Vitrectomy: A Review
Gaurav Paranjpe, Pravin Jain and Manish Nagpal.
Retina Foundation, Ahmedabad.
INTRODUCTION
Pars plana vitrectomy as a technique has revolutionized retinal surgery since its advent and initial report by Machemer et al 1. It allowed the removal of traction by an internal method, essential in retinal detachment procedures, as well as provided an active management modality for vitreous haemorrhage and opened the door for surgical intervention in a myriad of retinal pathologies.
Since that time, the evolution of vitrectomy surgery has seen experimentation and implementation of smaller surgical instruments aimed at greater functionality and minimalization of ocular trauma. The basis of a sutureless pars plana sclerotomy was to stabilize intraocular pressure (IOP) during surgery, with a truly closed system, as well as reduce surgical time by removing the need for sutured wound closure. Wound and suture related complications such as leakage, irritation, and scleral pigmentary changes could also be avoided. Concerns regarding wound competence in a sutureless procedure have seen the modification of the conventional straight incision to such techniques as angled, beveled, oblique, and scleral tunnel incisions.
HISTORY:
Von Graefe was the first one to invade the sacrosanct vitreous in 1863. Earlier period of vitreous surgery began in 1889, extended through the 1960’s and was the domain of relatively few courageous surgeons. These ophthalmologists approached the vitreous pathology either through the pars plana or more commonly through the anterior segment.
David Kasner in 1968 removed all the diseased vitreous in case of amyloidosis of vitreous by his so called ‘Open Sky’ Vitrectomy. In doing so he not only opened the cornea but also opened the sky of ocular surgery for ophthalmic surgeons. But this open sky route had its inherent problem of making the eye aphakic, large instruments obscuring the view of operating plane and open eye leading to globe collapse. Earlier technique of radical vitreous surgery included the replacement of diseased vitreous with numerous substances including silicon oil, collagen, hyaluronic acid, cerebrospinal fluid, cadaver vitreous and synthetic polymers.
It took almost 100 years, ever since the invasion of vitreous by various workers to develop a machine which could cut and aspirate the vitreous. Dr. Robert Machemer began working on vitreous surgery by introducing a rotating drill in the egg shell by removing egg white. In April 20, 1970, first closed Vitrectomy was performed on a human eye. As Machemer puts it, “This man had been blind for years; he had vision of finger counting at 2 feet, slight cataract and his vitreous was opaque. We were very lucky to select a patient with a condition that we know today to be easiest to treat, just haemorrhage. We were also lucky that we did not have any complication. One can imagine the enthusiasm that we had when the first operation was a full success and the patient could see 20/50.”
In 1971, Machemer et al described the use of a 17-guage vitreous cutter, with a diameter of 1.5 mm through a 2.3 mm scleral incision. This instrument, the vitreous infusion suction cutter (VISC), consisted of an inner and outer tube. The outer tube was stationary with an opening, inside which, was the rotating opening of the inner tube with sharp edges. Suction was applied to the inner tube to draw vitreous into the openings and the rotating sharp edge would cut the material. The instrument was connected to a rheostat to alter rotation speed, an infusion system, and a syringe that allowed manual application of suction. The fibreoptic system to provide endoillumination was introduced in 1972 , and was added as a sleeve around the tube.2 All these procedures were 2 port procedures as infusion and cutter/suction function were done through a single probe.
The 2 port approach was modified in 1974, with the introduction of a 20-gauge vitrector (0.9 mm ) 3. This was the origin of the three port, pars plana sclerotomy system that became the gold standard in vitrectomy surgery. It involved the creation of three access ports with a 1.4 mm linear sclerotomy. This was undertaken with a myringo-vitreal-retinal (MVR) blade. One port had an infusion line sewn into place, while the remaining two were utilized for introduction of a light source and a vitreous instrument such as a cutter. At the completion of the procedure, these ports were traditionally closed with an absorbable suture.
Conor O’Malley and Ralph Heinz also developed a lightweight, reusable, bellows-driven, pneumatic, axial cutter driven by the Ocutome 800 console (Berkley Bioengineering, 1972). Gholam Peyman developed the electric solenoid driven axial (guillotine) cutter at about the same time R. Kloti in Europe developed a three port system with an electric cutter.
The introduction of endophotocoagulation by Charles Schepens allowed retinopexy, hemostasis, and pan retinal photocoagulation without corneal or iris damage.His first used the Zeiss xenon source . Subsequently Maurice Landers and Jay Fleischman with chares schepens simultaneously and independently developed endophotocoagulation systems using an argon laser source. Later Yasuo Tano developed the near-IR diode laser source and finally Alcon and Iridex developed 532 nm, diode pumped sources.
In 1996, Chen 4 described a technique for creating a self-sealing, pars plana sclerotomy. This involved an initial scleral incision based 6 mm posterior to the limbus, creating a scleral flap that was theoretically self-sealing. Kwok et al 5 described a variation on this method with an initial radial incision, still placed 3-4 mm behind the corneoscleral limbus. They used a 20-guage round body hypodermic needle rather than a MVR blade.
De Juan and Hickingbotham 6 devised and introduced a range of 25-guage instruments in 1990 for use through conventional sclerotomies. However, it was only in 2002, with the advent of the microcannulae array, that the 25-gauge transconjunctival sutureless vitrectomy (TSV) system was introduced by Fujii et al 7. This was followed by the introduction of a 23-gauge system by Eckardt in 2005. 8
Initially, both 23- and 25-gauge systems were available with a limited gamut of intraocular instruments. However, as the techniques rapidly became widely utilized, almost all intraocular instruments have been developed and made available for sutureless vitrectomy systems.
Objectives of Vitrectomy
- Clearing the media & access to diseased retina,
- Creating a space for internal tamponade
- To cut Vitreo-Retinal Membranes
- To release vitreoretinal traction
- Retinal manipulation and reattachment
- Removal of tissue or foreign material & to obtain vitreous biopsy
Indications for Vitrectomy 9
There is a rapid innovation in the technology of vitreous surgery and along with it the indications of Vitrectomy keep on increasing / changing.
These indications can be broadly divided into anterior Segment indications and posterior Segment indications.
Anterior Segment 1. Opacities of the media
2. Anterior segment reconstruction as for in Adherent leucoma 3.Lens surgery
4. Complications due to Vitreous in Anterior Segment.
5. Miscellaneous conditions such as epithelial cysts, epithelial downgrowth / ingrowth etc. |
Posterior Segment These can be divided into diagnostic and therapeutic 1. Diagnostic indications
2. Non-resolving vitreous opacities like vitreous haemorrhage, amyloidosis, membranes
4. Vitreous opacities like haemorrhage, membrane, amyloidosis
6. Retinal Detachment: -
7. Epiretinal Membrane |
