|Year : 1991 | Volume
| Issue : 2 | Page : 41-43
Scleral buckling with hydrogel implant
Taraprasad Das, P Namperumalsamy
Aravind Eye Hospital & Post-graduate Institute of Opthalmology,Anna Nagar, Madurai-625 020, India
Aravind Eye Hospital & Post-graduate Institute of Opthalmology,Anna Nagar, Madurai-625 020
Source of Support: None, Conflict of Interest: None
The hydrogel implant for scleral buckling, first developed in 1980, is said to combine the advantages of both solid silicone rubber and silicone sponges. But it is still not widely used. Our clinical experience with the hydrogel implant used in 23 cases of rhegmatogenous retinal detachment is described. It was used both as exoplant and implant. Anatomical success was achieved in 91% of the cases. There was no infection, erosion, migration of extrusion of the buckle. The advantages are that it is soft, elastic, nontoxic, and nonpyogenic; it is devoid of infection and postoperatively it swells up, for additional heightening of the buckle. This new material appears to combine the advantages of both silicone sponge and solid silicon rubber thereby providing an ideal buckling material.
Keywords: Hydrogel Implant, Scleral Buckling, Rhegmatogenous Retinal Detachment
|How to cite this article:|
Das T, Namperumalsamy P. Scleral buckling with hydrogel implant. Indian J Ophthalmol 1991;39:41-3
| Introduction|| |
Scleral buckling is an efficacious procedure for closing retinal breaks in the surgical repair of rhegmatogenous retinal detachment . At present two types of synthetic silicone rubber are used for buckling, solid silicone and silicone sponge. Both the materials have their advocates, and both the materials have their own advantages and disadvantages,-but of late more and more retinal surgeons tend to use the silicone sponge as the buckling material than the solid silicone implants. The advantages of silicone sponge over solid silicone implants are that the sponge, because of soft consistency, does not result in underlying scleral necrosis and it swells up post operatively to produce additional heightening of the buckle. The disadvantages are that it results in more incidence of infection, migration and extrusion.
Solid implants with smooth surfaces are less likely to cause infections than are spongy materials, for a sponge that absorbs body fluids provides a good medium for bacterial incubation. Also, silicone sponge is not a true sponge, but a silicon foam rubber with cavities and macropores on the cut surfaces. The inter cellular walls are easily ruptured by heat sterilization, squeezing and stretching . This results in interconnecting spaces within the sponge; these pores and spaces absorb body fluid and may harbor organisms. Reported infection rates after scleral buckling with silicone sponge ranges from 2.7% to 18.0% , With solid silicone rubber, the infection rate is between 0.2% and 5.4% ,, but pressure necrosis, erosion and extrusion can occur.
To obviate some of these problems associated with both solid silicone and silicone sponge a new material made of methyl acrylate and 2-hydroxy ethylacrylate was developed and described by Refojo and co-workers in 1980'. Experimental and clinical experiences since then accumulated ,,,
suggest that this new material is a safe and effective material combining the advantages of both solid silicone rubber and silicone sponge in scleral buckling for retinal detachment. To the best of our knowledge this material is not being. clinically tried in this country. Our experiences of this hydrogel implant used in 23 eyes in the past one year and followed up for at least six months is the basis of this report. The biochemical nature of this new buckling material, the technique of surgery and results, with a brief review of the works published to date on hydrogel implants are subsequently described.
| Material and methods|| |
The twenty three patients in whom the hydrophilic acrylate or hydrogel buckles were used, formed part of 153 patients operated for rhegmatogenous retinal detachment during the first half of 1988. These were non consecutive eyes in whom hydrogel implants were used either as meridional devices to prevent fishmouth phenomenon during surgery (20 eyes) or as circumferential implant (3 eyes). In seventeen eyes the hydrogel was used as a meridional implant under solid silicone segmental buckle and in three eyes it was used as radial exoplants [Table - 1]. Fourteen eyes had phakic retinal detachment, seven eyes had aphakic retinal detachment and two eyes had pseudophakic retinal detachment. The age of the patients ranged from 17 to 75 years.
