The surgical management of eyes with coexisting visually significant corneal pathology and cataract is challenging. There are 2 common options for treatment of such cases, and each option has its own advantages and disadvantages.1–3 The first option is a triple procedure consisting of simultaneous penetrating keratoplasty (PKP), extracapsular cataract extraction, and intraocular lens (IOL) implantation.4 The second option is to perform keratoplasty followed months later by cataract extraction and IOL implantation.5 The triple procedure allows rapid visual recovery and avoids a second surgery, which may be inconvenient in elderly patients and add to the cost. However, the resultant postoperative refraction is far away from the target refraction in many cases because of variation in the keratometric readings caused by the corneal pathology, with subsequent inability to predict the IOL power correctly.1–3,6–8 However, the 2-stage procedure provides a postoperative refraction closer to emmetropia because of better calculation of the IOL power using keratometric readings of the transplanted clear cornea. But visual recovery is delayed for many months, and there is a risk of graft failure due to endothelial loss during subsequent phacoemulsification.5,9–11 To achieve the optimal postoperative target refraction with preservation of the corneal endothelium, we pursued a new option for treatment of visually significant corneal opacity and cataract, consisting of performing PKP and cataract extraction in 1 setting, followed by secondary IOL implantation after removal of corneal sutures and stabilization of keratometric readings. Thus, the aim of this study was to report the outcomes of a new 2-stage surgical option for the management of coexisting visually significant corneal opacity and cataract.
PATIENTS AND METHODS
Since 2014, we have adopted a new approach to surgically treat eyes with visually significant corneal opacities and cataract. This new 2-step procedure entailed performing simultaneous PKP and cataract surgery, with postponing IOL implantation until removal of all corneal sutures and stabilization of keratometric readings. During the period from April 2014 to September 2017, the patients' medical records were revised for this retrospective analysis. We considered single-eyed patients, patients with poor vision in the contralateral eye, patients anxious for rapid visual recovery, and children liable to develop amblyopia not eligible for this 2-stage procedure. Exclusion criteria were history of herpetic keratitis, previous intraocular surgery, glaucoma, posterior segment pathology, tear in the posterior capsule during cataract extraction, and patients who developed signs of graft failure before secondary IOL implantation. All patients should have at least 6 months of follow-up after secondary IOL implantation. The study was conducted in Al Fath Eye Hospital, Zagazig, Egypt, in accordance with the WMA Declaration of Helsinki—Ethical Principles for Medical Research Involving Human Subjects. All eyes were subjected to preoperative full ophthalmic examination including visual acuity [(logarithm of the minimum angle of resolution (logMAR)], manifest refraction, slit-lamp biomicroscopy, applanation tonometry, dilated fundus examination (when possible), and B-scan ultrasound. The IOL power was calculated with the IOL master (Zeiss IOL Master 500; Carl Zeiss, Oberkochen, Germany) using the SRK/T formula and targeting emmetropia in all the operated eyes.
All procedures of PKP and cataract extraction were performed under general anesthesia. Phacoemulsification without IOL implantation was performed before trephination if corneal opacity was not dense enough to preclude acceptable visualization during surgery. In eyes with dense or diffuse corneal opacity, open-sky cataract extraction was performed after fixation of a Flieringa ring to the sclera and corneal trephination. The donor cornea was punched out from the endothelial side using a Barron donor punch (Katena Products, Denville, NJ) with a diameter 0.25 mm to 0.5 mm larger than that of the recipient. The recipient cornea was trephined using a Hessburg–Barron vacuum trephine (Katena Products, Denville, NJ) of diameter 7.75 to 8.00 mm. The corneal button was then excised with curved corneal scissors. Anterior capsulorhexis was performed, and then the nucleus was expressed using bimanual push and pull hooks, and the cortex was aspirated using the Simcoe irrigation/aspiration cannula. After suturing the donor cornea with the main 4 interrupted 10-0 nylon sutures, 12 interrupted 10-0 nylon sutures were added. At the conclusion of surgery, sutures that were too loose or too tight were replaced to minimize postoperative corneal astigmatism. We intensified the frequency of topical steroids in the early postoperative period after PKP, in addition to the use of cycloplegic eye drops to minimize the possibility of postoperative inflammation and its consequences. Secondary IOL implantation was performed after removal of all corneal sutures. A foldable 3-piece acrylic IOL (Tecnis 3-Piece Acrylic ZA 9002; Abbott Medical Optics Inc, Santa Ana, CA, or Sensar 3-Piece Acrylic AR 40; Abbott Medical Optics Inc, Santa Ana, CA) was implanted in the ciliary sulcus through a 2.8-mm peripheral superotemporal corneal incision after filling the anterior chamber with a dispersive viscoelastic material (Viscoat; Alcon Surgical, Puurs, Belgium). Then, the viscoelastic material was thoroughly removed through 2 side-port incisions. Postoperatively, all eyes received topical antibiotic and steroid eye drops for a few weeks after each surgery. Both cylindrical and spherical refractive powers and keratometric readings were measured using an auto-keratorefractometer (KR-800 A; Topcon, Tokyo, Japan). Corneal endothelial cell density (ECD) (cells/mm2) was measured before and after IOL implantation by specular microscopy (Topcon SP-2000P; Topcon America Corp, Paramus, NJ).
