Equipment |
2 |
|
2.1Devices
2.1.1Operating Microscope
The optical quality of the surgical microscopes is excellent in all current models of the major manufacturers. For the retinal surgeon it is, however, important that several functions are integrated into the foot pedal, for example, a switch for choosing the microscope light or an inverter, if needed.
2.1.2Binocular Indirect Ophthalmo Microscope (BIOM System)
To obtain a sufÞcient view of the posterior segment, one needs either a plano-con- cave contact lens which is directly placed onto the cornea, or a highly refractive lens (60D, 90D, 120D) which is placed in front of the lens of the surgical microscope comparable to indirect ophthalmoscopes. This results in an inverted image. By ßicking a reversal system (so-called inverter) into the parallel beam path of the operating microscope, an upright image is created (e.g., using the Òstereo diagonal inverter (SDI)Ó of Oculus) (see Appendix, Companies).
We use the BIOM system (Binocular Indirect Ophthalmo Microscope) of Oculus and the EIBOS system by Moeller-Wedel. Both systems offer excellent optical images with a variety of different magniÞcations and Þelds of view. Based on our personal experience, the BIOM offers more ßexibility and a better view of the retinal periphery. The EIBOS system is extremely robust and has the additional advantage of an inbuilt inverter that avoids the need for manual inversion when changing from the posterior segment to the anterior segment view during the surgery. Other companies also offer excellent alternatives, for example, Topcon (OFFISS) and Volk (OPTIFLEX).
U. Spandau, H. Heimann, Practical Handbook for Small-Gauge Vitrectomy, |
7 |
DOI 10.1007/ 978-3-642-23294-7_2, © Springer-Verlag Berlin Heidelberg 2012 |
|
8 |
2 Equipment |
|
|
The OFFISS system allows the surgeon to use the microscope light and to refrain from endoillumination. Thus, the central 40¡ of the retina can be viewed with the OFFISS system; for a wide-angle observation, an endoillumination is needed. The Topcon OFFISS system is used in combination with a special operating microscope from Topcon.
The Volk OPTIFLEX system is relatively new on the market, and it offers good optical properties. So far, we have not had sufÞcient experience with this system in order to compare it to the other systems mentioned above.
With the Oculus BIOM system, we use three different types of lenses: 120D for a wide peripheral view, 90D as our standard lens for most applications, and the 60D high magniÞcation lens for macular surgery. In addition, an inverter is needed to invert the image for surgery (Fig. 4.7). This has to be turned on or off every time one switches between anterior segment or posterior segment view.
We usually start with a 90D lens for core vitrectomy and posterior vitreous detachment. We then switch to the 120D lens to trim the vitreous base. We then switch to the 60D lens if we perform macular surgery. A good alternative is a planoconcave contact lens, which is placed directly onto the cornea. We then usually switch back to the 120D for complete trimming of the vitreous base and to inspect the peripheral retina for breaks. In cases of retinal detachment surgery, we recommend beginning the surgery with the wide-angle 120D lens to view the peripheral retina and to identify retinal breaks from the beginning of the surgery.
Important: The BIOM provides a mirror image. Therefore, an inverter is installed in the microscope, which turns the mirror image of the BIOM. If you ßick the BIOM in, activate the inverter to gain an accurate image. Similarly, if you ßick the BIOM out, you have to activate the inverter in order to get an upright image.
2.1.3Vitrectomy Machine
An extensive range of high-quality vitrectomy machines by several manufacturers are now available on the market. They have a cutting speed of approximately 2,500 cuts/min. Of great importance are the ÒßuidicsÓ (vacuum, ßow rate) of the machine. A sophisticated coordination of these parameters allows a high-speed and less traumatic vitrectomy in a closed system. Further, an easy switch between phacoand vitrectomy-mode is important. In addition, the vitrectomy machines should have an active injection and extraction feature. This is utilized to inject or remove silicone oil. One can also connect the ßuid needle to the active aspiration and work with active suction. This generation of vitrectomy machines has an integrated light source, which is sufÞcient for a light pipe but not for a chandelier light. An external light source and a laser must, therefore, be purchased separately.
The latest generation of vitrectomy machines such as ÒConstellationÓ from Alcon or ÒStellaris PCÓ from Bausch & Lomb have a cutting speed of 5,000 cuts/min. They provide an integrated light source that is strong enough for a chandelier light. The ÒConstellationÓ has an IOP control, an intergrated laser and a powerful ßuid extraction mode, which reduces the surgery time for a silicone oil removal to 1Ð2 min.