> Many factors, like light scattering and imperfections in the eye’s optics, keep light from coming into sharp focus on the retina, Buabeng said.

> The study also found that iris pigmentation influenced how far apart the two light points needed to be before viewers could distinguish them as separate points. Using a standardized iris color chart, researchers classified each participant’s eye color before analyzing the results. Participants with lighter-colored irises, particularly blue eyes, experienced greater light scatter than those with darker brown irises.

Sounds like the research took a next step beyond previous studies on the same subject. You know, basically how science is supposed to work. Something anyone giving a flippant reply here could have figured out if they actually had read the article.