Posterior segment endoscopy brings unique views for diagnosis

TAKE HOME MESSAGE: Endoscopy can be valuable in identifying and addressing problems in the posterior segment.

By Cheryl Guttman Krader; Reviewed by Roger Goldberg, MD, MBA

San Francisco Bay Area, CA-Endoscopy is a valuable addition to the vitreoretinal surgeon’s toolbox-enabling visualization of the posterior segment in situations when the traditional view through the operating microscope is limited.

The recent introduction of a higher-resolution, 23-gauge endoscope (Beaver-Visitec, formerly Endo Optiks) represents an important advance and further lowers the barriers for adopting the technique, according to Roger Goldberg, MD, MBA.

“The 23-gauge endoscope fits through the valved microincisional cannula systems that vitreoretinal surgeons are now using routinely,” said Dr. Goldberg, vitreoretinal surgeon, Bay Area Retina Associates, San Francisco Bay Area, CA. “There is a learning curve for implementing endoscopy, but once surgeons become comfortable with it they will find more and more applications for its use.

“A new 10,000-pixel, 23-gauge endoscope nearly doubles the resolution while expanding the field of view from 90° to 125°,” he added.

Role in visualization

The historic and still primary role for posterior segment endoscopy is to allow visualization in eyes with compromised anterior segments. In eyes with corneal or anterior chamber opacification, use of the endoscope eliminates the need for simultaneous or sequential anterior segment surgery, which minimizes operating room time and resources and avoids the need to coordinate schedules among multiple surgeons.

In addition, visualizing and being able to address problems due to pathology in the retro-iris space is another category of cases when the endoscope can be helpful. This can occur in such cases as hypotony due to anterior proliferative vitreoretinopathy (PVR), persistent cystoid macular edema (CME) after complicated cataract surgery with retained lens fragments, and endophthalmitis.

“The advantage of using endoscopy in eyes with anterior PVR is that it enables the identification and release of traction on the ciliary body,” Dr. Goldberg said.

“Without an endoscope, surgeons can use scleral depression to bring the area behind the iris into view through the pupil,” he added. “However, that maneuver requires a skilled assistant, and it distorts the natural anatomy, limiting identification of the traction points.”

Dr. Goldberg said he has used endoscopy to identify and remove lens fragments hidden behind the iris in a patient who had a ruptured posterior capsule during cataract surgery.

“The cataract surgeon thought all of the lens material had been successfully removed, and nothing was visible on a postoperative dilated fundus exam,” he said. “However, the cystoid macular edema persisted, and we found lens fragments behind the iris that were easily identified and removed with the endoscope and vitreous cutter.”

Sometimes, the endoscope is useful both for bypassing anterior segment opacification and identifying retro-iris pathology. For example, Dr. Goldberg cited a case of persistent inflammation after a tap and inject and subsequent vitrectomy for endophthalmitis.

“The view through the cornea was not perfect, so use of the endoscope was planned preoperatively,” Dr. Goldberg said. “During the case, we found what appeared to be an abscess behind the iris. The endoscope made it easy to find and remove with the vitreous cutter. It’s logical that this may help hasten the resolution of inflammation.”

In eyes undergoing glaucoma tube surgery with pars plana placement, endoscopic examination at the end of the procedure allows confirmation that the tube is free of vitreous. In a related situation, Dr. Goldberg said posterior segment endoscopy allowed him to identify and manage vitreous that was plugging a non-functioning pars plana tube.

Getting comfortable

Endoscopy in ophthalmology is gaining traction through endoscopic cyclophotocoagulation (ECP) done from an anterior approach at the time of cataract surgery, Dr. Goldberg noted.

“As the installed base of endoscopy units increases, more and more retinal surgeons will find they have an endoscope available to them,” he said. “This makes it more readily accessible to learn.”

Since there is a learning curve to using the endoscope, Dr. Goldberg suggested surgeons avoid the most complicated cases early on. In order to gain familiarity with the technique, he suggested inserting the endoscope at the end of cases when a 23-gauge valved system is used.

By taking just a few extra minutes in each case, surgeons can begin to get a feel for the different perspective-both depth and field of view-and how much the image changes with just a slight rotation of the endoscope, he said.

“Feeling comfortable knowing where you are in the eye and how close to the target tissue to hold the endoscope is key,” Dr. Goldberg said. “There is a trade-off between resolution and field of view, though the new, higher-resolution, 23-gauge probes help improve both components of this.”

One tip Dr. Goldberg suggested to those getting started with endoscopy is to identify the optic nerve and macula immediately and use those landmarks to orient the endoscopy probe initially.

“The learning curve is really quite manageable, and I suspect vitreoretinal surgeons, who are used to thinking in a 3-D perspective, will pick up the technique very quickly,” he said.

Roger Goldberg, MD, MBA

E: rgoldberg.eymd@gmail.com

Dr. Goldberg has no relevant financial interest to disclose.