which case the association with trauma is said to be less. Atopic dermatitis (Katsura and Hida 1984) and Down’s syndrome (Ahmad and Pruett 1976) have been associated with retinal dialysis.

The slow progression of retinal detachment means that most cases can be scheduled for surgery on a daytime list as opposed to emergency surgery, the exception being the case which appears immediately after trauma.

Occasionally, a very late presentation of retinal dialysis is associated with C grade PVR. These are very difficult to fix; see PVR.

7.5.2Surgery for Retinal Dialysis

The approach is the same as the non-drain procedure, but a few adaptations are required to cope with the particular characteristics of the dialysis. The operation can be technically demanding, but the results are potentially very good.

Table 7.1 Difficulty rating of surgery for retinal dialysis

7.5.2.1 Search

Particular attention should be paid to the ora serrata over 360° because this is the position of any likely pathology. The indentation is very anterior as you are indenting the ora and therefore requires good control of the movement of the eye; use the muscle slings to fix the position of the eye (rest your fifth finger on the sling to stabilise the eye) during indentation. Carefully examine the ends of the dialysis for small extra dialysis. Very shallow dialysis will close when indented and can be missed. Move your indent in a circumferential direction around the ora so that the dialysis is partially opened on the edge of the indent to overcome this problem. I have seen U tears (surprisingly) accompanying the dialysis on rare occasion; therefore, the whole retina needs to be searched.

7.5.2.2 Cryotherapy

This requires confluence of the burns (see Sect. 7.5.2.4). Dialysis often extends from extraocular muscle insertion to extraocular muscle insertion (usually the inferior rectus to lateral rectus); therefore, the retinopexy is over a large area. The dialysis at its apex often seems too far away from the indent internally to achieve a cryotherapy burn. However, it is usually possible to obtain all the burns required. Be particularly aware of which parts of the retina you have treated (avoid overlapping the burns too much), to limit the number

of burns but still achieve confluence. It is important that the retina has been sealed along all of the extent of the dialysis by the retinopexy because removal of the plombage postoperatively is sometimes required (to reverse complications from its anterior position, e.g. poor cosmesis or diplopia).

7.5.2.3 Marking the Break

For large dialysis, mark the ends, or the position of any satellite dialysis, and also the apex. The ends are usually at the muscle insertions, but it is important to know exactly where in case extension of the plombage under the muscle is required running the risk of postoperative diplopia (especially with the superior and inferior recti). The apex may extend further posteriorly than the ends of the dialysis requiring bowing of the plombage to ensure that the dialysis will fall onto the smallest plombage.

7.5.2.4 Plombage

Select a sponge that will cover the required area. A 4-mm sponge is preferred because it will be less prominent postoperatively than a 5 mm. However, the elevations of some dialyses are very high and may require the latter. If the dialysis is small, two sutures will be sufficient, which with a 4-mm sponge is unlikely to compromise the optic nerve circulation (check it after suture tying in any case). Larger dialyses require three sutures, one at each end and one at the apex. Insert the sutures as usual placing the ‘marks’ on the sclera centrally between the suture bites. Tie one of the sutures at one end of the plomb. Perform a paracentesis and remove approximately 0.15 ml of aqueous. This avoids occlusion of the optic nerve circulation. Tie the middle suture. The softer eye eases the production of a high indent at the apex. Finally, tie the last suture. Softening of the eye causes the plombage to produce an internal indent rather than being proud of the eye (resulting in poor cosmesis or disturbance the function of the extraocular muscles).

7.5.2.5 Checking the Indent

Check the optic nerve. View the indent, which should go past the ends of the dialysis slightly, and judge that the dialysis will fall on to the apex of the indent or slightly onto the anterior border (remember parallax). Trim the ends of the indent and slope the ends 45° to help reduce the protrusion of the sponge at its ends. Check that Tenon’s is not caught up in the sutures, and sew up the conjunctiva.

