Laser in situ keratomileusis outcomes following radial keratotomy, astigmatic keratotomy, photorefractive keratectomy, and penetrating keratoplasty

Laser in situ keratomileusis outcomes following radial keratotomy, astigmatic keratotomy, photorefractive keratectomy, and penetrating keratoplasty

J CATARACT REFRACT SURG - VOL 31, NOVEMBER 2005 Laser in situ keratomileusis outcomes following radial keratotomy, astigmatic keratotomy, photorefrac...

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J CATARACT REFRACT SURG - VOL 31, NOVEMBER 2005

Laser in situ keratomileusis outcomes following radial keratotomy, astigmatic keratotomy, photorefractive keratectomy, and penetrating keratoplasty Natalie A. Afshari, MD, Frank Schirra, MD, Peter A. Rapoza, MD, Jonathan H. Talamo, MD, Klaus Ludwig, MD, Ron A. Adelman, MD, Kenneth R. Kenyon, MD

PURPOSE: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) to enhance refractive status following other corneal surgical procedures. SETTING: Clinical office-based practice. METHODS: Seventy-one eyes of 57 patients had LASIK for refractive errors following radial keratotomy (n Z 22), astigmatic keratotomy (n Z 13), photorefractive keratectomy (n Z 18), and penetrating keratoplasty (n Z 18). A Moria LSK-1 microkeratome was used with a Visx S2 or Wavelight Allegretto excimer laser. Data were acquired by retrospective chart review of all appropriately qualified patients. RESULTS: The mean preoperative manifest refractive spherical equivalent (MRSE) was ÿ3.93 diopters (D) G 2.83 (SD) in myopic eyes and C1.43 G 1.79 D in hyperopic eyes. The mean time from the initial corneal surgical procedure to LASIK was 65.0 months. The mean post-LASIK follow-up was 9.40 months (range 1 to 42 months). Postoperatively, the mean MRSE was ÿ0.85 G 1.42 D in myopic eyes (P<.0001) and ÿ0.16 G 1.09 D in hyperopic eyes (P<.0001). Enhancement by LASIK was required in 14% of eyes. CONCLUSION: In eyes that have had a variety of previous corneal surgeries, LASIK offers a safe and predictable method for enhancing refractive results. J Cataract Refract Surg 2005; 31:2093–2100 Q 2005 ASCRS and ESCRS

Patient satisfaction is the ultimate goal of any refractive surgical procedure. Thus, patients often require enhancement following an initial procedure to reach their targeted visual outcome. The enhancement rate has been reported to be about 30% in patients who have had radial keratotomy (RK).1,2 The Prospective Evaluation of Radial Keratotomy study3 reports that 25% to 30% of patients who were treated with RK were hyperopic 10 years after treatment and as many as 43% of post-RK patients had a hyperopic shift of 1.00 diopter (D) or more. Undercorrection and regression following myopic photorefractive keratectomy (PRK) are the most common problems of this procedure and are dependent on the primary magnitude of the refractive error.4,5 Undercorrection of more than 1.00 D has been reported in only 2.7% of eyes with myopia up to 6.00 D but in 42.8% of eyes with myopia greater than 10.00 D.6 Q 2005 ASCRS and ESCRS Published by Elsevier Inc.

Penetrating keratoplasty (PKP) is the most commonly performed transplantation in the United States, with more than 35 000 procedures performed each year.7 Multiple operative variables, specifically corneal sutures, exert a profound effect on the sphericity of the transplanted cornea. Residual refractive errors, including high astigmatism averaging 4.0 to 5.0 D, are commonly seen following PKP.8 Hence, 20% of patients who have had PKP are reported to require refractive surgery.9 The association of potentially severe haze and regression with PRK following RK or PKP has led to increased interest in laser in situ keratomileusis (LASIK) as the preferred surgical method for correction of post–corneal surgery refractive errors. Because LASIK offers refractive ablation under a hinged flap, which accelerates visual recovery, lessens postoperative pain, and reduces wound remodeling, haze, and regression, we investigated whether the usual benefits of LASIK could be safely and predictably 0886-3350/05/$-see front matter doi:10.1016/j.jcrs.2005.08.025

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applied in eyes that had been treated with other corneal surgeries.

