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

The success rate of cataract surgery in the developed world is typically quoted as 98% or higher. However, as with any procedure performed on the complex human body, things can go wrong. Approximately 0.5% of patients undergoing cataract surgery experience a severe complication with significant visual impact; in the USA with around 2-3 million surgeries performed every year, this represents up to 15 000 patients with vision loss following what should be a sight-restoring procedure. Although a 98% success rate is pretty good, it’s important not to go into cataract surgery “blind” to the potential complications.

Many of the side effects experienced after cataract extraction are short-lived and resolve with time or a simple follow-up procedure. Those complications with more severe visual effects are rare.

Dry eye. Approximately 10% of patients will experience dry eye symptoms after cataract surgery. This is thought to arise from the corneal nerves being damaged from steps necessary during the procedure and possibly also some irritation from the post-operative eye drops. Dryness symptoms peak around a week post-operatively but then gradually improve over the following one to three months. A comparison of dry eye symptoms in patients undergoing femtosecond laser-assisted surgery (FLACS) versus the traditional phacoemulsification technique found that immediately after surgery, FLACS exacerbated dry eye more so than phacoemulsification but by three months this difference was insignificant. Unfortunately, most patients undergoing cataract surgery already have pre-existing risk factors for dry eye, such as age. The use of appropriate lubricant drops is sufficient to alleviate the discomfort in most cases.

Glare sensitivity. Many patients with cataract will report glare sensitivity pre-operatively as the opacities of the cataract scatter light coming into the eye. Post-operatively, glare arises as more light can now enter the eye once the obstructive cataract has been removed. In most cases, this sensitivity will decrease over time; in the meantime, the use of sunglasses or tinted lenses as needed is a good idea. For patients who have had a multifocal intraocular lens (IOL) implant, the design of this implant can exacerbate glare particularly at night (and particularly when driving at night, which is likely when you particularly don’t want to be dazzled by glare). Careful discussion with your eye surgeon prior to the operation can help to avoid this problem if you often need to drive in night conditions.

Dysphotopsia. Dysphotopsia refers to unwanted images in the vision. Positive dysphotopsias after cataract surgery manifest as streaks or flashes of light in the peripheral vision, thought to arise from the reflection and refraction of light through the edge of the IOL. Unfortunately, positive dysphotopsias do not tend to diminish with time, but most patients become accustomed to the experience and their overall vision is still much better than pre-operatively. A negative dysphotopsia can present as a dark arc or shadow in the vision and is caused by the placement of the IOL and the resultant optics. Negative dysphotopsias do tend to improve with time, from about 15% of patients immediately after surgery reporting this side effect to only 3% a year later.

Posterior capsular opacification (PCO). PCO is often called a “second cataract” (though this is slightly misleading as PCO is not a real cataract) and occurs from the growth of residual epithelial cells on the capsular bag from which the original cataract had been removed, causing a return of the hazy, cloudy vision you would have experienced with the first (real) cataract. PCO can occur months or even years after cataract surgery and is easily treated with a quick laser procedure to zap the proliferating cells.

Serious complications. Endophthalmitis refers to a severe infection inside the eyeball, usually as a result of bacterial contamination, and occurs at a rate of about 0.1% in the US. The bacteria may come from unsterile equipment used during the procedure or from the usual bacteria that colonizes human skin entering the eye. Endophthalmitis must be aggressively treated with antibiotics but even so, may result in permanently damaged vision. Retinal detachment is another potentially devastating complication and can occur even up to years after a successful cataract procedure. It is exceedingly uncommon (about 1 in 3000 cases) but needs urgent surgical attention to save the vision if it happens. Flashing lights in the vision, dark shadows coming across the visual field, and specks or floaters in the vision can be indications of a retinal detachment.

Other potential complications and side effects of cataract surgery exist, such as swelling of the cornea (the transparent front surface of the eye) or the macula (a part of the retina relating to central vision) immediately after the procedure. The presence of a residual prescription, such as remaining long- or short-sightedness, may disappoint many patients who may have been expecting to have perfect uncorrected vision after the procedure. Nonetheless, the resultant vision is usually much better than when the cataract was still present and can be easily improved further with eyeglasses or contact lenses as needed.

Certain factors can increase your odds of encountering an issue during cataract surgery. While most of these cannot be modified, knowing that these risk factors are present helps your eye surgeon to advise you and prepare appropriately. Older age was found to be associated with a higher risk of complication, including endophthalmitis, when compared to those under 60 years old undergoing cataract extraction. Male gender has been linked to a 23% increased risk of complication, possibly due to poorer compliance with post-operative instructions such as the use of eye drops, and differences in the types of resident bacteria present when compared to women. A certain medication for the treatment of prostate concerns, tamsulosin, may add to the explanation of why men experience more cataract surgery complications. Existing medical conditions such as diabetic eye disease, Marfan syndrome, Fuch’s corneal endothelial dystrophy, and pseudoexfoliation also contribute an elevated risk of complications occurring either during or after a cataract operation.

Eye surgery can be daunting for anyone. Although this is not an exhaustive list of all the potential side effects or risk factors for complications during cataract surgery, hopefully it has been a good eye-opener to the complexities of operating on this intricate organ we call the eyeball.

 

 

 

References

How to improve your odds of successful cataract surgery. https://www.lifeextension.com/magazine/2015/11/how-to-improve-your-odds-of-successful-cataract-surgery/page-01

Review of evaluation of dry eye after femtosecond laser-assisted cataract surgery: a prospective study. https://www.eyeworld.org/article-review-of–evaluation-of-dry-eye-after–femtosecond-laser-assisted-cataract-surgery–a-prospective-study

Effects of femtosecond laser-assisted cataract surgery on dry eye. https://www.ncbi.nlm.nih.gov/pubmed/30542462

Incidence and pattern of dry eye after cataract surgery. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3827040/

Know what signs will resolve on their own after cataract surgery. https://www.healio.com/optometry/comanagement/news/print/primary-care-optometry-news/%7B57b3538e-15d6-417a-917a-b9288aa2ede3%7D/know-what-signs-will-resolve-on-their-own-after-cataract-surgery

Dysphotopsia: not just black and white. https://www.reviewofophthalmology.com/article/dysphotopsia-not-just-black-and-white

Posterior capsule opacification. https://eyewiki.aao.org/Posterior_capsule_opacification

What are the risks of cataract surgery? https://www.visionaware.org/info/your-eye-condition/cataracts/risks-of-cataract-surgery/125

Serious adverse events after cataract surgery. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3777802/

 

 


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