- Email: [email protected]
Excimer laser surgery for correction of ametropia after cataract surgery
J CATARACT REFRACT SURG - VOL 31, NOVEMBER 2005
Excimer laser surgery for correction of ametropia after cataract surgery Irene C. Kuo, MD, Terrence P. O’Brien, MD, Aimee T. Broman, MA, Mehdi Ghajarnia, MD, Nada S. Jabbur, MD
PURPOSE: To review the cases of patients who had excimer laser refractive surgery to correct unintentional or undesired ametropia after cataract extraction with intraocular lens (IOL) implantation. SETTING: Wilmer Laser Vision Correction Center, Wilmer Eye Institute, Baltimore, Maryland, USA. METHODS: In this retrospective noncomparative review of consecutive cases, the Wilmer Laser Vision Correction Center’s database was searched for patients who had laser in situ keratomileusis or photorefractive keratectomy to correct ametropia after cataract extraction with IOL implantation. RESULTS: Using the Visx Star excimer laser system (Visx, Inc.), 11 procedures were performed in 11 eyes of 10 patients a mean of 47 months (range 2 to 216 months) after cataract extraction with IOL implantation. Except for 1 patient with a silicone plate lens, all patients received 3-piece poly(methyl methacrylate) lenses. The mean age at time of excimer treatment was 75 years (range 70 to 81 years). Before laser surgery, the mean spherical equivalent of patient eyes was ÿ3.76 diopters (D) G 2.50 (SD) (range ÿ6.50 to C0.75 D), spherical refraction ranged from ÿ9.00 D to plano, and the highest cylindrical refraction was C5.50 D. At last follow-up (mean 12.2 months; range 1 to 38 months), the mean manifest spherical equivalent was ÿ0.88 G 1.43 D (range ÿ2.75 to C2.13 D). Changes in mean manifest spherical equivalent were highly significant (P Z .03, Wilcoxon signed rank test for paired values). There was no difference between targeted and achieved postoperative refraction (P Z .34, Wilcoxon test). Increasing age was correlated with a hyperopic shift (r Z 0.525, P Z .05). All patients were satisfied with their final uncorrected visual acuity (UCVA), which improved in every case. Except for 1 patient in whom an epiretinal membrane developed, best spectacle-corrected visual acuity remained unchanged or improved. CONCLUSIONS: In this series of patients, who were a few decades older than the typical excimer laser candidate, laser refractive surgery was a safe, effective, and predictable method to correct ametropia after cataract extraction with IOL implantation. It may be a viable, noninvasive alternative to intraocular surgery, which has potential complications. Although satisfactory for all patients, final UCVA was not as high as that reported in laser refractive surgery patients in general, and this result may be because of prior cataract extraction with IOL implantation or increased age. J Cataract Refract Surg 2005; 31:2104–2110 Q 2005 ASCRS and ESCRS
Although its refractive implications may be overlooked relative to the capabilities of laser refractive surgery,1 cataract surgery may be considered the oldest and most commonly performed refractive surgery procedure. Formulas for choosing the proper intraocular lens (IOL) abound, some of which are more accurate in ametropic eyes2 or eyes that have had previous laser refractive surgery.3–5 Despite advanced surgical techniques and a variety of formulas, ametropia can be an unintended result of uneventful cataract extraction with IOL implantation. In other instances, a patient who chooses to have postoperative monovision may change his or her mind after cataract extraction with IOL implantation and desire plano refraction instead. Solutions Q 2005 ASCRS and ESCRS Published by Elsevier Inc.
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to these 2 situations include (1) spectacle wear, (2) contact lens wear, and (3) exchange of the IOL. However, further intraocular surgery, especially many years after cataract extraction with IOL implantation, can be risky in some eyes because of a low corneal endothelial cell count, the possibility of cystoid macular edema, or difficulty extricating an encapsulated lens, which could increase the risk for intraocular inflammation or vitreous loss. In such eyes, noninvasive laser refractive surgery might be a safer alternative. In this report, the characteristics and clinical course of a series of patients who had such surgery to correct ametropia after cataract extraction with IOL implantation are described. 0886-3350/05/$-see front matter doi:10.1016/j.jcrs.2005.08.023
CORRECTION OF AMETROPIA AFTER CATARACT SURGERY USING EXCIMER LASER SURGERY
PATIENTS AND METHODS The study was conducted under a protocol approved by the Johns Hopkins University Institutional Review Board and conducted in accordance with the tenets of the Declaration of Helsinski. The Refractive Surgery Service at the Wilmer Eye Institute has maintained a prospective database of all patients who had laser refractive surgery since January 1, 1997. All refractive surgical candidates have a thorough preoperative evaluation, including detailed medical, ocular, and social history; preoperative uncorrected visual acuity (UCVA); best spectacle-corrected visual acuity (BSCVA); corneal topography (Zeiss Humphrey Meditec) and Orbscan (Bausch & Lomb); corneal pachymetry by ultrasound and by Orbscan; biomicroscopic examination; pupillary examination; Schirmer testing, dilated examination; cycloplegic refraction; and cycloplegic visual acuity. In all 14 cases, excimer laser surgery was an off-label use of the technology to which patients gave informed consent in preference to IOL exchange or incisional surgery. Choice of laser procedure was based on the best medical and surgical judgment of the treating surgeon. In some instances, the amount of myopia determined the choice of procedure; in 1 patient, poorly adherent epithelium led to the choice of photorefractive keratectomy (PRK) over laser in situ keratomileusis (LASIK). The laser platforms used were the Visx 20/20, S2, S3, and S4. The Hansatome (Bausch & Lomb) and Amadeus (Advanced Medical Optics) microkeratomes were used with 140 mm or 160 mm plates. Fluence was 160 mJ/cm, ablation zone ranged from a 6.0 mm to 6.5 mm with or without blend out to 8.0 mm, and the laser pulse rate was 6.0 Hz or 10.0 Hz. All patients had surgery before approval of custom ablation using the Visx platform. Patients were recommended to return for examination 1 day, 1 week, 1 month, 6 months, and 1 year after laser refractive surgery. Uncorrected visual acuity and BSCVA were recorded, as were patient complaints and findings of biomicroscopic examination.
RESULTS Preoperative Characteristics
Through October 2004, 14 patients were identified as having had laser refractive surgery for ametropia after cataract extraction with IOL implantation; 10 patient charts
Accepted for publication January 14, 2005. From the Wilmer Eye Institute, Baltimore, Maryland, USA. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Washington, DC, USA, April 2005. Supported by an unrestricted grant from Research to Prevent Blindness, New York, New York, USA. Dr. Jabbur and Dr. O’Brien have received honoraria and travel reimbursements from Visx, Inc., Santa Clara, California. Dr. O’Brien is a consultant/advisor for Bausch & Lomb. Dr. Jabbur is an ad hoc consultant and clinical investigator for Visx, Inc. No other author has a financial or proprietary interest in any material or method mentioned. Reprint requests to Irene C. Kuo, MD, Wilmer Eye Institute, 4924 Campbell Boulevard, #100 Baltimore, Maryland 21236, USA. E-mail: [email protected].