RK (n=13)

AK (n=6)

PRK (n=12)

PKP (n=11)

120

PATIENTS AND METHODS A retrospective chart review of all patients who had LASIK following RK, astigmatic keratotomy (AK), PRK, or PKP was performed. All surgeries were performed by the authors and were done with the Moria LSK-1 microkeratome and the Visx S2 or Wavelight Allegretto excimer laser. Data collected included date of initial surgery, diagnosis before LASIK, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and manifest refractive spherical equivalent (MRSE). Follow-up was 1, 3, 6, and 12 months following LASIK. At each follow-up visit, UCVA, BCVA, and MRSE were determined. Statistical analysis was performed using Microsoft Excel and SAS version 8.2. The Wilcoxon signed rank test was used to assess the significance of the median difference in preoperative and postoperative MRSEs. The means are reported with standard deviations; where appropriate, P values are given.

RESULTS

Seventy-one eyes of 57 patients had LASIK for refractive errors following RK (n Z 22), AK (n Z 13), PRK (n Z 18), and PKP (n Z 18). The mean preoperative MRSE was ÿ3.93 D G 2.83 (SD) in myopic eyes and C1.43 G 1.79 D in hyperopic eyes. The mean time from the initial surgical procedure to LASIK was 65.0 months. For the entire cohort of patients, the mean follow-up was 9.40 months (range 1 to 42 months). Forty-two eyes completed at least 3 months of follow-up post-LASIK (Figure 1). The mean postoperative MRSE was ÿ0.85 G 1.42 D in myopic eyes and ÿ0.16 G 1.09 D in hyperopic eyes. Fourteen percent of the operated eyes had LASIK enhancement. The refractive results and the preoperative patient characteristics in each group are shown in Tables 1 and 2, respectively.

Accepted for publication March 11, 2005. From Duke University Eye Center (Afshari), Duke University Medical Center, Durham, North Carolina, Schepens Eye Research Institute (Schirra, Kenyon), Harvard Medical School (Schirra, Rapoza, Talamo, Kenyon) and Cornea Consultants and Laser Eye Consultants of Boston (Rapoza, Talamo, Kenyon), Boston, Massachusetts, and Yale University Eye Center (Adelman), New Haven, Connecticut, USA, and Augenklinik LMU (Ludwig), Munich, Germany. Supported by a Career Development Award from Research to Prevent Blindness (Dr. Afshari). No author has a financial or proprietary interest in any material or method mentioned. Reprint requests to Natalie A. Afshari, MD, Duke University Eye Center, Duke University Medical Center Box 3802, Durham, North Carolina 27705, USA. E-mail: [email protected].

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% of eyes

100 80 60 40 20 0

20/20 or better

20/25 or better

20/30 or better

20/40 or better

20/50 or better

20/60 or 20/100 or better better

Figure 1. Patients’ UCVA 3 months after LASIK.

Radial Keratotomy Group

The mean preoperative MRSE in myopic and hyperopic RK eyes was ÿ2.79 G 1.13 D (n Z 3) and C1.88 G 1.45 D (n Z 19), respectively. The mean time from RK to LASIK was 72.48 months. The mean postLASIK follow-up was 9.37 months (range 1 to 30 months). At 3 months (n Z 13), the UCVA was 20/20 or better in 4 eyes (31%), 20/30 or better in 8 eyes (62%), 20/40 or better in 9 eyes (69%), and 20/100 or better in all 13 eyes (100%) (Figure 1). The percentage of eyes in which the UCVA was 20/30 or better at 1, 3, 6, and 12 months is shown in Figure 2. One eye (6%) lost 2 lines of BCVA, 3 eyes (18%) lost 1 line, 4 eyes (24%) gained 1 line, and 1 eye (6%) gained 3 lines (Figure 3). One month after LASIK, the mean MRSE was C0.75 D in myopic eyes and ÿ0.53 G 0.98 D in hyperopic eyes. At the last follow-up, the mean MRSE was C0.25 G 0.35 D and ÿ0.33 G 1.32 D, respectively; 75% of eyes were within G1.00 D of emmetropia (Figure 4). In hyperopic eyes, there was a statistically significant improvement in the refractive error from preoperatively to 1 month and the last follow-up (P!.05). Two eyes (9%) required further LASIK enhancement. No case of infection or interstitial keratitis was encountered. One patient who had an enhancement procedure required uneventful mechanical debridement of 2 RK incisions after dehiscence and epithelialization. Astigmatic Keratotomy Group

