New endothelial keratoplasty, phacoemulsification, and intraocular lens implantation triple procedure: Comparison with conventional triple procedure

ARTICLE

New endothelial keratoplasty, phacoemulsification, and intraocular lens implantation triple procedure: Comparison with conventional triple procedure Prema Padmanabhan, MS, Sonali Kisan Warade, MS, Kunjal Sejpal, DNB

PURPOSE: To compare the clinical outcomes of a new triple procedure comprising endothelial keratoplasty, phacoemulsification, and intraocular lens (IOL) implantation and a conventional triple procedure comprising penetrating keratoplasty, extracapsular cataract extraction, and IOL implantation. SETTING: Cornea Services, Medical Research Foundation, Chennai, Tamil Nadu, India. METHODS: In this prospective nonrandomized study, the new triple procedure was performed in eyes with predominant endothelial dysfunction and coexisting cataract and the conventional triple procedure, in eyes with opacities affecting other layers of the cornea. Outcome measures were intraoperative and postoperative complications, 3-month postoperative distance visual acuity, refractive status, mean corneal power, corneal topography, and endothelial cell loss. The outcomes in the 2 groups were compared. RESULTS: The new procedure group comprised 54 eyes and the conventional procedure group, 26 eyes. All grafts in both groups were clear 3 months postoperatively. The IOL was fixated in the capsular bag in all eyes in the new procedure group and 23% of eyes in the conventional procedure group. Postoperatively, persistent epithelial defects, uveitis, glaucoma, and posterior capsule opacification were significantly more frequent in the conventional procedure group. Visual acuity was significantly better and the postoperative refractive status more predictable in the new procedure group. Endothelial cell loss was greater in the new procedure group than in the conventional group, although the difference was not statistically significant. CONCLUSION: The new triple procedure was safer than the conventional triple procedure and resulted in better visual outcomes, a more predictable refractive error, a smoother corneal contour, and a tectonically stronger globe. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2010; 36:1142–1148 Q 2010 ASCRS and ESCRS

The art and science of combining cataract surgery with intraocular lens (IOL) implantation and penetrating keratoplasty (PKP) were described in 19761 for patients with coexisting corneal disease and cataract. Popularly referred to as the triple procedure, the technique obviated the need for a second surgical procedure, provided quicker visual rehabilitation, and protected the transplanted cornea from surgical damage by sequential cataract surgery. The most common indication for the triple procedure has been Fuchs endothelial dystrophy.2 1142

Q 2010 ASCRS and ESCRS Published by Elsevier Inc.

Although excellent anatomical results have been reported,3–5 postoperative refractive errors are highly unpredictable because the changes in corneal curvature after keratoplasty are erratic and irregular.6 Other disadvantages include those of any PKP procedure, such as delayed and incomplete wound healing that leads to wound dehiscence in some cases, high and irregular astigmatism, suture-related complications, and graft rejection, even years after surgery.7–9 In the past decade, selective endothelial keratoplasty has become the preferred surgical approach 0886-3350/$dsee front matter doi:10.1016/j.jcrs.2010.01.022