All patients were examined on the first postoperative day and at 1 week, 1 month, 3 months, and 6 months after secondary IOL implantation. At each follow-up visit, eyes were examined for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error, astigmatism, corneal clarity, and ECD. The mean percentage of graft endothelial cell loss after IOL implantation, the deviation of the postoperative mean spherical equivalent from the target refraction, which was emmetropia, and the mean UDVA were reported at 1, 3, and 6 months postoperatively. The percentage of mean endothelial cell loss was defined as the percent reduction of ECD from that of the corneal graft and was calculated using the following equation: preoperative mean ECD – postoperative mean ECD/preoperative mean ECD × 100. According to the graft status at the final follow-up examination, graft survival was categorized as clear, endothelial decompensation, or recurrence of original disease. Statistical analysis of preoperative and postoperative data was performed using the Student paired t test. Graft survival was analyzed using the Fisher exact test. The number of eyes within ±2.0 D or ±1.0 D of the target refractive error was analyzed using the Fisher exact test. P < 0.05 was considered statistically significant.
Twenty-nine eyes of 29 patients with visually significant central corneal opacity and cataract have been operated by this new 2-step procedure during the duration of the study. Their ages ranged from 39 to 68 years, and the mean age was 55.6 ± 8.9 years. Nineteen patients (65.5%) were men, and 10 patients (34.5%) were women. The indications for PKP were stromal scar in 19 eyes (65.5%), stromal dystrophy in 8 eyes (27.6%), and Fuchs dystrophy in 2 eyes (7.4%). None of the eyes in the study had failed previous PKP. All eyes underwent simultaneous PKP and cataract extraction in the first surgery, followed by secondary IOL implantation several months later. Cataract was removed by phacoemulsification before corneal trephination in 15 eyes (51.7%) in which there was fair visualization through corneal opacity. Open-sky extracapsular cataract extraction (ECCE) was performed in 14 eyes (48.3%) in which corneal opacity was too dense to allow safe phacoemulsification. The mean interval between cataract extraction and secondary IOL implantation was 13.3 ± 2.2 months (range 10–17 months).
Before the first surgery, the mean UDVA was 1.94 ± 0.46 (range 1.0–2.48), and the mean CDVA was 1.56 ± 0.42 (range 0.8–2.2). One month after PKP, the mean UDVA was 1.34 ± 0.33 (range: 1.0–1.90), and the mean CDVA was 0.63 ± 0.32 (range 0.0–0.8). After PKP, the mean ECD was 2314 ± 113 cells (range: 1814–2901 cells) at 1 month and was 2198 ± 311 cells (range: 1788–2804 cells) just before secondary IOL implantation. Fine iridocapsular adhesions were encountered in 4 eyes (13.8%) and were released using the viscoelastic substance during the procedure of secondary IOL implantation. Posterior capsule opacification of variable degrees was detected in 4 eyes (13.8%) and was polished and aspirated during the second surgery before implanting the IOL. The mean power of the secondary implanted IOL was 20.79 ± 4.34 D (range 11.5–29.5 D).
Before IOL implantation, the mean spherical equivalent was +11.75 ± 3.38 D (range: +2.5 to +18 D). After IOL implantation, the mean spherical equivalent was nearly stable for 6 months and significantly improved to −0.29 ± 1.32 D (range −2.25 to 0.75 D) at 1 month, −0.21 ± 0.99 D (range: −2.5 to 1.25 D) at 3 months, and −0.19 ± 0.93 D (range: −1.75 to 1.25 D) at 6 months (P = 0.003) (Table 1). The postoperative mean astigmatism component was −2.88 ± 1.13 D (range: −1.75 to −3.75 D) at 1 month, −2.54 ± 1.39 D (range: −1.25 to −3.75 D) at 3 months, and −2.59 ± 1.21 D (range: −1.75 to −3.75 D) at 6 months. Twenty-six eyes (89.7%) were within ±2 D of the target refraction, and 15 eyes (51.7%) were within ±1 D of the target refraction, 6 months after IOL implantation (Table 1 and Fig. 1).
