Brit. J. Ophthal. (1973) 57, f31

Prophylactic encirclementJ. R. HUDSON, J. J. KANSKI, AND A. R. ELKINGTONMoorfields Eye Hospital, High Holborn, London, JV.C. i.

The basic requirements for successful prophylaxis of retinal detachment are first, thedetection and accurate localization of all retinal breaks, and any lesions that may predisposeto them; secondly, the counteraction of vitreous traction; and thirdly, the production ofan adhesive chorio-retinitis in the correct location to achieve permanent sealing of allactual and potential retinal breaks. In addition, the chosen procedure should cause aslittle damage as possible to the eye and its adnexa.There are several ways in which this may be achieved. In cases with no evidence of

vitreous traction, such as those with degenerative round holes or tears with free operculain the vitreous and no retinal elevation around the break, simple treatment with eithercryopexy or photocoagulation is all that is necessary. However, when there is evidence ofmoderate vitreous traction, as with U-shaped tears with some evidence of retinal elevationalong their edges, local indentation is indicated, in addition to the production of achorio-retinitis.

Severe vitreous traction is signified by multiple U-shaped tears, which may occur inseveral quadrants, and it should be suspected if there are large areas of predisposing lesions,or a giant tear, in the fellow eye. In such cases, the creation of a permanent scleral buckleby encircling the globe should be considered.

Encircling operations have become established procedures in certain cases of retinaldetachment, since the original description by Schepens (I957) and Arruga (1958), buttheir use as a prophylactic measure in eyes with flat retinae has not previously been reportedin the literature. Since August, I968, the procedure has been carried out in this unit oneighteen carefully selected patients, and the purpose of this paper is to explain the rationaleof this approach and to give the results of the patients treated so far.

Operative techniquePreoperatively the pupil is dilated with drops of atropine I per cent., and Genticin drops are instilledinto the conjunctival sac every 2 hours to eliminate pathogenic organisms.The operation is carried out under general anaesthesia, using fluothane, and as soon as the patient

is anaesthetized an intravenous injection of Diamox 500 mg. is given to reduce the intraocularpressure, so that the encircling band may later be tightened without inducing an ocular hypertension(mannitol or urea may similarly be used).A speculum is inserted, and the conjunctiva incised 6 mm. from the limbus right round the globe,

and the sclera exposed; traction sutures are placed beneath the rectus muscles. All retinal breaksand degenerative areas in need of treatment are carefully localized using the indirect ophthalmoscopeand their posterior limits are marked on the sclera, using either the cautery or a black suture. beforetheir position is re-checked by scleral indentation. These areas are then usually treated withcryopexy, although in Cases iI and I 7, no application was made at the time of surgery.The eye is encircled with a silicone rod, or 2 mm. strap, so that the retinal pathology lies on the

anterior slope of the resulting ridge. Mattress sutures of s/o braided terylene are placed in eachquadrant in such a way that the encircling element can glide through the sutures and yet is preventedfrom slipping either forward or backwards.

Received for publicationi January 15, 1973Address for reprints: J. J. Kanski, Moorfieldls Eye Hospital, High Holborn, Lonidoni, W.C.u

5. R. Hudson, J. 7. Kanski, and A. R. Elkington

The ideal depth of the ridge is about i mm. and this can be achieved by shortening the encirclingelement by 7 mm. (Hamilton and Taylor, I972). The details are worth emphasizing.The encircling element is initially drawn up to lie gently against the globe, but it is released to

ensure that it is not under tension. Sutures are then placed around the two ends of the strap tomark the point at which they overlap, before the strap is tightened. The site ofcrossing is temporarilyheld with artery forceps, and the traction is released before the distance between the sutures ismeasured. This process is repeated until the distance between the marker sutures is 7 mm. whenthe strap may be secured. Alternatively a Watzke sleeve can be used. The optic disc must beobserved periodically to ensure that the central retinal artery is not occluded.The conjunctiva is closed with interrupted sutures of 6/o catgut and the eye is padded.

Postoperatively, drops of atropine I per cent. and Genticin are instilled once a day and a carefulcheck is made daily for any signs of a rise in intraocular pressure. The patient is mobilized on theday after the operation and is discharged home a week later. The patient can return to work 3weeks after surgery.The operation is not without its potential hazards since, if the encircling element is drawn up too

tightly, anterior segment necrosis, occlusion of the central retinal artery, and "strap pain" may becatastrophic consequences. But, provided the surgeon follows meticulously the technique described,these complications should not occur.

