Blueberry Effects on Dark Vision and Glare Recovery

Not Applicable

Completed

• Conditions: Blindness and Low Vision

• 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

Study Timeline

• Study Start: 2005-07
• Primary Completion: 2006-07
• Study Completion: 2006-07
• Study First Submitted: 2013-05-23
• Status Verified: 2013-09
• Study First Submitted QC: 2013-09-11
• Last Update Submitted: 2013-09-11
• Study First Posted: 2013-09-16
• Last Update Posted: 2013-09-16

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 72

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

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

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