Multifocal IOL for patients who have 'distant-dominant lifestyles' and wish to remain spectacle-free
When I have patients who wish to be spectacle free after cataract surgery, I normally select a multifocal IOL for distant-dominant vision. The lens (AcrySof IQ ReSTOR, Alcon Laboratories, Fort Worth, Texas, USA) is bilaterally implanted and provides patients with a high likelihood of being able to see at distance and near without spectacles for the majority of their visual tasks.
Reducing visual disturbances
The +2.5 IOL has two important differences relative to the +3.0 model. First, the near add is further out, providing a near focus at about 55 cm, or approximately a 1.75 D add. Second, the light distribution favours distance vision, with 70% to 90% of light directed to the distant focus, depending on pupil size. This significantly reduces the potential for glare and halos, as these types of visual disturbances are generally due to the unfocused near light when viewing distant objects, particularly in dim light.
Determining patient lifestyle
When the patient responses show a pattern that indicates spectacle use for reading is acceptable, but that the patient would prefer to be less dependent on spectacles for such activities as computer use and playing cards and is concerned with the potential for visual disturbances, the ReSTOR +2.5 lens becomes an option.
As an example, PD is a 76-year-old female in my practice who spends a great deal of her time cooking. She also reads extensively and uses a +3.00 add for that task. Her primary desire was to be able to cook without depending on reading glasses, and she had some concern about the glare and halos possible with a multifocal IOL. I implanted her with bilateral +2.5 lenses and she enjoys excellent distant vision (1.2, or 20/15) two months after surgery. Her binocular near vision is J1 from about 40 cm to 65 cm, which she finds excellent for her kitchen work. She uses spectacles for reading and reports no apparent halos.
While the +2.5 lens has only recently been made available in Europe I have implanted the lens in more than 20 eyes to date. Of these, eight were mixed with a contralateral +3.0 lens, in an effort to obtain the 'best of both worlds'. However, there are challenges with this approach, as patients are more likely to compare vision in each eye and, of course, they will never be the same. The primary motivation is to minimize the likelihood of visual disturbances while providing usable intermediate and near vision and the best way to accomplish this is with the bilateral 2.5 design. A review of the literature suggests that for multifocal IOLs, in general, a bilateral implantation strategy provides the best overall results.
It is important to note that the 2.5 lens is not a replacement for the +3.0. This lens, in a sense, fills a gap between patients who wish they had better near vision than that which is provided with a single vision lens, but who are concerned with the potential for glare and halos. The +2.5 lens gives me a new multifocal option that addresses both of these concerns. Near vision will not be as good, or as close, as with the +3.0 lens, but is expected to be much better than with a monofocal lens with only marginally more visual disturbances likely. I always tell patients, after implantation of the (+2.5 D) lens, that their distance vision will be virtually uncompromised while they will have some ability to read at intermediate and near, particularly in good light. I usually inform the patients choosing the +3.0 lens that it gives them the greatest likelihood of freedom from spectacles for the majority of their visual tasks, but they may experience some glare and halos, which tends to become less noticeable over time.
Both of these multifocal IOLs are available in a toric design, making them excellent options for patients with astigmatism who wish to be less dependent on spectacles after cataract surgery.
Dr Francesco Carones is the Cofounder and Medical Director of the Carones Ophthalmology Center in Milan, Italy. He can be contacted by E-mail: firstname.lastname@example.org
Dr Carones is a consultant for Alcon Laboratories.