NEW VERSUS CONVENTIONAL TRIPLE PROCEDURE

for conditions in which the primary pathology is in the corneal endothelium, as in Fuchs endothelial dystrophy.10 There is ample evidence that endothelial keratoplasty results in a tectonically stable globe with a smooth surface contour and minimal changes in corneal power and astigmatism.11 With the proven advantages of endothelial keratoplasty over PKP and of phacoemulsification over manual extracapsular cataract extraction (ECCE), the stage has been set for a paradigm shift in our approach to eyes with coexisting endothelium dysfunction and cataract. Simultaneous endothelial keratoplasty, phacoemulsification, and IOL implantation has been termed the new triple procedure, and initial results confirm that it provides rapid visual rehabilitation with predictable and acceptable refractive results.12,13 Although a few studies have compared endothelial keratoplasty and PKP,14,15 to our knowledge no study has compared the new triple procedure (endothelial keratoplasty, phacoemulsification, and IOL implantation) with the conventional triple procedure (PKP, ECCE, and IOL implantation). The aim of this study was to compare the anatomic, visual, refractive, topographic, and clinical outcomes of the 2 triple procedures. PATIENTS AND METHODS This prospective nonrandomized study was approved by an institutional review board and adhered to the tenets of the Declaration of Helsinki. All patients enrolled in the study provided informed consent. The new triple procedure was performed in eyes with corneal edema from endothelial disease and coexisting cataractous changes. The conventional triple procedure was performed in eyes with corneal opacities involving other layers of the cornea and coexisting cataractous changes. Patients with previous corneal transplants, infectious keratitis, ocular surface disease, or uncontrolled glaucoma were excluded from the study. All patients had a detailed ocular examination including retinoscopy and refraction (when possible), slitlamp evaluation, intraocular pressure measurement, and fundus evaluation (when possible). Ultrasound B-scan (Alcon, Inc.) was performed if the fundus could not be visualized. Keratometry (Appasamy Associates), pachymetry (SP3000, Tomey Corp.), specular microscopy (Noncon Robo, Konan

Submitted: October 29, 2009. Final revision submitted: December 19, 2009. Accepted: January 12, 2010. From the Medical and Vision Research Foundation, Chennai, Tamil Nadu, India. Corresponding author: Prema Padmanabhan, MS, Medical Director and Director of Cornea and Refractive Service, Medical Research Foundation, Sankara Nethralaya, 18 College Road, Chennai–600 006, Tamil Nadu, India. E-mail: [email protected].

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Medical), and corneal topography (TMS4, Tomey Corp.) were performed when possible. Donor corneoscleral rims stored in McCarey-Kaufman media were assessed by specular microscopy. Postoperatively, manifest refraction, keratometry, corneal topography, specular microscopy, and pachymetry were performed at 6 weeks and 3 months.

Intraocular Lens Power Calculation The axial length was measured by ultrasound A-scan (AL1000, Tomey Corp.). Manual keratometry was attempted in all eyes; the keratometry (K) values were used in IOL power calculation only if the mires were clear. If manual keratometry was not satisfactory, corneal topography was used to determine the mean simulated K value. If the keratograph mires were too distorted, a standard K reading (44.0 diopters [D]) was used for IOL power calculation.

Surgical Technique All new triple procedures were performed by the same surgeon (P.P.). The conventional triple procedures were performed by 1 of 4 experienced corneal surgeons at the same institution. In both techniques, local (peribulbar) anesthesia was used.

New Triple Procedure A 5.0 mm scleral tunnel incision was created in the superotemporal quadrant in right eyes and in the superonasal quadrant in left eyes. A 2.8 mm entry into the anterior chamber was made through the scleral tunnel incision with a keratome. Two limbal paracenteses were created 2.0 mm on either side of the scleral incision. Standard phacoemulsification was followed by implantation of a foldable IOL in the capsular bag. If visualization was difficult, the edematous corneal epithelium was debrided. The host epithelium was marked with an 8.0 mm trephine. A reverse-bent Sinskey hook was used to score and strip Descemet membrane under cover of sodium hyaluronate 1% (Healon). The entry into the anterior chamber was widened up to 5.0 mm with a keratome, and all ophthalmic viscosurgical device was removed with the irrigation/aspiration (I/A) handpiece. The donor corneal disk was fashioned manually after the donor corneoscleral rim was placed on the artificial anterior chamber (Bausch & Lomb), and 8.0 mm of the dissected disk was punched with a trephine. The donor disk was folded like a taco (60:40), held with a purpose-designed noncrushing forceps, and slipped into the anterior chamber of the recipient, where it was allowed to unfold. The scleral incision was sutured with 4 interrupted 10-0 monofilament nylon. A bubble of air injected through 1 paracentesis held the donor corneal disk in place. Two radial incisions on the corneal surface allowed interface fluid to be tapped. After good approximation of the donor disk and the stromal surface of the host was ensured, a freely mobile bubble of air was left in the anterior chamber. The eye was patched and the patient instructed to lie supine for at least 2 hours. Conventional Triple Procedure A Flieringa ring was sutured for scleral support. The host cornea was trephined with a 7.5 mm or 8.0 mm disposable manual trephine (Storz, Bausch & Lomb). A beer-can capsulotomy was created with a capsulotome. Open-sky ECCE was performed by gentle nucleus delivery followed by manual I/A with a Simcoe I/A cannula. A posterior chamber IOL was implanted, with an attempt made to place it in the capsular bag. The

