Night Vision and Carotenoids (NVC): A Randomized Placebo Controlled Clinical Trial on Effects of Carotenoid Supplementation on Night Vision in Older Adults.

Twilight and low luminance levels are visually challenging environments for the elderly, especially when driving at night. Carotenoid rich diets are known to increase macular pigment optical density (MPOD), which in turn leads to an improvement in visual function. It is not known whether augmenting MPOD can lead to a decrease in vision related night driving difficulties. Additionally, it is unknown if carotenoid supplementation provides additional measurable benefits to one's useful field of view (UFOV) along with a decreased composite crash risk score. The aim of the study was to evaluate changes in night vision function and UFOV in individuals that took carotenoid vitamin supplements for a six-month period compared to a placebo group. METHODS: A prospective, randomized, double-blind, six-month trial of a 14 mg zeaxanthin/7 mg lutein-based supplement was carried out. Participants were randomized into active or placebo group (approx 2:1). RESULTS: n = 33 participants (26 males/7 females) participated with 93% capsule intake compliance in the supplemented group (n = 24) and placebo group (n = 9). MPOD (mean/standard error SE) in the active group increased in the Right eye from 0.35 density units (du)/0.04 SE to 0.41 du/0.05 SE; p < 0.001 and in the Left eye from 0.35 du/0.05 SE to 0.37 du, p > 0.05). The supplemented group showed significant improvements in contrast sensitivity with glare in both eyes with improvements in LogMAR scores of 0.147 and 0.149, respectively (p = 0.02 and 0.01, respectively), monocularly tested glare recovery time improved 2.76 and 2.54 s, respectively, (p = 0.008 and p = 0.02), and we also noted a decreased preferred luminance required to complete visual tasks (p = 0.02 and 0.03). Improvements in UFOV scores of divided attention (p < 0.001) and improved composite crash risk score (p = 0.004) were seen in the supplemented group. The placebo group remained unchanged. CONCLUSIONS: The NVC demonstrates that augmenting MPOD in individuals with difficulty in night vision showed measurable benefits in numerous visual functions that are important for night vision driving in this small sample RCT. Additionally, we observed an improvement in UFOV divided attention test scores and decreased composite risk scores.

Cyanidin-3-glucoside extracted from mulberry fruit can reduce N-methyl-N-nitrosourea-induced retinal degeneration in rats.

PURPOSE: To investigate the effect of cyanidin-3-O-glucoside (C3G) on a rat retinal degeneration (RD) model. MATERIALS AND METHODS: Experimental RD was induced in rats by the intraperitoneal injection of N-methyl-N-nitrosourea (MNU) at 50 mg/kg. C3G extracted from mulberry (Morus alba L.) fruit (50 mg/kg) was orally administered, daily for 1, 2 and 4 weeks after MNU injection. The effects of C3G administration on MNU-induced RD retinas were histologically and functionally assessed by hematoxylin and eosin staining and electroretinography (ERG), respectively. The degree of retinal injury in C3G-administered RD rats was evaluated by immunohistochemistry with an antibody against glial fibrillary acidic protein (GFAP). The preferential protective effect of C3G on scotopic vision was examined by western blot analysis. RESULTS: Marked loss of photoreceptors in the outer nuclear layer (ONL) was observed in RD rats at 2 and 4 weeks after MNU injection, while the ONL in the MNU-induced RD rats given C3G was relatively well preserved. Immunohistochemistry with anti-GFAP showed that retinal injury was also reduced in the retinas of the rats given C3G. Functional assessment by using ERG recordings showed that scotopic ERG responses were significantly increased in RD rats given C3G for 4 weeks (p < 0.01) compared with that of untreated RD rats. In the RD rats given short-term C3G (for 1 and 2 weeks), the increase in ERG responses was not significant. In addition, western blot analysis showed that rhodopsin level in the C3G-administered RD retinas significantly increased compared to that in the non-administered RD retinas (p < 0.05), whereas red/green opsin level did not show any significant difference. CONCLUSIONS: Long-term administration of C3G extracted from mulberry fruit could structurally reduce photoreceptor damage and functionally improve scotopic visual functions in the RD rat model induced by MNU.

Negative impact of melatonin ingestion on the photopic electroretinogram of dogs.

Melatonin follows a circadian rhythm entrained by the light/dark cycle and plays a role in promoting light sensitivity at night. It has been suggested that melatonin and dopamine reciprocal inhibition may contribute to the switch between day and night vision. The purpose of this study was to investigate the impact of a high dose of melatonin administration on the photopic and scotopic electroretinogram (ERG) of dogs in the daytime, when it is not thought to be present. Photopic and scotopic ERG luminance response functions were obtained from 7 anaesthetized beagle dogs (3 males and 4 females), once without melatonin (control) and once after oral administration of melatonin (90 mg/dog). Vmax (maximal b-wave amplitude achieved) and logK (retinal sensitivity) were calculated from the derived luminance response function. Photopic flicker ERG was also recorded. In photopic condition, a-wave amplitude (control: -126.90 µV; with melatonin: -49.64 µV; p<0.001) and Vmax (control: 252.50 µV; with melatonin: 115.40 µV; p<0.001) were decreased. A significant reduction of the photopic flicker ERG amplitude was observed after melatonin ingestion. In scotopic condition, an overall difference was reported before and after melatonin ingestion for the a- and b-wave amplitude, but no change was significant for Vmax. Melatonin ingestion at a high dose during the day decreases the photopic amplitude of a- and b-wave, but has no impact on implicit time. This negative impact of melatonin on photopic system may serve to promote night vision.