The mean preoperative MRSE in myopic and hyperopic eyes was ÿ0.63 D (n Z 1) and C1.71 G 1.49 D (n Z 12), respectively. The mean time from AK to LASIK was 14.50 months. The mean post-LASIK follow-up was 5.39 months (range 1 to 12 months). At 3 months (n Z 6 eyes), the UCVA was 20/20 or better in 3 eyes (50%), 20/25 or better in 3 eyes (50%), 20/30 or better in 5 eyes (83%), and 20/100 or better in 6 eyes (100%) (Figure 1). The percentage of eyes in which UCVA was 20/30 or better

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Table 1. Laser in situ keratomileusis outcomes following RK, AK, PRK, and PKP.

Parameters Eyes per group, n Mean time from initial surgery to LASIK, months Follow-up range post-LASIK, day to months Mean follow-up post-LASIK, months Pre-LASIK mean MRSE (D) Myopic eyes Hyperopic eyes Pre-LASIK mean astigmatism (D) Pre-LASIK range of astigmatism (D) Post-LASIK mean MRSE at 1 month (D) Myopic eyes Hyperopic eyes Mean MRSE at final follow-up (D) Myopic eyes Hyperopic eyes LASIK enhancement, n (%) Percentage within G1.00 D of emmetropia Complications

RK

AK

PRK

PKP

22 72.48 1 to 30 9.37

13 14.50 1 to 12 5.39

18 41.40 1 to 37 12.0

18 116.5 1 to 42 9.67

ÿ2.79 G 1.13 C1.88 G 1.45 ÿ0.94 G 0.64 0.00 to ÿ2.00

ÿ0.63 C1.71 G 1.49 ÿ1.43 G 1.09 0.00 to ÿ3.75

ÿ2.10 G 1.46 C1.20 G 0.73 ÿ1.67 G 0.54 ÿ0.75 to ÿ2.5

ÿ5.86 G 2.74 ÿ0.60 G 3.24 ÿ5.65 G 2.49 ÿ2.25 to ÿ11.00

C0.75 ÿ0.53 G 0.98

ÿ0.13 G 0.88 ÿ0.13 G 0.55

C0.05 G 0.34 ÿ0.38 G 0.60

ÿ1.50 G 1.68 C0.22 G 1.13

C0.25 G 0.35 ÿ0.33 G 1.32 2 (9) 21 (75) 1 RK wound epithelialization

0.00 G 2.04 C0.03 G 0.64 1 (7.7) 13 (100) None

ÿ0.52 G 1.17 ÿ0.69 G 0.97 0 10 (81) None

ÿ1.23 G 1.50 C0.48 G 0.94 7 (39) 18 (70) 1 PKP wound dehiscence

AK Z astigmatic keratotomy; LASIK Z laser in situ keratomileusis; MRSE Z manifest refractive spherical equivalent; PKP Z penetrating keratoplasty; PRK Z photorefractive keratectomy; RK Z radial keratotomy

Table 2. Preoperative patient characteristics (N Z 71).

Procedure

n

(%)

Right eyes Left eyes RK Myopic eyes Hyperopic eyes AK Myopic eyes Hyperopic eyes PRK Myopic eyes Hyperopic eyes PKP Myopic eyes Hyperopic eyes

34 37 22 3 19 13 1 12 18 10 8 18 13 5

(48.0) (52.0) (31.0) (14.0) (86.0) (18.3) (8.0) (92.0) (25.4) (56.0) (44.0) (25.4) (72.0) (28.0)

AK Z astigmatic keratotomy; PKP Z penetrating keratoplasty; PRK Z photorefractive keratectomy; RK Z radial keratotomy

the improvement in mean MRSE from pre-LASIK to 1 month and the last follow-up was statistically significant (P!.05). One eye (7.7%) required LASIK enhancement, and there were no complications. Photorefractive Keratectomy Group