Pre operative work-up in addition to detail ocular history included external eye examination, tonometry, biomicroscopy of the anterior and posterior segments and indirect ophthalmoscopy with scleral depression and detail fundus drawing. The surgical procedures performed on 23 eyes are summarized in [Table - 1] and were similar to that described by Tolentino, Refojo and Schepens .
To place the accessory meridional hydrogel material beneath the solid silicone implant the recalcitrant retinal break was previously localised by indirect ophthalmoscopy; the sclera in this meridian was dissected posteriorly if the retinal break was lying posterior to the existing buckle and the flap was not dissected if the break was located on the buckle and the meridional piece was intended only to increase the buckle height in the area of retinal break. The hydrogel implant was cut and trimmed before inserting beneath the solid silicone implant and an additional mattress suture was placed on the scleral flap in the meridian of the accessory implant to produce a high buckle and to secure the implant.
The technique of intrascleral buckling with the Refojo hydrogel implantwas similarto that described previously by Schepens and his co-workers , Since in all the three cases where primary intrascleral hydrogel implant was used 360 o encirclage was also done, the grooved hydrogel implant was used. The length of the buckle depended on the pathological changes in the retina and vitreous, and the width of the scleral bed was equal to the width of the implant plus twice its thickness. The scleral bed was treated with diathermy. The encircling band was passed in the groove of the implant, anchored to the sclera in the quadrants where there was no implant and both the ends were tied with a clovehitch knot.
The technique of radial episcleral exoplant used in 3 eyes was similar to that described by Lincoff , and Ross . In all the cases an encircling band was placed over the episcleral hydrogel buckle under the scleral sutures; the band was anchored to the sclera in all the quadrants and both the ends were tied with a clovehitch knot.
Postopertively the patients were treated with systemic antibiotics (Cephalexin 1 gm/day), topical antibiotics and mydriatics. Topical steroids once a day was applied from the third postoperative day. The eyes were examined daily by indirect ophthalmoscopy and the external appearance of the eye was compared with eyes which had undergone scleral buckling using solid silicone implant only. Special enquiry was made as to any unusual pain or discomfort post operatively. The patients were normally discharged on the 8th post operative day and followed up 4,12 and 24 weeks after surgery. In each follow up visit, apart from examining the status of the retina by indirect ophthalmoscopy, corrected visual acuity, ocular motility and the cosmetic appearance of the eye was assessed.
| Results|| |
Out of twenty three eyes, revision surgery had to be done in three eyes - one phakic eye and two aphakic eyes - due to development of advanced proliferative vitreoretinopathy in two aphakic eyes and development of a new retinal break in the phakic eye. In both the aphakic eyes vitrectomy, scleral buckling and fluid air exchange was done and in the phakic eye the extent of the buckle was extended to cover the new retinal break. In both the aphakic eyes which were subjected to reoperation the retina did not reattach. Overall anatomical success was achieved in twenty one eyes (91.3%). The functional success defined as the final corrected visual acuity equal to or more than 6/60 was achieved in 18 eyes (78.26%). In three eyes where the retina was anatomically attached the visual acuity was less than 6/60 due to pre retinal fibrosis and macular puckering.
In all the cases, be it radial hydrogel under the solid silicone implant, or episcleral hydrogel explant, or circumferential hydrogel buckle, there was a smooth buckle in all the eyes and the radial buckle provided a high and effective meridional buckle to abort fishmouthing of a retinal break. There were no unusual findings externally during the early or late post operative periods. The location of the implant was permanent and remained stable in the late postoperative period. There was no migration of the buckle, and neither was there any erosion of the sclera or extrusion of the hydrogel implant. There was no abnormal reaction of the eye in the early postoperative period and there was no buckle infection at any time.
