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Spontaneous Dislocation of a Foldable Lens Following Phacotrabeculectomy and Implant Insertion: a Case Report
SHORT REPORT
Spontaneous Dislocation of a Foldable Lens Following Phacotrabeculectomy and Implant Insertion: a Case Report ALAN S. KOSMIN and PETER K. WISHART Royal Liverpool University Hospital, Liverpool, UK
Alan S. Kosmin and Peter K. Wishart. Spontaneous Dislocation of a Foldable Lens Following Phacotrabeculectomy and Implant Insertion: a Case Report. Eur. J. Implant Ref. Surg., 1995; 7: 253-254. Spontaneous postoperative dislocation of a foldable implant into the anterior chamber has not previously been recorded. Such a case of spontaneous implant (Chiron 32-CI0XX) dislocation in the early postoperative period is described following a phacotrabeculectomy procedure along with its successful surgical management. Possible mechanisms of spontaneous implant dislocation in this case were the development of a large post-operative choroidal detachment and the presence of a large capsulorrhexis. Keywords: Foldable lens; Phacotrabeculectomy; Lens dislocation.
incIsIon. Several authors have published their experience of insertion of foldable lenses performed with and without trabeculectomy [2-5]. We report a previously undocumented complication associated with foldable lens implants together with its management.
INTRODUCTION
Patients with cataract and glaucoma can be managed surgically with either separate cataract extraction and trabeculectomy operations or a procedure where the 2 are combined. Initially extracapsular cataract extraction (ECCE) with insertion of a polymethylmethacrylate (PMMA) lens was combined with trabeculectomy. More recently, phacoemulsification has become commonly used in combined procedures. The smaller incision associated with this technique provides the advantages of reduced surgically-induced astigmatism, quicker wound stabilization and speedier visual rehabilitation [1]. However, the use of small incisions limits the diameter of inflexible PMMA optic that can be passed into the eye, thereby introducing the potential problems of glare or reduced visual acuity should the small optic become decentred. In an attempt to overcome this problem many surgeons have changed to using foldable implants which allow insertion of a larger optic through a 3-4 mm Correspondence to: Mr A.S. Kosmin, St Paul's Eye Unit, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK. 0955-3681/95/040253 + 02 $08.0010
CASE REPORT
A 55-year-old man with cataract and glaucoma uncontrolled on medical therapy underwent a left phacotrabeculectomy with insertion of a foldable silicone lens implant with plate haptics (Chiron 32-C10XX). At surgery, the capsulorrhexis was seen to be about 7 mm in diameter and was larger temporally than considered ideal. Implant insertion into the capsular bag was uncomplicated. During the operation there was no anterior bulging of the anterior vitreous face [5]; a condition which has been reported to give rise to anterior displacement of the lens. Healon GV was carefully removed from the anterior chamber and capsular bag following lens insertion. The implant was not displaced following this manoeuvre and at the end of surgery the
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© 1995 W.B. Saunders Company Limited
254
Short Report
capsulorhexis margin remained intact [5] with the implant appearing stable within the capsular bag. G.cyclopentolate, 1%, and G.chloramphenicol were applied at the end of the procedure and a cartella shield was placed over the eye which remained undisturbed until the first review on the morning following surgery. At review, the inferior haptic was found to be displaced anteriorly through the pupil. The lens was unstable and the inferior haptic was intermittently touching the inferior corneal endothelium on eye movement. The superior haptic however remained within the capsular bag. There was a large inferonasal choroidal detachment which extended forward to involve the ciliary body, in addition the intraocular pressure (lOP) was low at 8 mmHg. Attempts to replace the lens behind the pupil using mydiatics and supine posturing failed and a decision was made to replace the lens surgically on the second day following the initial operation. At surgery, a stab incision was made at 10 o'clock in the peripheral cornea in addition to the side-port stab incision at 2 o'clock that had been made at the initial operation for use of the second instrument which allowed a bimanual phacoemulsification technique. A lens 'dialler' and 'microfinger' (Karl Ilk, Illinois, USA) were inserted through the stab incisions and were positioned at the inferior margin of the optic at 5 and 7 o'clock. These instruments were then used to push the lens both superiorly and posteriorly until it became repositioned in the capsular bag. After repositioning of the lens the mild postoperative inflammation settled with routine use of G.pred. forte, 1%, q.d.s., and the choroidal detachment settled spontaneously. At 2 months following surgery the patient achieved a corrected left visual acuity of 616 with a refraction of -1.50 D spherel + 0.5 D cylinder; axis 60 degrees. There has been no lens decentration and the lOP remains within normal limits on no antiglaucomatous medication.