The mean preoperative MRSE in myopic eyes and hyperopic eyes was ÿ2.10 G 1.46 D (n Z 10) and C1.20 G 0.73 D (n Z 8), respectively. The mean time from PRK to LASIK was 41.40 months. The mean post-LASIK follow-up was 12.0 months (range 1 to 37 months). At 3 months (n Z 12 eyes), the UCVA was 20/20 or better in 7 eyes (58%), 20/25 or better in 9 eyes (75%), and 20/30 or better RK

AK

PRK

PKP

120 100

% Eyes

at all times postoperatively is shown in Figure 2. The change in BCVA is shown in Figure 3; no eye lost more than 2 lines of BCVA, 4 eyes (31%) lost 1 line, 3 eyes (23%) gained 1 line, and 1 eye (8%) gained 2 lines. At 1 month, the mean MRSE was ÿ0.13 G 0.88 D in myopic eyes and ÿ0.13 G 0.55 D in hyperopic eyes. At the last follow-up, the mean MRSE was 0.00 G 2.04 D and C0.03 G 0.64 D, respectively; 100% of eyes were within G1.00 D of emmetropia (Figure 5). In hyperopic eyes,

80 60 40 20 0

1 month

3 months

6 months

12 months

Figure 2. The percentage of eyes with a UCVA of 20/30 or better at all time points.

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% of Eyes

RK

90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

-4

-3

-2

AK

-1

PRK

0

in 12 eyes (100%) (Figure 1). The percentage of eyes in which UCVA was 20/30 or better at 1, 3, 6, and 12 months is shown in Figure 2. No eye lost more than 2 lines of BCVA; 1 eye (8%) lost 2 lines, 1 eye (8%) lost 1 line, and 1 eye (8%) gained 1 line (Figure 3). At 1 month, the mean MRSE was C0.05 G 0.34 D in myopic eyes and ÿ0.38 G 0.60 D in hyperopic eyes. At the last follow-up, the mean MRSE was ÿ0.52 G 1.17 and ÿ0.69 G 0.97 D, respectively; 81% of eyes were within G1.00 D of emmetropia (Figure 6). The improvement in mean MRSE from preLASIK to post-LASIK in myopic and hyperopic eyes was not statistically significant (PO.05). There were no complications such as anterior stromal haze or diffuse lamellar keratitis, and no LASIK enhancements were required.

PKP

1

2

Loss

3

4

Gain

Figure 3. Change in BCVA.

7

Penetrating Keratoplasty Group 6

Achieved (D)

5 4 3 2 1 0

0

1

2

3

4

5

6

7

Attempted (D)

The mean preoperative MRSE in myopic eyes (n Z 13) was ÿ5.86 G 2.74 D. In hyperopic eyes (n Z 5), it was ÿ0.60 G 3.24 D because 4 eyes had mixed astigmatism. The mean astigmatism before LASIK was ÿ5.65 G 2.49 D (range ÿ2.25 D toÿ11.00 D). The most common indications for PKP were keratoconus (n Z 11; 61%), astigmatism (n Z 6; 33%), and traumatic corneal scar (n Z 1; 6%) (Table 3). In all cases, suture removal was completed at least 6 months before LASIK. The mean time from PKP to LASIK was 116.5 months. The mean post-LASIK follow-up was 9.67 months (range 1 to 42 months). At 3 months (n Z 11), the UCVA was 20/20 or better in 1 eye (9%), 20/25 or better in 2 eyes (18%), 20/30 or better in 3 eyes (27%), 20/40 or better in 4 eyes (36%), 20/50 or better in 6 eyes (55%), 20/60 or better in 7 eyes (64%),

Figure 4. Attempted versus achieved refraction in the RK group (n Z 21); 75% of eyes were within G1.00 D of emmetropia at the last follow-up. 9 6

8 7

Achieved (D)

Achieved SE (D)

5 4 3 2

6 5 4 3 2

1 0

1 0

1

2

3

4

5

6

0

0

Figure 5. Attempted versus achieved refraction in the AK group (n Z 13); 100% of eyes were within G1.00 D of emmetropia at the last follow-up.

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2

4

6

8

Attempted (D)

Attempted SE (D)

Figure 6. Attempted versus achieved refraction in the PRK group (n Z 18); 81% of eyes were within G1.00 D of emmetropia at the last follow-up.