| Discussion|| |
The present day technique of retinal detachment surgery involves use of non absorbable buckling material to produce the desired indentation of the sclera. The two most frequently used materials are solid silicone rubber and soft silicone sponge. But there is a continuous search for better scleral buckling material and one of them which has emerged promising are the hydrogels. Three of the several hydrogels tried experimentally in the past which have got the potential of being used on human subjects are polyglyceryl methacrylate (PGMA), poly 2-hydroxy ethyl acrylate (PHEA) and copolymer of 2-hydroxy ethyl acrylate with methyl acrylate and ethylene diacrylate (MAI) ,, Of these three the MAI hydrogel was found to be the most suitable both experimentally and on human subjects ,,. It is soft in the dry state and becomes softer when hydrated. It can be autoclaved repeatedly if placed with saline in a glass bottle that is closed with a rubber cap. It is softer than either solid silicone rubber or silicone sponge. It is not damaged when used as an episcleral implant under sutures that exert pressure on the implant.
This study involves non consecutive eyes with retinal detachment where the new hydrogel implant was used. The majority of cases were the ones where fishmouthing was suspected and to prevent such occurrence additional meridional buckling material was needed. The hydrogel material was used alone in six cases - three as episcleral radial buckles and three as circumferential buckles. We found that this material is readily adaptable for both intrascleral and episcleral buckling techniques and maintains an effective and stable buckle without any erosion, extrusion, infection and cosmetic disfigurement. Because it is soft, smooth and convex it maintains a desirably high buckle. The same could also be obtained with silicone sponge. However, the latter is more susceptible to infection as it has dead spaces . A major advantage of the hydrogel implant is that it does not have dead spaces like the silicone sponge. In cross-section this hydrogel polymer measures only 30-50° A which is approximately 100 times smaller than the smallest known bacterial spore. This renders this material less likely to be invaded by bacteria . Soaked in antibiotics it absorb and releases antibiotics  thus reducing the chances of infection still further.
The other properties of this hydrophilic implant were described by Refojo and co-workers  in 1980 and Ho et al  in 1984. The hydrogel implant contains approximately 17% isotonic saline. It swells in water, it absorbs and releases antibiotics and it is nontoxic whether implanted episclerally, intrasclerally or in the anterior chamber . It is not electrostatically charged, and therefore does not attract lint or dust . In two previous reports , the clinical trials in human subjects were also found to be extremely encouraging. It has also been observed that the hydrogel implant produces a fibrous capsule over the scleral bed as early as 4 weeks after implantation. This capsule appears to strengthen the scleral bed and is supposed to make the reoperations in cases of recurrent retinal detachment easy and safe . To the best of our knowledge this new scleral buckling material has not yet been used in this country. At present the material is dispensed in a pre sterilized hydrophilic state in a glass bottle containing normal saline. At the beginning of the surgery, the glass bottle is opened, the implant is taken out by a pair of sterile forceps and soaked in suitable antibiotics (we use cephaloridine) till it is actually implanted into the eye. It comes both with grooves and without; the grooved hydrogel is used for circumferential buckling when the encircling band is also used. The nongrooved hydrogel is suitable for all other situations.
| References|| |
Schepens CL: Retinal detachment and Allied Diseases. Philadelphia, W.B. Saunders, p.333-343, 1983.
Refojo MF: Sustained release of antibiotics from scleral buckling materials II. Silicone sponge. Ophthalmic Res, 7:459. 1975
Hahn HS, Lincoff A, Lincoff H and Kreissig I: Infection after sponge implantation for scleral buckling. Am. J. Ophthalmol, 87:180, 1979
Russo CE and Ruiz RS: Silicone sponge rejection: Early and late complications in retinal detachment surgery. Arch. Ophthalmol, 85:647, 1971
McMeel JW, Naegele DF, Pollalis S, Badrinath SS, Murphy PL: Acute and subacute infections following scleral buckling operations. Ophthalmology, 85:341,1978
Das TP & Namperumalsamy P: Aphakic retinal detachment. J. Madras State Oph. Assoc, 20:2:24, 1983
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[Table - 1]