(11 eyes) were located (Table 1). There were 7 women and 3 men. The mean age was 75 years G 4.3 (SD) (range 70 to 81 years). Four cataract extraction with IOL implantation procedures were performed outside the Wilmer Eye Institute. The mean time between cataract surgery and laser surgery was 47 months (range 2 to 216 months). Six right eyes and 5 left eyes had excimer laser surgery. Before cataract extraction with IOL implantation, emmetropia was the goal in 9 patients; only 1 patient (case 5) gave informed consent for postoperative monovision status. Her surgeon implanted a Chiron silicone plate lens, and although she had desired postcataract surgery monovision, she became more myopic than desired and the lens became fibrosed. All other IOLs were 3-piece poly(methyl methacrylate). Cataract surgery in 1 patient (case 4) was complicated by a posterior capsule tear and vitreous loss for which an anterior vitrectomy was performed; and an anterior chamber IOL was placed. All patients had normal anterior segment and posterior segment examinations before laser surgery; no patient had evidence of corneal edema, which might be expected to alter tissue ablation by the excimer laser. Visual Acuity and Refraction
In the 10 patients whose charts were located, 11 procedures were performed in 11 eyes; LASIK was performed in 6 eyes and PRK in 5 eyes (Table 1). The mean age of LASIK and PRK patients was 72 years and 78 years, respectively. One patient (case 10) had had 1 LASIK operation 2 years before cataract extraction with IOL implantation, but no other patient had had previous laser surgery. The range of preoperative spherical refraction was ÿ9.00 diopters (D) to plano (Table 2). The maximum preoperative cylindrical refraction was C5.50 D. The mean spherical equivalent was ÿ3.76 G 2.50 D (range ÿ6.50 to C0.75 D). There were no patients with mixed astigmatism. Before laser refractive surgery, most patients desired emmetropia in the operative eye; overall, the mean attempted spherical equivalent was ÿ3.28 G 2.64 D (range ÿ6.50 to C0.75 D). Three patients requested postoperative monovision status, and these eyes were targeted between ÿ1.50 D and ÿ2.00 D. In general, patients requiring higher amounts of spherical or cylindrical correction had LASIK; they were also younger than the PRK patients (P Z .02; Figure 1). The mean attempted spherical and cylindrical corrections for the LASIK patients were ÿ4.38 D and C2.92 D, respectively (Table 2). The mean attempted spherical and cylindrical corrections for the PRK patients were ÿ4.15 D and C0.85 D, respectively. The difference in cylindrical correction was statistically significant (P Z .05, Wilcoxon test).
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Table 1. Clinical characteristics of patients having excimer laser surgery for ametropia after cataract extraction with IOL implantation.
Case/Eye
Age (Y)/Sex
1/OS 2/OS 3/OS 4/OD 5/OD 6/OD
76/M 81/F 80/F 81/M 72/F 74/F
7/OD
73/F
8/OS 9/OD 9/OS 10/OD
70/F 71/F 71/F 71/M
History/Reason for Laser Surgery
Time From CE-IOL to Laser Surgery (Mo)
UCVA
120 36 15 7 11 216
20/60 !20/400 20/200 !20/400 20/400 !20/400
2
!20/400
2 51 51 15
20/400 20/400 20/50 20/25
High myopia prior to CE-IOL; residual myopia after CE-IOL Myopia Myopia; vitreous loss during CE; AC IOL placed Myopia High myopia and astigmatism after one IOL exchange; h/o retinal detachment before CE-IOL. S/p orbital decompression for Grave’s disease; high myopia prior to CE-IOL; residual myopia and anisometropia and ocular surface drying Myopia Myopia Myopia One LASIK procedure before CE-IOL; monocular diplopia and astigmatism after CE-IOL.
AC IOL Z anterior chamber intraocular lens implant; BSCVA Z best spectacle-corrected visual acuity; CE Z cataract extraction; CE-IOL Z cataract extraction with intraocular lens implantation; LASIK Z laser in situ keratomileusis; OD Z right eye; OS Z left eye; PRK Z photorefractive keratectomy; S/p Z status post; UCVA Z uncorrected visual acuity
The mean attempted spherical equivalent was ÿ2.92 G 3.03 D for the LASIK patients and ÿ3.73 G 2.33 D for the PRK patients, respectively. This difference was not statistically significant (P Z.54, Wilcoxon test). Mean length of follow-up after laser refractive surgery was 12.2 months (range 1 to 38 months). At last follow-up, the range of spherical refraction was ÿ3.00 to C1.50 D, and the highest cylindrical refraction was C2.00 D. The mean spherical refraction was ÿ1.11 D; the mean cylindrical refraction was C0.48 D. The mean manifest spherical equivalent at last follow-up was ÿ0.88 G 1.43 D (range ÿ2.75 to C2.13 D; Table 2). The changes in mean manifest
spherical equivalent were statistically significant between paired preoperative and postoperative values (P Z.03, Wilcoxon test). Postoperatively, older patients became more hyperopic than intended (r Z 0.528, P Z .05; Figure 1). However, there was no over all difference between achieved and targeted manifest spherical equivalents (P Z.34, Wilcoxon test). In addition, there was no correlation between length of follow-up and attainment of intended correction (r Z ÿ0.38, P Z .12). Likewise, there was no correlation between time from cataract extraction with IOL implantation to excimer laser surgery and attainment of intended correction (r Z 0.069, P Z .36). Because 2 PRK patients,
Table 2. Comparison of preoperative and postoperative values.
Mean G SD (Range) Parameter Spherical refraction (D) Cylindrical refraction (D) Manifest refractive spherical equivalent (D) Attempted spherical equivalent (D) Attempted spherical correction for LASIK patients (D) Cylindrical refraction for LASIK patients (D) (Attempted) spherical equivalent for LASIK patients (D) Attempted spherical correction for PRK patients (D) Cylindrical refraction for PRK patients (D) (Attempted) spherical equivalent for PRK patients (D) UCVA BSCVA
Preoperative
Postoperative
ÿ4.75 G 2.94 (ÿ9.00 to plano) C1.98 G 1.80 (plano to C5.50) ÿ3.76 G 2.50 (ÿ6.50 to C0.75) ÿ3.28 G 2.64 (ÿ6.50 to C0.75) ÿ4.38 G 3.69 (ÿ9.00 to plano) C2.92 G 1.90 (C1.00 to C5.50) ÿ2.92 G 3.03 (ÿ6.50 to C0.75) ÿ4.15 G 2.72 (ÿ8.50 to ÿ2.00) C0.85 G 0.80 (plano to C2.00) ÿ3.73 G 2.33 (ÿ7.50 to ÿ1.88) 20/400 20/25
ÿ1.11 G 1.33 (ÿ3.00 to C1.50) C0.48 G 0.65 (plano to C 2.00) ÿ0.88 G 1.43 (ÿ2.75 to C2.13)
C0.54 G 0.78 (plano to C2.00) ÿ1.23 G 1.20 (ÿ2.75 to plano) C0.40 G 0.52 (plano to C1.25) ÿ0.45 G 1.70 (ÿ2.63 G C2.13) 20/30 20/25
BSCVA Z best spectacle-corrected visual acuity; LASIK Z laser in situ keratomileusis; PRK Z photorefractive keratectomy; UCVA Z uncorrected visual acuity
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Table 1 (cont.)
