One study done by Luther Fry at his own clinic monitored patients with one eye implanted with an aspheric lens and the other not., has also had patients implanted with a standard IOL in one eye and an aspheric lens in the other eye."My experience suggests that if the refractive error is plano or very close to plano in both eyes, or if the patient has enough residual refractive error that he or she chooses to wear spectacle correction, then the patient will notice a difference in terms of color, clarity and brightness, favoring the aspheric lens," he says.And being centered in the bag may not be the same as being centered in the line of sight.
Standard IOLs, which add positive spherical aberration to the optical system, do not create major problems if they decenter.
And pupil size tends to decrease with age, so an 84-year-old patient—who also has an 84-year-old macula—may not notice the difference.
On the other hand, a 50-year-old guy who still works and drives at night with larger pupils in scotopic conditions may notice.
So it's not clear if the average person can distinguish in that situation, either."In any case," he adds, "practical issues may make all of this a moot point, at least for the time being.
One recent study indicated that the most useful residual amount of asphericity to target may depend on the full spectrum of corneal higher order aberrations, not just on corneal spherical aberration alone.