Part II: Phacoemulsification (PCS) vs. Femtosecond Laser-Assisted Cataract Surgery (FLACS)

So, you’ve decided that it’s time to have your cataracts removed. This became clear after you mistook Joan’s roaming pet rabbit for the bowl during your weekly casual game of lawn bowls; unfortunately, due to your cataracts this is currently the only thing that is clear. A brief foray into the world wide web using the search term “cataract surgery” quickly makes evident that while the surgical procedure itself is exceedingly common and relatively straightforward, there are a few decisions to be made – for example, whether you go with FLACS or phaco, and which IOL option is best for you, whatever these words mean!

FLACS vs phacoemulsfication
FLACS (femtosecond laser assisted cataract surgery) and phacoemulsification are both techniques employed for the actual cataract operation. FLACS is a more recently developed method involving the use of a laser to create the corneal incision to access the inside of the eye, open the capsular bag in which the cataract sits (a step known as a capsulotomy), and also to help break up the cataract into smaller fragments for removal. In phacoemulsification, a scalpel blade is used by the surgeon to create the incision in the cornea and another handheld tool used to create the capsulotomy, meaning greater reliance on the steady hands of your surgeon. An ultrasound tool is used in both FLACS and phacoemulsification but because the femtosecond laser can also be applied to break up the cataract into smaller pieces and then uses ultrasound waves to complete this process while the traditional phacoemulsification technique employs only ultrasound waves for this step, higher amounts of potentially-damaging energy is introduced to the internal structures of the eye during phacoemulsification.
The steps of the surgery which involve the femtosecond laser have been shown to have more reliable, repeatable results, such as the precision of the capsulotomy leading to better stability and centration of the intraocular lens implant. All this being said, the numerous studies conducted on the benefits of FLACS over phacoemulsification have not been unanimous in concluding better results are achieved with FLACS; in fact, most studies have found a negligible difference in the final visual acuity between eyes treated with FLACS and those treated with phacoemulsification. For some challenging patients, FLACS does have a clearer advantage, such as pediatric cases or hard, dense cataracts that would require very high amounts of ultrasound energy to fragment. On the other hand, there are a number of cases where FLACS should be avoided, such as patients having difficulty with sitting or lying on the treatment bed due to obesity, tremors, or skeletal abnormalities, or those with other existing eye conditions that may be exacerbated by the application of a laser.
Femtosecond laser assisted surgery is considerably more expensive than traditional phacoemulsification and is often considered to not be a cost-effective option, especially when phacoemulsification is still a highly successful technique.

Intraocular Lenses (IOLs)
Once the cataract has been removed from the eye, a silicone or acrylic implant is put in its place, known as an IOL or intraocular lens. A well-chosen IOL, coupled with accurate pre-operative biometric measurements and an uncomplicated procedure at the steady hands of your surgeon can greatly reduce your dependency on eyeglasses and contact lenses after cataract surgery.

Monofocal IOLs are implants which correct for one focusing distance. Typically, patients choose to have this set for clear long-distance vision so as to see the other end of the bowling green clearly, which means they will later require glasses for near vision. Some people may prefer to be short-sighted after their cataract surgery and wear distance spectacles as needed, such as those who spend most of their day on activities like reading or petting their rabbit. Astigmatism, a type of refractive error usually resulting from uneven curvature of the cornea of the eye, can also be addressed with what is known as a toric IOL.

In more recent times, medical technology has advanced to a stage that allows surgeons to offer multifocal or accommodative IOLs. As the name suggests, multifocal IOLs contain multiple zones of differing focal points within the implant, meaning that it allows a greater depth of focus. For some people this means they no longer need eyeglasses for either long distance or near vision as the brain learns to adapt around this vision through the multifocal IOL. However, because of this design, some patients experience issues with glare and haloes at night-time, and a decrease in contrast sensitivity. This makes multifocal IOLs not a suitable option for everyone, such as a truck driver who is often on the road at night, and some patients with multifocal IOLs may still prefer to have additional eyeglasses to help with certain tasks such as reading small print.
In a normal human eye, a ring of muscle attached around the capsular bag of the lens called the ciliary muscle contracts and relaxes to adjust the shape of the lens sitting inside the capsular bag to change the focusing distance in a process known as accommodation. As humans age into the mid-forties, the accommodative ability of the eye decreases as the natural lens becomes stiffer and less able to change shape to adjust its focus; this is known as presbyopia. Accommodative IOLs are a synthetic implant with the ability to flex or change position within the eye to alter its power, mimicking the accommodation of a natural lens in a young human. While current technology has not provided us with an accommodative lens that fully restores near vision to the days of Joan’s early 20s, it can make life a lot freer from the use of reading spectacles. Compared to monofocal IOLs, both multifocal and accommodative implants come at a higher price.

For some patients who may not be suitable or keen for multifocal or accommodative IOLs, a nifty monofocal arrangement known as monovision exists. This involves implanting a monofocal IOL for distance vision in one eye and a monofocal IOL for near vision in the other and the brain learns to pay attention to which eye provides the clearer vision depending on the task required. Similar to the other IOL options, monovision is not suitable for all patients and it is best to trial this arrangement in contact lenses before undergoing surgery.

While it is evident that a few decisions must be made when considering cataract surgery, your optometrist and ophthalmologist are the best people to discuss your visual needs with to steer you in the right direction. And of course, don’t forget to apologize to Joan for rolling her rabbit down the bowling green.

 

References
Femtosecond cataract surgery. https://eyewiki.aao.org/Femtosecond_Cataract_Surgery
A review of laser-assisted versus traditional phacoemulsification cataract surgery. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5449299/
Femtosecond laser-assisted versus phacoemulsification for cataract extraction and intraocular lens implantation: clinical outcomes review. https://www.ncbi.nlm.nih.gov/pubmed/28914688
Multifocal intraocular lenses: types, outcomes, complications and how to solve them. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5747227/
Accommodative intraocular lenses: where are we and where are we going. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5485553/

 

 


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