2.1.4Laser Device

Again, there are numerous providers of laser devices. A frequently used device is the 532-nm diode laser OcuLight GL from Iridex (see Chap. 7).

2.1.5Cryo Console

A Cryo machine (DORC, ERBE) should be at our disposal in the operating room. Indications are a cryopexy of a retinal break, the retina, or the ciliary body due to neovascular glaucoma. Cryopexy is nowadays performed less frequently during vitrectomies because cryotherapy leads to more anterior segment trauma and is more difÞcult to perform through a closed conjunctiva compared to 20-gauge surgery with conjunctival incisions. In addition, cryotherapy has been associated with a higher rate of PVR formation in some studies of retinal detachment surgery. Finally, the chorioretinal scar formation appears several days later following cryotherapy compared to laser retinopexy.

2.1.6Light Source

The light source is either external or can be integrated into the vitrectomy machine. In general, the internal light sources have traditionally been weaker than external light sources. When using a chandelier light, one has to use a very powerful light source. Synergetics offer an external photon source, and DORC and Alcon offer an external xenon light source (see Chap. 7). The new vitrectomy machines ÒConstellationÓ of Alcon and ÒStellaris PCÓ from Bausch & Lomb have an internal light source that is strong enough for use with a chandelier light.

2.2Standard Instruments for Pars Plana Vitrectomy

Retinal surgery is a very Òinstruments orientatedÓ surgical discipline and necessitates that you acquaint yourself with the variety of high-quality microsurgical instruments designed for speciÞc tasks, many more than with phacoemulsiÞcation. In order to become a good retinal surgeon, you need to know the different applications of this wide range of instruments and consequently increase your skills in this Þeld of surgery. In addition, retinal surgery is ÒneurosurgeryÓ in that one comes into direct contact with neural tissue. In general, such surgery is associated with the risk of transmitting CreutzfeldtÐJacob disease in countries where this disease is prevalent. Therefore, there is an increasing trend to use single-use instruments in vitreoretinal surgery wherever possible. Reusable instruments, which used to be the norm just a few years ago, are disappearing from the market. This is especially the case in the UK and France. The positive side effect for the surgeon is that one is always provided with new and sharp instruments of very high quality nowadays. On the

Fig. 2.1 The new Alcon Edgeplus trocar with handle and scleral marker. Available for 23 gauge and 25 gauge

Fig. 2.2 Geuder one step trocar with handle. Geuder: G 33 445

downside, this can reduce the number of available instruments and options available to the surgeon. Further, this trend is also associated with higher costs. In the following section, various surgical instruments are introduced.

One unfortunate trend in modern vitrectomy machines is that there are no international standards and the essential parts of the instrumentarium are usually not interchangeable between different manufacturers. Moreover, some manufacturers provide some of the essential tools as part of an Òall-in-oneÓ vitrectomy pack only. This means, for example, that a broken light pipe or a vitreous cutter that inadvertently touched the non-sterile part of the microscope can only be replaced by opening another surgical pack, which is more expensive than an individually packed single-use instrument. Therefore, the cost and availability of vitrectomy packs and the provision of spare instruments as individually packed units should be included in the negotiations regarding the purchase of a new vitrectomy machine.

Trocar cannulas

An increasing number of companies offer trocars for 23and 25-gauge surgery (Alcon, DORC, Geuder, Oertli; Figs. 2.1 and 2.2). Depending on the manufacturer, these trocars are offered with or without valves and as a two-step (incision knife and trocar separately) or as a one-step system (incision knife and trocar combined).

Trocars with valves are particularly useful for beginners, as they prevent hypotension and collapse of the globe during the surgery (Fig. 2.3a, b). It is however important to notice that with valved trocars, one works within a closed system. For example, when injecting ßuid or gas, corresponding drainage or pressure control has to be ensured via the second port or the infusion system in order to avoid a signiÞcant rise in intraocular pressure. Using trocars without valves requires some manipulatory practice, as in certain situations, a plug needs to be inserted into the trocar in order to avoid hypotension (Fig. 2.4). The advantage of trocars without valves is that an intraocular hypertension, for example, when injecting silicone oil, is easier to control and to avoid.

Today there is a clear tendency towards trocars with valves. We, therefore, recommend getting acquainted with valved trocars.

Fig. 2.5 Scleral marker. Braunstein Þxed caliper. Bausch & Lomb, Storz instruments: E2402

Fig. 2.6 High-speed vitreous cutter. This 23-gauge vitreous cutter has a cut rate of 2,500 cuts/min. The newest vitreous cutter on the market by Alcon has a cut rate of 5,000 cuts/min. The advantages of the high-speed vitreous cutter can be particularly useful in a detachment surgery, as the detached retina remains very stable

Scleral marker

Easy-to-use instrument to mark the position of the sclerotomy on the sclera: 3.5 mm for pseudophakic eyes and 4.0 mm for phakic eyes (Fig. 2.5). Some manufacturers (e.g., Alcon) incorporate a marker in the handle of the trocar blade, thereby avoiding the need for changing instruments at the beginning of the surgery.