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donor corneal button, which was 0.5 mm larger in diameter than the recipient bed, was sutured with 16 interrupted or 24-bite continuous 10-0 monofilament nylon.

Outcome Measures Intraoperative and postoperative complications were recorded in all eyes. Clinical features, postoperative corrected distance visual acuity (CDVA), refractive spherical and cylindrical errors, corneal topography regularity and asymmetry indices, mean corneal power, and endothelial cell loss 3 months after surgery were documented and compared between the new triple procedure group and the conventional triple procedure group. Statistical analysis was performed using SPSS software (version 14, SPSS, Inc.).

RESULTS Table 1 shows the preoperative characteristics of the patients by group. The new triple procedure group comprised 54 eyes of 54 patients (27 men, 27 women). All patients in this group had corneal edema from endothelial dysfunction: 49 eyes had Fuchs endothelial dystrophy and 5 eyes had endothelial decompensation associated with irido-corneal-endothelial (ICE) syndrome. The conventional triple procedure group comprised 26 eyes of 26 patients (16 men, 10 women). Thirteen eyes had dense corneal scars from healed infectious keratitis, trauma, or corneal dystrophies and 13 eyes had advanced bullous keratopathy associated with Fuchs endothelial dystrophy or ICE syndrome in which subepithelial scarring and stromal haze had rendered the eye unsuitable for Descemet-stripping endothelial keratoplasty (DSEK). The host cornea was trephined with a 7.5 mm trephine in 13 eyes and an 8.0 mm trephine in 13 eyes. The mean corneal endothelial cell count in the donor eyes in the new triple procedures was significantly higher than that used in the conventional triple procedures. This finding was coincidental because there was no preselection of donor eyes for either procedure.

Table 1. Preoperative patient characteristics by groups. Triple Procedure Variable

New

Conventional P Value*

Patient (n) 54 26 d Mean age (y) G SD 55.88 G 11.07 49.65 G 15.5 .07326 Mean CDVA 1.07 G 0.63 1.74 G 0.41 !.0001 (logMAR) G SD ECD of donor cornea 1798.5 G 370.2 1600.2 G 265.7 .0169 (cells/mm2) G SD CDVA Z corrected distance visual acuity; ECD Z endothelial cell density P!.05 statistically significant

Table 2 shows the postoperative results and a comparison with preoperative parameters (paired t test) and between the 2 groups (independent t test). Preoperative refraction, keratometry, and topographic measurements were unreliable in most eyes in the conventional group because of corneal scarring. All grafts in both groups were clear at the 3-month follow-up. The improvement in CDVA from preoperatively to postoperatively was statistically significant in both groups (P!.001) The postoperative CDVA was statistically significantly better in the new triple procedure group than in the conventional group (P Z .0001). There was no statistically significant difference in mean postoperative spherical refraction between the new procedure group and the conventional procedure group (P Z .61). The range of the spherical refractive error, however, was wider in the conventional procedure group than in the new procedure group. The difference between groups in the mean postoperative refractive cylinder was statistically significant (P Z .0001). In the new triple procedure group, there was no statistically significant difference between the preoperative and postoperative refractive cylinder (P Z .64). The mean postoperative average K was significantly flatter than the mean preoperative average K in the new procedure group (P Z .011) and was significantly flatter than the postoperative mean average K in the conventional procedure group (P!.001). The topographic indices of surface regularity and surface asymmetry were significantly less in the new procedure group (P Z .001 and P Z .017, respectively). The endothelial cell loss at 3 months was higher in the new procedure group than in the conventional procedure group; however, the difference was not statistically significant (P Z .55). Although the IOL could be placed in the capsular bag in all eyes in the new procedure group, it was placed outside the bag in 20 eyes (66.9%) in the conventional procedure group. Table 3 shows the postoperative complications by group. Two complications that occurred in the conventional procedure group (persistent epithelial defect and suture-related problems) did not occur in the new procedure group. The epithelial defects lasted longer than 72 hours. The cases of postoperative uveitis in the conventional procedure group required more intensive treatment with topical steroidal agents; some cases required oral steroidal agents. The case of postoperative uveitis in the new procedure group responded to an increased frequency of topical steroidal agents. The cases of early posterior capsule haze probably represented swollen cortical remnants. The incidence of all postoperative complications was statistically significantly higher in