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significant improvement in MRSE compared with the preLASIK refraction in myopic eyes (P!.05) but not in hyperopic eyes. At the last follow-up, the mean astigmatism had decreased to ÿ1.94 G 1.43 D (range 0.00 D to 5.00 D). Seven patients (39%) had LASIK enhancement. No infection, interstitial keratitis, or flap displacement was encountered. However, 1 patient who had PKP for keratoconus 20 years earlier developed dehiscence of the keratoplasty wound that was evident on the first postoperative day and required repair with multiple 10-0 nylon sutures.

Achieved (D)

10

8

6

4

DISCUSSION

2

0

0

2

4

6

8

10

12

Attempted (D) Figure 7. Attempted versus achieved refraction in the PKP group (n Z 18); 70% of eyes were within G1.00 D of emmetropia at the last follow-up.

Table 3. Indications for original PKP.

Eyes Diagnosis

n

(%)

Keratoconus Astigmatism Traumatic corneal scar

11 6 1

(61) (33) (6)

PKP Z penetrating keratoplasty.

and 20/100 or better in 8 eyes (73%) (Figure 1). The percentage of eyes in which UCVA was 20/30 or better at 1, 3, 6, and 12 months is shown in Figure 2. One eye (6%) lost 2 lines of BCVA, 3 eyes (17%) lost 1 line, 5 eyes (28%) gained 1 line, 2 eyes (11%) gained 2 lines, and 3 eyes (17%) gained 3 lines (Figure 3). At 1 month, the mean MRSE was ÿ1.50 G 1.68 D in myopic eyes and C0.22 G 1.13 D in hyperopic eyes. At the final follow-up, mean MRSE ÿ1.23 G 1.56 D and C0.48 G 0.94 D, respectively; 70% of eyes were within G1.00 D of emmetropia (Figure 7). At 1 month and at the last follow-up, there was a statistically

The application of refractive surgery following various corneal surgical procedures such as RK, AK, PRK, or PKP is designed to optimize functional visual outcomes. The decision to perform refractive surgery following such procedures is determined by the objective visual result and the patient’s subjective satisfaction. Enhancement rates and final refractive results are dependent on the surgeon’s experience and nomogram predictability, as well as more subjective factors such as patient expectations. Because LASIK offers refractive ablation under a hinged corneal flap, it lessens postoperative pain and reduces wound remodeling, haze, and regression. The association of potentially severe haze and regression following PRK in eyes with prior RK, PRK, or PKP led to increased interest in LASIK as the preferred surgical means for refractive correction in these cases. However, because prophylactic use of mitomycin-C (MMC) after PRK now appears to prevent corneal haze safely and effectively, PRK with intraoperative topical MMC is increasingly applicable in these high-risk patients.10,11 Laser in situ keratomileusis after RK and AK has been debated. The results of various studies are summarized in Table 4. Our analysis of 22 eyes that had LASIK post-RK for correction of myopia or hyperopia found major improvement in the preoperative refractive error (from ÿ2.79 G 1.13 D to C0.25 G 0.35 D in myopic eyes and from C1.88 G 1.45 D to ÿ0.33 G 1.32 D in hyperopic eyes). The sole complication was 1 eye that had epithelialization of an RK incision following additional enhancement. In the current study, 100% of patients who had LASIK following AK improved to within G1.00 D of

Table 4. Complications at any time in postoperative course.

Eyes Procedure RK PKP

Complication

Intervention

n

(%)

Dehiscence and epithelialization of several RK incisions Dehiscence of PKP wound

Surgical debridement Repair with multiple 10-0 nylon sutures

1 1

(4.5) (5.5)

PKP Z penetrating keratoplasty; RK Z radial keratotomy

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Table 5A. Studies of LASIK outcomes following RK.