High-speed vitreous cutter

High-speed vitreous cutters have a cut-rate of 2,500 cuts/min (Fig. 2.6). The new vitreous cutters from Alcon (Constellation) have a cut rate of 5,000 cuts/min. A 23-gauge (high-speed) vitrector cuts the vitreous body almost as fast as a normal 20-gauge cutter. High-speed cutters exert less strain on the retina and are therefore less traumatic. This enables manipulations closer to the retina with less risk of aspirating the retina and causing an iatrogenic break. This is possible due to a high ßow rate (ßow) in the central vitreous (the aspiration port of the vitrector is fully open) and a low ßow rate in the periphery (the aspiration port of the vitrector is minimally open).

With the foot pedal, one can switch between the two functions of the vitreous cutter: Firstly, you can cut and aspirate (vacuum) and secondly, you can only aspirate. Indications for combined cutting and aspirating are the removal of the vitreous, blood clots or soft lens fragments, iridectomy, etc.. Indications for aspirating are induction of PVD, aspiration of liqueÞed blood, subretinal ßuid, etc.. The vitreous cutter cannot cut solid tissue such as Þbrosed lens capsule or hard lens fragments. A Þbrosed lens capsule is segmented and removed with scissors and forceps. Hard lens fragments necessitate the use of a fragmatome. This is currently not available for 25or 23-gauge surgery. However, it is usually not a problem to enlarge one of the ports for the introduction of a 20-gauge fragmatome if needed (for details see chapter. 8).

Combined fibre optic and vitreous cutter

This vitreous cutter is combined with a light Þbre. Indication: Vitrectomy of vitreous base. With one hand you can indent the retina and cut the vitreous base with the other hand. A better alternative is the use of a normal vitreous cutter and a chandelier light as the illumination is much better.

(High-speed illuminated vitrectomy (2,500 cuts). DORC. 2267.IL).

Fig. 2.7 Fragmatome handpiece. Indication: Removal of a dropped nucleus. Alcon Accurus fragmatome. In addition, you need the fragmatome accessory pack (REF 1021HP)

Fragmatome

The fragmatome can be used to emulsify a dropped nucleus in the vitreous cavity (Fig. 2.7). It is available in 23-gauge but is used without a trocar cannula. A fragmatome is difÞcult to use. On the one hand, it is less powerful than a normal phaco handpiece. On the other hand, it can exert high levels of suction in the posterior segment. Aspiration of the vitreous or the retina into the handpiece must be avoided. Lens fragments tend to jump away from the needle tip. In such cases, one must aspirate the fragments in the needle tip before emulsiÞcation (see Appendix, Materials).

Light fibres (endoillumination)

There are two types of endoillumination: hand-held light pipes (light probes) and Þxed endoillumination (chandeliers).

Light pipes are available with different sized cones of light. For routine cases, one holds the light pipe with the non-dominant hand and the vitreous cutter with the dominant hand. A chandelier light is Þxed in the sclera and illuminates the entire fundus. This enables bimanual surgery and allows the surgeon to use a second active instrument in addition to the vitreous cutter. Chandelier lights are available from many different suppliers. The 25-gauge chandelier light of Synergetics has the great advantage of a rigid cable and a broad baseplate, which sticks Þrmly in the sclera. Good alternatives are the 25-gauge chandelier light of Alcon and the 23-gauge chandelier light of DORC which are easily inserted into a 25-gauge and 23-gauge trocar, respectively (for details, see Materials). More difÞcult to insert is the 27-gauge twinlight from DORC. It consists of two light Þbres, which are both inserted at the 12 oÕclock position. For optimal illumination of a chandelier light, an external light source (Photon, Xenon) is required.

The choice of light source depends on the difÞculty of the case and the personal preference of the surgeon. While chandelier lights have their deÞnite advantages of freeing up your non-dominant hand to use a second instrument and provide better illumination for video recording of the surgery, a hand-held light probe still provides a more focussed and brighter light for most situations, for example, membrane peeling and delamination. It also depends on your routine method of trimming the vitreous base. One of the authors (HH) uses ÒtraditionalÓ hand-held endoillumination for the vast majority of routine cases (macular holes, retinal detachment, proliferative diabetic retinopathy) and performs trimming of the vitreous base using external indentation with the light pipe; this enables transscleral illumination of the

Fig. 2.8 A 23-gauge ßuid (backßush instrument). Passive aspiration: Leave the side opening open. Intraocular ßuid will ßow out through the side opening. If you press Þrmly on the silicone tubing, the ßuid needle squirts ßuid out, e.g., to remove epiretinal blood. DORC. 1281.C

Fig. 2.9 A ßuid needle with a silicone tip (backßush instrument with brush tip). Indication is non-traumatic work on the retinal surface. For example, if you wish to aspirate a residual perßuorocarbon droplet from the retina. DORC. 1281. BTD06

vitreous base whilst indenting the sclera from the outside with the light pipe. The other author (US) uses the hand-held light pipe only for macular peeling and for silicone oil removals. For all other cases, he uses a chandelier light which in his opinion opens a whole new world of surgical possibilities.

