Visualization and Illumination
Optimal visualization is required for vitreoretinal surgery. Many surgeons utilize wide-angle visualization systems for all cases because of habit, video considerations, or the perception that a second surgeon is required to hold a contact lens. A plano (flat) contact lens provides significantly greater lateral and axial (depth) resolution than a noncontact (BIOM, Oculus Optikgeräte GmbH, Wetzlar-Dutenhofen, Germany; EIBOS, Möller-Wedel, Wedel, Germany) or contact-based (Volks Reinverting Operating Lens System, Volk Optical, Inc., Mentor, Ohio; AVI Panoramic Wide-Angle Viewing System, Advanced Visual Instruments, Inc., New York) wide-angle visualization system. A plano contact lens should be used for all macular and traction retinal detachment surgeries. Surgical technicians usually do an excellent job of holding the contact lens if they are comfortably seated, view through a stereo observer tube, and are treated with respect. Assistant surgeons frequently mentally focus on the surgical procedure instead of positioning the contact and require reminders to center the lens. Sewed-on contact lenses were developed to eliminate the need for an assistant to hold the lens but create many problems. Bleeding and bubbles under the lens, use of expensive viscoelastics, cost of sutures, suboptimal centering, and damage to the conjunctiva are all potential problems with sewed-on lenses. Sewed-on contact lenses are inappropriate for 23/25-gauge, sutureless, transconjunctival surgery because of inherent conjunctival damage and bleeding. Self-stabilizing contact lenses are useful if a steadyhanded assistant is not available, but they still require frequent recentering by the assistant. Prism lenses can be used for viewing the periphery but slow down the surgery and can lead to lens or retinal damage because of paradoxical movement. Indirect ophthalmoscope viewing for vitrectomy is grossly inferior to operating microscope-endoilluminator viewing. The author does not agree with the use of microscope-mounted slit lamp illumination during vitrectomy because of light scattering by the cornea and lens as well as other issues.Wide-angle visualization should be used for all rhegmatogenous retinal detachment cases, proliferative vitreoretinopathy, and giant breaks when viewing the periphery. On occasion, wide-angle visualization is necessary to visualize the peripheral portion of the posterior vitreous cortex when operating large tabletop diabetic traction retinal detachments. Wide-angle viewing is ideal to examine the periphery for iatrogenic retinal breaks after the completion of vitrectomy and for removal of peripheral intraocular foreign bodies or lens fragments, especially at the inferior vitreous base. Contact-based wide-angle visualization (Volk, AVI) provides 10 degrees greater field of view than noncontact viewing (BIOM) and eliminates all corneal asphericity, which is common after cataract surgery, LASIK, photorefractive keratectomy, limbal relaxing incisions, radial keratotomy, astigmatic keratotomy, penetrating keratoplasty, pterygium surgery, and corneal lacerations. Noncontact wide-angle visualization systems require much greater ocular rotation than contact-based systems for viewing the periphery, thereby increasing the 25-gauge tool flex problem. The most recent generation of articulated and flexible laser probes as well as stiffer vitreous cutters, scissors, forceps, and endoilluminators virtually eliminate the 25-gauge tool flex issue.
ILLUMINATION
Wide-angle visualization requires some form of wide-angle illumination. The principal author prefers the standard 25-gauge, 78-degree endoilluminator to chandelier or Torpedo devices. Focal illumination, specular illumination, and retroillumination are better for visualizing clear, colorless vitreous, internal limiting membrane (ILM), and shiny epiretinal membranes than diffuse illumination produced by chandeliers and Tornambe Torpedoes (Insight Instruments, Stuart, Florida and Alcon Laboratories, Fort Worth, Texas). Slit lamp biomicroscopy was developed to provide focal illumination, retroillumination, and specular illumination to
better visualize transparent structures. Specular illumination is used when looking for ILM or shiny epiretinal membranes, similar to the way an oblique light source is used to inspect a shiny surface after sanding, painting, cleaning, or waxing. Retroillumination is produced by reflected light from the white sclera transmitted through the retina, retinal pigment epithelium, and choroid; it is therefore more useful in lightly pigmented eyes. Another very effective way to produce retroillumination is to reflect endoilluminator light from the metal surface of the vitreous cutter; this technique cannot be performed with a chandelier or Tornambe Torpedo. The author uses this technique consciously, but it is likely that many surgeons use this technique instinctively. Focal illumination is utilized by positioning the endoilluminator near the port of the vitreous cutter, scissors, or forceps; the surgeon should be careful to use minimal light intensity when near the macula.
better visualize transparent structures. Specular illumination is used when looking for ILM or shiny epiretinal membranes, similar to the way an oblique light source is used to inspect a shiny surface after sanding, painting, cleaning, or waxing. Retroillumination is produced by reflected light from the white sclera transmitted through the retina, retinal pigment epithelium, and choroid; it is therefore more useful in lightly pigmented eyes. Another very effective way to produce retroillumination is to reflect endoilluminator light from the metal surface of the vitreous cutter; this technique cannot be performed with a chandelier or Tornambe Torpedo. The author uses this technique consciously, but it is likely that many surgeons use this technique instinctively. Focal illumination is utilized by positioning the endoilluminator near the port of the vitreous cutter, scissors, or forceps; the surgeon should be careful to use minimal light intensity when near the macula.
Some surgeons use a chandelier or Torpedo to enable bimanual surgery, typically using forceps in one hand and scissors or a vitreous cutter in the other, although a pic or microvitreoretinal (MVR) blade can be used as well. Scissors produce a push-out force, which increases with each use if they are reusable scissors and further increases with the reuse of disposable scissors. Bimanual surgery is often used to offset this push-out force using forceps in one hand for epiretinal membrane stabilization and scissors or the vitreous cutter in the other. The author uses disposable curved scissors for both segmentation and delamination and rarely performs bimanual surgery.
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