Refraction Before Laser Refractive Surgery and BSCVA ÿ2.00 C0.25 160 ÿ5.00 C1.25 035 ÿ4.00 sph ÿ8.50 C2.00 065 ÿ4.75 C0.75 175 ÿ7.00 C5.50 015 ÿ9.00 C5.00 180 ÿ4.25 C2.75 025 ÿ6.75 C1.75 175 ÿ1.00 C1.00 180 Plano C1.50 125
20/20 20/30 20/25 20/25 20/20 20/50 20/30 20/20 20/40 20/20 20/20
Attempted Monovision Correction
Laser Refractive Procedure
Length of Follow-up (Mo)
UCVA at Last Follow-up
No No Yes ÿ2.00 sph No Yes ÿ1.50 sph No No Yes ÿ1.75 sph No No No
PRK PRK PRK PRK PRK LASIK LASIK LASIK LASIK LASIK LASIK
3 3 2 27 13 38 3 24 1 1 19
20/30 20/60 20/30 20/30 20/100 20/30 20/50 20/100 20/30 20/30 20/30
Achieved minus Intended Refraction, Diopters
as opposed to 1 LASIK patient, requested undercorrection for monovision, one would expect the postoperative results for PRK patients to be more myopic, but the postoperative mean spherical equivalent was more myopic in the LASIK group (Table 2). However, the difference between the 2 groups was not statistically different (P Z.64, Wilcoxon test). There was no difference in postoperative spherical or cylindrical refraction between the PRK and LASIK groups using the same test (P Z.41 and P Z 1.0, respectively, Wilcoxon test). All patients experienced improvement in UCVA. Before laser refractive surgery, 7 of 11 eyes (64%) had
2
1
Refraction and BSCVA at Last Follow-up ÿ0.25 sph C1.50 C1.25 068 ÿ0.75 sph ÿ1.00 C0.50 180 ÿ2.75 C0.25 180 ÿ1.75 C0.75 065 ÿ3.00 C0.50 078 ÿ2.50 sph ÿ1.00 C2.00 180 Plano ÿ0.75 sph
20/20 20/20 20/25 20/30 20/20 20/30 20/30 20/20 20/30 20/30 20/20
UCVA of 20/400 or worse and 1 eye (9%) had UCVA better than 20/40. After laser refractive surgery, the best UCVA was 20/30. Seven of 11 eyes (64%) had postoperative UCVA of 20/30 and 2 (18%) had UCVA of 20/50 or 20/60. The 2 eyes with postoperative UCVA of 20/100 were in patients who had requested postoperative monovision and were satisfied with their postoperative UCVA at distance and near. No eye had postoperative UCVA worse than 20/100. Except for 3 patients, all had unchanged BSCVA. Two patients (cases 2 and 6) gained 2 lines and 1 line of BSCVA, respectively. One patient (case 4) lost a line of BSCVA and had an epiretinal membrane diagnosed. No other patient had postoperative ocular pathology. No patient lost more than 1 line of BSCVA. All patients expressed subjective improvement in their quality of vision after laser surgery and described reduced dependence on spectacles. There were no intraoperative or postoperative complications.
0
DISCUSSION −1
−2 PRK LASIK 70
72
74
76
78
80
Age, years Figure 1. Positive correlation between age and the difference between achieved and intended refractions (r Z 0.528, P Z .05). Photorefractive keratectomy patients tended to be older than LASIK patients by an average of 6.3 years.
Laser refractive surgery to correct residual refractive error after primary laser procedures as well as after penetrating keratoplasty has been described,6–8 but, in contrast, there are few reports describing laser refractive surgery after cataract extraction with IOL implantation.9–14 In this series of patients, approximately 3 decades older than the average laser refractive surgery patient and with varying degrees of ametropia (though with a predominance of myopic patients), we show that laser refractive surgery can be a safe, effective, and predictable alternative to intraocular procedures. However, longer follow-up as well as comparison of UCVA in such patients in contrast to laser refractive surgery patients in general are needed.
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Although cataract extraction with IOL implantation is a highly successful refractive procedure, ‘‘surprises’’ in postoperative residual refractive error can still occur. In a recent survey of reasons for explantation of or secondary intervention after a foldable IOL implantation, dislocation/ decentration (which can lead to ametropia) was the most common followed by incorrect lens power.15 Incorrect lens power was the most common reason for explantation of 1-piece hydrophobic acrylic IOLs with haptics and the 3-piece hydrophobic acrylic IOL,15 which was explanted in 10 of 11 eyes in our series. Established surgical options include a piggyback IOL or a lens exchange. However, there are risks associated with these intraocular procedures, including corneal edema, intraocular inflammation, increased IOP, vitreous loss, cystoid macular edema, and retinal detachment (RD). Because uneventful phacoemulsification with IOL implantation is associated with corneal endothelial cell loss and with increased rate of cell loss compared with the rate in healthy unoperated eyes and because endothelial cell count decreases with increasing age,16–19 one can deduce that additional intraocular procedures in elderly patients increase the risk for corneal decompensation. Moreover, an IOL exchange can induce damage to angle structures and potentially increase the risk for glaucoma, the prevalence of which increases with age, such that the prevalence of glaucoma in the eighth decade is 2.89%.20 Retinal detachment is another risk of cataract surgery and IOL exchange, although the risk for RD is increased in younger patients who have cataract extraction with IOL implantation.21–23 Two patients (cases 1 and 7) had axial myopia before cataract surgery, a known risk factor for RD.21,22 The risk for RD also increases when intraocular complications occur during cataract surgery.22 One patient (case 4) had had cataract extraction with IOL implantation complicated by vitreous loss and prolonged postoperative corneal edema. Another patient (case 6) had already had 3 intraocular procedures (RD repair, cataract extraction with IOL implantation, and IOL exchange) at the time she desired correction of her ametropia. In such patients who cannot or will not use a contact lens or spectacles after cataract extraction with IOL implantation, the risks associated with further intraocular surgery might justify a less invasive procedure, such as laser refractive surgery. The results in this patient series suggest that laser refractive surgery for postcataract surgery ametropia is safe, effective, and predictable, although the length of follow-up in some patients was limited. Except for BSCVA, which (with the exception of case 4, an epiretinal membrane) remained unchanged or improved, all other parameters improved. Mean spherical and cylindrical refractions were reduced after laser refractive surgery, as were their respective standard deviations and ranges. Another measure of the predictability of laser refractive surgery in these
