All IOL manufacturers offer plenty of printed material as well as animated video to show your patients their options. These resources can help patients better understand the benefits of premium IOLs.
If a patient is interested in a multifocal IOL, I adhere to the recommended guidelines for patient candidacy. Our office works mainly with Alcon IOLs, so I have more experience with them. We like the patient to be hyperopic; however, these patients tend to have a larger angle kappa.
Angle kappa is the difference between the pupillary axis and the visual axis (Figure 5).5 It is defined as the angle between the visual axis (line connecting the fixation point with the fovea) and the pupillary axis (line that perpendicularly passes through the entrance pupil and the center of curvature of the cornea).
It can be identified clinically by the nasal displacement of the corneal light reflex from the pupil center, and it represents a misalignment of light passing through the refractive surface of the cornea and the bundle of light formed by the pupil.5 Angle kappa is not affected by gender, and it tends to decrease with age.
A large angle kappa is important clinically because it may lead to alignment errors and decentration during laser refractive cataract surgery. Decentration of the IOL can lead to photopic phenomena (glare and halos) as well as decrease in lens effectiveness. An option to compensate for a large angle kappa is to purposely decenter the IOL toward the visual axis. Centering the IOL on the corneal reflex will greatly reduce the incidence of photopic phenomena. A decentered IOL can decrease multifocal function.
Let the patient know multifocal IOLs are not for everyone, and clinical measurements will determine if the patient is a good candidate.
Higher order aberrations consist of spherical aberration, coma, and trefoil. Corneal coma is an imperfection that results in off-axis point sources such as stars appearing to have a tail—or coma. Vertical coma is the most common higher order aberration in patients with keratoconus, corneal injuries, or abrasions.6
One study involving 119 eyes undergoing uncomplicated cataract surgery with a 2.2-mm incision showed those patients who received a superior incision showed significant negative changes in vertical coma. Patients who had a nasal incision showed significant changes in oblique trefoil, and those that had a temporal incision had insignificant changes in higher order aberrations.7
We make sure the corneal coma is less than 0.32 µm for each eye. The angle kappa should be less than 0.43 mm for ReStor (Alcon) and 0.50 mm for Tecnis (Johnson & Johnson Vision Care) IOL. Also, the photopic pupil size should be no smaller than 2.0 mm and the mesopic pupil size no larger than 6.00 mm. I find this data on Marco OPD.
Patients who currently wear multifocal contact lenses may also be good candidates. They tend to have more realistic expectations as well as those with an easy-going personality.
Tell patients the brain will learn to adapt to the new vision with an IOL. This is called neuroadaptation, and it can take several months to adapt. Look at the patient as a whole. For example, a patient who is a +6.00 D hyperope with a mature cataract will be thrilled with her new vision. However, a -3.00 D myope with mild to moderate cataracts may be a bit more critical of the results.