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Table 2. Comparison of 3-month postoperative and preoperative parameters in each group and intergroup comparison. Triple Procedure New Parameter Mean CDVA (logMAR) Sphere (D) Mean Range Cylinder (D) Mean Range Keratometry (D) Mean Range Mean SRI Mean SAI Mean EC loss (cells/mm2) EC loss (%)

Conventional

Preop

Postop

P Value*

P Value†

Preop

Postop

P Value*

1.07 G 0.63

0.26 G 0.15

.000 .008

.0001 .61

1.74 G 0.41

0.87 G 0.46

.001 NA

0.28 G 1.95 d

1.63 G 1.39 0.0 to 4.0

NA NA

2.04 G 3.17 4.5 to 5.5

NA NA

4.35 G 2.32 0.0 to 8.0

NA NA NA NA d d

45.88 G 2.34 42.0 to 50.2 2.28 G 0.92 3.3 G 1.86 150.5 G 99.5 9.4

.64 0.67 G 1.44 d

.011 44.34 G 2.17 d 1.57 G 0.62 2.42 G 1.48 d d

.0001

1.02 G 0.69 0.0 to 3.0 42.66 G 1.68 39.4 to 45.0 0.63 G 0.26 0.54 G 0.72 395.1 G 117.3 22.0

.001 .001 .058 d

NA

.000

.001 .017 0.55 d

NA

NA NA .15 d

Means G SD CDVA Z corrected distance visual acuity; EC Z endothelial cell; NA Z data not available; SAI Z surface asymmetry index; SRI Z surface regularity index *Comparison between postoperative and preoperative values (paired t test); P!.05 statistically significant † Intergroup comparison (Student t test); P!.05 statistically significant

the conventional procedure group than in the new procedure group. DISCUSSION The approach to a patient with coexisting corneal disease with cataract has witnessed several changes. Corneal transplantation and cataract surgery can be performed simultaneously or in 2 separate operations. The comparative merits of simultaneous versus sequential surgery have often been debated. Even though the refractive outcomes of sequential surgery were slightly closer to the target refraction than in simultaneous surgery,16 the triple procedure (simultaneous surgery) gained popularity because the transplanted cornea was not exposed to the trauma of a second surgery.

Table 3. Comparison of postoperative complications. Number (%) Complication

New Group

Conventional Group

P Value

Persistent epithelial defect Postoperative uveitis Secondary glaucoma Suture-related problems Posterior capsule haze

0 1 (1.85) 1 (1.85) 0 3 (5.55)

6 (23.11) 10 (38.5) 6 (23.1) 8 (32.5) 9 (34.6)