7.5.3Complications

The complications are as for non-drain procedures; however, the anterior placement of the plombage, the need for a long circumferential plombage and the need to insert under vertical recti increase the chance of some complications.

•Diplopia. Surgery around the vertical recti is more likely to induce diplopia because the vertical fusion range is less than the horizontal. If diplopia occurs, removing the plombage early will usually alleviate the problem.

Note: The plombage can be removed as soon as the retinopexy has sealed the break, for example, 10 days.

•Cosmesis. The plombage may be visible because of the anterior placement and the inferotemporal position of many dialyses.

Note: Some surgeons because of the possibility of poor cosmesis use solid silicone explants but perform external drainage of SRF with its attendant risks.

•Trapped foveal SRF occurs because of the chronicity of the RRD.

•Failure of reattachment is rare if the indent is in the correct place; fish mouthing (folding of the break on a circumferential indent) does not seem to happen. I have seen a dialysis held off the indent by two retinal cysts. The patient was reoperated with removal of the original indent and a radial plomb placed on the unattached area of the break between the two cysts.

7.5.4Giant Retinal Dialysis

This is a rare presentation in which the dialysis is more than 90°. The presentation in my experience has occurred in patients with an odd traumatic history such as patients who may injure their own eyes, for example, schizophrenia or patients who are under institutional care from neurological deficit (e.g. cerebral palsy). Non-drain surgery will not work in these, and a PPV will be required. The PHM will need to be detached from the retina, and the vitreous will be removed over the break to gain access to the SRF through the dialysis. Take care when you have instruments at the site of the break because you are very close to the lens which can be damaged. Apply laser retinopexy and minimal cryotherapy; use a long-acting gas or silicone oil.

7.5.5Dialysis and PVR

7.5.6Par Ciliaris Tear

This is a rare form of dialysis in which the tear is located in the pars plana. It occurs in severe blunt trauma and is usually seen in the superonasal quadrant. Consider the diagnosis in a child with a total shallow RRD of uncertain history (unfortunately, a common presentation in children) which is of unknown duration. These breaks are difficult to see and diagnose because of delay in presentation often accompanied with PVR. It is my only indication for an encircling explant, for example, 360° 7-mm wide solid silicone explant with an encircling band. If you can see the break, apply retinopexy. If not, use the explant on its own.

Surgical steps

•360° conjunctival perimetry.

•Sling all muscles.

•Search.

•Cryotherapy.

•Place four 5/0 polyester sutures spaced at 9 mm apart, one in each quadrant straddling the ora serrata.

•Insert the explant under the muscles and the sutures.

•Method 1.

–Insert the 2-mm silicone band starting superotemporally and returning there.

–Insert one end of the silicone band through a silicone sleeve, for example, Watzke sleeve (place the sleeve on a curved artery clip and open the clip to expand the sleeve), then insert the other end of the band from the other direction. Close the forceps and slip off the sleeve.

–Tighten the silicone band by pulling through about 1 cm.

•Method 2.

–Suture the two ends of the solid silicone explant together (insert the needle and suture directly into the explant) with a nonabsorbable suture.

•Check you have a diffuse indent and the optic nerve is perfusing.

•Close.

Subretinal bands are the commonest form of PVR in dialysis. Mostly these will allow use of the non-drain procedure and settling of the RRD with minimal tenting of the retina. Occasionally, more severe PVR is seen in grade C. This is very difficult to deal with and is usually seen with an odd presentation such as severe trauma and delay in diagnosis (e.g. in a child). Apply PVR techniques to treat (Chap. 7).

Note: These retinas are difficult to fix a decision to perform PPV, and oil must be taken very carefully. These eyes may have poor visual recovery, even if successful. They are cosmetically normal at presentation and relatively nonprogressive because of shallow RRD and formed vitreous; therefore, it may not be in your patient’s best interests to pursue multiple operations with attendant cosmetic changes to the