People's visual preferences differ. Before I had cataracts I wore contact lenses in monovision and liked that. However after a few years I tried multifocal contacts and noticed that the world seemed subtly more 3D and I preferred that. I hadn't noticed the redution in steropsis while the level of monovision had slowly increased, but noticed its return when I switched to multifocal contacts. Not everyone tolerates monovision, even if most do.
Despite the attempt to claim there are definitively "no" risks, rather than merely low risks, the American Academy of Ophthalmology notes issues regarding monovision LASIK which also apply to monovision using IOLs (they moderate links, google to find the source):
"Side effects of monovision LAISK is an important concept for both the surgeon, as well as the patient to understand, and never to be “brushed under the rug.” Side effects are a direct result of the imbalance or anisometropia caused by monovsion LASIK. Side effects include; blur or fog in distance or reading vision, glare and halos, especially at night, reduced night time vision, especially driving, reduced depth perception, an uncomfortable feeling, or even transient diplopia caused by temporary strabismus. Side effects for most patients will tend to decrease overtime as a patient adapts to their new vision. "
You'll notice btw the mention of "halos" in there, in contrast to the definitive assertion by a supposed "surgeon" that you won't have them. One article notes:
"Greenbaum's report[13] had little discussion regarding complications of pseudophakic monovision, but the incidence of halos or glare was 20% overall."
Studies show a slight increased risk of problematic falls in the elderly with monovision correction due to reduced depth perception. Even in the non-elderly, with the Symfony I appreciate having good vision with both eyes in front of my feet for good depth perception when jogging/hiking on trails that are rocky or with potential spots of black ice, etc. I also assume the odds are low I'll ever have a problem with 1 eye, but if I do then its useful to know I have a decent range of vision in the other.
Contrast sensitivity is reduced for distance and near in low light since you are mostly relying on the image from one eye for each end of the visual range.
One surgeon reports: "adjunct associate professor of ophthalmology, University of Minnesota, Minneapolis; and medical director, Chu Vision Institute, Bloomington, Minn., said that monovision is an important option for patients who are 40 years and older who want refractive surgery or presbyopia correction. "I do tell patients that a majority of patients do not tolerate the imbalance between their eyes but that I want them to hear about this as an option. I think it's important to determine the best situation for patients, whether it's through a contact lens trial or a discussion of past experience with monovision. I think following those general guidelines will help you be successful with monovision in your patients, "
Another paper on monovision in general, mostly with contact lenses, notes: "y. The present paper is a review of the literature on monovision. The success rate of monovision in adapted contact lens wearers is 59– 67%..." Although its notes a wide range of success rates including some higher: " (Levinger et al., 2006); and 91% for monovision pseudophakia following cataracts and 95% for clear lens pseudophakia (Greenbaum, 2002)".
Its an older paper, 2007, so its references to multifocal IOLs are to out of date technology and not relevant, but monovision shouldn't be much different.
re: "You will not have halos. "
Contrary to that absurd claim, competent surgeons, and those capable of reading realiable sources, explain that there is no IOL in existence that can guarantee you won't have problematic halos. People get problematic halos with monofocals, posts about them are around the net and recorded in lots of studies. Yes, most people don't have problematic halos with a monofocal, few enough that even a decent doctor won't bother mentioning it unless the topic arises. However if it does, its irresponsible to explicitly say someone "won't get halos".The net is full of complaints from patients who had unexpected results after doctors made statements seeming to be guarantees.
I'm hoping this supposed "surgeon" is still in training, I certainly would suggest people steer clear of anyone who exhibits either a lack of basic knowledge, or questionable reasoning regarding how to explain things to patients.
Increases in refractive error can raise the incidence of halos, e.g. even people wearing contact lenses in monovision have reported an increased incidence of halos with contact lenses in monovision, e.g. google (since they moderate links):
"THE EFFECT OF DIFFERENT MONOVISION CONTACT LENS POWERS ON THE VISUAL FUNCTION OF EMMETROPIC PRESBYOPIC PATIENTS (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)"