.0012 !.001 .0039 .001 .0012

Fuchs endothelial dystrophy is reported to be the most common indication (24.5%) for triple procedures in the Western population. The rate of 10-year graft survival after PKP for Fuchs endothelial dystrophy is reported to be as high as 90%.17 However, it is frustrating for patient and surgeon alike when patients with clear grafts remain functionally handicapped because of high, uncorrectable, and intolerable refractive errors. The tectonic instability of a full-thickness annular corneal wound and suture-related complications further compromise results of an otherwise successful graft. Endothelial keratoplasty, an elegant technique for selective replacement of dysfunctional corneal endothelium, is rapidly revolutionizing corneal transplantation.18 Its advantages over PKP have been well documented14,15,19 and far outweigh the risk for slight backscatter of light from the lamellar interface.20 Phacoemulsification has been established as a safer and more controlled approach to cataract surgery than manual ECCE. The small self-sealing incision reduces the risk for intraoperative suprachoroidal hemorrhage, and the continuous capsulorhexis ensures capsule fixation of the IOL. It stands to reason, then, that combining endothelial keratoplasty with phacoemulsification retains the advantages of both techniques, making the new triple procedure the preferred approach to patients with coexisting endothelial dysfunction and cataract.

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Conventional triple procedures have excellent anatomic success in terms of graft clarity and survival but only moderately good functional results.21–23 Nguyen et al.21 evaluated the visual and refractive results in a 1-year follow-up of 499 eyes that had the conventional triple procedure. The authors report that 61% of patients had a postoperative CDVA of 20/40 or better; however, 47% had a refractive error of less than 2.00 D shift from the target refraction of emmetropia. The results of the new triple procedure reported by Terry et al.13 are impressive. At the 1-year followup, 97% of 75 eyes had a postoperative CDVA of 20/ 40 or better and 97% were within G2.00 D of emmetropia. Bahar et al.19 compared 4 techniques: PKP, deep lamellar endothelial keratoplasty (DLEK), DSEK, and Descemet-stripping automated endothelial keratoplasty (DSAEK). The visual outcomes of all forms of endothelial keratoplasty were better than those of PKP. The present study is, to our knowledge, the first to compare the conventional triple procedure and the new triple procedure, even though the choice of surgery was not randomized. Both groups had excellent anatomic success; all grafts were clear at the last follow-up. The introduction of an interface with all forms of endothelial keratoplasty can be expected to have optical implications arising from its irregularity24,25 or from contaminants such as retained Descemet membrane fragments and trapped epithelial cells.26,27 Patel et al.20 found that backscatter after DLEK was higher than backscatter after PKP during much of the first year after surgery and was probably the result of an irregular donor–host interface. The backscatter would be expected to be less with an automated donor disk, as in DSAEK. Forward scatter, on the other hand, is believed to be caused by subepithelial fibrosis or irregularities in Bowman membrane, as often seen in Fuchs dystrophy.28 Although the CDVA in both groups in our study improved after surgery, the improvement was significantly greater in the new procedure group than in the conventional procedure group. It would be reasonable to conclude that the retention of a smooth corneal surface contour is more important than the introduction of a lamellar interface in determining visual outcome. The range of spherical and cylindrical postoperative refractive errors was wider in the conventional procedure group. Changes in corneal curvature are much more erratic after PKP than after endothelial keratoplasty, making IOL power calculations more difficult and resulting in unanticipated postoperative refractive errors in the conventional procedure.12 In our study, emmetropia was chosen as the target refraction; 25% of eyes in the conventional triple procedure group and 50% of eyes in the new triple