DISCUSSION
Postoperative hypotony as occurred in this case may occur following phacotrabeculectomy and lead to choroidal detachment [1]. We hypothesize that the large choroidal detachment found in this case led to the dislocation of the implant and suggest the following mechanism by which it occurred. The choroidal detachment produced a force with an
anterior vector on the flexible implant. This force could have resulted from 2 mechanisms. First, as the ciliary body detached it rotated anteriorly around the scleral spur, this anteriorly-directed motion was transmitted to the implant via the posterior lens capsule to which the ciliary body was connected by the zonules. Second, the large choroidal detachment occupied space in the posterior segment causing anterior displacement of the vitreous with consequent forward bulging of the anterior vitreous face and posterior capsule. The ciliary body rotation may also have resulted in the inferior capsulorhexis margin becoming drawn downwards. Thus the anteriorly-directed force acting on the implant may have led to the inferior haptic being pushed forward over the down-drawn capsulorhexis margin and then through the dilated pupil. Four factors could have promoted the occurrence of lens dislocation in this case. First, the formation of a large choroidal detachment, the formation of which may well have been promoted by the second factor, postoperative ocular hypotony which is a common postoperative complication of trabeculectomy [1]. In addition the relatively low pressure in the anterior chamber may have reduced opposition to the anterior bulging of the posterior capsule which has been implicated in the hypothesized method of lens dislocation described above. Third, the ability of the implant to be deformed may well have aided its extrusion from the capsular bag. Last, the creation of a relatively large capsulorhexis may have facilitated the escape of the implant from the capsular bag. We have learnt from this case the need to create a smaller and central capsulorhexis in cases where foldable implants are used in operations predisposing to ocular hypotony and choroidal detachment such as phacotrabeculectomy. REFERENCES 1 PK Wishart, MW Austin. Combined cataract extraction and trabeculectomy: phacoemulsification compared with extracapsular technique. Ophth. Surg., 1993; 24: 814-82l. 2 JS Cummings. Postoperative complications and uncorrected acuities after implantation of plate haptic silicone and three piece silicone intraocular lenses. J. Cataract. Refract. Surg., 1993; 19: 263-274. 3 A Wedrich, R Menapace, U Radax, P Papapanos, M Amon. Combined small-incision cataract surgery and trabeculectomy technique and results. Int. Ophthalmol., 1992; 16: 409-414. 4 WA Lyle, JC Jin. Comparison of a 3- and 6-mm incision in combined phacoemulsification and trabeculectomy. Am. J. Ophthalmol., 1991; 111: 189-196. 5 JS Cumming. Surgical complications and visual acuity results in 536 cases of plate haptic silicone lens implantation. J. Cataract Refract. Surg., 1993; 19: 275-277.
Eur J Implant Ref Surg, Vol 7, August 1995
Spontaneous Dislocation of a Foldable Lens Following Phacotrabeculectomy and Implant Insertion: a Case Report ALAN S. KOSMIN and PETER K. WISHART Royal Liverpool University Hospital, Liverpool, UK
Alan S. Kosmin and Peter K. Wishart. Spontaneous Dislocation of a Foldable Lens Following Phacotrabeculectomy and Implant Insertion: a Case Report. Eur. J. Implant Ref. Surg., 1995; 7: 253-254. Spontaneous postoperative dislocation of a foldable implant into the anterior chamber has not previously been recorded. Such a case of spontaneous implant (Chiron 32-CI0XX) dislocation in the early postoperative period is described following a phacotrabeculectomy procedure along with its successful surgical management. Possible mechanisms of spontaneous implant dislocation in this case were the development of a large post-operative choroidal detachment and the presence of a large capsulorrhexis. Keywords: Foldable lens; Phacotrabeculectomy; Lens dislocation.
incIsIon. Several authors have published their experience of insertion of foldable lenses performed with and without trabeculectomy [2-5]. We report a previously undocumented complication associated with foldable lens implants together with its management.
