Improving astigmatism correction with a rotation-stable, bitoric, aspherical IOL and coaxial MICS

Implantation of the bitoric, aspherical intraocular lens (IOL), *Acri.Comfort 646 TLC (*Acri.Tec), is rotation-stable and associated with excellent levels of astigmatism correction in cataract patients, according to Detlev Breyer, a high volume surgeon of ZeitzBreyer-Augenheilkunde an den Schadow Arkaden in Dusseldorf, Germany.

It is thought that between 5 and 10% of cataract patients have a corneal astigmatism of more than 1.5 D, hence, interest in reducing astigmatism simultaneously with cataract surgery or clear lens extraction has grown in recent years.

Implantation of a toric IOL to correct astigmatism is known to offer advantages over other available methods, such as astigmatic keratotomy and clear corneal incisions, because of the excellent optical quality of the lenses, a higher reliability, a stable eyeball and no postoperative foreign body sensations. However, many surgeons have voiced postoperative rotation of the lens as an inborn concern with this lens type.

Dr Breyer put a new kind of toric lens to the test to see whether similar complications existed and he presented his findings during a free paper session and an instructional course.

As well as benefiting from a toric and aspherical design, the *Acri.Comfort 646 TLC can also be implanted through a microincision. Dr Breyer advised that he now routinely employs coaxial microincision cataract surgery (CO-MICS) and implants the lens through a 1.6 to 1.8 mm incision. According to Dr Breyer, this method of surgery avoids the induction of astigmatism, does not stretch collagen fibres, and is preferably performed in continuous phaco rather than pulsed mode. According to Dr Breyer, an unexpected advantage of CO-MICS surgery is the smooth fluidics and phacodynamics compared with standard microincision cataract surgery.

Since November 2005, Dr Breyer has implanted 23 eyes of 14 patients with the bitoric, aspherical MICS lens and these patients were included within the treatment group. Inclusion criteria for implantation included regular corneal astigmatism with low asymmetries and astigmatism >2.0 D. The lens was injected with a cartridge and injector through a 2.6 mm incision and a superimposed monitor foil (DOC and ESCRS, Breyer et. al.) was used to optimise the position of the IOL.

According to Dr Breyer, immediate postoperative re-rotation was only necessary in one of his cases whilst the remaining cases demonstrated absolute rotational stability up to one year postoperatively.

At one-year follow-up, he found more than 90% of patients showed an astigmatism of <1 D and 75% of all patients had an astigmatism of <0.75 D, in comparison to an average astigmatism of more than 3.5 D preoperatively.

According to Dr Breyer, postoperative rotation was not a concern with the bitoric, aspherical *Acri.Comfort 646 IOL.

Because of the induced astigmatism with conventional phaco through a 2.6 mm incision that he has witnessed so far, he has changed his surgical routine to incorporate the implantation of this IOL using the CO-MICS method in his astigmatic cataract patients. Dr Breyer also uses the lens in clear lens extraction procedures in patients with higher astigmatisms.