procedure group were within G1.00 D of emmetropia 3 months after surgery. Terry et al.13 chose a target refraction of 0.80 to 1.25 D; 73% of eyes were within G1.00 D of emmetropia 6 months after the new triple procedure. An inherent hyperopic shift has been observed after all forms of endothelial keratoplasty surgery29–31 and should be accounted for in the choice of the appropriate IOL.13 We believe that if we had aimed for approximately 1.25 D when choosing the IOL power and had been able to measure preoperative corneal power accurately in all cases, our refractive results would have been closer to emmetropia. The significant flattening of the anterior corneal curvature after DSEK, which is an the important reason for the hyperopic shift, could have been due to 1 or both of the following reasons: (1) corneal edema was reduced, and (2) the standard K value assumed preoperatively in some eyes may have been steeper than the actual value. The flattening was consistently seen in eyes in which preoperative measurements were reliable, signifying a true flattening after surgery. The magnitude and range of refractive astigmatism were significantly less after the new triple procedure (mean 1.02 G 0.69 D; range 0.0 to 3.0 D) than after the conventional triple procedure (mean 4.35 G 2.32 D; range 0.0 to 8.0 D). Several studies of refractive data after various forms of endothelial keratoplasty and PKP report lower astigmatism after endothelial keratoplasty (1.34 to 1.76 D)27,28 than after PKP (4.00 to 6.00 D).32–34 A direct comparison between endothelial keratoplasty and PKP by Heidemann et al.15 also showed a lower magnitude and smaller range of astigmatism after endothelial keratoplasty (mean 0.97 G 0.98 D; range 0.00 to 3.50 D) than after PKP (mean 2.58 G 1.93 D; range 0.00 to 6.00 D). The new triple procedure obviates the need for corneal sutures and ensures well-centered capsular bag placement of the IOL. Both factors are responsible for the low corneal- and IOLinduced astigmatism with this procedure. The topographic indices of corneal surface irregularity and asymmetry, which are indicative of the degree of irregular astigmatism, were also significantly lower with the new procedure than with the conventional procedure. Terry et al.13 made similar observations, suggesting that this could result in significantly better quality of vision after endothelial keratoplasty than after PKP. The conventional triple procedure uses an open-sky technique for cataract removal, which poses inherent difficulties in surgical technique and increases the risk for intraoperative and postoperative complications. The uncompensated posterior pressure makes capsulorhexis difficult, aspiration of cortex incomplete, and capsular bag placement of the IOL

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inconsistent. Methods described to achieve closedchamber cataract extraction include a 2-step approach of performing phacoemulsification through a hazy cornea35 or through a partially trephined cornea36 or the use of a temporary keratoprosthesis to temporarily replace the trephined cornea37 and proceeding with a PKP in the same sitting. The degree of corneal opacity and the skill of the surgeon would determine whether the 2-step approach is feasible, and the availability of the temporary keratoprosthesis and the constraints it would impose on the size of the graft would influence the surgeon’s choice. The advantages of performing closed-chamber phacoemulsification in the new triple procedure include better chances of a capsular bag placement of the IOL, a reduced risk for intraoperative complications (eg, posterior capsule tear, suprachoroidal hemorrhage), and a lower incidence of postoperative complications (eg, uveitis, secondary glaucoma, posterior capsule opacification). Eyes with preexisting risk factors for surface complications, secondary glaucoma, or postoperative uveitis were excluded from our study. However, all these complications occurred more frequently in the conventional procedure group than in the new procedure group. Postoperative uveitis and glaucoma are known risk factors for graft rejection and failure. The significantly lower incidence of these complications with the new triple procedure would therefore be beneficial for the long-term survival of these grafts. Visualization through a hazy cornea makes phacoemulsification slightly more challenging; however, visualization can be enhanced by epithelial debridement if necessary. Reepithelialization of an epithelial defect is faster after endothelial keratoplasty than after PKP, reflecting a healthier ocular surface uninterrupted by an annular corneal wound. The endothelial cell loss in the new triple procedure group (22%) was higher than in the conventional triple procedure group (9.4%). Although the difference did not reach statistical significance, the finding is in agreement with results in other studies, which report an endothelial cell loss ranging from 15.4% to 54.0% with various forms of endothelial keratoplasty38,39 and 11% to 29% with PKP 2 to 6 months postoperatively.40,41 Longer follow-ups are required to establish long-term viability with endothelial keratoplasty, especially because existing data are varied and insufficient. Surgical techniques and instrumentation are continuously evolving and aim at reducing trauma to the endothelium. In summary, the new triple procedure combines the advantages of endothelial keratoplasty and phacoemulsification and should be the preferred technique in eyes with endothelial dysfunction and coexisting cataract. The benefits stem from 3 important features;

