ORIGINAL ARTICLE
Year : 1994 | Volume
: 42 | Issue : 2 | Page : 75--80
Penetrating keratoplasty for pseudophakic bullous keratopathy
Vinay Agrawal, Mustali M Vagh, Virender Sangwan, Gullapalli N Rao
Sight Savers' Cornea Training Centre, L.V. Prasad Eye Institute, Hyderabad, India
Correspondence Address:
Gullapalli N Rao
L.V. Prasad Eye Institute, Road No. 2, Banjara Hills, Hyderabad 500 034
India
Abstract
Penetrating keratoplasty (PK) is the only definitive treatment for the visual rehabilitation of eyes with pseudophakic bullous keratopathy (PBK). Management of the intraocular lens (IOL) at the time of PK is dependent on lens-related factors and anterior segment abnormalities. We reviewed the results of PK in 81 cases of PBK done at our institute between November 1987 and May 1993. The original lens was an anterior chamber IOL in 26 (32.1%) eyes, iris claw lens in 38 (41.9%) eyes, and a posterior chamber IOL in 17 (20.98%) eyes. IOL explanation alone was done in 24 (29.6%) eyes. The original IOL was retained in 12 (14.9%) eyes and IOL exchange was done in 45 (55.5%) eyes. With a minimum follow-up period of 6 months, the graft remained clear in 54 (66.6%) and the commonest cause of graft failure was graft rejection (17.2%). The best-corrected visual acuity in our series was 20/40 or more in 11 (20.3%) eyes and 20/50 to 20/100 in 30 (55.5%) eyes. We recommend explantation of all closed-loop anterior chamber and iris claw IOLs, and that, anterior chamber reconstruction during PK IOL exchange should be done using a posterior chamber IOL or open-loop Kelman type AC IOL.
How to cite this article:
Agrawal V, Vagh MM, Sangwan V, Rao GN. Penetrating keratoplasty for pseudophakic bullous keratopathy.Indian J Ophthalmol 1994;42:75-80
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Agrawal V, Vagh MM, Sangwan V, Rao GN. Penetrating keratoplasty for pseudophakic bullous keratopathy. Indian J Ophthalmol [serial online] 1994 [cited 2023 Sep 30 ];42:75-80
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Full Text
Intraocular lens implantation is recognised as a major advance in the field of ophthalmic surgery in recent years. The high success rate and the safety of this visual rehabilitative procedure has made it the most popular method for correction of aphakia. This proliferation has also lead to greater incidence of sight-threatening complications, with pseudophakic bullous keratopathy (PBK) being a leading cause. Though the exact incidence of this condition is not well established due to obvious reasons, Stark et [1] all have reported a rate of corneal decompensation at one year to be 0.06% for posterior chamber (PC) IOLs, 1.2% for anterior chamber (AC) IOLs, and 1.5% for iris-fixated (IF) lenses. Long-term follow-up studies with iris-supported lenses have reported a 15% rate of PBK, [2] whereas it is 0.1 to 0.3% for extracapsular cataract extraction with PC IOL. [2],[3]
For the visual rehabilitation of patients with PBK,. penetrating keratoplasty remains the only definitive treatment. The topical issues in penetrating keratoplasty (PK) for PBK are related primarily to the events following removal of the host button and before the donor tissue is sutured in place. This centres primarily around the management of the existing IOL and the need for anterior segment reconstruction.
We studied the evolution in the management of the intraocular lens during penetrating keratoplasty for PBK at our institute over the last 5 years and herein report our experiences.
MATERIALS AND METHODS
Patient Profile
We retrospectively reviewed the records of 81 patients, who underwent penetrating keratoplasty for pseudophakic bullous keratopathy between November 1987 and May 1993. Patients with less than 6 months of postoperative follow-up, those who had had IOL removed before penetrating keratoplasty and regrafts, were excluded. The age of the patients ranged from 3 to 81 years with a mean age of 56.4 years. Of the 81 patients, 60 were males and 21 were females.
Surgical Technique
The recipient bed was prepared by centring a disposable trephine and a partial-thickness incision was made to about 50 to 80% depth. The size of the button ranged from 7.5 to 8.0 mm. The anterior chamber was entered with a No. 11 Bard-Parker blade and the excision of the recipient tissue was completed with corneal scissors. The primary IOL was explanted if it was: (1) unstable, dislocated, or was touching the corneal endothelium; (2) associated with distortion, erosion or extensive iris atrophy; (3) associated with peripheral anterior synechiae with or without raised intraocular pressure (IOP); (4) entangled with the vitreous; and (5) iris-supported or closed-loop AC IOL.
If vitreous was found in the anterior chamber, an anterior vitrectomy was performed with an automated vitrector. Iris adhesions were separated; using a blunt or sharp dissection under the cover of a viscoelastic substance (2% hydroxypropylmethylcellulose or sodium hyaluronate) to protect the surrounding tissue and to tamponade any bleeders.
In cases where an IOL exchange was planned, the dioptric power of the lens was calculated prior to surgery, using the SRK II regression formula. The keratometry reading of the fellow eye was taken when the reading from the affected eye could not be obtained.
