Numerous observational studies have examined the correlation between Lutein and Zeaxanthin concentrations in the macula, dietary intake and macular degeneration. Several studies have led to the hypothesis that dietary supplementation of Lutein and Zeaxanthin might protect the retina and delay the progression of age-related macular degeneration. The antioxidant carotenoids, Lutein and Zeaxanthin are also potential therapeutics for neuroprotection against retinal inflammatory diseases.

Ninety patients with atrophic age-related macular degeneration (AMD) were supplemented with 10 mg Lutein, 10 mg Lutein plus a broad-spectrum containing antioxidants/ vitamins/ minerals (Lutein+A) or placebo for 12 months. Lutein supplementation resulted in a significant improvement in visual acuity, objective visual function parameters, photo-stress recovery and contrast sensitivity (Richer et al., 2004).

In another Italian study, 50 patients with AMD were given daily cocktails containing antioxidants and 15 mg purified Lutein or placebo for 18 months, reported a 2-fold increase in visual acuity in AMD patients compared to the placebo group (Massacesi et al., 2001).

A 40 mg dose of Lutein daily for nine weeks significantly improved acuity among 16 patients diagnosed with retinitis pigmentosa (rare, inherited, degenerative disease characterized by atrophy of the light-sensing rods in the retina) (Dagnelie et al., 2000).

Dietary supplements containing Lutein and Zeaxanthin were shown to increase serum concentration of carotenoids and an increase in the density of macular pigments in healthy human volunteers (Bone et al., 2003).

A multicenter study on 356 subjects further emphasized this activity, wherein statistically decreased risk of AMD was witnessed up on dietary consumption of Lutein and Zeaxanthin (Seddon et al., 1994).

The role of Lutein in age-related cataracts was evaluated on 17 clinically diagnosed patients. Patients receiving Lutein showed statistically significant improvements in visual acuity and glare sensitivity and increased serum concentrations of Lutein (Olmedilla et al., 2003).

Long-term Supplementation: In this 20-year follow-up study, a total of 63,443 women and 38,603 men were followed up (from 1984 until 2010). Association between predicted plasma carotenoid scores and AMD were determined. Results from the cohort analysis revealed that comparing extreme quintiles of predicted plasma Lutein/Zeaxanthin score; there was a significant risk reduction for advanced AMD of about 40% in both women and men (Wu et al., 2015).

In a 6-month, randomized, controlled clinical trial of patients with type 1 and type 2 diabetes with no retinopathy or mild-to-moderate, non-proliferative retinopathy, a multi-component formula containing xanthophyll pigments (Lutein and Zeaxanthin), antioxidants and selected botanical extracts or placebo was given. Subjects on active supplement compared with placebo had significantly better visual function, an improvement in macular pigment optical density (MPOD) and retinal nerve fiber layer (Chous et al., 2015).