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Endoscopy beneficial when visualization is limited
A user offers three important pearls for best practice.
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Ophthalmic endoscopy continues to evolve as a powerful technique, especially in the domains of vitreoretinal and glaucoma surgery, namely endoscopic cyclophotocoagulation. Ophthalmic application of endoscopy dates back to 1934, when Thorpe designed an instrument for the removal of nonmagnetic intraocular foreign bodies by combining a Galilean telescope and an illumination source for direct monocular visualization via a 6.5-mm diameter shaft and an 8-mm scleral incision.
Technological advances in ocular endoscopy are evident from the E2 laser and endoscopy system (Endo Optiks), which uses a xenon light source (variable 175 W or 300 W), a diode laser (810 nm), an aiming beam (640 nm) and 23-gauge probes (0.56 mm). Ophthalmic endoscopy bypasses anterior segment opacities to permit visualization of both the anterior and posterior segments of the human eye. It also allows viewing of difficult-to-access areas such as the anterior chamber angle, retroiridial regions such as the ciliary body (pars plana, pars plicata), ciliary sulcus, peripheral lens and anterior retina.
Some of the limitations of ocular endoscopy include postoperative dependence of ultrasonography in cases of opaque anterior segment with poor visualization, extended rehabilitation period when subsequent anterior segment reconstruction is performed for visual improvement, and the surgeon’s learning curve to familiarize with the constant changes in perspective and visualization when using ocular endoscopy.
In this column, Dr. Liao describes the beneficial application of endoscopy in performing surgery in cases of compromised visualization.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor
Visualization is crucial to optimizing surgical outcomes; therefore, it is important to explore innovative imaging methods as technology advances. Ophthalmic endoscopy is a relatively new technology to which I was first introduced during my fellowship at Tufts and Ophthalmic Consultants of Boston. Since then, the endoscope (Endo Optiks) has become an invaluable part of my practice as a vitreoretinal specialist.
The major application of the endoscope is for cases in which the anterior segment is too cloudy for traditional viewing techniques. Significant cataract, corneal edema and iris abnormalities are common preoperative occurrences in patients with complex pathology. Even in routine cases, there are times when the view is excellent at the outset before dramatically degrading. This makes proper visualization of the retina difficult, if not impossible. During these times, endoscopic vitrectomy offers a distinct surgical advantage in terms of safety and outcomes.
An external view of an eye with corneal decompensation and iris abnormalities following complicated cataract surgery. Vitrectomy with traditional viewing methods would be difficult through such media opacities.
Source: Liao D
An external view of the same eye with the endoscope at the time of surgery.
The infusion cannula is visualized within the vitreous cavity using endoscopy. The cannula is seen safely located in the pars plana with vitreous fibers below.
The cutter is seen within the vitreous cavity surrounded by detached retina and hemorrhage.
The cutter is again visualized over detached retina. The endoscope is being held at this point in the case by the surgeon’s dominant hand and was switched to the opposing hand as needed.
Another application of endoscopy is in cases in which pathology exists anteriorly, such as over the pars plana or ciliary body. Eyes with anterior proliferative vitreoretinopathy can require deep scleral depression and/or lensectomy to view membranes using conventional techniques. With endoscopy, the surgeon has complete visual access to these areas with little difficulty.
The infusion cannula is visualized within the vitreous cavity using endoscopy. The cannula is seen safely located in the pars plana with vitreous fibers below.
Pearls for best practice
There are a few important points to remember when beginning to use the endoscope. First, maintaining proper image orientation can be initially challenging. This is because we are used to en face viewing of the posterior pole through the operating microscope. While holding the endoscope probe, small rotational movements can significantly change image orientation on the viewing screen. Therefore, orienting the scope before entering the eye and maintaining that orientation during the case allows the user to safely manipulate instruments within the vitreous cavity.
A view of the macula flat under perfluorocarbon. The fovea is to the left and the nerve is to the right.
Laser in attached retina at the edge of a relaxing retinectomy. Laser is being applied by means of a traditional probe, but can be applied through the endoscope probe as well.
A soft tip extrusion cannula is shown removing residual perfluorocarbon liquid in the silicone oil filled vitreous cavity. The retina remains attached.
A flat retina under silicone oil at the conclusion of the case. A chandelier light assists with diffuse illumination.
Second, finding the optimal distance been the scope and tissue to be viewed is critical. Positioning the scope tip closer to tissue improves resolution and illumination but decreases field of vision on the video screen. Thus, keeping an intermediate distance from probe to tissue optimally balances image quality and viewing area.
Lastly, the use of complementary techniques, such as illumination via chandelier lighting or staining via dyes and triamcinolone, can be helpful during endoscopy.
A memorable case
I was recently referred a patient who had undergone complicated cataract extraction. He presented with corneal decompensation, iris synechiae, choroidal hemorrhage and total retinal detachment. Without extensive anterior segment reconstruction, repair of the detachment would have been impossible using traditional viewing methods. With the help of the endoscope, I was able to visually confirm and release adhesions of the retina to the anterior segment, flatten the retina using perfluorocarbon, and apply laser and silicone oil tamponade. The use of the endoscope was pivotal in this case and gave me the ability to confidently address the patient’s pathology with good visualization.
While I typically utilize the endoscope a few times a month, having it available has been useful during both routine and complex surgeries. Ultimately, it is a valuable complementary tool upon which I can rely when there is no other practical way to complete a case.
References:
Kawashima S, et al. Expert Rev Med Devices. 2014;doi:10.1586/17434440.2014.882226.Thorpe H. Trans Am Acad Ophthalmol Otolaryngol. 1934;39:422-424.
Wong SC, et al. Curr Opin Ophthalmol. 2014;doi:10.1097/ICU.0000000000000052.
Wong SC, et al. Dev Ophthalmol. 2014;doi:10.1159/000360456.
For more information:
David Liao, MD, PhD, is in practice at Retina-Vitreous Associates Medical Group. He can be reached at dliao@laretina.com.Edited by Thomas “TJ” John, MD, a clinical associate professor at Loyola University at Chicago and in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at 708-429-2223; email: tjcornea@gmail.com.
Disclosure: Liao and John have no relevant financial disclosures.