Blueberry Effects on Dark Vision and Glare Recovery

Blindness and Low Vision Clinical Trial

Official title:

Placebo-controlled Cross-over Studies Examining Blueberries Effects on Dark Vision and Recovery After Photo-bleaching

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01942746
• Other study ID #: Blueberries and Vision
• Status: Completed
• Phase: N/A
• First received: May 23, 2013
• Last updated: September 11, 2013
• Start date: July 2005
• Est. completion date: July 2006

Study information

• Verified date: September 2013
• Source: Atlantic Food and Horticulture Research Center
• Contact: n/a
• Is FDA regulated: No
• Health authority: CANADA: Dalhousie University under the Tripartitite Council for Ethics on Reseach Involving Humansunder the tenets of the Declaration of Helsinki
• Study type: Interventional

Clinical Trial Summary

Clinical evidence for effects of plant anthocyanins on vision, and particularly night vision is controversial. Two clinical trials were conducted to investigate whether blueberry juice consumption affected visual dark adaptation, functional night vision, and recovery after photo-bleaching of the retina. One trial (S2) employed a 3 week intervention and washout period, and two doses of blueberries plus a placebo. The other trial (L1) employed a 12 week intervention plus an 8 week washout and tested one blueberry juice dose against a juice placebo.

Description:

Vision Tests: 1. Dark adaptometry, 2. scotopic visual acuity, 3. scotopic contrast sensitivity, 4. rod/cone conversion, 5. recovery after retinal photobleaching

Recruitment information / eligibility

• Status: Completed
• Enrollment: 72
• Est. completion date: July 2006
• Est. primary completion date: July 2006
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 35 Years to 65 Years

Eligibility

Inclusion Criteria:

• visual acuity better than 6/7.5 on EDTRS acuity chart at 2.5m

• visual contrast sensitivity within normal range at 2.5m as tested on Visteck 3000

• stereo acuity better than 80 seconds of arc on Frisby stereoacuity test

• no ocular history other than refractive glasses

• no family history of eye disease

Exclusion Criteria:

• family history of retinal degeneration, glaucoma, diabetes, hypertension, cataract, or amblyopia (dimness in vision).

• evidence in subject (upon examination) of amblyopia (dimness in vision), manifest strabismus (unable to focus both eyes on one spot), or anisotropia (non-uniform responsiveness between both eyes).

• intraocular pressure above 21mmHG from an average of three measures using Mentor tonopen-XL

Study Design

Allocation: Non-Randomized, Endpoint Classification: Pharmacodynamics Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Outcomes Assessor), Primary Purpose: Basic Science

Related Conditions & MeSH terms

• Blindness
• Blindness and Low Vision
• Vision, Low

Intervention

Dietary Supplement:
• Blueberry Juice S2
Blueberry Juice S2 was commercially prepared single strength blueberry juice composed of a 50:50 blend of Rubel (Vaccinium corymbosum L.) and Tifblue (Vaccinium ashei Reade) cultivars. Colorimetric analysis showed that S2 juice contained 6.04 (SD=0.20) mg anthocyanins (C3G) eq/g dry mass.
• Blueberry Capsules S2
Commercially prepared single strength blueberry juice composed of a 50:50 blend of Rubel (Vaccinium corymbosum L.) and Tifblue (Vaccinium ashei Reade) cultivars was freeze dried then powdered and encapsulated in gelatin capsules. Colorimetric analysis indicated an anthocyanin concentration in the powder of 2.37(SD=0.18) mg C3G eq per capsule.
• Placebo Capsule S2
Placebo Capsule S2 (containing no anthocyanins) were prepared by freeze drying red beets and grinding them to fine powder before encapsulating in gelatine capsules. Red beets do not contain anthocyanins.
• Placebo Juice L1
Placebo juice was prepared from water, sugars, citric acid, sodium citrate, and artificial colors and flavours, then pasteurized. The placebo juice contains no anthocyanins.
• Blueberry Juice L1
Blueberry Juice L1 was commercially prepared single strength blueberry juice composed of a 50:50 blend of Rubel (Vaccinium corymbosum L.) and Tifblue (Vaccinium ashei Reade) cultivars. Colorimetric analysis showed that L1 juice contained 6.83 (SD=0.20) mg cyanidin-3-glucoside equivalents (C3GE)/g dry mass at the start of the study, declining to 5.52 (SD=0.09) mg C3GE/g dry mass after 3 months refrigerated storage.

