Publication Exclusive: Femtosecond laser allows fine-tuning of capsulotomy size

Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a joint society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.

As more surgeons have access to femtosecond laser technology for cataract surgery, we are now able to fine-tune our procedure in ways we never thought possible. One area is the capsulotomy. While we have long understood the importance of a circular and well-centered capsulotomy, we now are able to discuss the importance of fractions of a millimeter when it comes to capsulotomy size. Twenty years ago, this discussion would have seemed irrelevant, but now, we are able to see how much more precision we have gained in our technique to allow patients to achieve the best outcomes possible.

This month, Carlos Buznego, MD, and Jennifer Loh, MD, discuss the merits of adjusting the capsulotomy size. We hope you enjoy the discussion.

Kenneth A. Beckman, MD, FACS, OSN CEDARS/ASPENS Debates Editor

Laser capsulorrhexis: How small is too small?

The femtosecond laser has provided ophthalmic surgeons with an incredibly precise instrument to facilitate cataract surgery. However, surgeons are sometimes faced with uncertainty as how to best utilize this powerful new tool.

Laser capsulotomy is among the most important uses of the femto laser. A well-formed capsulorrhexis is widely accepted as the most important step in successful cataract surgery. A perfectly formed and centered rhexis maximizes the strength of the capsular bag, minimizes posterior capsule opacification and facilitates consistent effective lens position.

Some early experience with laser capsulotomy suggested that a rhexis diameter of less than 5 mm was associated with weakened tensile strength and increased risk of capsular breakage. Anatomical studies suggested that the maximal thickness of the anterior capsule is seen at diameters of 4.9 mm to 5.5 mm. In addition, Packer and colleagues found that capsulorrhexis strength was statistically stronger in a 5.5-mm capsulorrhexis compared with a 4-mm capsulorrhexis. These factors have contributed to the widespread acceptance of a 5- to 5.5-mm capsulorrhexis by the majority of femto laser cataract surgeons.

However, how should we manage patients with poorly dilating pupils? This can be a relatively large proportion of our cataract patients. Risk factors for pupillary miosis include pseudoexfoliation, alpha blocker usage, diabetes, glaucoma, uveitis and prior trauma. Should we simply defer to manual capsulorrhexis? Should we utilize a device to expand the pupil and proceed with femto laser capsulorrhexis and re-dock an “open” eye? Or can we perform femto laser capsulorrhexis in patients with suboptimal pupil size?

Our center has had good experience utilizing femto laser capsulorrhexis in patients with dilated pupils of less than 5 mm. Trattler and colleagues reported a series of 39 cases of small-diameter capsulorrhexes performed by seven different surgeons utilizing the same Lensar laser. Patients in this series had femto laser capsulorrhexis performed with diameters ranging from 3.9 mm to 4.9 mm. The limited series showed successful and uncomplicated cataract surgeries in all of the patients.

Our experience confirms that when performed with caution, femto laser capsulorrhexis can be utilized for cataract surgery patients with dilated pupils under 5 mm in diameter. In fact, these patients who are at higher risk for surgical complications benefit from the consistency of the perfectly formed capsulorrhexis and the laser nuclear fragmentation that follows.

Click here to read the full publication exclusive, CEDARS/ASPENS Debates, published in Ocular Surgery News U.S. Edition, December 25, 2015.