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patients was the lack of difference between targeted and achieved refraction. The fact that 1 PRK patient became hyperopic most likely explains the larger standard deviation and less myopic mean postoperative spherical refraction and spherical equivalent in PRK patients compared with LASIK patients (Table 2). However, conclusions should not be drawn from a comparison of LASIK and PRK in overall spherical equivalent, spherical refraction, and cylindrical refraction because small sample sizes limit statistical power. In addition, although attainment of intended correction was not correlated with length of follow-up and patient satisfaction after excimer laser surgery was very high, longer follow-up of a larger group of patients would be important to determine the efficacy, safety, and predictability of this technique. Although the postoperative UCVA in these patients improved in every case, the overall postoperative UCVA was not as good as that reported from laser refractive surgery patients in general. One reason may be age; on average, these patients were more than 3 decades older than the average refractive surgery patient24,25 or even the refractive enhancement patient.26 Several reports document an association between age and results of laser refractive surgery, including decreased efficiency of spherical ablation,27 an increased rate of enhancement procedures (which would imply less predictable refractive results from the original surgery),26,28 possibly diminished stromal wound healing,29 potential interactions between the aging eye, changes in corneal optics induced by PRK,29 and an increased incidence of corneal abrasions.30–32 One of these studies found a hyperopic shift in older patients who had LASIK for myopic astigmatism,27 as we found in our series, although our series included PRK patients who also happened to be older than the LASIK patients by an average of 6.3 years. Other factors besides age might have affected the outcomes in this patient series. Mechanical distortion of the eye from previous cataract extraction with IOL implantation (eg, stability of a nonsutured clear corneal wound or the IOL) may occur during buildup of suction in LASIK and thus alter postoperative results12; however, such distortion cannot explain results after PRK. Another possibility is that corneal wound healing after laser surgery is somehow different in patients who have had prior cataract extraction with IOL implantation. Subclinical corneal edema might be expected to decrease the efficacy of any excimer laser treatment, and we cannot rule out this possibility in our patient series. However, it is unlikely that cataract extraction with IOL implantation itself affects the outcomes of laser surgery because the procedures in this patient series were performed before custom ablation and the only parameters programmed into the laser treatment, refraction, and keratometry readings are not expected to change after cataract extraction with IOL implantation. Last,
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perhaps ‘‘overall UCVA’’ may lack significance in a series of patients with such heterogeneous preoperative characteristics. There have been few reports describing laser refractive surgery after cataract extraction with IOL implantation.9–14 In 1 report, PRK was the sole treatment offered to 24 patients (31 eyes) with ametropia after cataract extraction with IOL implantation (age range 27 to 65 years; mean 47 years), and the authors report that UCVA, BSCVA, mean spherical equivalent, astigmatism, and anisometropia improved as early as 1 week after surgery.9 The authors of another published report conclude that at 6 months of follow-up, LASIK was effective and safe for correction of astigmatism after extracapsular cataract extraction with posterior chamber IOL implantation. Grade 2 diffuse lamellar keratitis (DLK) occurred in 3 of 20 (15%) eyes and resolved with topical and systemic steroids.10 The reason for the high incidence of DLK in these patients was unknown. Diffuse lamellar keratitis did not occur in any of our patients. Laser in situ keratomileusis was studied in close to 300 patients who were pseudophakic or with phakic IOLs (bioptics); refraction was stable for 4 years, and the procedure produced predictable refractive results.13 A small body of literature exists on RD in myopic eyes after LASIK33,34; in the largest series of such patients, the reported prevalence of RD was 0.08%.33 However, on average, these LASIK patients were young, and the average refraction of those who experienced an RD was ÿ8.75 D, meaning these patients were already at increased risk for a detachment regardless of LASIK. Whether the risk for RD should be included in the informed consent for LASIK in patients with ametropia after cataract extraction with IOL implantation remains unknown.33–35 Weaknesses of the current study include its retrospective nature, the varying lengths of follow-up, and lack of randomization for laser vision correction procedures. Length of follow-up was limited by patients who were lost to follow-up. This problem was most significant in 2 patients (cases 2 and 7) who had an unexplained refractive error after laser surgery and whose length of follow-up was only 3 months. However, the patient in case 7 also had ocular surface disease, which might have confounded attempts at refraction. Regarding lack of randomization, some of the patients might have done well with either LASIK or PRK. In this small series of patients with varying lengths of follow-up, we show that laser refractive surgery can be a safe and effective (off-label) surgical method to correct ametropia after cataract extraction with IOL implantation in an elderly population. This modality may be especially useful in patients who have had complicated previous intraocular surgery and in patients at increased risk for complications from further intraocular surgery. Further studies
with custom ablation, longer follow-up, and randomization of patients would be helpful. Because an IOL would be expected to alter wavefront data, improved software to capture wavefront data from pseudophakic patients will likely need to be developed. An improved understanding of how age affects corneal wound-healing changes will also be crucial.
