functional and structural changes in the RP patients, including Ganzfeld Electroretinogram, Humphrey Visual Field Analyser (Zeiss, Dublin, USA) and Spectral-domain Optical Coherent Tomography (SD-OCT) (Heidelberg Engineering, USA).

Interventions

  • Dietary Supplement: Lycium Barbarum
    • Traditional Chinese Herbs
  • Dietary Supplement: Placebo
    • Placebo

Arms, Groups and Cohorts

  • Experimental: Lycium Barbarum
    • Daily Lycium Barbarum dosage: 10g of granules for 12 months
  • Placebo Comparator: Placebo
    • Placebo

Clinical Trial Outcome Measures

Primary Measures

  • ETDRS Visual Acuity (High Contrast)
    • Time Frame: 12 months
    • The high contrast visual acuity will be measured at the time point of baseline and 12 months. Visual acuity is to measure the eye’s ability to resolve fine detail with full refractive error correction. The change of acuity (sec of arc) between 12-month time point and baseline will be provided to show the effect of interventions. The changes of the treatment group will be compared with the changes of the placebo group to illustrate the treatment effect of Lycium Barbarum.

Secondary Measures

  • Visual Field Sensitivity
    • Time Frame: 12 months
    • Humphrey Visual Field Analyser will be used to measure the brightness sensitivity across the central 30 degree visual field at time point of baseline and 12 months. Visual field is to measure the size of the field of view and the sensitivity of the corresponding locations of the field of view. The change of sensitivity (dB) between 12-month time point and baseline will be provide to show the effects of interventions. The changes of the treatment group will be compared with the changes of the placebo group to illustrate the treatment effect of Lycium Barbarum
  • Amplitudes of Flash Electroretinogram
    • Time Frame: 12 months
    • The cone responses from electroretinogram will be measured at the time point of baseline and 12 months. The cone response is related to the activity of the cone photoreceptor under light stimulation. The change of cone response b-wave amplitude (uV) between 12-month and baseline will be provided to show the effect of interventions. The b-wave amplitude is to measure the magnitude of electrical responses of cone cells in the retina. The changes of the treatment group will be compared with the changes of the placebo group to illustrate the treatment effect of Lycium Barbarum.
  • Implicit Times of Flash Electroretinogram
    • Time Frame: 12 months
    • The cone responses from electroretinogram will be measured at the time point of baseline and 12 months. The cone response is related to the activity of the cone photoreceptor under light stimulation. The change of cone response b-wave implicit time (ms) between 12-month and baseline will be provided to show the effect of interventions. The b-wave implicit time is to measure the physiological changes of cone cells in the retina. The changes of the treatment group will be compared with the changes of the placebo group to illustrate the treatment effect of Lycium Barbarum.

Participating in This Clinical Trial

Inclusion Criteria

Ocular conditions:

  • Retinitis pigmentosa;
  • best corrected VA LogMAR 0.20 or better;
  • Humphrey Visual Field Analysis (HVFA) 30-2 total mean defect > or = 250 Decibel;
  • Intra-ocular pressure (IOP) <21 mmHg;
  • van Herrick ratio < or = 0.5;
  • no other ocular diseases

Dietary conditions:

  • Fruit and vegetable intake <10 servings/day;
  • spinach or kale intake < or = serving/day;
  • dietary lutein intake < or = 5.4mg/day;
  • no intake of cod liver oil or omega-3 capsules;
  • dietary Lycium barbarum intake < or =10 fruits/week;
  • supplement intake < or = 5000 IU/day of Vit. A and < or = 30 IU/day of Vit. E;
  • alcoholic consumption < or = 3 beverages/day

Exclusion Criteria

  • BMI > 40;
  • intake of any anticoagulants (especially Warfarin),
  • pregnant or planning to be pregnant;
  • smoking;
  • other clinically significant systemic diseases, eg. diabetes, liver disease and heart disease

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 70 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • The Hong Kong Polytechnic University
  • Collaborator
    • The University of Hong Kong
  • Provider of Information About this Clinical Study
    • Principal Investigator: Henry HL Chan, PhD, Associate Professor – The Hong Kong Polytechnic University
  • Overall Official(s)
    • Henry HL Chan, PhD, Principal Investigator, The Hong Kong Polytechnic University

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