LRI: A simple way to enhance refractive outcomes during cataract surgery

Introduction

Cataract surgery presents a one-time opportunity to optimize visual performance, health, and lifestyle. Whether it's to correct presbyopia or to provide good vision more like that of a healthy younger person, today's high-technology multifocal and aspheric IOLs now give both surgeons and patients more treatment options.

Limbal relaxing incisions (LRIs) give ophthalmic surgeons the opportunity to correct astigmatism at the time of surgery, providing even better visual outcomes to meet patients' growing expectations.

New intraocular lens (IOL) technology has made it possible to provide cataract patients with vision more like that of young adults. For those patients who desire spectacle independence, the Premium multifiocal and accommodating IOLs can provide a full range of vision under various light conditions. For those patients who are not candidates for a Premium lens or don't mind wearing glasses for close distances, the New Technology IOLs are designed to reduce spherical aberration to zero for safer, sharper distance vision. To maximize the "wow" factor that is possible with these lenses, it is necessary to correct any existing astigmatism during cataract surgery to less than 0.5 diopters (D).

Astigmatism overview

Astigmatism is an abnormality of the eye in which vision is blurred by an irregularly shaped cornea. One axis of the cornea is steeper than the other, causing the cornea to distort images. There are four different types of astigmatism based on which axis is steepest: With-the-rule (WTR), Against-the-rule (ATR), Oblique and Irregular.

Treating astigmatism at the cornea is the most logical approach. During cataract surgery, it is possible to correct some or all of this defect through a simple incision-an LRI.

 

 

 

Limbal relaxing incision overview

LRIs "relax" the steep axis of astigmatism and allow the eye to heal into a more spherical shape. The LRI is made in the limbus, near where the clear cornea and sclera meet. Any residual astigmatism may be treated postoperatively through an additional LRI.

The goal of today's cataract surgeon is to target precise refractive outcomes within 0.5 diopters (D) of sphere and cylinder. In many patients, this goal can be achieved by performing LRIs to reduce astigmatism during the cataract procedure.

 

 

 

Astigmatism in cataract patients

Cataract surgery and limbal relaxing incisions give surgeons the opportunity to correct astigmatism, spherical error, and lenticular opacity at the same time. Since LRI correction is based on the patient's actual corneal cylinder and is not dependent upon the diopter steps of a lens, LRIs have gained widespread acceptance among cataract surgeons. According to the 2006 Leaming Study, 46% of cataract surgeons in the US treat astigmatism with LRIs during cataract treatment.

 

 

 

 

 

LRI effectiveness

Most astigmatism can be corrected during cataract surgery with LRIs. An Olson peer-reviewed study on the effectiveness of LRIs showed:

• 60% average reduction of cylinder
• 79% of patients were corrected to less than 1.0 D of cylinder
• 59% of patients were corrected to less than 0.5 D of cylinder

The 60% average reduction in cylinder compares favorably with results achieved using toric IOLs. A leading toric IOL results in a 54.8% mean reduction in astigmatism.