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19. Ravalico G, Tognetto D, Baccara F, Lovisato A. Corneal endothelial protection by different viscoelastics during phacoemulsification. J Cataract Refract Surg 1997; 23:433–439 20. Tielsch JM, Sommer A, Katz J, et al. Racial variations in the prevalence of primary open-angle glaucoma; the Baltimore Eye Survey. J Am Med Assoc 1991; 266:369–374 21. Olsen G, Olson RJ. Update on a long-term, prospective study of capsulotomy and retinal detachment rates after cataract surgery. J Cataract Refract Surg 2000; 26:1017–1021; erratum 2001; 27:180 22. Nielsen NE, Naeser K. Epidemiology of retinal detachment following extracapsular cataract extraction: a follow-up study with an analysis of risk factors. J Cataract Refract Surg 1993; 19:675–680 23. Ravalico G, Michieli C, Vattovani O, Tognetto D. Retinal detachment after cataract extraction and refractive lens exchange in highly myopic patients. J Cataract Refract Surg 2003; 29:39–44 24. Nagy ZZ, Pala´gyi-Dea´k I, Kelemen E, Kova´cs A. Wavefront-guided photorefractive keratectomy for myopia and myopic astigmatism. J Refract Surg 2002; 18:S615–S619 25. Miller AE, McCulley JP, Bowman RW, et al. Patient satisfaction after LASIK for myopia. CLAO J 2001; 27:84–88 26. Hersh PS, Fry KL, Bishop DS. Incidence and associations of retreatment after LASIK. Ophthalmology 2003; 110:748–754 27. Huang D, Stulting RD, Carr JD, et al. Multiple regression and vector analyses of laser in situ keratomileusis for myopia and astigmatism. J Refract Surg 1999; 15:538–549
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28. Hu DJ, Feder RS, Basti S, et al. Predictive formula for calculating the probability of LASIK enhancement. J Cataract Refract Surg 2004; 30: 363–368 29. Hersh PS, Schein OD, Steinert R. Characteristics influencing outcomes of excimer laser photorefractive keratectomy; the Summit Refractive Keratectomy Phase III Study Group. Ophthalmology 1996; 103: 1962–1969 30. Jabbur NS, O’Brien TP. Incidence of intraoperative corneal abrasions and correlation with age using the Hansatome and Amadeus microkeratomes during laser in situ keratomileusis. J Cataract Refract Surg 2003; 29:1174–1178 31. Bashour M. Risk factors for epithelial erosions in laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:1780–1788 32. Tekwani NH, Huang D. Risk factors for intraoperative epithelial defect in laser in-situ keratomileusis. Am J Ophthalmol 2002; 134:311–316 33. Arevalo JF, Ramirez E, Suarez E, et al. Retinal detachment in myopic eyes after laser in situ keratomileusis. J Refract Surg 2002; 18:708– 714 34. Arevalo JF, Ramirez E, Suarez E, et al. Rhegmatogenous retinal detachment in myopic eyes after laser in situ keratomileusis; frequency, characteristics, and mechanism. J Cataract Refract Surg 2001; 27: 674–680 35. Flaxel CJ, Choi YH, Sheety M, et al. Proposed mechanism for retinal tears after LASIK; an experimental model. Ophthalmology 2004; 111:24–27
J CATARACT REFRACT SURG - VOL 31, NOVEMBER 2005
Excimer laser surgery for correction of ametropia after cataract surgery Irene C. Kuo, MD, Terrence P. O’Brien, MD, Aimee T. Broman, MA, Mehdi Ghajarnia, MD, Nada S. Jabbur, MD
PURPOSE: To review the cases of patients who had excimer laser refractive surgery to correct unintentional or undesired ametropia after cataract extraction with intraocular lens (IOL) implantation. SETTING: Wilmer Laser Vision Correction Center, Wilmer Eye Institute, Baltimore, Maryland, USA. METHODS: In this retrospective noncomparative review of consecutive cases, the Wilmer Laser Vision Correction Center’s database was searched for patients who had laser in situ keratomileusis or photorefractive keratectomy to correct ametropia after cataract extraction with IOL implantation. RESULTS: Using the Visx Star excimer laser system (Visx, Inc.), 11 procedures were performed in 11 eyes of 10 patients a mean of 47 months (range 2 to 216 months) after cataract extraction with IOL implantation. Except for 1 patient with a silicone plate lens, all patients received 3-piece poly(methyl methacrylate) lenses. The mean age at time of excimer treatment was 75 years (range 70 to 81 years). Before laser surgery, the mean spherical equivalent of patient eyes was ÿ3.76 diopters (D) G 2.50 (SD) (range ÿ6.50 to C0.75 D), spherical refraction ranged from ÿ9.00 D to plano, and the highest cylindrical refraction was C5.50 D. At last follow-up (mean 12.2 months; range 1 to 38 months), the mean manifest spherical equivalent was ÿ0.88 G 1.43 D (range ÿ2.75 to C2.13 D). Changes in mean manifest spherical equivalent were highly significant (P Z .03, Wilcoxon signed rank test for paired values). There was no difference between targeted and achieved postoperative refraction (P Z .34, Wilcoxon test). Increasing age was correlated with a hyperopic shift (r Z 0.525, P Z .05). All patients were satisfied with their final uncorrected visual acuity (UCVA), which improved in every case. Except for 1 patient in whom an epiretinal membrane developed, best spectacle-corrected visual acuity remained unchanged or improved. CONCLUSIONS: In this series of patients, who were a few decades older than the typical excimer laser candidate, laser refractive surgery was a safe, effective, and predictable method to correct ametropia after cataract extraction with IOL implantation. It may be a viable, noninvasive alternative to intraocular surgery, which has potential complications. Although satisfactory for all patients, final UCVA was not as high as that reported in laser refractive surgery patients in general, and this result may be because of prior cataract extraction with IOL implantation or increased age. J Cataract Refract Surg 2005; 31:2104–2110 Q 2005 ASCRS and ESCRS
Although its refractive implications may be overlooked relative to the capabilities of laser refractive surgery,1 cataract surgery may be considered the oldest and most commonly performed refractive surgery procedure. Formulas for choosing the proper intraocular lens (IOL) abound, some of which are more accurate in ametropic eyes2 or eyes that have had previous laser refractive surgery.3–5 Despite advanced surgical techniques and a variety of formulas, ametropia can be an unintended result of uneventful cataract extraction with IOL implantation. In other instances, a patient who chooses to have postoperative monovision may change his or her mind after cataract extraction with IOL implantation and desire plano refraction instead. Solutions Q 2005 ASCRS and ESCRS Published by Elsevier Inc.
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to these 2 situations include (1) spectacle wear, (2) contact lens wear, and (3) exchange of the IOL. However, further intraocular surgery, especially many years after cataract extraction with IOL implantation, can be risky in some eyes because of a low corneal endothelial cell count, the possibility of cystoid macular edema, or difficulty extricating an encapsulated lens, which could increase the risk for intraocular inflammation or vitreous loss. In such eyes, noninvasive laser refractive surgery might be a safer alternative. In this report, the characteristics and clinical course of a series of patients who had such surgery to correct ametropia after cataract extraction with IOL implantation are described. 0886-3350/05/$-see front matter doi:10.1016/j.jcrs.2005.08.023
CORRECTION OF AMETROPIA AFTER CATARACT SURGERY USING EXCIMER LASER SURGERY
PATIENTS AND METHODS The study was conducted under a protocol approved by the Johns Hopkins University Institutional Review Board and conducted in accordance with the tenets of the Declaration of Helsinski. The Refractive Surgery Service at the Wilmer Eye Institute has maintained a prospective database of all patients who had laser refractive surgery since January 1, 1997. All refractive surgical candidates have a thorough preoperative evaluation, including detailed medical, ocular, and social history; preoperative uncorrected visual acuity (UCVA); best spectacle-corrected visual acuity (BSCVA); corneal topography (Zeiss Humphrey Meditec) and Orbscan (Bausch & Lomb); corneal pachymetry by ultrasound and by Orbscan; biomicroscopic examination; pupillary examination; Schirmer testing, dilated examination; cycloplegic refraction; and cycloplegic visual acuity. In all 14 cases, excimer laser surgery was an off-label use of the technology to which patients gave informed consent in preference to IOL exchange or incisional surgery. Choice of laser procedure was based on the best medical and surgical judgment of the treating surgeon. In some instances, the amount of myopia determined the choice of procedure; in 1 patient, poorly adherent epithelium led to the choice of photorefractive keratectomy (PRK) over laser in situ keratomileusis (LASIK). The laser platforms used were the Visx 20/20, S2, S3, and S4. The Hansatome (Bausch & Lomb) and Amadeus (Advanced Medical Optics) microkeratomes were used with 140 mm or 160 mm plates. Fluence was 160 mJ/cm, ablation zone ranged from a 6.0 mm to 6.5 mm with or without blend out to 8.0 mm, and the laser pulse rate was 6.0 Hz or 10.0 Hz. All patients had surgery before approval of custom ablation using the Visx platform. Patients were recommended to return for examination 1 day, 1 week, 1 month, 6 months, and 1 year after laser refractive surgery. Uncorrected visual acuity and BSCVA were recorded, as were patient complaints and findings of biomicroscopic examination.
