Precise alignment helps surgeons focus on best toric IOL post-op results

Capsulorhexis-guided lens confirms intended axis during surgery, decreases astigmatism

Reviewed by P. Dee Stephenson, MD, FACS

Approximately half of the population 60 years of age and over exhibits more than 1.0 diopter (D) of corneal astigmatism,^1-2 and one of the challenges surgeons face in treating pre-existing astigmatism is ensuring precise alignment of the toric intraocular lens (IOL).

If the lens is not accurately aligned along the intended meridian, the desired astigmatic correction may not be achieved, leaving a very unhappy patient, according to cataract surgeon P. Dee Stephenson, MD, FACS. Dr. Stephenson is in private practice at Stephenson Eye Associates in Venice, FL, and is president of the American College of Eye Surgeons.

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In a recent retrospective analysis of 54 eyes in which laser iris-registered femtosecond laser-assisted anterior capsular marks (IntelliAxis Refractive Capsulorhexis, LENSAR) were used to guide alignment of the Trulign toric IOL (Bausch + Lomb) and ORA (Optiwave Refractive Analysis, Alcon) was used to confirm intended axis during cataract surgery, astigmatism decreased significantly postoperatively (p<0.001), said Dr. Stephenson, who performed the procedures.

The mean preoperative corneal astigmatism was 1.01 D, while the mean residual refractive astigmatism was 0.11 D.

In addition, 94.6 % of eyes were within 0.5 D of postoperative refractive cylinder and 81.1% were within 0.25 D or less of postoperative refractive cylinder. No capsule complications were noted at any time during the study.

Postoperative uncorrected distance visual acuity of 20/30 was achieved in 97.3% of eyes, targeting for -0.50 in non-dominant eye, and none of the toric IOLs required repositioning at the time of surgery
or afterward. Data for the analysis was collected in follow-up visits four to six weeks postoperatively.

“The Intelliaxis Refractive Capsulorhexis is a safe and effective tool in aiding the alignment of toric IOL at the desired axis, thus reducing astigmatism and reducing postoperative spectacle dependence,
which leads to optimal patient satisfaction,” said Dr. Stephenson.

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The LENSAR system uses iris registration to accurately place the capsular marks on the intended axis while preforming the capsulotomy. Iris registration, based on high definition preoperative infrared
images obtained with numerous corneal diagnostic instruments in the clinic, allows precise correlation of corneal topographic and total corneal astigmatic
data with laser treatment, opening the way for accurate correction of astigmatism.

The capsular marks have the advantage of eliminating error due to the shortcomings inherent in marking the ocular surface, including surgical parallax, and do not impact the strength or extensibility of the capsulotomy, Dr. Stephenson said. These biochemically stable and permanent capsular marks may also help in postoperative rotation of the IOL and realignment procedures if needed.

"LENSAR’s iris registration-guided femtosecond laser-assisted capsular marks are precise and are vital to achieving accurate toric IOL positioning,” Dr. Stephenson said. “If the IOL rotates by 30 degrees, the astigmatism will remain the same but aligned at an axis other than the original steep axis.”

Capsular marks based on iris registration technology (to account for cyclorotation) are effective in aiding toric IOL alignmentmof IOL at desired axis, thus reducing astigmatism.

“These features can enhance precision and help improve outcomes during cataract surgery, thus improving patient satisfaction,” Dr. Stephenson concluded.

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This article was adapted from Dr. Stephenson's presentation at the 2019 meeting of the American Society of Cataract and Refractive Surgery in San Diego, CA. Dr. Stephenson is a speaker for Lensar, Alcon, and Bausch + Lomb. E: eyedrdee@aol.com

References:

1. Venkataraman A, Kalpana. Visual outcome and rotational stability of open loop toric intraocular lens implantation in Indian eyes. Indian J Ophthalmol. 2013; 61:626-629.
2. Mallias I, Mylova P, Tassiopoulou A. Correction of astigmatism with toric intraocular lenses.Ophthalmology Journal. 2017; 2:49-53.