**1. Introduction**

Vitreoretinal (VR) surgery is an ever-changing speciality with newer and more effective instruments and equipments being introduced constantly over time. Long gone were the days when 20 gauge vitrectomy was first introduced. We now have 23, 25 and 27 gauge systems with improved duty cycles and cut rates aiding the safety and results for patients [1, 2, 3]. Although the instruments maybe updated from time to time, certain basic VR surgical techniques remain core to any VR operation.

This chapter is aimed at taking the reader from the basics in learning and performing VR surgery, touching on the main basic principles and building on with surgical pearls, some of

which are not found in standard VR textbooks. Whenever possible, there will be a link provided to access short video clips to reiterate the techniques and concepts discussed, making this an interactive chapter. As such, the beginner and the intermediate-level surgeons will benefit from this chapter, with points for the advanced surgeon.

As there are many different models and types of vitrectomy machines, the discussion in this chapter will will focus on the concepts and techniques and parameters common to all ma‐ chines. It is expected that the reader is familiar with the commonly used instruments for VR surgery.

This chapter is not meant to substitute a standard VR surgery textbook but merely an infor‐ mative supplementary chapter focussing on practical techniques. The chapter is arranged in a gradual way of introducing VR surgery starting from simple cases through to more complex cases, with clinical pearls and discussion of techniques and learning points for each case. The approach to this chapter shall be case based. It is assumed that the readers would be familiar and well versed in the basic anatomy, physiology, and pathology of the eye. However, relevant consideration in basic sciences will be reiterated to highlighting surgical principles and concepts in a more memorable way. Each case is presented with learning points and is itemised for easier read and revision.

It is hoped that the techniques and approach to VR surgery discussed in this chapter will allow the reader to adopt a flexible and appropriate combination of techniques and approaches to meet the individual surgical requirements that each case merits, in a safe and controlled manner, given that VR can be an unforgiving subspecialty if not performed expertly.

## **2. General considerations for the new VR surgeons**

It is important to ensure that the patient is comfortable and the cornea is parallel with the floor. The surgeons position should also be comfortable.

*Please note that the anterior vitreous base is 1 mm in front of the recti insertion, and the posterior vitreous base is 3–5 mm behind the recti insertion. The ora is at the insertion line of all the recti except for the superior rectus, which is 1 mm in front of the superior rectus insertion.*

Setting up of the three port pars plana vitrectomy (PPV) is a crucial start of the surgery, and each step needs to be meticulously performed. The positions of the three trocars are in the inferotemporal quadrant, superotemporal quadrant, and superonasal quadrant. Each trocar should be placed at an appropriate distance from the limbus, with 4 mm away from the limbus if the patient is phakic and 3.5 mm away for pseudophakic patients.

Since most centres have moved towards small gauge ports [4, 5, 6], with many surgeons preferring the sutureless transconjunctival sclerostomies, the technique to perform the sclerostomies needs to be mentioned here. The trocar needs to be inserted obliquely (approx‐ imately 45°) till midscleral depth, before the trocar is reposition perpendicular to the sclera to complete the sclerostomy incision [7, 8]. This will result in a shelved wound for better selfsealing (similar idea as the main phacoemulsification corneal stepped incision for self-sealing effect). Recent evidence from endosurgical imaging techniques presented at the American Academy of Ophthalmology meeting 2015 shows that a 2-step insertion technique can cause trauma and 'stretch' to the pars plana possibly increasing a risk of an entry-site tear or haemorrhage. Therefore some experts recommend a 1-step insertion technique. Clinical experience suggests that this risk is low (1 in 300 cases).

which are not found in standard VR textbooks. Whenever possible, there will be a link provided to access short video clips to reiterate the techniques and concepts discussed, making this an interactive chapter. As such, the beginner and the intermediate-level surgeons will

As there are many different models and types of vitrectomy machines, the discussion in this chapter will will focus on the concepts and techniques and parameters common to all ma‐ chines. It is expected that the reader is familiar with the commonly used instruments for VR

This chapter is not meant to substitute a standard VR surgery textbook but merely an infor‐ mative supplementary chapter focussing on practical techniques. The chapter is arranged in a gradual way of introducing VR surgery starting from simple cases through to more complex cases, with clinical pearls and discussion of techniques and learning points for each case. The approach to this chapter shall be case based. It is assumed that the readers would be familiar and well versed in the basic anatomy, physiology, and pathology of the eye. However, relevant consideration in basic sciences will be reiterated to highlighting surgical principles and concepts in a more memorable way. Each case is presented with learning points and is itemised

It is hoped that the techniques and approach to VR surgery discussed in this chapter will allow the reader to adopt a flexible and appropriate combination of techniques and approaches to meet the individual surgical requirements that each case merits, in a safe and controlled

It is important to ensure that the patient is comfortable and the cornea is parallel with the floor.