RESULTS Preoperative Characteristics
Through October 2004, 14 patients were identified as having had laser refractive surgery for ametropia after cataract extraction with IOL implantation; 10 patient charts
Accepted for publication January 14, 2005. From the Wilmer Eye Institute, Baltimore, Maryland, USA. Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Washington, DC, USA, April 2005. Supported by an unrestricted grant from Research to Prevent Blindness, New York, New York, USA. Dr. Jabbur and Dr. O’Brien have received honoraria and travel reimbursements from Visx, Inc., Santa Clara, California. Dr. O’Brien is a consultant/advisor for Bausch & Lomb. Dr. Jabbur is an ad hoc consultant and clinical investigator for Visx, Inc. No other author has a financial or proprietary interest in any material or method mentioned. Reprint requests to Irene C. Kuo, MD, Wilmer Eye Institute, 4924 Campbell Boulevard, #100 Baltimore, Maryland 21236, USA. E-mail: [email protected].
(11 eyes) were located (Table 1). There were 7 women and 3 men. The mean age was 75 years G 4.3 (SD) (range 70 to 81 years). Four cataract extraction with IOL implantation procedures were performed outside the Wilmer Eye Institute. The mean time between cataract surgery and laser surgery was 47 months (range 2 to 216 months). Six right eyes and 5 left eyes had excimer laser surgery. Before cataract extraction with IOL implantation, emmetropia was the goal in 9 patients; only 1 patient (case 5) gave informed consent for postoperative monovision status. Her surgeon implanted a Chiron silicone plate lens, and although she had desired postcataract surgery monovision, she became more myopic than desired and the lens became fibrosed. All other IOLs were 3-piece poly(methyl methacrylate). Cataract surgery in 1 patient (case 4) was complicated by a posterior capsule tear and vitreous loss for which an anterior vitrectomy was performed; and an anterior chamber IOL was placed. All patients had normal anterior segment and posterior segment examinations before laser surgery; no patient had evidence of corneal edema, which might be expected to alter tissue ablation by the excimer laser. Visual Acuity and Refraction
In the 10 patients whose charts were located, 11 procedures were performed in 11 eyes; LASIK was performed in 6 eyes and PRK in 5 eyes (Table 1). The mean age of LASIK and PRK patients was 72 years and 78 years, respectively. One patient (case 10) had had 1 LASIK operation 2 years before cataract extraction with IOL implantation, but no other patient had had previous laser surgery. The range of preoperative spherical refraction was ÿ9.00 diopters (D) to plano (Table 2). The maximum preoperative cylindrical refraction was C5.50 D. The mean spherical equivalent was ÿ3.76 G 2.50 D (range ÿ6.50 to C0.75 D). There were no patients with mixed astigmatism. Before laser refractive surgery, most patients desired emmetropia in the operative eye; overall, the mean attempted spherical equivalent was ÿ3.28 G 2.64 D (range ÿ6.50 to C0.75 D). Three patients requested postoperative monovision status, and these eyes were targeted between ÿ1.50 D and ÿ2.00 D. In general, patients requiring higher amounts of spherical or cylindrical correction had LASIK; they were also younger than the PRK patients (P Z .02; Figure 1). The mean attempted spherical and cylindrical corrections for the LASIK patients were ÿ4.38 D and C2.92 D, respectively (Table 2). The mean attempted spherical and cylindrical corrections for the PRK patients were ÿ4.15 D and C0.85 D, respectively. The difference in cylindrical correction was statistically significant (P Z .05, Wilcoxon test).
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Table 1. Clinical characteristics of patients having excimer laser surgery for ametropia after cataract extraction with IOL implantation.
Case/Eye
Age (Y)/Sex
1/OS 2/OS 3/OS 4/OD 5/OD 6/OD
76/M 81/F 80/F 81/M 72/F 74/F
7/OD
73/F
8/OS 9/OD 9/OS 10/OD
70/F 71/F 71/F 71/M
History/Reason for Laser Surgery
Time From CE-IOL to Laser Surgery (Mo)
UCVA
120 36 15 7 11 216
20/60 !20/400 20/200 !20/400 20/400 !20/400
2
!20/400
2 51 51 15
20/400 20/400 20/50 20/25
High myopia prior to CE-IOL; residual myopia after CE-IOL Myopia Myopia; vitreous loss during CE; AC IOL placed Myopia High myopia and astigmatism after one IOL exchange; h/o retinal detachment before CE-IOL. S/p orbital decompression for Grave’s disease; high myopia prior to CE-IOL; residual myopia and anisometropia and ocular surface drying Myopia Myopia Myopia One LASIK procedure before CE-IOL; monocular diplopia and astigmatism after CE-IOL.
AC IOL Z anterior chamber intraocular lens implant; BSCVA Z best spectacle-corrected visual acuity; CE Z cataract extraction; CE-IOL Z cataract extraction with intraocular lens implantation; LASIK Z laser in situ keratomileusis; OD Z right eye; OS Z left eye; PRK Z photorefractive keratectomy; S/p Z status post; UCVA Z uncorrected visual acuity
The mean attempted spherical equivalent was ÿ2.92 G 3.03 D for the LASIK patients and ÿ3.73 G 2.33 D for the PRK patients, respectively. This difference was not statistically significant (P Z.54, Wilcoxon test). Mean length of follow-up after laser refractive surgery was 12.2 months (range 1 to 38 months). At last follow-up, the range of spherical refraction was ÿ3.00 to C1.50 D, and the highest cylindrical refraction was C2.00 D. The mean spherical refraction was ÿ1.11 D; the mean cylindrical refraction was C0.48 D. The mean manifest spherical equivalent at last follow-up was ÿ0.88 G 1.43 D (range ÿ2.75 to C2.13 D; Table 2). The changes in mean manifest
spherical equivalent were statistically significant between paired preoperative and postoperative values (P Z.03, Wilcoxon test). Postoperatively, older patients became more hyperopic than intended (r Z 0.528, P Z .05; Figure 1). However, there was no over all difference between achieved and targeted manifest spherical equivalents (P Z.34, Wilcoxon test). In addition, there was no correlation between length of follow-up and attainment of intended correction (r Z ÿ0.38, P Z .12). Likewise, there was no correlation between time from cataract extraction with IOL implantation to excimer laser surgery and attainment of intended correction (r Z 0.069, P Z .36). Because 2 PRK patients,
Table 2. Comparison of preoperative and postoperative values.
