Monofocal vs. multifocal lens exchange: What's best for your eyes?
31 October 2019
Understanding the difference
At Optimax, we offer a range of lens surgeries including implantable contact lenses, cataract surgery, and refractive lens exchanges. The processes for cataract surgery and a refractive lens exchange (RLE) are the same, both involving the removal of the eye’s natural lens and replacing it with an artificial lens. This lens can be either monofocal or multifocal, and the difference between the two is key. Implantable contact lenses differ in the fact that your eye’s natural lens remains in place, and we simply place an implantable lens between your natural lens and your iris. This is most suitable for patients under the age of 45 who still have good reading vision. Monofocal lenses in this instance wouldn’t be at all beneficial: the lens needs to have corrective power as it is inserted to eliminate a prescription. Therefore, for the purposes of this article, we will only be discussing the pros and cons of monofocal and multifocal lenses in RLE and cataract procedures.
As the name suggests, people have cataract surgery to remove cataracts. A cataract is when the eye’s natural lens becomes cloudy as a result of eye tissue breaking down and proteins clumping together. This tends to occur with age – generally after the age of 40 – and it is thought that 30% of British adults aged over 65 have some form of cataract in one or both eyes. When the lens clouds, it impairs vision, and can result in blindness if left to worsen. This is when cataract surgery comes in – it’s the most commonly performed elective surgery worldwide with 330,000 cataract operations performed in England each year… and a huge 18 million procedures are performed globally!
When you come to Optimax for cataract surgery or an RLE procedure, you will be given the choice of monofocal, multifocal or EDOF (extended depth of focus) lenses. NHS surgery offers a standard monofocal lens implant which corrects only the distance vision, meaning you will still rely on glasses for certain activities. However, our multifocal lens implants correct distance vision, intermediate vision, near vision, and astigmatism all at once. While a monofocal lens will be effective following the removal of the natural lens during cataract surgery, patients tend to opt for RLE in order to correct their prescription at the same time, effectively killing two birds with one stone. For this reason, they usually choose multifocal or EDOF lenses.
Generally, monofocal lenses correct distance vision, but we can have them made to correct a particular visual distance you desire. If you don’t mind still relying on glasses for specific tasks – such as reading – then monofocal lenses are suitable for your needs. If your job requires you to have excellent distance vision, for example as a professional driver, then monofocal lenses may actually be more suitable than multifocal or trifocal lenses.
If you want (or are only suitable for) monofocal lenses, but also want both your distance and reading vision corrected, then Monovision treatment may be an option. Monovision is a particular type of lens surgery where we correct one eye for reading and the other eye for distance vision. This allows you to have both good distance and close-up vision as each eye covers its respective visual range. This treatment, however, isn’t always suitable for everyone as not everyone can adjust to each eye working on independent distances. Therefore, following your consultation, we can offer a trial with contact lenses to mimic the final results, allowing you to see if Monovision treatment is something that could work for you.
Multifocal and trifocal lenses
Both of these types of lenses allow you to focus on multiple distances: multifocal provides sharp vision for near and distant ranges, while trifocal provides sharp vision for near, intermediate and distance vision (three distances, hence “tri”). Multifocal and trifocal lenses are incredibly popular when it comes to lens surgery at Optimax as they can provide total freedom from glasses and contact lenses.
Multifocal and trifocal lenses split the light that enters the eye to provide more than one focal point. This means that you can focus on three distances at the same time, potentially having even better vision than before you ever relied on glasses or contact lenses. Side effects can include some loss of contrasts and haloes around bright lights at night time, but the vast majority of Optimax patients have minimal problems and are very pleased with these types of lenses for RLE treatment.
Extended depth of focus (EDOF) lenses
EDOF lenses are a relatively new phenomenon in the refractive lens surgery world. The lenses are tolerant to mild amblyopia and subtle macular diseases, while also providing a better depth of focus. These make them more suitable for a wider range of patients, giving more people the opportunity to have their vision corrected. As the name would suggest, EDOF lenses also provide a better depth of focus, bending the light that enters the eye, allowing you to focus on both intermediate (80cm away) and far distances (around 100cm away).
Although you might still rely on reading glasses for very close vision or for reading small print, EDOF lenses have been proven to result in lower instances of glares and haloes at night, following treatment. Often, different types of lenses will be inserted into each eye, depending on the patient’s individual visual requirements.
Choosing the best option for you
Knowing exactly what will work best for you is impossible to know without having a consultation with an optometrist. Examining your eyes will give us a good idea of your suitability for different types of lenses, as does hearing about your lifestyle visual requirements. As previously mentioned, different jobs and hobbies can rely on different types of visual range, so hearing about your expectations of vision correction surgery will also help us make the right decision with you. Get in touch to book in for a free consultation and live life free from glasses!
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