*Please note that the anterior vitreous base is 1 mm in front of the recti insertion, and the posterior vitreous base is 3–5 mm behind the recti insertion. The ora is at the insertion line of all the recti except for the*

Setting up of the three port pars plana vitrectomy (PPV) is a crucial start of the surgery, and each step needs to be meticulously performed. The positions of the three trocars are in the inferotemporal quadrant, superotemporal quadrant, and superonasal quadrant. Each trocar should be placed at an appropriate distance from the limbus, with 4 mm away from the limbus

Since most centres have moved towards small gauge ports [4, 5, 6], with many surgeons preferring the sutureless transconjunctival sclerostomies, the technique to perform the sclerostomies needs to be mentioned here. The trocar needs to be inserted obliquely (approx‐ imately 45°) till midscleral depth, before the trocar is reposition perpendicular to the sclera to complete the sclerostomy incision [7, 8]. This will result in a shelved wound for better self-

manner, given that VR can be an unforgiving subspecialty if not performed expertly.

**2. General considerations for the new VR surgeons**

*superior rectus, which is 1 mm in front of the superior rectus insertion.*

if the patient is phakic and 3.5 mm away for pseudophakic patients.

The surgeons position should also be comfortable.

benefit from this chapter, with points for the advanced surgeon.

surgery.

140 Advances in Eye Surgery

for easier read and revision.

The infusion line needs to be checked and allowed to flow before insertion to allow air bubbles to be expelled before connecting to the inferotemporal trocar. Before switching on the infusion, check to make sure that the infusion cannula is in the vitreous cavity and not anywhere else, pointing towards the centre of the vitreous cavity. Then the infusion is switched on.Remember to switch on the inverter on the operating microscope to facilitate the correct view of the retina. Some systems such as the Carl Zeiss system do this automatically. Others will invert manually by a hand switch or a foot switch.

There are also many different types of binocular indirect ophthalmic microscope viewing system (BIOM system) for viewing the retina for VR surgery. Regardless of the system used, the basic principle for retinal surgical work (apart from macula work) requires a wide view. In this situation, the microscope is zoomed out to the maximum, and the BIOM lens is adjusted until a clear focus is obtained. Then the microscope is lowered until a wide clear view is obtained which involves the BIOM lens being a few millimetres away from the cornea.

The general principle of vitrectomy is to surgically remove most of the vitreous, to allow the surgeon to do whatever retinal work that is required. With the vitreous cavity illuminated (either with handheld light pipe or chandelier light), the vitrector is introduced into one of the trocars, and core vitrectomy is performed at the centre of the vitreous cavity. Then posterior vitreous detachment (PVD) is checked. If it is absent, then a PVD should be induced. If PVD is present, then peripheral shave of the vitreous should be performed after core vitrectomy. The peripheral shave is a dynamic process requiring constant eye–hand–feet coordination (moving the X–Y shift of the microscope foot pedal), moving around the vitreous base as the vitrectomy is going on. This will allow for optimal visualisation of the area being vitrectomised.

The technique to get a good thin shave of the vitreous is to tilt the eye as much as possible towards the vitrector with the vitrector being placed at the edge of the optimal peripheral retinal view. The peripheral shave is performed systematically. The vitrector is placed at the edge of the fundal view in order to get as close a shave as possible, with the vitrector being placed at a clock hour for approximately 10–15 seconds to ensure a good shave before moving on to the next clock hour. Especially for phakic eyes, it is important to not cross the midline to avoid lenticular touch. Ensure the port of the vitrector is always facing away from the retina to avoid retinal incarceration.

The induction of PVD requires certain basic consideration, although there are different approaches (varying among surgeons). As the vitreous is attached at its strongest point in the ora serrata and the optic disc, and the induction of PVD is done near the optic disc, the vitrector should be switched to aspiration only and directed towards the optic disc. By increasing the aspiration rate, the vitrector cutter orifice is swirled hovering above the optic disc in a slow methodical manner to capture the bulk of vitreous body before it is pulled tangentially away to the midperiphery of the retina, avoiding the macula and major arcades. Once reaching midperiphery, then the surgeon can switch to cut to release the tip of the vitrector from vitreous. The process is repeated until a definite PVD is obtained. Once PVD is induced, then the surgeon can continue with the peripheral shave as described above.

Now that we have reviewed the basic steps of vitrectomy, we are now going to discuss more techniques and methods tried and tested for a more effective and safer VR surgery through a case based discussion format.