Mean G SD (Range) Parameter Spherical refraction (D) Cylindrical refraction (D) Manifest refractive spherical equivalent (D) Attempted spherical equivalent (D) Attempted spherical correction for LASIK patients (D) Cylindrical refraction for LASIK patients (D) (Attempted) spherical equivalent for LASIK patients (D) Attempted spherical correction for PRK patients (D) Cylindrical refraction for PRK patients (D) (Attempted) spherical equivalent for PRK patients (D) UCVA BSCVA
Preoperative
Postoperative
ÿ4.75 G 2.94 (ÿ9.00 to plano) C1.98 G 1.80 (plano to C5.50) ÿ3.76 G 2.50 (ÿ6.50 to C0.75) ÿ3.28 G 2.64 (ÿ6.50 to C0.75) ÿ4.38 G 3.69 (ÿ9.00 to plano) C2.92 G 1.90 (C1.00 to C5.50) ÿ2.92 G 3.03 (ÿ6.50 to C0.75) ÿ4.15 G 2.72 (ÿ8.50 to ÿ2.00) C0.85 G 0.80 (plano to C2.00) ÿ3.73 G 2.33 (ÿ7.50 to ÿ1.88) 20/400 20/25
ÿ1.11 G 1.33 (ÿ3.00 to C1.50) C0.48 G 0.65 (plano to C 2.00) ÿ0.88 G 1.43 (ÿ2.75 to C2.13)
C0.54 G 0.78 (plano to C2.00) ÿ1.23 G 1.20 (ÿ2.75 to plano) C0.40 G 0.52 (plano to C1.25) ÿ0.45 G 1.70 (ÿ2.63 G C2.13) 20/30 20/25
BSCVA Z best spectacle-corrected visual acuity; LASIK Z laser in situ keratomileusis; PRK Z photorefractive keratectomy; UCVA Z uncorrected visual acuity
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Table 1 (cont.)
Refraction Before Laser Refractive Surgery and BSCVA ÿ2.00 C0.25 160 ÿ5.00 C1.25 035 ÿ4.00 sph ÿ8.50 C2.00 065 ÿ4.75 C0.75 175 ÿ7.00 C5.50 015 ÿ9.00 C5.00 180 ÿ4.25 C2.75 025 ÿ6.75 C1.75 175 ÿ1.00 C1.00 180 Plano C1.50 125
20/20 20/30 20/25 20/25 20/20 20/50 20/30 20/20 20/40 20/20 20/20
Attempted Monovision Correction
Laser Refractive Procedure
Length of Follow-up (Mo)
UCVA at Last Follow-up
No No Yes ÿ2.00 sph No Yes ÿ1.50 sph No No Yes ÿ1.75 sph No No No
PRK PRK PRK PRK PRK LASIK LASIK LASIK LASIK LASIK LASIK
3 3 2 27 13 38 3 24 1 1 19
20/30 20/60 20/30 20/30 20/100 20/30 20/50 20/100 20/30 20/30 20/30
Achieved minus Intended Refraction, Diopters
as opposed to 1 LASIK patient, requested undercorrection for monovision, one would expect the postoperative results for PRK patients to be more myopic, but the postoperative mean spherical equivalent was more myopic in the LASIK group (Table 2). However, the difference between the 2 groups was not statistically different (P Z.64, Wilcoxon test). There was no difference in postoperative spherical or cylindrical refraction between the PRK and LASIK groups using the same test (P Z.41 and P Z 1.0, respectively, Wilcoxon test). All patients experienced improvement in UCVA. Before laser refractive surgery, 7 of 11 eyes (64%) had
2
1
Refraction and BSCVA at Last Follow-up ÿ0.25 sph C1.50 C1.25 068 ÿ0.75 sph ÿ1.00 C0.50 180 ÿ2.75 C0.25 180 ÿ1.75 C0.75 065 ÿ3.00 C0.50 078 ÿ2.50 sph ÿ1.00 C2.00 180 Plano ÿ0.75 sph
20/20 20/20 20/25 20/30 20/20 20/30 20/30 20/20 20/30 20/30 20/20
UCVA of 20/400 or worse and 1 eye (9%) had UCVA better than 20/40. After laser refractive surgery, the best UCVA was 20/30. Seven of 11 eyes (64%) had postoperative UCVA of 20/30 and 2 (18%) had UCVA of 20/50 or 20/60. The 2 eyes with postoperative UCVA of 20/100 were in patients who had requested postoperative monovision and were satisfied with their postoperative UCVA at distance and near. No eye had postoperative UCVA worse than 20/100. Except for 3 patients, all had unchanged BSCVA. Two patients (cases 2 and 6) gained 2 lines and 1 line of BSCVA, respectively. One patient (case 4) lost a line of BSCVA and had an epiretinal membrane diagnosed. No other patient had postoperative ocular pathology. No patient lost more than 1 line of BSCVA. All patients expressed subjective improvement in their quality of vision after laser surgery and described reduced dependence on spectacles. There were no intraoperative or postoperative complications.
0
DISCUSSION −1
−2 PRK LASIK 70
72
74
76
78
80
Age, years Figure 1. Positive correlation between age and the difference between achieved and intended refractions (r Z 0.528, P Z .05). Photorefractive keratectomy patients tended to be older than LASIK patients by an average of 6.3 years.
Laser refractive surgery to correct residual refractive error after primary laser procedures as well as after penetrating keratoplasty has been described,6–8 but, in contrast, there are few reports describing laser refractive surgery after cataract extraction with IOL implantation.9–14 In this series of patients, approximately 3 decades older than the average laser refractive surgery patient and with varying degrees of ametropia (though with a predominance of myopic patients), we show that laser refractive surgery can be a safe, effective, and predictable alternative to intraocular procedures. However, longer follow-up as well as comparison of UCVA in such patients in contrast to laser refractive surgery patients in general are needed.