Fluid needle

The 23-gauge ßuid needle is a blunt needle which aspirates liquid by capillary force and pressure difference. The handpiece usually contains a ßexible or stiff plastic tube with an opening. This can be used in three ways: If the hole is uncovered, ßuid will be pushed out of the eye through the tip of the ßuid needle, exiting the eye through an opening in the handpiece driven by the intraocular pressure. The intraocular pressure is determined by the infusion pressure and the diameter and length of the cannula. If you place the index Þnger on the opening, there is no aspiration. If the hole is closed and the tubing is compressed, the ßuid needle will eject the small amount of ßuid within the eye. This can be used to ßush the retina or an intraocular lens. There are two versions of ßuid needles: with or without silicone tip (Figs. 2.8 and 2.9). With the silicone tip, more gentle manipulations close to the retinal surface are possible. However, these instruments are more expensive and usually not needed for most routine manipulations. Finally, one can connect the ßuid needle to active aspiration (active injection mode) and, henceforth, increase the suction power (Fig. 2.10). Mastering the handling of the ßuid needle is one of the key steps in improving the surgical skills of vitreoretinal surgeons (Fig. 2.11).

Scleral depressor

A scleral depressor indents the retina (Fig. 2.12). It is a standard instrument for pars plana vitrectomy. It is used for trimming of the vitreous base, in particular in retinal detachment surgery. With a 4-port vitrectomy and chandelier endoillumination, one

Fig. 2.10 Active aspiration:

A ßuid needle is attached to an infusion tube which is inserted into the vitrectomy machine. The active aspiration mode is activated. Close the opening of the tubing with your index Þnger and press the foot pedal. The intraocular ßuid is aspirated into the vitrectomy machine

Fig. 2.11 If the ßuid needle is clogged with debris, then ßush the ßuid needle by attaching a BSS-Þlled syringe

Fig. 2.12 A scleral depressor used to indent the retina. Geuder. G-32 715

can use the scleral depressor for bimanual trimming of the vitreous base using the vitreous cutter.

Alternatively, one can use a light pipe for external indentation and transscleral illumination of the vitreous base. This is straightforward with 23-gauge light pipes; with the more ßexible 25-gauge light pipes, one can perform this manoeuvre in the temporal and nasal quadrants by stabilizing the tip of the light pipe with the tip of your middle Þnger close to it. However, this is not possible at the 6 and 12 oÕclock positions.

One of the basic rules of vitrectomy is to Þnish all vitrectomies, no matter how ÒsimpleÓ and straightforward they are, with an internal search for retinal breaks at the vitreous base using endoillumination and a scleral depressor. When performing this examination, one has to make sure to view the entire retinal periphery over 360¡ up to the ora serrata. This is one of the most effective ways to reduce the rate of postoperative retinal detachments.

Laser probe

Fig. 2.13 A 23-gauge laser probe of DORC. The optical laser is curved so that the peripheral retina can be easily reached. DORC. 7223.IRI

Fig. 2.14 A 23-gauge endodiathermy handpiece. DORC. 1120.06

One can purchase straight or curved laser probes (Fig. 2.13). The curved laser is particularly suitable for the peripheral retina; the straight laser is easier for the central posterior pole. If you apply a peripheral laser treatment (break, peripheral ischemic retina), the use of a scleral depressor is recommended, which makes the break more accessible and avoids touching the lens. This can be performed either using a chandelier light and a scleral depressor or using the light pipe as a scleral depressor with transscleral illumination. Alternatively, you can use a laser Þbre with endoillumination (see below).

The use of the laser probe requires some training. A great proportion of intraoperative lens touch is caused by the tip of the endolaser. This is because the surgeon usually focuses on the area of illuminated retina that requires treatment and may forget about the position of the laser probe, in particular when indenting the vitreous base. One of the rules of laser treatment is not to cross the midline of the eye with the tip of the instrument when treating the retinal periphery on the opposite side.

Curved laser probes can be advanced and retracted through a mechanism within the handpiece. This requires some training before operating safely within the eye. Also, the ßexible part of the probe needs to be retracted before removing the instrument out of the eye. Otherwise, the probe will get stuck in the trocar, and the trocar will be removed with the instrument.

Combined laser and light fibre handpiece

This laser handpiece is combined with a light Þbre. Indications: Peripheral retinal breaks or ischemic retinopathy. With one hand you can indent the retina with the scleral depressor and treat the break with the other hand (Illuminated Laser Probe, 23G with Iridex adapter. DORC. 7510.IRI).

Endodiathermy probe

An endodiathermy is useful for cauterizing bleeding retinal vessels such as in diabetic retinopathy (Fig. 2.14) or before large and more central retinectomies. Another indication is to mark a break in retinal detachment surgery or in preparation for a retinotomy. There are usually two different types of endodiathermy probes: ÒActiveÓ endodiathermy probes are combined with a ßuid needle. This is very useful when treating an acute intraocular haemorrhage. The ßuid needle drains the haemorrhage, enabling localisation of the bleeding site, which can then simultaneously be treated