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Innovations | Sep 2007

Top 10 Phaco Innovations

Many advances have been made in the past few years.

Techniques and instrumentation for phacoemulsification have come a long way, with many advances made within the past few years. These evolutionary and revolutionary changes have made our modern methods for surgery safer, more efficient, and less traumatic, with better visual function for our patients. Below is a list of what I feel are the top 10 recent surgical innovations for phacoemulsification and cataract surgery.

Loose zonules can transform an otherwise straightforward surgery into a difficult case with a high risk of complications and visual dysfunction. Capsular tension rings (CTRs) can stabilize the capsular bag during phaco surgery as well as provide long-term support to ensure IOL centration. New available variants include the (1) Cionni modified CTR (Morcher GmbH, Stuttgart, Germany) that allows suture fixation, (2) Ahmed capsular tension segments (CTS; Morcher GmbH) that provide focal support, and (3) Henderson CTR (in development) that permits easier cortex removal.

Nonpreserved intracameral medications have enhanced phaco surgery. We can use lidocaine to enhance anesthesia, epinephrine to dilate the pupil and increase iris tone, and cholinergics to induce miosis. The landmark European Society of Cataract and Refractive Surgeons (ESCRS) study showed that intracameral cefuroxime may help to prevent endophthalmitis, and using depot injections of vancomycin may have the same benefit. Triamcinolone may be used to stain prolapsed vitreous as well as effectively control postoperative inflammation in difficult cases. If white mature cataracts limit the surgical view, the anterior capsule may be dyed with trypan blue to facilitate capsulorrhexis creation.

Computer-controlled modulations of phaco power have enabled us to decrease phaco energy so dramatically that pseudophakic bullous keratopathy and phaco incision burns are now nearly extinct. The abilities to vary the duty cycle used in pulse mode and perform a high pulse rate and a brief phaco burst are now widely available on many platforms. By reducing phaco energy delivered into the eye, we move toward phaco-assisted vacuum aspiration of the cataract, with clear corneas and good vision occurring immediately after surgery. Because the phaco needle stays cool, the silicone sleeve may be removed, and we can use smaller incisions.

Removing the sleeve and using just the bare phaco needle can significantly decrease the incision size. With this biaxial technique (Figure 1), fluid infusion is moved to a second incision via use of an irrigating chopper, allowing for smaller incisions, and more importantly, separated infusion within the eye. The inflow fluid can be directed to keep a posterior capsule away from the phaco needle or to bring nuclear material to the phaco tip. To keep up with the trend toward smaller incisions, thinner sleeves were developed that allow coaxial small-incision phacoemulsification. Now, surgeons have a choice between biaxial or coaxial microincisional cataract surgery.

With smaller incisions, we need smaller instruments. The adoption of retina-style microinstrumentation has advanced how we handle complex phaco and anterior segment cases. New 23- and 25-gauge intraocular scissors, grasping forceps, tying forceps, and manipulators are available for anterior segment surgery. Performing a purse-string suture of the iris used to be complex, with many incisions required. Now, the tiny 10–0 nylon suture and entire curved needle may be placed within the anterior chamber, and the procedure is performed via two paracentesis incisions. With these specialized instruments, cutting an IOL, creating a peripheral iridectomy, or creating a pediatric capsulorrhexis may now be performed within a formed anterior chamber.

Viscoelastics were originally designed to protect the corneal endothelium and provide a degree of anterior chamber stability. With the full spectrum of viscoelastics now available, we have the ability to do more. The techniques of viscomydriasis for enlarging a pupil, creating compartments within the eye, preventing vitreous prolapse, controlling iris floppiness and extrusion, coating corneal epithelium, and lubricating injector systems are all possible due to our palette of viscoelastics. We have dispersives, cohesives, viscoadaptives, and combination agents that address nearly all surgical situations.

A frequent cause of complications during phaco surgery is fluid surge, which may result in a broken posterior capsule, vitreous prolapse, or retinal pathology. Hardware and software controls to limit surge have increased intraoperative safety and improved the range of fluidics management. Flow-restrictive devices (Figure 2) use the laws of fluidic resistance to ensure that inflow is greater than outflow, thereby decreasing surge. New fluid pumps, and the software that control them, allow better reaction time and faster return to a steady state. As we begin to perform cataract surgery earlier and as refractive lens exchange cases increase, fluidics control is becoming more important than ultrasound delivery.

Even with recent advances in safety, all surgeons inadvertently break the posterior capsule during surgery from time to time. Having the ability to remedy the situation, perform a small vitrectomy, and still implant the lens of choice can make these complications easier to deal with. The 25-gauge vitrectomy system is a tool that all cataract and anterior segment surgeons should learn to use, because it allows for a safe and efficient anterior vitrectomy via small incisions within a closed chamber. This 25-gauge system is also helpful in complex cases (eg, traumatic cataracts with preexisting vitreous prolapse, congenital lensectomy surgery in infants).

Traditional I/A tips allow metal to contact the delicate posterior capsule, which may result in a rupture. Alternately, a soft silicone I/A tip (Figure 3) has a cushion effect, protecting the posterior capsule. The cobblestone-textured finish allows gentle scrubbing of the capsular bag and mechanical removal of any lens cortex. There is no point in performing exacting lens calculations, microincisional techniques, and premium lens implantation if the capsule breaks, the vitreous prolapses, and the patient ends up with cystoid macular edema. Due to this innovation, the incidence of a posterior capsule rupture during I/A and cortex removal has been near zero in my practice for years.

The goal of phaco or lens-based surgery is to restore the health and level of vision found in normal youth, principally eliminating refractive errors and restoring a wide range of focal distances. The holy grail of ophthalmology is the reversal of presbyopia, and although multifocal lenses may effectively provide a wide range of vision, nothing is better than restoring true accommodation. The current generation of accommodating IOLs is better than their predecessors, and we can expect that every subsequent generation will be better than the previous. The accommodative amplitude and range of functional vision will continue to increase as the technology progresses. Look at the incredible advances in phaco machines, instrumentation, IOLs, and viscoelastics over the last decade—this same level of progression will occur with accommodating IOLs. I firmly believe that the future of lens surgery will be refractive lens exchange with accommodating IOLs for presbyopia reversal, and that is why it is the most important phaco innovation.

Uday Devgan, MD, FACS, practices at the Maloney Vision Institute, in Los Angeles, and is Chief of Ophthalmology, Olive View-UCLA Medical Center. Dr. Devgan states that he is a consultant for Allergan, Advanced Medical Optics, Bausch & Lomb, Eyeonics, Ista Pharmaceuticals, and STAAR Surgical, and has received award funds and travel support from Alcon. He may be reached at +1 310 208 3937; devgan@ucla.edu.