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that is, there is no disturbance to the corneal surface, there is no full-thickness corneal wound, and it is not an open-sky procedure. It is, therefore, a safer surgical technique than the conventional triple procedure with a lower risk for intraoperative and postoperative complications; results in better, quicker visual rehabilitation with more predictable and stable refractive results; and leaves a tectonically stronger globe. REFERENCES 1. Taylor DM. Keratoplasty and intraocular lenses. Ophthalmic Surg 1976; 7(1):31–42 2. Green M, Chow A, Apel A. Outcomes of combined penetrating keratoplasty and cataract extraction compared with penetrating keratoplasty alone. Clin Exp Ophthalmol 2007; 35:324–329 3. Hunkeler JD, Hyde LL. The triple procedure. Combined penetrating keratoplasty, extracapsular cataract extraction and lens implantation; an expanded experience. Am Intra-Ocular Implant Soc J 1983; 9:20–24 4. Crawford GJ, Stulting RD, Waring GO III, Van Meter WS, Wilson LA. The triple procedure; analysis of outcome, refraction, and intraocular lens power calculation. Ophthalmology 1986; 93:817–824 5. Katz HR, Forster RK. Intraocular lens calculation in combined penetrating keratoplasty, cataract extraction and intraocular lens implantation. Ophthalmology 1985; 92:1203–1207 6. Binder PS. The triple procedure; refractive result. 1985 update. Ophthalmology 1986; 93:1482–1488 7. Maeno A, Naor J, Lee HM, Hunter WS, Rootman DS. Three decades of corneal transplantation: indications and patient characteristics. Cornea 2000; 19:7–11 8. Mamalis N, Anderson CW, Kreisler KR, Lundergan MK, Olson RJ. Changing trends in the indications for penetrating keratoplasty. Arch Ophthalmol 1992; 110:1409–1411 9. Pineros O, Cohen EJ, Rapuano CJ, Laibson PR. Long-term results after penetrating keratoplasty for Fuchs’ endothelial dystrophy. Arch Ophthalmol 1996; 114:15–18 10. Terry MA. Endothelial keratoplasty: history, current state, and future directions [editorial]. Cornea 2006; 25:873–878 11. Melles GRJ, Eggink FAGJ, Lander F, Pels E, Rietveld FJR, Beekhuis WH, Binder PS. A surgical technique for posterior lamellar keratoplasty. Cornea 1998; 17:618–626 12. Covert DJ, Koenig SB. New triple procedure: Descemet’s stripping and automated endothelial keratoplasty combined with phacoemulsification and intraocular lens implantation. Ophthalmology 2007; 114:1272–1277 13. Terry MA, Shamie N, Chen ES, Phillips PM, Shah AK, Hoar KL, Friend DJ. Endothelial keratoplasty for Fuchs’ dystrophy with cataract; complications and clinical results with the new triple procedure. Ophthalmology 2009; 116:631–639 14. Hjortdal J, Ehlers N. Descemet’s stripping automated endothelial keratoplasty and penetrating keratoplasty for Fuchs’ endothelial dystrophy. Acta Ophthalmol (Oxf) 2009; 87:310–314 15. Heidemann DG, Dunn SP, Chow CYC. Comparison of deep lamellar endothelial keratoplasty and penetrating keratoplasty in patients with Fuchs endothelial dystrophy. Cornea 2008; 27:161–167 16. Hayashi K, Hayashi H. Simultaneous versus sequential penetrating keratoplasty and cataract surgery. Cornea 2006; 25:1020–1025 17. Thompson RW Jr, Price MO, Bowers PJ, Price FW Jr. Longterm graft survival after penetrating keratoplasty. Ophthalmology 2003; 110:1396–1402

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First autor: Prema Padmanabhan, MS Medical and Vision Research Foundation, Chennai, Tamil Nadu, India