Presbyopia (age-related farsightedness) is caused by the reduced ability to focus on near objects due to loss of elasticity of the crystalline lens after age 45. A study showed that after supplementing 6 mg of astaxanthin 77% of subjects felt an improvement in seeing nearby objects and a decrease in blurred vision.
This was followed by alleviation of eye strain and shoulder stiffness. Improvements were also documented by objective measurements. The pupillary constriction ratio, used to assess the accommodative function of the eye, showed an overall improvement of 19% after supplementation of astaxanthin. Indicators improved just two weeks in to the study.
Therefore, the researchers concluded that astaxanthin may slow down the progression of presbyopia in middle-aged and elderly people11.
In another study volunteers were given different doses of astaxanthin (0 mg, 2 mg, 4 mg and 12 mg per day). After ingestion of astaxanthin for 28 consecutive days, the uncorrected far visual acuity significantly improved in groups receiving 4 mg and 12 mg doses. Statistically viable improvement was also documented for accommodation amplitude/speed (refocusing from near to far objects and vice versa)12.
11. Shiratori et al. (2005). Effect of astaxanthin on accommodation and asthenopia- Efficacy identification study in healthy volunteers. J. Clin. Therap. Med., 21(5):543-556
12. Nakamura A et al. Changes in visual function following peroral Astaxanthin Jpn J Clin Ophthalmol. 2004. 58(6): 1051-1054