8.4.3Severe PVR

(C6–C8)

Additional surgical steps: Operation 1

Insert heavy liquids. Stain with trypan blue. Peel PVR membranes. Flatten the macula.

Close breaks if possible with tamponade superiorly and indentation inferiorly, and apply retinopexy.

Insert silicone oil. Operation 2

Insert heavy liquids. Stain with trypan blue. Peel PVR membranes. Diathermy blood vessels. Incise along retinectomy.

Remove the redundant anterior retina.

Check for folds and perform radial cuts in the retina if required.

Insert silicone oil.

Apply laser retinopexy (with cryopexy to the apices if required).

Operation 3

Remove the silicone oil.

In more severe PVR, and depending on the location of retinal breaks, and also in grade B PVR where there is a diffuse shortening of the retina without the ability to remove surface membrane, a three-stage approach is recommended. At the first operation, perform a vitrectomy and peel as much membrane as possible. Heavy liquid will allow opening of the retina peroperatively (Coll et al. 1995). However, shortening of the retina itself is likely to prevent the retina from re-settling on the back of the eye fully. Heavy liquid will ‘flatter’ the appearance of reattachment of the retina because of its high density and may cause an underestimation of the degree of residual traction. Do not be tempted to perform a retinectomy at this stage, as in the early stages of the PVR process, when cytokines and growth factors are still present and cells are still activated, there is a risk that the retinectomy will end up as a ‘roller-blind’ contraction of the retina, in which the inferior retina rolls up through the macula. This is irredeemable. Therefore, fill the eye up with oil, which, in most circumstances, will flatten two-thirds of the retina, leaving the inferior retina detached because of its shortening. With the macula in place, the retina can be left for 3–6 months

Table 8.4 Difficulty rating for surgery for severe PVR

for the PVR process to become quiescent. Then perform a second operation and cut the inferior retina as far peripherally as is possible to perform a retinectomy.

Shortened

retina

Cord length of eye wall

Fig. 8.26 PVR will shorten the cord length of the retina. The orange line, indicating the retina, cannot return to the circumference of the posterior pole (the blue line) if it is anchored at both points anteriorly and posteriorly (a). By cutting the retina (relieving retinectomy), the retina can be allowed to slip back into place (b)

a

Silicone oil

b

Retinectomy

Fig. 8.27 Silicone oil insertion can be used in conjunction with inferior retinectomies. It is probable that the oil does not tamponade the whole extent of the retinectomy. However, the oil allows satisfactory adhesion of the retinectomy scar probably because a thin layer of fluid is present between the oil and the retinectomy, which prevents subretinal fluid accumulation. Insert oil to flatten most of the retina (a) at operation 1 and perform retinectomy later in operation 2 (b)

Fig. 8.28 After the first operation for reattachment of most of the retina in moderate PVR, there will be persistent inferior SRF but the macula should be flat

Fig. 8.30 Retinectomies performed early can produce extensive scarring because the PVR process is still active

Fig. 8.29 This OCT shows a flat macula under oil with inferior RRD

8.4.3.1 The Relieving Retinectomy

The edges of the retinectomy should at least reach the 8 and 4 o’clock meridians and will have to go at least 1 clock hour into non-scarred retina on each upper aspect. Therefore, it is common to have a retinectomy which is 150–180°. First, diathermy the peripheral retinal blood vessels that are visible to avoid bleeding. Then use a vertical cutting scissor to fashion the retinectomy, cutting through the diathermy points. At this stage, the infusion can be attached to balanced salt solution to keep the eye inflated. Any oil that leaks from the eye will be replaced by balanced salt solution, and this will help provide some space for your instruments. If the eye is full of oil, there is less space for the instruments to cut the retina which makes the operation technically more demanding. Use the

Fig. 8.31 Using a sequence of surgeries with delay before the retinectomy may produce a cleaner retinectomy edge which is less likely to fail

vitreous cutter to remove the anterior retina. Try and remove the entire anterior retina, as any remnants will cause retinal neovascularisation and iris neovascularisation (Bourke and Cooling 1996) or may contract causing detachment of the ciliary body and hypotony.