Principles of vitreoretinal surgery: Techniques and technologies

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CHAPTER 58 Principles of vitreoretinal surgery

Techniques and technologies

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Robert Machemer, the inventor of pars plana vitrectomy, wrote his seminal monograph in 19751, having done more than 500 vitrectomies at that time: ‘Pars plana vitrectomy is not an easy type of surgery. Some formal or informal training with an experienced vitreous surgeon is highly recommended.’ Bearing this in mind, it is clear that this chapter cannot teach vitreoretinal surgeons in practical terms. It should help, however, to deliver a basis to understand the principle techniques of current vitreoretinal surgery. This might be of advice in numerous clinical situations occurring during vitreoretinal surgery – a procedure simply called ‘vitrectomy’.

History and concept of vitreoretinal surgery

Fifteen years after his first publication on vitreous removal in a closed system, Machemer wrote, ‘the next step was treatment of the retina itself. It takes an unconventional mind to break major taboos …2.’ It was Machemer himself who previously broke with the greatest taboo. When he left Germany to join the Bascom Palmer Eye Institute, vitreous removal was thought of subsequently resulting in phthisis. In Miami, Machemer came across Kasner whose revolutionary clinical work of the 1960s has proved that an eye can also function without the vitreous3. Machemer and Parel developed the vitreous infusion suction cutter (VISC), a 17-gauge instrument which combined suction, cutting, infusion, and illumination properties in one handpiece4. For the first time, it was possible to remove vitreous hemorrhage obscuring the optical axis, which otherwise had to be left untreated5,6. The VISC, however, required a 2.7 mm sclerotomy, and the turbulence the infusion caused at the tip of the vitrectomy port made selective removal of the vitreous difficult. O’Malley and Heintz separated the infusion line from the vitrectomy probe and opened a third sclerotomy for additional instruments, thereby creating the 20-gauge three-port approach which still serves as a standard for vitrectomy almost 40 years later7. At the same time, and in collaboration with Oertli instruments (Berneck, Switzerland), Klöti in Zürich developed the ‘Klöti’-stripper for vitreous removal, which is still in daily use in many vitreoretinal services over the world8,9.

The new and spectacular technique of vitrectomy seemed to offer the solution for all problems in the vitreous cavity2. Not only was the optical axis cleared of vitreous opacities, but also the retina itself could now be approached. Epiretinal membranes were removed, and traction was released from the retina10. In the mid-1970s, however, it gradually became more obvious that the expectations pinned on vitrectomy especially regarding the treatment of complicated forms of retinal detachment could not be fulfilled. At the same time, Scott in Cambridge used silicone oil as a tamponade of otherwise untreatable retinal breaks, a technique initially introduced by Cibis1114. As a logical consequence of development, also knowing Machemer’s approach, Haut in Paris combined both techniques, i.e. vitrectomy and silicone oil as an internal tamponade, and the combination of vitreous removal with traction release and silicone oil tamponade has become the method of choice in the treatment of complicated forms of retinal detachment2,15.

Surgical approach

For 20-gauge vitrectomy, a conjunctival incision is performed at the limbus both nasally and temporally (Fig. 58.1). Episcleral vessels are cauterized. A microvitreoretinal (MVR) blade is kept perpendicular to the sclera at 3.5–4 mm distance from the limbus as mentioned above. Care is taken to aim toward the midvitreous cavity to reduce the risk of hitting the lens or damaging the retina. The infusion cannula is typically placed inferotemorally. Therefore, a 7-0 Vicryl suture on a spatulated needle is placed in a mattress fashion at the sclerotomy site. A slip knot is tied and holds the infusion line in place. At the end of vitrectomy, the slip knot is loosened and the same mattress suture is used to close the sclerotomy.

Care should be taken to ensure that the infusion line enters the vitreous cavity, and not the suprachoroidal space. The infusion cannula must be visualized through the dilated pupil by rotating the eye away from the surgeon while the infusion line is grasped and gently pushed toward the central vitreous cavity. Once the position of the infusion cannula has been confirmed, the infusion is turned on (Fig. 58.2).

Superonasal and superotemporal sclerotomies are placed approximately 120–160° apart to facilitate manipulation within the vitreous cavity and to allow access to the entire retina. Some surgeons use sew-on contact viewing systems; others fixate the eye by passing a suture beneath the recti. Given modern wide-angle viewing systems such as the BIOM and others, however, there is no need to do so, and the eye can be better rotated and manipulated without fixation.