Study

Eyes (n) 24

Preop Error (D)

Postop Error (D)

14

ÿ3.48 G 3.52

ÿ0.04 G 0.87

Yong et al.25 Francesconi and coauthors26

16 47*

ÿ3.14 G 3.04 C3.40 G 1.60

C0.16 G 0.68 79% within G1.00 D of emmetropia

Agarwal et al.27 Clausse et al.28

10 80

ÿ6.05 G 1.98 C2.36 G 1.17

ÿ1.26 G 0.32 C0.62 G 0.611

Lipshitz et al.29 Attia et al.30

15 11 overcorrected, 9 undercorrected

C3.08 G 1.02 Group with post-RK overcorrection: C1.54 G 0.78 D (0.25 to 2.50 D); group with post RK undercorrection: ÿ2.66 G 2.09 D (ÿ0.75 to ÿ6.25) ÿ1.40 G 0.57 D (ÿ0.87 to ÿ2.50 D) (SE)

C0.16 G 0.73 91% had improvement or no change in BCVA

Forseto and coauthors

Shah and coauthors31

9

ÿ0.156 G 0.174

Comment Follow-up 12.64 G 5.02 mo Follow-up 8.3 mo 4 eyes lost 2 Snellen lines secondary to epithelial ingrowth, 8 eyes had intraoperative incision openings 2 eyes lost 1 line of VA 4 eyes had epithelial ingrowth, 2 eyes had stromal opacity, 2 eyes had epithelial defect No complications Follow-up 6 mo

Follow-up O13 mo

BCVA Z best corrected visual acuity; RK Z radial keratotomy; SE Z spherical equivalent; VA Z visual acuity *Patients

emmetropia. The refractive error improved from ÿ0.63 D preoperatively to 0.00 D postoperatively in myopic eyes and from C1.71 G 1.49 D preoperatively to C0.03 G 0.64 D postoperatively in hyperopic eyes (P!.05). There are several published reports of LASIK after ¨ zdamar and coauthors12 evaluated 45 eyes of 25 paPRK. O tients treated with LASIK for myopic regression 18.5 months after PRK. The mean spherical equivalent (SE) improved from ÿ5.96 G 3.06 D to ÿ0.67 G 0.77 D 6 months postoperatively. In our study, the mean refractive error in 18 eyes that had had LASIK after PRK improved from ÿ2.10 G 1.46 D to ÿ0.52 G 1.17 D (PO.05) in myopic eyes and from C1.20 G 0.73 D to ÿ0.69 G 0.97 D in hyperopic eyes (PO.05). There were no complications.

Previous studies of LASIK following PKP show varied results13–23 and are summarized in Tables 5A, 5B, and 5C. The recently reported large series by Hardten and coauthors23 demonstrates a reduction in mean SE from ÿ4.19 G 3.38 D preoperatively to ÿ0.61 G 1.81 D 2 years postoperatively, although with somewhat increased frequency of epithelial ingrowth and graft failure. Our findings are in agreement with these studies and reveal an improvement in the mean MRSE from ÿ5.86 G 2.74 D preoperatively to ÿ1.23 G 1.50 D postoperatively in myopic eyes (P!.05) and from ÿ0.60 G 3.24 D preoperatively to C0.48 G 0.94 D postoperatively in hyperopic eyes (PO.05). In summary, our study confirms that LASIK following other surgeries is not only feasible but can also be helpful

Table 5B. Studies of LASIK outcomes following PRK.

Study O¨zdamar and coauthors Agarwal et al.27 Lazaro et al.32

2098

12

Eyes (n)

Preop Error (D)

Postop Error (D)

45 10 36

1.66 G 1.26 ÿ3.38 G 1.30 0% of eyes within G0.5 D of emmetropia

0.77 G 0.93 ÿ0.55 G 0.40 77.7% of eyes within G0.5 D of emmetropia

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Comment Follow-up 6 mo Follow-up O12 mo

LASIK FOLLOWING OTHER CORNEAL SURGICAL PROCEDURES

Table 5C. Previous studies of LASIK outcomes following PKP.

