Case #20: Woman in her 50s from Ome (multifocal lens: ActiveFocus)

She first visited us for consultation about cataract surgery with multifocal lenses because of poor near vision, eye strain, and glare when driving at night. At work she types on a computer while looking at documents at hand, so she wished to see well at 30–40 cm, and she also drives at night frequently. I too have lived near Ome, so I understood well the need to drive; we thought it necessary to choose a lens with few halos and glare and recommended ActiveFocus.
ActiveFocus's add is about +2.0 D, so if it is set for distance, the near focal distance would theoretically be 50 cm (1/2 m). So, to see at her desired 30 cm (to reach +3.0 D), we operated with micro-monovision, setting the non-dominant eye's target refraction at −1.0 D and the dominant eye's at −0.25 to −0.5 D. As a result, there was no postoperative refractive error, refraction was on target, and she was delighted, saying everything from computer work to night driving was very comfortable.
Because the non-dominant eye's refraction was set at −1.0 D to secure near vision, its distance vision stayed at about 0.6, but the dominant eye's vision was 1.2, so binocular distance vision was good, and the difference between the eyes did not bother her at all. A difference of about 0.75 D between the eyes is not usually noticeable, but we have seen a patient operated on elsewhere who was greatly bothered by a 1.0 D difference and came to consult about a lens exchange, so this seems to vary between individuals.
Patients often ask us things like, "If you set it at −0.5 D, will I see 1.2?", but this seems to depend on preoperative refraction and other conditions, so it really cannot be known until after surgery. If you consult us, we will advise you based on theory and experience from your preoperative test results, so please feel free to come in.