RETINA PEARLS: Fundus Visualization With Wide-angle Viewing Systems
These devices allow surgeons to recognize fundus pathology and treat lesions safely and effectively.
In this issue of Retina Today, Masahito Ohji, MD, provides an overview of wide-angle fundus viewing systems.
We extend an invitation to readers to submit pearls for publication in Retina Today. Please send submissions for consideration to Ingrid U. Scott, MD, MPH (email@example.com); or Dean Eliott, MD (firstname.lastname@example.org). We look forward to hearing from you.
—Ingrid U. Scott, MD, MPH; and Dean Eliott, MD
Vitrectomy is unique because surgeons cannot see the surgical field—the fundus—without the aid of devices or instruments. It is imperative that surgeons are able to view the fundus to perform precise vitrectomy procedures. Several devices and instruments are available for fundus viewing, including floating lenses and wide-angle viewing systems. This article discusses some of the wide-angle viewing systems.
Preferences and Trends (PAT) surveys1,2 conducted by the American Society of Retina Specialists reveal that most vitreoretinal surgeons currently use a wide-angle viewing system. These systems provide a wider field of view compared with floating lenses, allowing surgeons to recognize peripheral fundus pathology better and to treat lesions more safely and efficiently. Having a wider field of view of the fundus has become increasingly important with 23- and 25-gauge microincision vitrectomy surgery (MIVS) because it is difficult to rotate the patient’s globe and indent the sclera during vitrectomy. Additionally, wideangle viewing systems provide a relatively good view of the fundus in eyes with small pupils or mild corneal opacity. Furthermore, surgeons do not have to change the lens during fluid-air exchange.
There are several kinds of wide-angle viewing systems, and they are typically broadly classified as contact-lens and noncontact systems. Each system has advantages and disadvantages, as described below.
Manfred Spitznas, MD, first described the Binocular Indirect Ophthalmo Microscope (BIOM; Oculus, Wetzlar, Germany), one of the original wide-angle viewing systems, in 1987.3 The BIOM incorporates the principle of indirect ophthalmoscopy into the operating microscope. According to PAT surveys, this is the most commonly used wide-angle viewing system among vitreoretinal surgeons.1,2 Initially, the BIOM required manual focus adjustment and an image inverter. This technology has evolved; the latest version of the BIOM system, BIOM IV, includes an automatic inverter and focus adjustment with a footswitch.
The Optical Fiber Free Intravitreal Surgery System (OFFISS; Topcon Medical Systems, Oakland, NJ), developed in 2003 by Masayuki Horiguchi, MD,4 is a wide-angle viewing system for the OMS-800 Operation Microscope (Topcon Medical). The technology is similar to the BIOM system. The lens has a large diameter, which allows fundus viewing to the ora serrata. With OFFISS, surgeons can adjust the focus using the microscope’s footswitch.
A unique feature of the OFFISS system is that the illumination is incorporated into the microscope. Surgeons can see the fundus without using a light pipe. Therefore, this technology allows surgeons to perform a bimanual technique with regular instruments.
The Peyman-Wessels-Landers 132 D Upright Vitrectomy Lens (PWL; Ocular Instruments, Bellevue, WA) provides wide-field, upright images without an inverter because of an internal prismatic system.5 It is less expensive than other noncontact systems. The focus can be adjusted with the footswitch.
One possible disadvantage of this system is that it may be difficult to maintain an appropriate x-y-z position with tilting when the device is attached to the wrist rest or to the microscope with the standard clamp, straight rods, and linkage system. Recently, we developed a holding system for the PWL lens to overcome this potential disadvantage. 6 The lens holder consists of three parts: the holding device, the rotating bar, and the lens holder. The holding device is fixed to the microscope and holds the rotating bar. The lens holder is fixed with a screw to the window at the lower part of the rotating bar.
When the surgeon sets up the new holding system, the lens holder can be easily and precisely held at the center of the light axis (Figure 1). Surgeons obtain a wide-field image of the fundus through the PWL lens held with the lens holder. It is easy to remove the lens temporarily when performing a procedure in the anterior segment without the fundus viewing system and to move it back to the center of the optical axis to see the fundus. Another advantage of the system is that surgeons can see the sclerotomy or 23- or 25-gauge cannula directly under the microscope by rotating the lens holder a little off the center of the optical axis (Figure 2).
The Resight 700 (Carl Zeiss Meditec AG, Jena, Germany) is the wide-angle viewing system incorporated into the Lumera 700 microscope (Carl Zeiss Meditec). This technology can hold two lenses, a 127.00 D lens for wide-angle viewing and a 60.00 D lens for magnifying images of the posterior pole. These lenses provide clear fundus images with minimal distortion. The fundus image is automatically inverted by Resight’s Invertertube E. Users can also adjust the focus with the footswitch of the microscope through an internal focusing system.
The wide-angle viewing systems are useful and, in my opinion, essential for MIVS. However, lower magnification makes it difficult to perform precise procedures in the macular area, such as internal limiting membrane removal. The Resight 700 has a magnifying lens as one of its two lens options, which is useful for this maneuver.
Yasuo Tano, MD, developed a sutureless ring system to hold a contact lens on the cornea by yoking it to the ocular speculum; this device is especially useful for MIVS.7 Shunji Kusaka, MD, recently developed a new sutureless ring system for MIVS.8 The silicone ring, strung between two cannulas, holds the metal ring of the contact lens in place (Figure 3). The silicone band is easy to take on and off. For surgical cases, we prepare several sets of magnifying contact lenses, silicone bands, and the lens rings in an autoclavable box. In most cases, I use a combination of this set and the PWL system.
Surgeons can choose a wide-angle viewing system according to their preferences. Ultimately, wide-angle viewing systems are essential for vitrectomy, particularly for MIVS.
Masahito Ohji, MD, is Professor and Chairman of the Department of Ophthalmology, Shiga University of Medical Science, Japan. Dr. Ohji is a Retina Today Editorial Board member. He did not acknowledge any financial interest in the products or companies mentioned in this article. Dr. Ohji may be reached at +81 77 548 2276; email@example.com.
Ingrid U. Scott, MD, MPH, is Professor of Ophthalmology and Public Health Sciences, Penn State College of Medicine, Department of Ophthalmology, and is a Retina Today Editorial Board member. She may be reached by phone: +1 717 531 4662; fax: +1 717 531 8783; or via e-mail: firstname.lastname@example.org.
Dean Eliott, MD, is Professor of Ophthalmology and Director of Clinical Affairs, Doheny Eye Institute, Keck School of Medicine at USC, and is a Retina Today Editorial Board member. He may be reached by phone: +1 323 442 6582; fax: +1 323 442 6766; or via e-mail: email@example.com.
TOP 5 ARTICLES FROM 2010
- A New Treatment for Chronic Central Serous Retinopathy
Micropulse yellow laser resolves leakage and retinal detachment without scarring or retinal damage.
By André Maia, MD, PHD
- Clinical Implications of the BRAVO and CRUISE Trials
How should physicians apply this new information in their treatment of CRVO and BRVO?
By David M. Brown, MD, FACS
- When to Treat and Not to Treat Patients With Central Serous Retinopathy
Reduced-fluence PDT is the current accepted treatment for CSR.
By Francesco Boscia, MD
- Fluidics in Modern Vitrectomy
- Sustained- release Corticosteroid Delivery Systems
Implant technology offers promising solutions to the burden of repeated injections for retinal diseases.
By Szilard Kiss, MD