Two new studies add to the growing body of evidence that a new approach to cataract surgery may be safer and more efficient than today's standard procedure of phacoemulsification.
The new approach, using a special femtosecond laser (more info here and here), is FDA-approved in the United States, but not yet widely available in the US. Research reported at the 2011 American Academy of Ophthalmology conference in Orlando by William W. Culbertson, MD, of the Bascom Palmer Eye Institute at the University of Miami School of Medicine, and by Mark Packer, MD, of Oregon Health and Sciences University, confirms several advantages of laser cataract surgery.
Dr. Culbertson's team studied how pre-treating cataracts with the femtosecond laser affected the level of ultrasound energy needed to soften the cataracts. This emulsification is performed so that the cataracts can be easily suctioned out. Surgeons want to use the lowest possible level of ultrasound energy, since in a small percentage of patients, it is associated with slower recovery of good vision after surgery and/or problems with the cornea, which is the clear outer layer of the eye. Ideally, in appropriate cases, ultrasound use would be eliminated altogether.
In Dr. Culbertson's prospective, randomized study, patients had laser cataract surgery with a femtosecond laser in one eye and the standard cataract procedure, called phacoemulsification, in the other. Laser surgery included a laser capsulotomy, which is a circular incision in the lens capsule, followed by laser lens fragmentation, then ultrasound emulsification and aspiration. Lens fragmentation involved using the laser to split the lens into sections and then soften it by etching cross-hatch patterns on its surface. Standard surgery included a manual incision, followed by ultrasound emulsification and aspiration. After cataract removal by either method, intraocular lenses were inserted into eyes to replace the natural lens and provide appropriate vision correction for each patient.
The use of ultrasound energy use was reduced by 45 percent in the laser pre-treated eyes compared with the eyes that received the standard cataract surgery procedure. Also, surgical manipulation of the eye was reduced by 45 percent in eyes that received laser pre-treatment as compared to manual standard surgery. This study involved the most common types of cataracts, those graded 1- 4. Dr. Culbertson notes that these findings may not apply to higher grade cataracts.In clinical practice, surgeons would expect safer, faster cataract surgery when laser pre-treatment is performed before cataract removal, as per Dr. Culbertson, with the combination of precision and simplification possible with the femtosecond laser represents a major advance for this surgery.
Laser lens fragmentation also demonstrates that it can protect the corneal endothelial cells. Dr. Packer and his colleagues at the Oregon Health and Sciences University in Portland, Oregon, assessed the safety of laser cataract surgery vis-a-vis loss of corneal endothelial cells, as measured after cataract surgery. Measuring endothelial cell loss (measured by a test referred to as specular microscopy) is one of the most important ways to assess the safety of new cataract surgery techniques and technology. These cells are important since they preserve the clarity of the cornea, which is important, since they do not regenerate and hence have to last a lifetime to preserve corneal clarity. Dr. Packer's study found that with laser lens fragmentation, there was no loss of endothelial cells, while eyes that received standard treatment had cell loss of one to seven percent.
Earlier studies of femtosecond laser cataract surgery have found other advantages. The laser allows the surgeon to make smaller, more precise incisions, and to perform improved capsulotomies (the initial cut in the anterior capsule of the lens to ease in removal of the cataract and insertion and secure placement of the intraocular lens (IOP) placement). This secure placement reduces the possibility of displacement of the IOL. Also, laser cataract surgery appears to improve results in patients who opt for advanced technology IOLs, plus corrective corneal incisions, to achieve good all-distance vision.
Femtosecond lasers have been used by ophthalmologists for years in refractive surgery such as LASIK, in-corneal transplants, and in other procedures. In 2009, a new type of femtosecond laser that could reach deep enough into the eye to be used in cataract removal was approved by the FDA.