Just before secondary IOL implantation, the mean UDVA was 1.47 ± 0.56 (range: 1.0–2.0), and the mean CDVA was 0.64 ± 0.29 (range: 0.0–0.8). After IOL implantation, the mean UDVA significantly improved to 0.42 ± 0.27 (range: 0.1–0.7) at 1 month, 0.38 ± 0.23 (range: 0.0–0.7) at 3 months, and 0.34 ± 0.18 (range: 0.0–0.6) at 6 months (P = 0.017). In addition, the mean CDVA significantly improved to 0.34 ± 0.10 (range: 0.0–0.6) at 1 month, 0.27 ± 0.27 (range: 0.0–0.4) at 3 months, and 0.18 ± 0.29 (range: 0.0–0.2) at 6 months (P = 0.014) (Table 1 and Fig. 2).
After secondary IOL implantation, the mean percentage of corneal endothelial cell loss was 3.6% at 1 month, 7% at 3 months, and 7.3% at 6 months (P = 0.16) (Table 1). Figure 3 shows the correlation between the ECDs before and 6 months after IOL implantation in all eyes of the study. Graft survival was 100% at 6 months after IOL implantation. No eyes showed postoperative signs of graft rejection, recurrence of the original disease, or elevation of IOP.
Eyes with coexisting corneal opacification and cataract are currently treated with 1 of the 2 alternatives: a triple procedure in 1 session including PKP, cataract extraction, and IOL implantation4 or a 2-stage procedure composed of PKP followed months later by cataract extraction and IOL implantation.5 Both procedures are well established and provide an acceptable visual outcome for such cases, despite having some drawbacks.1–10 The main drawback of the triple procedure is the postoperative high refractive error caused by inaccurate IOL power calculation due to unpredictable keratometric values at the time of surgery.1,2,6–10 However, the 2-stage procedure is associated with a refractive error closer to the target refraction, but visual recovery is delayed, and there is a potential for significant corneal endothelial cell loss during phacoemulsification and possibly graft failure.2,5,9–14 Many surgeons do not prefer the 2-stage procedure because of concern over final graft clarity. Graft failure in eyes undergoing the 2-stage procedure ranged from 0% to 66% in the literature.5,12–16 This big difference between the results of different studies was mainly related to variation in the technique of cataract surgery, which has evolved over years, and variation in the underlying corneal pathology between the studies.
In this study, a new 2-stage alternative (simultaneous–sequential technique) was pursued for treatment of coexisting corneal opacification and cataract in an attempt to achieve the advantages and avoid the drawbacks of the 2 established surgical options. In this approach, PKP and cataract extraction were performed simultaneously in 1 session, and sequential secondary IOL implantation was performed in a second session after removal of corneal sutures. With this technique, IOL power calculation will be more accurate and based on actual keratometric values, and the endothelium of the corneal graft will not be damaged by mechanical trauma or ultrasonic power during phacoemulsification.
Cataract surgery basically induces some endothelial damage, and any small marginal increase in endothelial cell loss could be enough for corneal graft failure to occur or to be hastened. Graft endothelial cell loss due to phacoemulsification and IOL implantation (as in the conventional 2-stage technique) is expected to be more than that caused by IOL implantation alone (as in our approach). Postponing cataract extraction to a second surgery when the corneal stitches are removed after approximately 1 year (as in the conventional 2-stage technique) will allow cataract to be harder and will necessitate a longer ultrasound time, and this may have a devastating effect on the corneal graft endothelium. However, performing cataract extraction during the first surgery with PKP (as in our approach) will save the endothelium of the corneal graft from being damaged by the ultrasound of phacoemulsification and by mechanical trauma and consequently will have a favorable effect on graft survival.
In this study, there were no statistically significant differences between the ECDs before and after secondary IOL implantation up to 6 months postoperatively. The mean percentage of endothelial cell loss after IOL implantation was 7.3% at 6 months. Higher percentages of endothelial cell loss at 6 months postoperatively were reported by Hayashi and Hayashi2 and Den et al17 (11.6% and 32.2%, respectively) using the conventional 2-stage technique. Corneal graft endothelial cell loss (6 months after surgery) in eyes in which cataract was removed by phacoemulsification was higher than that in eyes in which cataract was removed by ECCE (22.9% vs. 11.9%).18 However, 1 study15 reported a similar percentage of endothelial cell loss by performing cataract extraction and IOL implantation as the second procedure. The lower percentage of endothelial cell loss recorded in the present study could be attributed to the minimal intraocular manipulations associated with implanting an IOL only without cataract extraction. Consequently, no cases of endothelial decompensation have occurred up to 6 months after secondary IOL implantation.
