By Martin Uram, MD, MPH;special to Modern Retina
While use of the endoscope is widespread, there are still surgeons who feel the microscope is sufficient. However, the increased visualization that the endoscope provides is an invaluable tool that can significantly improve outcomes in a variety of cases, particularly retinal surgeries.
While the microscope has limited range, the endoscope allows for enhanced visualization of anterior structures that are not usually visible.
Laser endoscopes perform three main functions-they provide light, image, and laser. Rather than the 30º cone of light possible with a microscope, the endoscope provides a 120º to 140º lighted field that enables the surgeon to see anything within the eye. The endoscope also comes as 23-gauge, so can be used with 23-gauge cannula systems.
Conversely, the microscope only allows for top-to-bottom imaging. In the periphery it is difficult, or impossible, to see. As a great deal of pathology may lie within that peripheral zone, there is a much greater risk of missing outlying pathology.
There are also a variety of issues that may block imaging when performing a vitrectomy, such as a cloudy cornea, small pupil, cataracts, blood or opacities, or condensation on a lens implant. With an endoscope, none of this is a problem.
The microscope is indispensable, but the endoscope provides a great deal of versatility, especially with retinal diseases. When performing procedures, there will come a point when the retinal periphery is no longer visible through the BIOM.
The endoscope can then be placed so that every hole and degenerative spot in the retinal periphery is visible, allowing the surgeon to monitor the surgery and deliver laser to parts of the eye that are not usually visible. Using the endoscope can improve surgical skills and allow the performance of maneuvers in a wide variety of “every-day” cases that would take more time or would be difficult or impossible to complete.
Image 1. Endoscopic view of Sommering ring overlying pars plana.
A 53-year-old female presented with intermittent blurred vision. Upon examination, it was discovered this was due to a Sommering ring from cataract surgery that she had undergone decades prior.
As the eye would move, the ring would float in and out of her pupillary axis, blocking her vision. The only solution was to remove this lens material.
To do this, a three-port vitrectomy was performed using the laser endoscope for illumination and visualization. Once the vitreous was removed, the free-floating Sommering was addressed.
As the ring was large and extremely hard, it was not possible to remove it in one piece through the sclerotomy site. It was necessary to break the ring into smaller pieces. This can sometimes be accomplished by pressing forceps against it or cutting it with a vitrector.
Image 2. Endoscopic view of lifesaver-shaped Sommering ring with retinal periphery in the background.
As this patient’s ring had been in her eye for several decades, it was hard to break manually. The only way to remove it was to perform phaco-fragmentation, capturing the ring with suction through the frag tip and then apply phacoemulsification.
Image 3: Endoscopic view of Sommering ring on surface of highly myopic retina.
With free-floating lens material, the risk of retinal damage is increased as the surgeon “chases” the pieces around the vitreous cavity. Using an endoscope greatly reduces this risk as it enables visualization of most of the ocular interior allowing the surgeon to easily visualize and repeatedly capture the ring.
The Endo Optiks E2 Ophthalmic Laser Endoscopy System (Beaver Visitec Inc.) was used for this task. By holding the endoscope closer to the sclerotomy site, a panoramic view of the inside of the eye was created. Once the ring was located, the frag tip was directed toward the lens fragments lying on the surface of the retina, and aspirated into the port of the frag tip.
Then, while holding lens fragments in the mid-vitreous cavity, phaco-fragmentation was initiated. This process was repeated multiple times. Because the ring was easily visible through the endoscope, it was accomplished quickly.
Image 4: Endoscopic view of partially removed Sommering ring.
If attempted using only a microscope, this process can become frustrating as the fragments may fall into an area of the eye that is not visible through the microscope. Once the ring was completely removed, the incisions were closed.
Recovery was similar to traditional cataract surgery. Because the patient was a high myope, visual acuity of her aphakic eye was 20/25 at post-op Week 1.
Martin Uram, MD, MPH
Dr. Uram is an ophthalmologist with Monmouth Retinal Consultants and the founder and chairman of Endo Optiks Corp. He is also the inventor of the Ophthalmic Laser Microendoscope, for which he received the Thomas Alva Edison Patent Award.