INTRODUCTION
Patients with cataract and glaucoma can be managed surgically with either separate cataract extraction and trabeculectomy operations or a procedure where the 2 are combined. Initially extracapsular cataract extraction (ECCE) with insertion of a polymethylmethacrylate (PMMA) lens was combined with trabeculectomy. More recently, phacoemulsification has become commonly used in combined procedures. The smaller incision associated with this technique provides the advantages of reduced surgically-induced astigmatism, quicker wound stabilization and speedier visual rehabilitation [1]. However, the use of small incisions limits the diameter of inflexible PMMA optic that can be passed into the eye, thereby introducing the potential problems of glare or reduced visual acuity should the small optic become decentred. In an attempt to overcome this problem many surgeons have changed to using foldable implants which allow insertion of a larger optic through a 3-4 mm Correspondence to: Mr A.S. Kosmin, St Paul's Eye Unit, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK. 0955-3681/95/040253 + 02 $08.0010
CASE REPORT
A 55-year-old man with cataract and glaucoma uncontrolled on medical therapy underwent a left phacotrabeculectomy with insertion of a foldable silicone lens implant with plate haptics (Chiron 32-C10XX). At surgery, the capsulorrhexis was seen to be about 7 mm in diameter and was larger temporally than considered ideal. Implant insertion into the capsular bag was uncomplicated. During the operation there was no anterior bulging of the anterior vitreous face [5]; a condition which has been reported to give rise to anterior displacement of the lens. Healon GV was carefully removed from the anterior chamber and capsular bag following lens insertion. The implant was not displaced following this manoeuvre and at the end of surgery the
253
© 1995 W.B. Saunders Company Limited
254
Short Report
capsulorhexis margin remained intact [5] with the implant appearing stable within the capsular bag. G.cyclopentolate, 1%, and G.chloramphenicol were applied at the end of the procedure and a cartella shield was placed over the eye which remained undisturbed until the first review on the morning following surgery. At review, the inferior haptic was found to be displaced anteriorly through the pupil. The lens was unstable and the inferior haptic was intermittently touching the inferior corneal endothelium on eye movement. The superior haptic however remained within the capsular bag. There was a large inferonasal choroidal detachment which extended forward to involve the ciliary body, in addition the intraocular pressure (lOP) was low at 8 mmHg. Attempts to replace the lens behind the pupil using mydiatics and supine posturing failed and a decision was made to replace the lens surgically on the second day following the initial operation. At surgery, a stab incision was made at 10 o'clock in the peripheral cornea in addition to the side-port stab incision at 2 o'clock that had been made at the initial operation for use of the second instrument which allowed a bimanual phacoemulsification technique. A lens 'dialler' and 'microfinger' (Karl Ilk, Illinois, USA) were inserted through the stab incisions and were positioned at the inferior margin of the optic at 5 and 7 o'clock. These instruments were then used to push the lens both superiorly and posteriorly until it became repositioned in the capsular bag. After repositioning of the lens the mild postoperative inflammation settled with routine use of G.pred. forte, 1%, q.d.s., and the choroidal detachment settled spontaneously. At 2 months following surgery the patient achieved a corrected left visual acuity of 616 with a refraction of -1.50 D spherel + 0.5 D cylinder; axis 60 degrees. There has been no lens decentration and the lOP remains within normal limits on no antiglaucomatous medication.
DISCUSSION
Postoperative hypotony as occurred in this case may occur following phacotrabeculectomy and lead to choroidal detachment [1]. We hypothesize that the large choroidal detachment found in this case led to the dislocation of the implant and suggest the following mechanism by which it occurred. The choroidal detachment produced a force with an
anterior vector on the flexible implant. This force could have resulted from 2 mechanisms. First, as the ciliary body detached it rotated anteriorly around the scleral spur, this anteriorly-directed motion was transmitted to the implant via the posterior lens capsule to which the ciliary body was connected by the zonules. Second, the large choroidal detachment occupied space in the posterior segment causing anterior displacement of the vitreous with consequent forward bulging of the anterior vitreous face and posterior capsule. The ciliary body rotation may also have resulted in the inferior capsulorhexis margin becoming drawn downwards. Thus the anteriorly-directed force acting on the implant may have led to the inferior haptic being pushed forward over the down-drawn capsulorhexis margin and then through the dilated pupil. Four factors could have promoted the occurrence of lens dislocation in this case. First, the formation of a large choroidal detachment, the formation of which may well have been promoted by the second factor, postoperative ocular hypotony which is a common postoperative complication of trabeculectomy [1]. In addition the relatively low pressure in the anterior chamber may have reduced opposition to the anterior bulging of the posterior capsule which has been implicated in the hypothesized method of lens dislocation described above. Third, the ability of the implant to be deformed may well have aided its extrusion from the capsular bag. Last, the creation of a relatively large capsulorhexis may have facilitated the escape of the implant from the capsular bag. We have learnt from this case the need to create a smaller and central capsulorhexis in cases where foldable implants are used in operations predisposing to ocular hypotony and choroidal detachment such as phacotrabeculectomy. REFERENCES 1 PK Wishart, MW Austin. Combined cataract extraction and trabeculectomy: phacoemulsification compared with extracapsular technique. Ophth. Surg., 1993; 24: 814-82l. 2 JS Cummings. Postoperative complications and uncorrected acuities after implantation of plate haptic silicone and three piece silicone intraocular lenses. J. Cataract. Refract. Surg., 1993; 19: 263-274. 3 A Wedrich, R Menapace, U Radax, P Papapanos, M Amon. Combined small-incision cataract surgery and trabeculectomy technique and results. Int. Ophthalmol., 1992; 16: 409-414. 4 WA Lyle, JC Jin. Comparison of a 3- and 6-mm incision in combined phacoemulsification and trabeculectomy. Am. J. Ophthalmol., 1991; 111: 189-196. 5 JS Cumming. Surgical complications and visual acuity results in 536 cases of plate haptic silicone lens implantation. J. Cataract Refract. Surg., 1993; 19: 275-277.
Eur J Implant Ref Surg, Vol 7, August 1995