The donor button was punched from the endothelial side, using a disposable trephine of 0.5 mm larger diameter than the recipient bed.
Suturing of the graft to the recipient bed was achieved by 16 interrupted sutures using 10-0 nylon or a combination of 8 interrupted sutures with a single continuous suture.
Postoperative Management and Evaluation
In the first postoperative week, patients received Betnesol (betamethasone sodium phosphate 0.1%) eye drops at 2 to 4 hourly intervals and gentamicin 0.5% eye drops at 6 hourly intervals. Thereafter, they received only betnesol eye drops, the frequency of which was tapered over a period of 6 to 9 months. Patients were examined at one week, then at intervals of one month for 6 months and every 2 months upto one year. Thereafter, they were reviewed every six months. At every postoperative visit, the visual acuity was recorded and detailed slit-lamp examination was performed. Intraocular pressure was assessed by Goldmann applanation tonometer or proton electronic tonometer. Ocular fundus examination was performed with either a direct or indirect ophthalmoscope and degenerative maculopathy was diagnosed if preretinal fibrosis, drusen, or pigment disruption was present.
Graft clarity was defined as absence of stromal or epithelial oedema by slit-lamp examination and graft failure as persistent stromal and/or epithelial oedema.
RESULTS
Preoperative Observations
The study included 60 males and 21 females. The mean age of the patients was 56.4 years (range, 3 to 81 years). The mean interval between the original intraocular lens implantation and penetrating keratoplasty was 25.43 � 22.05 months (range, 2 to 72 months). The time interval between the original IOL implantation and appearance of PBK was 16.92 � 12.9 months (mean � S.D.) for the AC IOL group, 36.97 � 21.96 months for the iris-supported lenses, and 6.5 � 8.73 months for the PC IOL group of eyes. This difference in the onset of PBK after original IOL implantation was statistically significant (AC IOL vs PC IOL, p =0.0147; AC IOL vs iris-fixated lenses, p = 0.001; PC IOL vs iris-fixated lenses, p = 0.0001; Student's group t-test) depending on the type of lens used at the time of original surgery. The original lens was an anterior chamber lens in 26 (32.09%) eyes, iris claw lens in 38 (46.91 %), and a posterior chamber lens in 17 (20.98%) eyes [Table 1] and [Figure 1].
Of the 81 eyes included in this study, 75 eyes had a severe degree of central corneal oedema and the visual acuity was counting fingers or worse. In 6 eyes the degree of corneal oedema was less with the patients having a best-corrected visual acuity of 20/ 100 to 20/400. Preoperative intraocular pressure was less than 21 mm Hg in all eyes, with 20 eyes requiring antiglaucoma medication for control of intraocular pressure.
Intraoperative Findings
Vitreous prolapse into the anterior chamber and around the intraocular implant was present in 29 cases (10 with anterior chamber lenses, 15 with iris claw lenses, and 4 with posterior chamber lenses). In addition, there was vitreous disturbance in 6 eyes, necessitating anterior vitrectomy in 35 eyes. Malposition of the lens was seen in 7 eyes. Explantation of the intraocular lens involved separation of peripheral anterior synechiae in 21 eyes, and amputation of lens loops in 12 eyes. Iridoplasty was needed in 11 eyes to restore the anatomical configuration of the pupil after synechiolysis or to close previously existing sphincterotomies.
Intraocular lens explantation alone was done in 24 eyes rendering them aphakic after surgery. The original implant was retained in 12 eyes (11 with PC IOL and 1 with iris claw lens). In the remaining 45 eyes, the intraocular lens was exchanged. The style of intraocular lenses implanted included 40 posterior chamber lenses (27 scleral-fixated, 2 iris-fixated, and 11 sulcus-fixated) and 5 anterior chamber lenses [Table 1].
Graft Clarity
During the follow-up period, the graft remained clear in 54 (66.66%) eyes. The causes of failed graft were graft rejection (14 eyes), ocular surface problems (4 eyes), primary graft failure (3 eyes), endophthalmitis (1 eye), trauma leading to wound dehiscence (1 eye), and glaucoma (4 eyes). See [Table 2].
Visual Acuity
Of the eyes with clear grafts, best-corrected visual acuity of 20/40 or better was obtained in 11 (20.3%) eyes, 20/50 to 20/100 in 30 (55.55%) eyes, and 20/ 200 or worse in 13 (24.07%) eyes [Table 3].
Complications
Elevated Intraocular Pressure and Peripheral Anterior Synechiae: Twenty-eight (34.56%) eyes had an intraocular pressure greater than 21 mm Hg, beyond 2 weeks after surgery. In 21 eyes the intraocular pressure was controlled with a single (timolol 0.5% twice daily) antiglaucoma medication. Four eyes were successfully treated with a combination of antiglaucoma medications. Of the 28 eyes, four eyes failed to respond to medical therapy, 3 required cyclocryotherapy, and one required filtering surgery. In all these eyes,. however, intraocular pressure could not be controlled leading to graft failure.
