Two age groups, each composed of 12 healthy volunteers (6 men and 6 women), participated in the study: a younger group (mean age = 26.9 years, range: 21 to 36 years) and an older group (mean age = 72.7 years, range: 61 to 80 years). The young participants were university student volunteers; the older participants were recruited from the laboratory's established long-standing pool of healthy community-resident volunteers. Mean presenting acuity in the best eye was better for the younger observers ( M = −0.108 logMAR, range: 0.0 to −0.155 logMAR) than the older ones ( M = 0.013 logMAR, range: −0.155 to +0.176 logMAR), t(22) = 2.72, p < 0.05. Mean best corrected acuity in the better eye was better for the younger group ( M = −0.125 logMAR, range: 0.0 to −0.301 logMAR) than the older group ( M = −0.046 logMAR, range: 0.0 to −0.125 logMAR), t(22) = 2.55, p < 0.05. The dioptric difference between the presenting and best acuity refraction was virtually the same ( p = 0.92) for the younger ( M = 0.60 D, range: 0.0 to +1.5 D) and older ( M = 0.64 D, range: 0.0 to +3.5 D) participants.
None of the participants reported a chronic visual disorder or the use of a medication for a visual disorder. Two elderly participants had prior cataract surgery with IOL implantation (both about 2 years prior to the study). Three elderly men reported cardiovascular diseases and one elderly woman reported mild type II diabetes. None of the younger participants reported any general health problems.
The mean education levels of the younger (17.3 years, range: 15 to 19 years) and older participants (15.7 years, range: 12 to 22 years) did not differ significantly, t(22) = 1.63, p > 0.05. Testing was conducted in accord with an institutionally approved protocol for full informed consent.