Femtosecond Surgery

 

Femtosecond Laser Assisted Cataract Surgery

Information for referring optometrists

If you look at the history of cataract surgical technique over the last few decades, you will find a group of highly motivated surgeons in private practice, who were never satisfied that they were performing the best available operation for their patients. Surgeons in this group were always striving to perform better surgery. They were also active in teaching of other surgeons. Many personalities from Canada, the U.S.A, Japan and Europe became world famous among eye surgeons for their innovation.

Their colleagues argued that the increased effort and the financial cost of new innovations were simply not worthwhile; and that the surgical technique at the time was good enough to continue indefinitely.

At no time was this more visible than during the transition from large incision cataract “extraction” with sutured closure to small incision Phacoemulsification and foldable IOL insertion in the early 1990s. This was truly revolutionary.

History shows us that a succession of highly motivated and innovative surgeons subsequently invented new techniques to remove cataracts in their quest for perfection. Much of their efforts were directed at how to remove the nucleus of the cataract most efficiently with the minimal amount of trauma.  Colourful terminology such as “divide and conquer, phaco chop, phaco pre chop” began to enter the lexicon of eye surgeons. These surgeons incrementally raised the standard of surgery over a period of time. Their cumulative efforts have resulted in much better outcomes for patients.

Major breakthroughs and true paradigm shifts are few and far between. Thus far, these have occurred once or twice in the professional lifetime of an eye surgeon. Surgeons who were unable to master the new technique retired from operating. Often times a major breakthrough or a paradigm shift was not recognized for what it was, until after the event.

Eye Surgeons are now offered the benefits of Femtosecond Laser Assisted Cataract Surgery. Some surgeons argue that their current surgical technique is so good that it cannot be improved upon, that their surgical results are so good that they cannot see any benefit from the new technology.  I find this attitude to be extremely puzzling. So long as the surgical success rate of surgery is less than 100%, and the complication rate is not zero, there will always be room for improvement.

The first step in adopting the new technology is to admit that a precision machine can do certain parts of the operation better than a surgeon’s hands with manual instruments (forceps for the capsulorhexis opening in the anterior capsule) with visualization through an operating microscope.

Femtosecond Laser has a wavelength that is infrared and not visible to the eye. It will penetrate tissue that is transparent to infrared light. This includes cornea, lens capsule and cataract (if not completely opaque viz mature and white). “Femto” refers to the very short duration of the laser pulse. It is 10 to the power of minus 15 of a second. Ultra short packets of high energy are released. Gas bubbles are created. A computer controls the depth of delivery and the direction of the laser. It is in effect a “cutting” laser.

A real time OCT images the location of front and back of the cornea. It images the iris. It locates the anterior capsule, central lens and the posterior capsule. The OCT has micron accuracy (one thousandth of a millimeter). It has far greater resolution than the surgeon’s eyes.

The laser is located in a room separate from the operating room (The Laser Room). The patient must be coupled to the laser, a procedure called “docking” to enable real time OCT localization to direct the computer controlled laser beam.

The surgeon and staff will program the laser computer to the chosen surgical parameters including:-

  • capsulotomy (perfectly round opening in the anterior capsule) -  diameter and location

  • predivision of the nucleus- shape and number of fragments

The laser will create a perfectly circular opening in the anterior capsule of an exact chosen diameter. It is impossible for the surgeon to create such perfectly round openings of consistent shape, size and centration. Rare complications of surgery related to imperfect manual capsulorhexis openings are avoided.

The nucleus of the cataract is pre divided by laser into segments of a shape and number programmed by the surgeon. In the past, this was achieved by the phacoemulsification probe (“trench divide and conquer, phaco chop, four quadrants cracking etc). The consequent reduction of phacoemulsification time and power, the reduction in surgical time and the reduction in the volume of irrigating fluid is beneficial to the corneal endothelium. The laser will not penetrate the posterior capsule. The surgeon rarely does.

Femtosecond laser assisted cataract surgery is ideal for patients who have compromised corneas (corneal guttae). Patients with normal corneas should also benefit.

Femtosecond laser assisted cataract surgery is ideal for patients with weak zonular ligaments such as in Pseudoexfoliation Syndrome.

The laser part of surgery is performed under topical anaesthesia with no sedation and full patient cooperation and awareness.  The surgeon will speak to the patient in the Laser Room. The patient will be asked to fixate on a light. The patient will be reassured that all is going well. As the patient is not sedated, this is the part of the operation that they will remember. They will remember a pleasant experience. Immediately after laser, the eye has not yet been entered.

If the patient requires a Toric IOL for astigmatism, the 0 -180 degree axis is marked on the limbus with ink. The patient will be seated upright in front of a slit lamp (cyclotorsion is frequent when the patient lies on the operating table).

Patients are then transferred into the operating room (The Operating Theatre) where they meet the Anaesthetist. Intravenous sedation is given at the discretion of the anaesthetist. The eye is prepared with Betadine and a sterile drape is applied. The same sterile technique that is used for conventional surgery is applied.  An operating microscope is used (Microsurgical Removal of the Cataract). The nucleus is removed with the phaco probe. The cortex is removed with the irrigation aspiration probe. The Intraocular Lens (IOL) is injected into the viscoelastic inflated capsular bag as usual. The incisions self-seal.

Typically in my hands, removal of the cataract is performed under topical anaesthesia. There is an option to use a local anaesthetic injection block if necessary. I do not pad or cover the eye if surgery was performed under topical anaesthesia. My patients walk out of the operating theatre.

 

In summary, Femtolaser Assisted Cataract surgery is the first fundamental change in the way that cataract surgery has been performed for the last 20 years.
Femtosecond Laser Assisted Cataract surgery is:-

  • more precise, accurate and reproducible

  • a  more safe method of cataract surgery

  • more gentle on the corneal endothelium

  • the operation that I would want for myself if I needed cataract surgery

I must however emphasize that most improvements in surgical technique are incremental, and not always a quantum leap forward or revolutionary.  Manual phacoemulsification is an excellent surgical technique that has been refined over 30 years. It may remain the most frequently performed cataract operation for some years to come. Femto second laser offers an improvement over an already good surgical technique which has already achieved excellent visual results and improvement in the quality of life for millions of patients worldwide.