Advances in Cataract Surgery

Majed Alkharashi; Walter J Stark; Yassine J Daoud

Disclosures

Expert Rev Ophthalmol. 2013;8(5):447-456. 

In This Article

Femtosecond Laser-Assisted Cataract Surgery

Since the introduction of the Nd:YAG laser in the treatment of posterior capsular opacity, laser technology has proven to be safe and effective for the treatment of many ophthalmic diseases. Indeed, laser-assisted eye surgery has proven to be safer and superior to surgical-instrument-assisted eye surgery. A good example of this is the outcome of femtosecond laser-assisted vs microkeratome-assisted flap creation in LASIK surgery.[69]

In 2010, the FDA granted clearance to LenSx system (Alcon). This marked a new era for femtosecond laser-assisted cataract surgery (FLACS). Since then, three other laser systems have been granted FDA approval for FLACS. These systems are Catalys (Optimedica, Santa Clara, CA, USA), LensAR (LensAR Inc, Orlando, FL, USA) and Victus (Technolas GMBH Munich, Germany). These systems have three key applications in cataract surgery, namely: anterior capsulotomy, lens fragmentation, corneal wound construction.[70] The systems are fairly similar with the main differences being variations in the docking mechanism and the mechanism of image acquisition.[71]

There are certain advantageous and disadvantages to FLACS. Indeed, FLACS is an area of active research as well as debate among cataract surgeons.

Nagy et al. showed that femtosecond laser-assisted capsulotomies are significantly more accurate and reproducible in terms of their centration, shape and size compared to manual capsulotomies.[72] These findings have been supported by subsequent studies.[73] Indeed, one study found femtolaser-assisted capsulotomies had a mean deviation from intended diameter of 29 ± 26 μm, compared to 337 ± 258 μm for the manual technique.[74] This is clinically significant since the size of the capsulorhexis might affect the IOL position within the capsular bag. On the one hand, a small capsulorhexis (<5.5 mm) has been linked to capsular fibrosis and hyperopic shift.[75] On the other hand, a large capsulorhexis is associated with increased rates of tilt, decentration and posterior capsular opacification.[76,77] Indeed, manual capsulotomy has six-times higher risk of IOL decentration than FLACS.[78] Thus, FLACS is expected to yield a more accurate effective lens position, IOL calculation, uncorrected visual acuity, and decreased higher order aberrations, IOL calculation and uncorrected visual acuity. However, the results of the few published studies are inconsistent and thus more research is needed.[79–81]

FLACS can also perform lens fragmentation with subsequent decrease in phacoemulsification time as well as the ultrasound energy amount that is used.[72,82] Other studies have showed that FLACS causes significantly less corneal swelling on the first post-operative day compared to conventional technique,[83] but this effect was not significant at later follow-up dates. Consuming less ultrasound energy will likely help preserve corneal endothelial cells in the long term. This is important as surgeons are operating on patients earlier and health of the endothelium is essential over their long postoperative lifespan.

A third important step in cataract surgery is corneal wound construction. Femtosecond-assisted corneal wounds have been shown to be more stable, reproducible and predictable.[82,84] This may have the potential of preventing wound leakage and may lessen the possibility of endophthalmitis.

In patients with corneal astigmatism, femtosecond lasers have the ability to produce accurate, reproducible, and controlled arcuate incisions in an effort to achieve post-operative emmetropia.

The greatest disadvantage of FLACS is financial. It is estimated that the laser system costs US$400,000–500,000 to acquire, plus a 'click-fee' of US$150–400 per patient plus US$40,000 annual maintenance fee. Thus, a practice is required to operate on approximately 600 FLACS cases a year to financially justify acquiring the laser system.[85]

In summary, in a relatively short period of time, cataract surgery was transformed from a procedure that was wrought with significant morbidities and rather high risk of vision loss to one of the safest procedures in modern medicine. The patients' as well as the doctors' expectations are ever increasing. Twenty years ago, cataract surgery main aim was that of visual rehabilitation. Today, cataract surgery is becoming a refractive procedure with relatively few side effects and excellent safety and efficacy.

processing....