Of the 28 eyes showing elevated intraocular pressure postoperatively, 22 showed the presence of peripheral anterior synechiae from 60 to 360� visible without a goniolens. Only 6 eyes had no visible peripheral synechiae. In another 9 eyes, peripheral anterior synechiae were present extending 30 to 60� of the angle without elevation of IOP [Table 4].
Cystoid and Degenerative Maculopathy: Details of retinal evaluation was available in only 33 patients. Of these 33 eyes, cystoid macular oedema was noted in 4 and 2 eyes had age-related macular degeneration. Of the four eyes with macular oedema, one eye had a visual acuity of better than 20/40, two had 20/200, and one had counting fingers at one metre [Table 4].
DISCUSSION
The success of our attempts to restore vision in eyes with pseudophakic bullous keratopathy is dependent, to a large extent, on the successful management of the intraocular lens at the time of surgery. [4],[5] The three available options for the management of IOL at the time of keratoplasty are to retain, or remove without replacement, or to replace the lens. Each of these approaches has been advocated at some point of time.
Earlier reports [6] advocated the retention of the original IOL However, this has not been corroborated by later investigations. Sugar [7] who analysed 469 patients with grafts for PBK found the failure rate with retained lens to be 34% for AC IOLs (closed-loop type), 29% for iris-supported lenses, and 6% for PC IOLs. This high rate of graft failure associated with retained IOLs prompted recommendation for routine IOL removal at the time of penetrating keratoplasty in these cases. [8] Although this approach produced better results for graft clarity, it created problems related to binocular vision in patients where the fellow eye was phakic or pseudophakic. [9] This stimulated the introduction of IOL exchange.
This concept is based on the assumption that the original lens was responsible for the development of PBK and consequently can produce deleterious effect on the grafted cornea also. Evidence to support this contention has come from the long-term success with intraocular lens exchange reported in most series. [7],[10],[11],[12] The results of our study are in a phase of overlap between the stages of IOL removal and exchange, as is evident from the number of eyes left aphakic at the end of surgery. Selection of the best style of IOL for exchange is difficult and only short�-term results are available. In the absence of sufficient posterior capsular support, one-piece AC lenses of the Kelman Multiflex style have been used widely for IOL exchange with good results, [13] and the endothelial cell loss with these AC IOLs has been comparable to sutured PC lenses. [8] Since the AC IOLs are associated with damage to the angle structures and increased incidence of peripheral anterior synechiae formation, the evolution in techniques of insertion of sutured PC IOL continues. Similar results as with AC IOLs have been reported using the scleral or iris-fixation techniques. [12],[14],[15] The number of cases in our study are inadequate to enable us to make any comparisons. Currently, the recommendations we follow agree largely with those of Speaker et all [16] and are outlined in [Figure 2].
There is sufficient evidence from both clinical and his top athologica1 studies showing extensive derangement of the anterior segment of the eye in some cases of PBK . [17]sub Our experience and that of other authors suggest that anterior segment reconstruction during penetrating keratoplasty produce a better anatomical outcome. [10],[18] The components of such reconstruction procedure includes anterior vitrectomy, gonioplasty, and iridoplasty. Anterior vitrectomy (to remove vitreous from the anterior chamber) can reduce cystoid macular oedema [19] and prevent decentring of the IOL by the vitreous strands. Gonioplasty and iridoplasty attempt to restore the pupil to its normal round configuration and also serve to : (1) prevent development of glaucoma and allograft rejection, related to formation of anterior synechiae due to the centripetal tension exerted on the iris; (2) give additional support for the anterior chamber lens if it is to be implanted; and (3) improve the optical function of the iris. [18]
Two phenomena in our experience need special discussion. Though the reported rate of graft clarity stands at 88 to 95%, [10],[11],[12] the rate in our series was only 66%. This could possibly be due to the high rate cr graft rejection as a cause of graft failure (17.28%). This high rate of graft failure from graft rejection was due to inordinate delay in the patient seeking treatment after the onset of graft rejection in most of our cases. Support for this comes from Hill et al, [20] who found that delayed diagnosis was associated with an increased rate of irreversibility and thus graft failure. An additional feature contributing to lower success rate was primary graft failure which was unexpectantly higher in our series. This is a reflection of the poor quality of donor cornea even though traditional methods of evaluation have failed to demonstrate any specific abnormalities predisposing to endothelial failure. Secondly, the number of patients in our series with visual acuity better than 20/40 was 20.3%, as compared to the reported figures of 30 to 60%. [10],[14] This can be explained by the increased duration and severity of factors like corneal oedema, iridocyclitis, glaucoma, and cystoid macular oedema. Eyes having few of these complications over a short time are likely to achieve better results than those with many complications of long duration. [10] Based on these observations, we currently follow the procedure mentioned below.
Explantation of all iris-fixated lenses / closed�loop AC IOLs.
To perform IOL exchange either with a PC IOL or an open-loop Kelman type AC IOL.
To avoid delay in corneal surgery once PBK is diagnosed (if penetrating keratoplasty is considered as a viable option for/by the patient).
Anterior segment reconstruction and monitoring of IOP, both, before and after corneal surgery.
References
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