Locations

Country	Name	City	State
Canada	Atlantic Food and Horicultural Research Center	Kentville	Nova Scotia

Sponsors (3)

Lead Sponsor	Collaborator
Atlantic Food and Horticulture Research Center	Department of Ophthalmology, Faculty of Medicine, Dalhousie University, U.S. Highbush Blueberry Council

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Other	Visual acuity and contrast sensitivity testing after dark adaptation (S2).	After dark adaptation testing (primary outcome measure) and before measuring rate of recovery from photo stress (secondary outcome) visual acuity in darkness and contrast sensitivity in darkness was measured using defined optotypes with different degrees of crowding and contrast. Performance was defined as the number of correct answers in 12 tests of acuity and 8 tests of contrast sensitivity.	Testing preintervention and testing for changes after 3 weeks of intervention and 3 weeks of washout	No
Other	Visual acuity and contrast sensitivity testing after dark adaptation (L1).	After dark adaptation testing (primary outcome measure) and before testing rate of recovery from photo stress (secondary outcome) visual acuity in darkness and contrast sensitivity in darkness was measured using defined optotypes with different degrees of crowding and contrast. Performance was defined as the number of correct answers in 12 tests of acuity and 8 tests of contrast sensitivity.	Testing preintervention and testing for changes after 8 & 12 weeks of intervention and 4 & 8 weeks of washout
Primary	Rate of vision adaptation to low light after blueberry juice and placebo ingestion for 3 weeks (S2).	Effect of blueberry products and placebo on the rate of vision adaptation to low light. The rate of vision adaptation is measured by lowest perceptible light intensity after 30 min of darkness (dark threshold); time to reach dark threshold (min); time to reach rod/cone transition (min) [Time Frame: Pre-intervention, after 3 weeks intervention, again after a 3 week washout.] [Designated as safety issue: No]	Pre-intervention, and changes after 3 weeks of intervention, and again after 3 weeks of washout	No
Primary	Rate of vision adaptation to low light after ingestion of blueberry juice and placebo for 12 weeks (L1).	Effect of blueberry products and placebo on the rate of vision adaptation to low light. The rate of vision adaptation is measured by lowest perceptible light intensity after 30 min of darkness (dark threshold); time to reach dark threshold (min); time to reach rod/cone transition (min) [Time Frame: Pre-intervention, after 8 and 12 weeks intervention, and again after 4 and 8 weeks washout] [Designated as safety issue: No]	Preintervention, and changes after 8 and 12 weeks of intervention and after 4 and 8 weeks of washout	No
Secondary	Rate of recovery of visual acuity after retinal photostress (S2).	After dark adaptation testing (primary outcome) and contrast sensitivity and visual acuity testing (other pre-specified outcome measures), participants are subjected to photostress of the retina using bright light. The time (sec) required to recover pre-stress acuity is measured.	Pre-intervention testing and testing for changes after 3 weeks of intervention and 3 weeks of washout	No
Secondary	Rate of recovery of visual acquity after retinal photostress (L1).	After dark adaptation testing (primary outcome) and contrast sensitivity and visual acuity testing (other pre-specified outcome measures) participants are subjected to photostress of the retina using bright light. The time (sec) required to recover pre-stress acuity is measured.	Pre-intervention and then testing for changes after 8 and 12 weeks of intervention and 4 and 8 weeks of washout.