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Although cataract extraction with IOL implantation is a highly successful refractive procedure, ‘‘surprises’’ in postoperative residual refractive error can still occur. In a recent survey of reasons for explantation of or secondary intervention after a foldable IOL implantation, dislocation/ decentration (which can lead to ametropia) was the most common followed by incorrect lens power.15 Incorrect lens power was the most common reason for explantation of 1-piece hydrophobic acrylic IOLs with haptics and the 3-piece hydrophobic acrylic IOL,15 which was explanted in 10 of 11 eyes in our series. Established surgical options include a piggyback IOL or a lens exchange. However, there are risks associated with these intraocular procedures, including corneal edema, intraocular inflammation, increased IOP, vitreous loss, cystoid macular edema, and retinal detachment (RD). Because uneventful phacoemulsification with IOL implantation is associated with corneal endothelial cell loss and with increased rate of cell loss compared with the rate in healthy unoperated eyes and because endothelial cell count decreases with increasing age,16–19 one can deduce that additional intraocular procedures in elderly patients increase the risk for corneal decompensation. Moreover, an IOL exchange can induce damage to angle structures and potentially increase the risk for glaucoma, the prevalence of which increases with age, such that the prevalence of glaucoma in the eighth decade is 2.89%.20 Retinal detachment is another risk of cataract surgery and IOL exchange, although the risk for RD is increased in younger patients who have cataract extraction with IOL implantation.21–23 Two patients (cases 1 and 7) had axial myopia before cataract surgery, a known risk factor for RD.21,22 The risk for RD also increases when intraocular complications occur during cataract surgery.22 One patient (case 4) had had cataract extraction with IOL implantation complicated by vitreous loss and prolonged postoperative corneal edema. Another patient (case 6) had already had 3 intraocular procedures (RD repair, cataract extraction with IOL implantation, and IOL exchange) at the time she desired correction of her ametropia. In such patients who cannot or will not use a contact lens or spectacles after cataract extraction with IOL implantation, the risks associated with further intraocular surgery might justify a less invasive procedure, such as laser refractive surgery. The results in this patient series suggest that laser refractive surgery for postcataract surgery ametropia is safe, effective, and predictable, although the length of follow-up in some patients was limited. Except for BSCVA, which (with the exception of case 4, an epiretinal membrane) remained unchanged or improved, all other parameters improved. Mean spherical and cylindrical refractions were reduced after laser refractive surgery, as were their respective standard deviations and ranges. Another measure of the predictability of laser refractive surgery in these
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patients was the lack of difference between targeted and achieved refraction. The fact that 1 PRK patient became hyperopic most likely explains the larger standard deviation and less myopic mean postoperative spherical refraction and spherical equivalent in PRK patients compared with LASIK patients (Table 2). However, conclusions should not be drawn from a comparison of LASIK and PRK in overall spherical equivalent, spherical refraction, and cylindrical refraction because small sample sizes limit statistical power. In addition, although attainment of intended correction was not correlated with length of follow-up and patient satisfaction after excimer laser surgery was very high, longer follow-up of a larger group of patients would be important to determine the efficacy, safety, and predictability of this technique. Although the postoperative UCVA in these patients improved in every case, the overall postoperative UCVA was not as good as that reported from laser refractive surgery patients in general. One reason may be age; on average, these patients were more than 3 decades older than the average refractive surgery patient24,25 or even the refractive enhancement patient.26 Several reports document an association between age and results of laser refractive surgery, including decreased efficiency of spherical ablation,27 an increased rate of enhancement procedures (which would imply less predictable refractive results from the original surgery),26,28 possibly diminished stromal wound healing,29 potential interactions between the aging eye, changes in corneal optics induced by PRK,29 and an increased incidence of corneal abrasions.30–32 One of these studies found a hyperopic shift in older patients who had LASIK for myopic astigmatism,27 as we found in our series, although our series included PRK patients who also happened to be older than the LASIK patients by an average of 6.3 years. Other factors besides age might have affected the outcomes in this patient series. Mechanical distortion of the eye from previous cataract extraction with IOL implantation (eg, stability of a nonsutured clear corneal wound or the IOL) may occur during buildup of suction in LASIK and thus alter postoperative results12; however, such distortion cannot explain results after PRK. Another possibility is that corneal wound healing after laser surgery is somehow different in patients who have had prior cataract extraction with IOL implantation. Subclinical corneal edema might be expected to decrease the efficacy of any excimer laser treatment, and we cannot rule out this possibility in our patient series. However, it is unlikely that cataract extraction with IOL implantation itself affects the outcomes of laser surgery because the procedures in this patient series were performed before custom ablation and the only parameters programmed into the laser treatment, refraction, and keratometry readings are not expected to change after cataract extraction with IOL implantation. Last,
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perhaps ‘‘overall UCVA’’ may lack significance in a series of patients with such heterogeneous preoperative characteristics. There have been few reports describing laser refractive surgery after cataract extraction with IOL implantation.9–14 In 1 report, PRK was the sole treatment offered to 24 patients (31 eyes) with ametropia after cataract extraction with IOL implantation (age range 27 to 65 years; mean 47 years), and the authors report that UCVA, BSCVA, mean spherical equivalent, astigmatism, and anisometropia improved as early as 1 week after surgery.9 The authors of another published report conclude that at 6 months of follow-up, LASIK was effective and safe for correction of astigmatism after extracapsular cataract extraction with posterior chamber IOL implantation. Grade 2 diffuse lamellar keratitis (DLK) occurred in 3 of 20 (15%) eyes and resolved with topical and systemic steroids.10 The reason for the high incidence of DLK in these patients was unknown. Diffuse lamellar keratitis did not occur in any of our patients. Laser in situ keratomileusis was studied in close to 300 patients who were pseudophakic or with phakic IOLs (bioptics); refraction was stable for 4 years, and the procedure produced predictable refractive results.13 A small body of literature exists on RD in myopic eyes after LASIK33,34; in the largest series of such patients, the reported prevalence of RD was 0.08%.33 However, on average, these LASIK patients were young, and the average refraction of those who experienced an RD was ÿ8.75 D, meaning these patients were already at increased risk for a detachment regardless of LASIK. Whether the risk for RD should be included in the informed consent for LASIK in patients with ametropia after cataract extraction with IOL implantation remains unknown.33–35 Weaknesses of the current study include its retrospective nature, the varying lengths of follow-up, and lack of randomization for laser vision correction procedures. Length of follow-up was limited by patients who were lost to follow-up. This problem was most significant in 2 patients (cases 2 and 7) who had an unexplained refractive error after laser surgery and whose length of follow-up was only 3 months. However, the patient in case 7 also had ocular surface disease, which might have confounded attempts at refraction. Regarding lack of randomization, some of the patients might have done well with either LASIK or PRK. In this small series of patients with varying lengths of follow-up, we show that laser refractive surgery can be a safe and effective (off-label) surgical method to correct ametropia after cataract extraction with IOL implantation in an elderly population. This modality may be especially useful in patients who have had complicated previous intraocular surgery and in patients at increased risk for complications from further intraocular surgery. Further studies
with custom ablation, longer follow-up, and randomization of patients would be helpful. Because an IOL would be expected to alter wavefront data, improved software to capture wavefront data from pseudophakic patients will likely need to be developed. An improved understanding of how age affects corneal wound-healing changes will also be crucial.
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