What are some advantages and limitations when it comes to monofocal vs trifocal IOLs?

The actual choice here is between monofocal (single vision) IOLs and PRESBYOPIA-correcting IOLs, not just trifocals (or multifocal) ones.
There is a trade-off between getting uncorrected reading vision along with good distance vision and overall quality of vision. For example, the tri-and multifocal IOLs reduce contrast sensitivity some along with creating concentric rings around lights at night. The sharpest and highest quality distance vision is usually best achieved with an aspheric, monofocal IOL.

But there other ways to achieve both: the Crystalens is an accommodating IOL although the amount of accommodation is not always up to the expectations of many patients. There is also the segmented presbyopia-correcting IOL: the SLB3, rebranded the Clearview IOL. These are not nearly as likely to create halos or reduce contrast.

Overall, it is important to remember two things about IOLs:
  1. Patients tend to judge success with ANY IOL by unconsciously comparing their post-op vision to the very best corrected vision they had when young.
  2. There is NO IOL that can come close to the overall quality of vision afforded by the young, natural lens in the human eye.

This does not mean they are all inferior, but rather that achieving the best visual results post-cataract surgery is not simply a matter of having "the best" IOL "installed."

J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic