Is monovision a better option than trifocal IOLs?


If you’re considering cataract surgery, you’re probably weighing up the options available to reduce your dependence on reading glasses. Trifocal intraocular lenses (IOLs) are the latest thing but is there a less expensive option that allows you to forget about reading glasses for much of the time? Read on to learn why monovision can be a great option for cataract patients.

What is monovision?

We’ve written about this in the past, mostly in relation to laser eye surgery. This is where one eye is deliberately more clearly focused for distance and the other eye for intermediate (or close) vision. Even with two healthy eyes, one is the dominant eye, and does the lion’s share of the workload. This eye is generally corrected for best possible distance vision in all cataract and lens replacement procedures.  But if the other is also healthy and fully functioning, it often makes sense to give it slightly less clear distance vision in exchange for clearer intermediate and close vision. This allows greater independence from reading glasses, especially in daylight and for day to day situations such as meetings, restaurants, shopping, using your phone etc. It can be liberating. This system uses monofocal IOLs, which allow crisp vision for each eye at the targeted focal point, whether that is distance, intermediate or near.

What are the pros and cons?

Premium trifocal IOLs provide an alternative to monovision, allowing binocular vision at all distances. Another alternative is to simply have both eyes as clear as possible for distance vision (using monofocal IOLs) and wear a pair of glasses for reading and intermediate vision.  Here are some of the key points about all three systems:

table IOL.png

When is monovision not an option?

For this system to provide adequate vision, you need to have two healthy and fully-functioning eyes. Eye diseases such as macular degeneration and glaucoma require the best possible binocular distance vision in order to maximise your ability to cope with the visual compromise caused by the disease.  The same goes for a lazy eye; if you have one eye that – although free from disease – does not see well even with glasses, your best outcome will be both eyes focussed for distance and a pair of reading glasses for close and intermediate work.

The other time when monovision is not the best option is when your goal after surgery is to be independent from glasses at all distances – far, intermediate and close. Provided you can tolerate some compromise to the crispness of your vision, especially in lower light conditions, you may be better off with a premium trifocal IOL. For the carefully chosen patient, and with an experienced surgeon, this is a better option for full freedom from glasses.

It is also possible to use multifocal IOLs to provide distance vision for both eyes as well as a range of near and intermediate vision, which is slightly different in each eye. All of these options will be considered by an experienced surgeon prior to surgery.