Study Arenas and coauthors

Eyes (n) 13

Parisi and coauthors14

Donnenfeld et al.15

Koay and coauthors16

4 3

23

8

Malecha and coauthors17

20

Spadea and coauthors18

4

Kwitko and coauthors19

14

Hardten and coauthors23 Forseto and coauthors33

57

Nassralla and coauthors34

8

22

Rashad35

19

Webber and coauthors36

25

Preop Error (D) ÿ10.75 (SE) ÿ2.87 (astig) Case 1: C5.00 ÿ1.50  167 Case 2: C1.25 ÿ6.00  170 Case 3: ÿ7.00 ÿ1.25  60 ÿ7.58 G 4.42 (SE) 3.64 G 1.72 (astig)

Postop Error (D) ÿ2.37 (SE) ÿ3.50 (astig)* Case 1: C0.00 ÿ1.25  5 Case 2: C1.25 ÿ6.00  25 Case 3: C1.00 ÿ0.75  80 ÿ1.57 G 1.20 (SE) 1.29 G 1.04 (astig)

Comment Follow-up 7 mo (LASIK performed 1.7 to 9 years post-PKP) LASIK 2 years post-PKP

Results at 12 mo: no flap or PKP complications (LASIK was performed mean 44 mo post-PKP and 35.3 mo after suture removal) ÿ6.79 G 4.17 D (SE) ÿ0.64 G 1.92 D (SE) Follow-up 8.6 mo: no eyes lost lines of BCVA C4.24 G 2.81 D (sphere) Mean sphere reduced by 3.93 D Follow-up 5 mo 4.05 G 1.71 D (cylinder) (80.0%) and mean cylinder reduced by 2.83 D (69.9%) Case 1: ÿ11 ÿ4.5  85 Case 1: ÿ1 ÿ2.5  70 Follow-up 24, 18, 12, and Case 2: ÿ8 Case 2: ÿ0.5 12 mo, respectively Case 3: ÿ4.5 ÿ11  95 Case 3: ÿ0.5 ÿ3.5  100 Case 4: ÿ4.5 ÿ4  120 Case 4: C0.5 Myopia ÿ5.33 G 4.22 Myopia C0.19 G 1.71 Follow-up O1 yr: Hyperopia C5.04 G 3.32 Hyperopia C 0.42 G 0.46 49% retreatment, Astig 5.37 G 2.12 Astig 2.82 G 2.42 5 eyes lost 1 Snellen line of VA, 1 buttonhole flap, 2 eyes had epithelial ingrowth, 1 pseudophakic eye had RD ÿ4.19 G 3.38 D (SE) ÿ0.61 G 1.81 D (SE) Mean follow-up 21.4 G 14.2 mo 4.67 G 2.18 (astig) 1.94 G 1.35 D (astig) (range 3 to 60 mo) ÿ4.55 (SE) 0.67 (SE) Follow-up O6 mo 4.24 (astig) 1.79 (astig) (LASIK was performed mean 5.3 years post-PKP) ÿ4.50 D (range ÿ3.00 ÿ0.75 D (range ÿ1.50 UCVA improved by to ÿ7.25 D) (SE) to C0.50 D) (SE) 2 or more lines in all eyes; no eyes lost lines of BCVA, and 3 eyes (37.5%) gained lines of BCVA 3.50 D (range 1.50 1.25 D (range 0.75 to 5.00 D) (astig) to 2.00 D) (astig) 9.21 G 1.95 D (range 6.50 0.50 G 1.75 D (range 0.50 57.9% of eyes within G1.00 D to 14.50 D) (astig) to 1.75 D) (astig) of refractive astigmatism; no ÿ2.14 G 2.11 D (range ÿ7.00 C0.43 G 0.82 D (range ÿ1.00 eyes lost lines of BCVA to C1.25 D) (sphere) to C1.75 D) (sphere) ÿ5.20 D (SE) ÿ0.24 D (SE) Follow-up 1 mo (25 eyes); 8.67 D (astig) 2.48 D (astig) all eyes gained between 0 and 6 lines of BCVA

astig Z astigmatism; BCVA Z best corrected visual acuity; LASIK Z laser in situ keratomileusis; PKP Z penetrating keratoplasty; RD Z retinal detachment; RK Z radial keratotomy; SE Z spherical equivalent; UCVA Z uncorrected visual acuity; VA Z visual acuity *Note increase in astigmatism.

