Bilberry reduces video-screen eye fatigue: Healthy pupil constriction and dilation
Reading on a video screen is more taxing than reading printed text due to screen glare, poor lighting or posture, or viewing at the wrong distance or angle, among other reasons. People on computers tend to blink less than while reading print, drying the eyes and contributing to strain.
In this study, 32 healthy adults with video screen eye fatigue took a placebo or 120 mg of anthocyanin-rich bilberry extract powder per day. After six weeks, compared to placebo, those taking bilberry had smoother constriction and dilation of the pupils, clearer vision, less watery eyes, and less eye fatigue.
Discussing the findings, doctors said one of the symptoms of video-screen eye strain is a decrease in pupil constriction and dilation. “Pupillary constriction increases the depth of focus and contributes to the expansion of the clear vision region,” doctors said, meaning smooth constriction increases the range of distance people can clearly see.
Reference: Functional Foods in Health and Disease; 2021; Vol. 11, No. 3, 116-46
Flavonoids improve outcomes in AMD: Quercetin and the catechins
One type of age-related macular degeneration (AMD) produces new, leaky blood vessels under the macula and retina of the eye, quickly distorting or destroying vision in the center of the field of vision. In this study, 494 participants with this “wet” form of AMD got standard anti-blood-vessel-growth therapy for 12 months. Doctors validated flavonoids in the diet using a food-frequency questionnaire.
Those who got the least of three types of flavonoids in the diet; quercetin, epigallocatechin, and epigallocatechin-gallate, had significantly worse vision than those who got the most of these flavonoids. The low-flavonoid group was also twice as likely to have leaky blood vessels and fluid beneath the macula and retina.
Discussing the findings, doctors said in addition to having general antioxidant and anti-inflammatory effects, quercetin and the catechins may inhibit abnormal blood-vessel-forming activity in the eye, may slow the progression of wet AMD, and help preserve the central field of vision.
Reference: European Journal of Nutrition; 2021, s00394-021-02582-4
Nutrients preserve vision in aging: Lutein, zeaxanthin improved night vision
Driving at dusk and at night is difficult for many, especially older adults, as the useful field of view (UFOV)—the area visible without moving the head or eye—shrinks with age. Evidence suggests carotenoid pigments in the macula of the eye that support healthy vision may play a role.
In this study, 33 men and women, average age 63, with 20/25 vision or better, took a placebo or two carotenoids: 7 mg of lutein plus 14 mg of zeaxanthin, per day. After six months, while the placebo group had not changed, those taking lutein and zeaxanthin recovered vision in both eyes more quickly under glare conditions, and had better vision in low-light conditions. Also, macular pigment optical density—the amount of carotenoids in the macula—improved in both the left and right eyes of those taking lutein and zeaxanthin, but did not change for placebo.
Reference: Nutrients; 2021, Vol. 13, No. 9, nu13093191
EPA and DHA reduced early-stage AMD
People with age-related macular degeneration (AMD) gradually lose sight in the center of the field of vision. In addition to carotenoids, fatty acids such as EPA and DHA appear to be protective.
In this review of 11 AMD studies covering 167,581 participants, and ranging from three to 28 years, doctors compared the amounts of EPA and DHA in the diets and the chances for developing early-stage AMD. Overall, those with good amounts of EPA and DHA in the diet were less likely to develop early AMD. Doctors found a direct link: each 1 gram per day increase in EPA and DHA reduced chances for early AMD by 60 and 50 percent, respectively.
Discussing the findings, doctors said EPA and DHA—found in fish oil—were the only polyunsaturated fatty acids they studied that delivered a benefit in reducing chances for early AMD.
Reference: European Journal of Nutrition; 2021, Vol. 60, No. 6, 3013-27