and about 6–8 ml of this mixture are injected. Hylase is hyaluronidase, which is an enzyme that can be added to the local anaesthetic solution when administering perior retrobulbar anaesthesia. It promotes akinesia and is standard in some departments, whereas it is never used in others.

Pits & Pearls

If revisional surgery within several days of the initial surgery is necessary, consider general anaesthesia, in particular after retinal detachment surgery with cryotherapy and extensive extraocular manipulations. The local anaesthetic is less effective in inflamed tissue, and the procedure can be more painful under local anaesthesia than anticipated.

Pits & Pearls

When performing potentially painful surgery under general anaesthesia (cryotherapy, extensive extraocular manipulations), consider giving a small amount of subtenons anaesthesia at the end of the surgery. This significantly reduces the pain in the immediate postoperative period when the patient is waking up and recovering from the general anaesthesia.

Pits & Pearls No. 6

If you are using Hylase with retrobulbar anaesthesia, one vial can be used for multiple cases during one surgical session. We routinely dilute one vial (1,500 IU) with 10 ml saline for injection and then use 1 ml of this added to our local anaesthetic mixture.

3.6Combined Surgery: Phaco/IOL and Pars Plana Vitrectomy

There is an increasing trend towards combined surgery (phaco/IOL + vitrectomy) in patients over 60 years. This prevents the need for a second procedure (phaco/IOL) that will be required in almost every patient in this age group within 1–2 years postoperatively. Additionally, the disadvantages of cataract development (decreased vision, increasing myopization, need for additional examinations) are avoided. Finally, manipulations at the vitreous base are significantly easier to perform in

pseudophakic patients. This is of particular importance in retinal detachment cases. A lens touch is a serious complication. It will always result in rapid cataract development and creates a potential point of capsular damage during phaco/IOL. This again may cause prolapse of the posterior segment tamponade into the anterior chamber.

It must also be mentioned that several colleagues try to avoid combined surgery if possible, even in patients above the age of 60 years or patients with moderate cataracts. The reasons for this are that the lens also has a potential barrier function between the anterior and posterior segment. Increasing anterior chamber inflammation can sometimes be seen following combined surgery. In addition, more anterior segment problems can be seen compared to a two-step approach (for example, posterior synechiae or lens capture). Finally, some authors argue that the additional anterior segment trauma together with the loss of barrier function may also increase posterior segment inflammation and may cause higher rates of cystoid macular oedema. These hypotheses have never been examined in a prospective randomized trial. The authors usually combine vitrectomy with phaco/IOL in patients with moderate to advanced cataracts and in patients above the age of 60 years. In patients under 60 years with a clear lens, a lens-sparing vitrectomy should be performed.

Pits & Pearls

If at all possible, try to establish biometry and IOL calculations as part of the routine preoperative assessment in all cases of phakic patients undergoing pars plana vitrectomy. This will enable you to perform unplanned phaco/IOL in cases of intraoperative lens touch if needed and provide you with the correct biometry should you need to use silicone oil as a tamponade (which greatly impairs the precision of biometry measurements).

There are two major surgical steps to understand and become skilled at if you wish to master pars plana vitrectomy: (1) To correctly assess the relationship of the posterior vitreous face and the retina, leading to completion of a posterior vitreous detachment (PVD) during surgery; and (2) trimming the vitreous base and operating in this area without touching the lens in phakic eyes. Therefore, before the start of any pars plana vitrectomy, always ask yourself two questions: Is a PVD present and is the eye pseudophakic or phakic? A PVD should be induced in all posterior vitrectomies (some authors propose not to induce a PVD in asteroid hyalosis or floaters, as the vitreous cortex adheres firmly to the retina and a PVD can induce breaks; however, a PVD will eventually occur in most of these patients, and this can either result in a ‘recurrence’ of floaters or retinal breaks). The attached posterior vitreous is more important than most people think. It is involved in many retinal pathologies (maculopathy, diabetic retinopathy) and should therefore be removed by a PVD. For the beginner, the induction of PVD is often not easy. A PVD can be seen at the slit lamp or by ultrasound. Intraoperatively, you can stain the vitreous to determine if a PVD is present or not.