Cone Rescue in Retinitis Pigmentosa by the Treatment of Lycium Barbarum

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.

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).

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.

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

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.

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.

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

Chan HH, Lam HI, Choi KY, Li SZ, Lakshmanan Y, Yu WY, Chang RC, Lai JS, So KF. Delay of cone degeneration in retinitis pigmentosa using a 12-month treatment with Lycium barbarum supplement. J Ethnopharmacol. 2019 May 23;236:336-344. doi: 10.1016/j.jep.2019.03.023. Epub 2019 Mar 12.