The mean spherical equivalent was nearly stable for 6 months and significantly improved to −0.19 ± 0.93 six months after IOL implantation, and most of it was due to corneal astigmatism occurring after PKP and not due to pure spherical error. The recorded mean SE was within ±2.0 D of the target refraction in 26 eyes (89.7%) and within ±1 D of the target refraction in 15 eyes (51.7%). The results of this study are comparable to those of other studies that used the conventional 2-stage approach. Claudia et al1 and Hayashi and Hayashi2 reported SE within ±2 D in 22 eyes (92%) and 16 eyes (70%), respectively. Hsiao et al15 reported a mean postoperative refractive error of −1.49 ± 1.39 D, and 19 eyes (73%) had SE refraction within ±2 D of emmetropia. In all the aforementioned studies including our study, accurate keratometric values, anterior chamber depth, and axial length of the operated eye were used in IOL power calculation formulae. However, the current results are much better than the results of all the studies that used the triple procedure, whether they have used a standard constant keratometry value, or keratometry values of the fellow healthy eye, or a multiple regression analysis with surgeon specific values.1,10,19,20 Claudia et al,1 Hayashi and Hayashi,2 and Javadi et al8 reported SE within ±2 D of the target refraction in 18 eyes (50%), 15 eyes (39%), and 35 eyes (46.05%), respectively. In this study, suture manipulation performed at the end of keratoplasty surgery helped to reduce postoperative astigmatism. The mean cylindrical error was −2.59 ± 1.21 D (range: −1.75 to −3.75 D) 6 months after secondary IOL implantation. This value of astigmatic error is considered mild to moderate21 and permitted its correction with spectacles. However, 5 patients were unhappy, and further laser vision correction was discussed.
In the present study, UDVA and CDVA significantly improved to 0.34 ± 0.18 logMAR units and 0.18 ± 0.29 logMAR units, respectively, 6 months after IOL implantation. Our results are comparable to those of Hsiao et al,15 who used the conventional 2-stage approach and reported a UDVA of 0.7 logMAR units or better in 83% of eyes and a CDVA of at least 0.3 logMAR units in 81% of eyes included in their study. The level of improvement of postoperative UDVA and CDVA reported in this study was higher than the 1.00 ± 0.87 logMAR units (UDVA) and the 0.44 ± 0.33 logMAR units (CDVA) of improvement achieved after the triple procedure reported by Javadi et al.8 The difference may be explained by accurate prediction of IOL power that necessitates accurate keratometry values, axial length measurement, and anterior chamber depth, all of which can be altered after PKP. Using our described 2-step approach, all these parameters have been stabilized at the time of secondary IOL implantation, so the postoperative spherical refraction was close to the target refraction with no large variations as in the cases of the triple procedure.
Controlling postoperative intraocular inflammation is crucial for maintenance of graft clarity and prevention of capsular adhesions and pupillary membranes, which could make secondary IOL implantation difficult. Cataract was removed by phacoemulsification before corneal trephination in 15 eyes (51.7%) in which there was fair visualization through corneal opacity. Open-sky ECCE was performed in 14 eyes (48.3%) in which corneal opacity was so dense to allow safe phacoemulsification When comparing eyes in which cataract was treated by phacoemulsification with those treated by ECCE, no statistically significant differences were detected as regards the mean percentage of endothelial cell loss, the postoperative mean spherical error, and the mean UDVA. Javadi et al8 reported that the IOL position had no effect on the rate of graft rejection reactions. However, the IOL was implanted in the sulcus in all eyes of the study to avoid any effect on the visual results or corneal endothelium caused by variation in the IOL position. No complications related to IOL implantation in the sulcus were reported up to the end of follow-up period. A foldable 3-piece acrylic IOL was used in all eyes of the study to avoid or minimize postoperative complications such as uveitis–glaucoma–hyphema (UGH) and pigment dispersion, which are known to be complications of the single-piece IOL implanted in the sulcus. The foldable 3-piece acrylic IOL has thin, posteriorly angulated C-shaped prolene haptics that provide sufficient posterior iris clearance, good IOL centration, and secure fixation, which in turn ensures long-term fixation and avoids IOL movement or tilting that can induce uveitis, hyphema, glaucoma, and pigment dispersion.22,23
In eyes with coexisting corneal opacities and cataract, if it is feasible for the patient to undergo a 2-stage procedure, performing PKP and cataract extraction as a first step and then delaying IOL implantation until removal of corneal sutures will allow accurate IOL power calculation and favorable refractive outcome. Moreover, this new approach saves the corneal graft's endothelium and avoids its damage, the brunt of cataract surgery, thus promoting graft survival.
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Keywords:Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
secondary IOL implantation; corneal pathology and cataract; penetrating keratoplasty; simultaneous sequential technique