Results

Between April, I968, and August, I97I, prophylactic encirclement was carried out oneighteen patients (14 males and 4 females). Fourteen eyes were myopic, of which sevenhad a correction of -575 D sph. or more, while two were aphakic and two wereemmetropic. The patients varied in age from 25 to 69 years, and five of them gave afamily history of retinal detachment.Only one fellow eye was normal (Case 5). Of the remaining seventeen, thirteen had

been previously treated for a detachment (four successfully but nine unsuccessfully),whilst four had received prophylactic treatment for retinal breaks.Two patients (Cases 2 and 6) required postoperative photocoagulation to seal breaks

which had not been covered by the encirclement, and two others (Cases i and 8)subsequently developed breaks behind the ridge which necessitated further treatment.The fundus picture after operation in Cases 5, I2, I3, and 14 is shown in the colour

plate (opposite); the appearance before operation is also shown for Case I 2.Complications were encountered in three patients: Case I I developed a transient rise

in intraocular pressure but no further sequelae, Case 6 developed a mild anterior segmentnecrosis causing a cataract, and Case 5 complained of slight diplopia due to a paresis of theinferior rectus.

After a follow-up period of i to 5 years, no detachment has developed in sixteen of theeighteen patients. In the two patients in whom the retina became detached (Cases I 7 andI8), surgery was successful in Case I7 but failed in Case I8.

Full details of the eighteen patients are given in the Table, with diagrams of the treatedeye before and after operation and also of the fellow eye.

Discussion

The decision whether or not to advise prophylaxis is often difficult, since the ideals of anentirely safe and yet effective procedure cannot be guaranteed, but faced with the reported

532

PROPHrLACTIC ENCIRCLEMENT

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To fae page 532

Prophylactic encirclement

cases prophylactic encirclement seemed justifiable, even if this original approach provedcontroversial. The indications for the operation have yet to be exactly defined, but thefindings in the eye at risk, the history and appearance of the fellow eye, and the familyhistory will be decisive.The essential merits of prophylactic encirclement are two-fold: First, a permanent

circumferential buckle is achieved in the equatorial region which, by reducing the volumeof the eye, helps to eliminate vitreous traction on existing or potential retinal breaks.Secondly, multiple breaks in different quadrants can commonly be sealed by this onemanoeuvre. In addition, since a new ora serrata is created, a "barrage effect" isproduced, so sealing off any breaks anterior to the buckle which may have been overlookedor inadequately sealed or which may have developed postoperatively.The Table (overleaf) shows that Cases I to 7 had one or more large U-shaped tears and,

in at least two other quadrants, lesions predisposing to retinal detachment, namely, retinalbreaks or lattice degeneration in the presence of vitreous traction; Cases 8 to I8 hadsimilar pathology in more than two quadrants. Consequently, all eyes were judged likelyto develop detachment. This likelihood was enhanced when the eighteen fellow eyeswere studied, since nine of them had had unsuccessful retinal detachment operationspreviously; four had had detachments but had been successfully treated; and a further fourhad been treated prophylactically for retinal breaks. Only one fellow eye was normal.

Five patients gave a family history of detachment and interestingly Cases I 7 and i 8(who alone re-detached) were related and belonged to a family many of whose memberssuffer from vitreo-retinal degeneration.The great danger of encircling an eye prophylactically is that the encircling element

may be drawn too tight, since there is no subretinal fluid to release to make the eye softer.This occurred in one patient (Case 6) operated upon early in the series but, if the minutiaeof the technique are observed, this should not occur. Case I I suffered a transientrise in tension for 48 hours, but this was easily controlled and no untoward sequelaedeveloped.

Fortunately, the repeated applications of the cryoprobe can markedly reduce the oculartension and, when many such applications are made, as in treating extensive areas ofretinal pathology, the eye may prove conveniently soft and allow a satisfactory ridge to beachieved without any subsequent rise in pressure.

In no patient did complications arise during surgery. One patient (Case 5) subsequentlycomplained of diplopia due to a paresis of the inferior rectus of the operated eye, but sincehe had binocular single vision in the primary position, no muscle surgery was undertaken.Apart from Case 6, already referred to, only one patient (Case I4) had a lowered

postoperative visual acuity. He was known to have had lens opacities before surgery and,since his visual acuity fell merely from 6/36 to 6/6o over a 2-year period, the deteriorationwas probably unrelated to the operation. Thus, a properly executed encirclement shouldhave no adverse effect upon the patient's visual acuity-Two patients (Cases 2 and 6) required further treatment because some of the original

retinal breaks lay too far back to be sealed by the encirclement. It proved simple toapply photocoagulation to these areas later, and no new tears have developed. In contrast,fresh breaks developed behind the ridge in a further two patients (Cases I and 8) but againphotocoagulation was successful in sealing them and in none of these four patients has aretinal detachment yet developed. Thus, in only two of the eighteen eyes treated, has adetachment occurred subsequently.

533

Y. R. Hudson, J. 5. Kanski, and A. R. Elkington

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Summary

Of eighteen carefully selected high-risk patients in whom the globe was encircled prophy-lactically, two subsequently detached.The rationale, technique, and results of this new procedure are discussed.

Reference

HAMILTON, A. M., and TAYLOR, w. (I972) Brit. i. Ophthal., 56, 695