Standardized small black soybean extract improves tear film stability and dry eye-related symptoms: a 12 week randomized placebo-controlled trial.

Dry eye disease is associated with tear film instability and ocular discomfort, which may be exacerbated by prolonged visual display terminal (VDT) exposure. This 12-week randomized, double-blind, placebo-controlled trial enrolled 100 adults with dry eye symptoms and ocular fatigue, randomly assigned 1 : 1 to oral supplementation with standardized small black soybean extract (SSBS) or matched placebo. The primary efficacy endpoint was tear film break-up time (TBUT); secondary endpoints included the Ocular Surface Disease Index (OSDI) score, visual analogue scale (VAS) scores, and objective ocular surface parameters. In the per-protocol set (n = 81), SSBS supplementation produced a significantly greater improvement in TBUT than placebo at Week 12 (+0.35 ± 1.54 vs. -0.33 ± 1.46 s; p = 0.0457; ANCOVA p = 0.0397). SSBS also produced a significantly greater reduction in OSDI total score compared with placebo (-22.41 ± 23.16 vs. -12.65 ± 14.59; p = 0.0252; ANCOVA p = 0.0359), with significant improvement in the ocular symptoms subscale. Exploratory subgroup analyses suggested greater symptom improvement in subjects with severe baseline symptoms and favorable changes in tear secretion and conjunctival hyperemia in subjects with high digital device exposure. No clinically meaningful safety concerns were identified. The between-group difference in TBUT was modest and the subgroup analyses were exploratory; accordingly, these results indicate a consistent signal that SSBS supplementation may support tear film stability and alleviate dry eye-related symptoms.