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

Abstract

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.

Reply to Green-Gomez et al. Comment on “Richer et al. Night Vision and Carotenoids (NVC): A Randomized Placebo Controlled Clinical Trial on Effects of Carotenoid Supplementation on Night Vision in Older Adults. Nutrients 2021, 13, 3191”

“…These studies only observed primarily naive individuals that were not trained in this technology. In the present study [2], we find that the standard error is the same for both the baseline and final visits for macular pigment (MP) measurements, and it is therefore unlikely that this sample is different or special. We hope this is now clear.…”

“…Thank you for pointing out an error in a single data point in Figure 1B [2]. However, the text is correct.…”

“…As explained in Section 2.2 of our publication [2] (Instrumentation,)-The Vimetrics Central Vison Analyzer, a device developed by an ophthalmologist, measures the resolution threshold of each eye at fixation within six presentation modules representing varying degrees of contrast reduction under photopic and mesopic luminance conditions that represent real-world vision tasks at presentation times that simulate real-world fixations [9], and, as such, have demonstrated improved correlations with task performance under those conditions compared with chart measurements. Those with visual acuities below 20/100 were not tested or included.…”

“…Preferred Luminance-One can determine from a visual inspection of Figure 3 [2] that there is an appreciable difference between placebo and intervention groups in terms of change from baseline to 6 months, right and left eyes compared to the baseline data (t-test p = 0.02 and 0.03, respectively) using the simple clinical device and the statistical constraints imposed by post-randomization heterogeneity of variance.…”

“…In addition, we believe that we have not overstated the data in our Communication. All NVC peer reviews can be found at Nutrients [2].…”