Blueberry Effects on Dark Vision and Glare Recovery
- Conditions
- Blindness and Low Vision
- Interventions
- Dietary Supplement: Blueberry Capsules S2Dietary Supplement: Placebo Capsule S2Dietary Supplement: Blueberry Juice S2Dietary Supplement: Placebo Juice L1Dietary Supplement: Blueberry Juice L1
- Registration Number
- NCT01942746
- Lead Sponsor
- Atlantic Food and Horticulture Research Center
- Brief 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.
- Detailed Description
Vision Tests: 1. Dark adaptometry, 2. scotopic visual acuity, 3. scotopic contrast sensitivity, 4. rod/cone conversion, 5. recovery after retinal photobleaching
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 72
- 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
- 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
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description Blueberry Capsules Blueberry Capsules S2 Commercially prepared single strength blueberry juice which was composed of a 50:50 blend of two highbush blueberry species (Vaccinium corymbosum L. 'Rubel' and V. ashei Reade 'TifBlue')was freeze dried to a powder and encapsulated in gelatin capsules (Blueberry Capsules S2). Volunteers consumed 3 capsules/daily (7.11mg anthocyanin (as C3G eq) for 3 weeks. Placebo Placebo Capsule S2 Volunteers consumed in S2 three placebo capsules daily for 3 weeks. In L1 volunteers consumed 300ml placebo juice for twelve weeks. Placebo products contained no anthocyanins. Placebo Placebo Juice L1 Volunteers consumed in S2 three placebo capsules daily for 3 weeks. In L1 volunteers consumed 300ml placebo juice for twelve weeks. Placebo products contained no anthocyanins. Blueberry Juice Blueberry Juice S2 Commercially prepared single strength blueberry juice which was composed of a 50:50 blend of two highbush blueberry species (Vaccinium corymbosum L. 'Rubel' and V. ashei Reade 'TifBlue'). Volunteers consumed 300 mls of juice/day (247-271 mg anthocyanins (as C3G) daily) while on this intervention, for either 3 weeks (Blueberry Juice S2) or 12 weeks (Blueberry Juice L1). Blueberry Juice Blueberry Juice L1 Commercially prepared single strength blueberry juice which was composed of a 50:50 blend of two highbush blueberry species (Vaccinium corymbosum L. 'Rubel' and V. ashei Reade 'TifBlue'). Volunteers consumed 300 mls of juice/day (247-271 mg anthocyanins (as C3G) daily) while on this intervention, for either 3 weeks (Blueberry Juice S2) or 12 weeks (Blueberry Juice L1).
- Primary Outcome Measures
Name Time Method Rate of vision adaptation to low light after blueberry juice and placebo ingestion for 3 weeks (S2). Pre-intervention, and changes after 3 weeks of intervention, and again after 3 weeks of washout 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) \[Time Frame: Pre-intervention, after 3 weeks intervention, again after a 3 week washout.\] \[Designated as safety issue: No\]
Rate of vision adaptation to low light after ingestion of blueberry juice and placebo for 12 weeks (L1). Preintervention, and changes after 8 and 12 weeks of intervention and after 4 and 8 weeks of washout 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) \[Time Frame: Pre-intervention, after 8 and 12 weeks intervention, and again after 4 and 8 weeks washout\] \[Designated as safety issue: No\]
- Secondary Outcome Measures
Name Time Method Rate of recovery of visual acuity after retinal photostress (S2). Pre-intervention testing and testing for changes after 3 weeks of intervention and 3 weeks of washout 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.
Rate of recovery of visual acquity after retinal photostress (L1). Pre-intervention and then testing for changes after 8 and 12 weeks of intervention and 4 and 8 weeks of washout. 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.
Trial Locations
- Locations (1)
Atlantic Food and Horicultural Research Center
🇨🇦Kentville, Nova Scotia, Canada