Benefits of a Precise Capsulorhexis

One of the main advantages of LACS is the ability to consistently create a highly regular and perfectly circular capsulorhexis. Presbyopia-correcting IOLs that employ diffractive optics require near-perfect centration within the capsular bag to function optimally. While a skilled cataract surgeon can consistently make a quality capsulorhexis, some degree of irregularity is unavoidable. Much like trying to draw a circle by hand, there is always variability. This challenge increases when zonules are weak or white cataracts make the capsule challenging to visualize.

A consistent and perfectly circular capsulorhexis facilitates centration of the intraocular lens and reduces the incidence of IOL tilt. This is more critical with presbyopia-correcting IOLs than with monofocal implants and may decrease the prevalence of bothersome dysphotopsias that can occur with presbyopia-correcting IOLs.

The size of a laser-created capsulorhexis can also be modified to accommodate the diameter of the IOL optic. This size-matched approach, coupled with a perfectly circular capsulotomy and a better centered IOL, provides consistent overlap of the anterior portion of the capsule with the optic edge. This ideal alignment also helps to reduce the incidence of posterior capsular opacification.

Benefits of Precision Limbal Relaxing Incisions

Low amounts of uncorrected corneal astigmatism may not bother cataract patients who choose monofocal IOLs, and certainly not if they expect to wear fine-tuning spectacles for best function. However, for those electing to have presbyopia-correcting IOLs, mild residual astigmatism can negatively affect lens implant performance and be a significant source of dissatisfaction. OCT technology coupled with the precision of the femtosecond laser results in LRI formation that is perfect in depth, length, and regularity—far more so than LRIs created manually.

Femtosecond LRIs can treat corneal astigmatism ranging from 0.5 to 1.5D by incising the corneal stroma and flattening the steep meridian. Laser LRIs have shown to be more accurate in addressing corneal astigmatism below 1.25D when compared to toric IOLs. Additionally, laser LRIs can be designed to avoid breaching the overlying corneal epithelium, thereby negating any additional post-operative ocular surface discomfort. If needed, surgeons can titrate the effect of laser LRIs as the eye heals by opening the anterior surface of the corneal epithelium to further reduce astigmatism.

Patients with dense arcus or peripheral corneal scars may not be good candidates, as the femtosecond laser is less capable of forming accurate LRIs in opaque tissue.

Benefits of Nuclear Pre-fragmentation

In cataract surgery, phaco-emulsification is typically used to break down the lens for removal. Ultrasonic energy causes oxidative stress and produces free radicals that can damage the corneal endothelium. This is particularly worrisome when patients have compromised endothelium, as seen post corneal transplant or in cases of Fuch’s endothelial dystrophy. If the cataract is mature and the cornea has significant guttata, the patient may be at increased risk for decompensation secondary to additional phaco energy required to liquefy the cataract.

A skilled cataract surgeon will always employ techniques to minimize the effective phacoemulsification time. With LACS, surgeons can use the laser to pre-treat and fragment the cataract before the capsulorhexis is created. Linear fragmentation patterns segment the nucleus, thereby softening harder, more mature cataracts. This effectively reduces ultrasound energy delivered to the corneal endothelium. Laser pre-fragmentation also reduces the risk of corneal edema in hyperopic patients with shallow anterior chambers.