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in improving visual acuity and does not involve major complication risks. Laser in situ keratomileusis combines a high degree of patient convenience and comfort with a safe and predictable method for enhancing refractive results in eyes that have been treated with a variety of previous corneal surgeries. REFERENCES 1. Gayton JL, Van der Karr M, Sanders V. Radial keratotomy enhancements for residual myopia. J Refract Surg 1997; 13:374–381 2. Werblin TP, Stafford GM. The Casebeer system for predictable keratorefractive surgery; one-year evaluation of 205 consecutive eyes. Ophthalmology 1993; 100:1095–1102 3. Waring GO III, Lynn MJ, McDonnell PJ. Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study 10 years after surgery; the PERK Study Group. Arch Ophthalmol 1994; 112:1298–1308 4. Kim J-H, Sah WJ, Park CK, et al. Myopic regression after photorefractive keratectomy. Ophthalmic Surg Lasers 1996; 27(suppl):S435–S439 5. Vajpayee RB, McCarty CA, Aldred GF, Taylor HR. Undercorrection after excimer laser refractive surgery; the Excimer Laser Group. Am J Ophthalmol 1996; 122:801–807 6. Seiler T, Jean B. Photorefractive keratectomy as a second attempt to correct myopia after radial keratotomy. Refract Corneal Surg 1992; 8:211–214 7. Verdier DD. Penetrating keratoplasty. In: Krachmer JH, Mannis MJ, Holland EJ, eds, Cornea. St Louis, MD, Mosby, 1997; Vol 3:1581–1592 8. Reing CS, Speaker MG. Postkeratoplasty astigmatism. In: Krachmer JH, Mannis MJ, Holland EJ, eds, Cornea. St Louis, MO, Mosby, 1997; Vol 3: 1675–1685 9. Kirkness CM, Ficker LA, Steele ADMcG, Rice NSC. Refractive surgery for graft-induced astigmatism after penetrating keratoplasty for keratoconus. Ophthalmology 1991; 98:1786–1792 10. Majmudar PA, Forstot SL, Dennis RF, et al. Topical mitomycin-C for subepithelial fibrosis after refractive corneal surgery. Ophthalmology 2000; 107:89–94 11. Kim T, Pak JH, Lee SY, Tchah H. Mitomycin C-induced reduction of keratocytes and fibroblasts after photorefractive keratectomy. Invest Ophthalmol Vis Sci 2004; 45:2978–2984 12. O¨zdamar A, xS ener B, Aras C, Aktunc¸ R. Laser in situ keratomileusis after photorefractive keratectomy for myopic regression. J Cataract Refract Surg 1998; 24:1208–1211 13. Arenas E, Maglione A. Laser in situ keratomileusis for astigmatism and myopia after penetrating keratoplasty. J Refract Surg 1997; 13:27–32 14. Parisi A, Salchow DJ, Zirm ME, Stieldorf C. Laser in situ keratomileusis after automated lamellar keratoplasty and penetrating keratoplasty. J Cataract Refract Surg 1997; 23:1114–1118 15. Donnenfeld ED, Kornstein HS, Amin A, et al. Laser in situ keratomileusis for correction of myopia and astigmatism after penetrating keratoplasty. Ophthalmology 1999; 106:1966–1974; discussion by JH Talamo, 1974–1975 16. Koay PYP, McGhee CNH, Weed KH, Craig JP. Laser in situ keratomileusis for ametropia after penetrating keratoplasty. J Refract Surg 2000; 16:140–147

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17. Malecha MA, Holland EJ. Correction of myopia and astigmatism after penetrating keratoplasty with laser in situ keratomileusis. Cornea 2002; 21:564–569 18. Spadea L, Mosca L, Balestrazzi E. Effectiveness of LASIK to correct refractive error after penetrating keratoplasty. Ophthalmic Surg Lasers 2000; 31:111–120 19. Kwitko S, Marinho DR, Ramos Filho S. Laser in situ keratomileusis after penetrating keratoplasty. J Cataract Refract Surg 2001; 27:374–379 20. Vajpayee RB, Sharma N, Sinha R, et al. Laser in-situ keratomileusis after penetrating keratoplasty. Surv Ophthalmol 2003; 48:503–514 21. Busin M, Zambianchi L, Garzione F, et al. Two-stage laser in situ keratomileusis to correct refractive errors after penetrating keratoplasty. J Refract Surg 2003; 19:301–308 22. Lee GA, Pe´rez-Santonja JJ, Maloof A, et al. Effects of lamellar keratotomy on postkeratoplasty astigmatism. Br J Ophthalmol 2003; 87: 432–435 23. Hardten DR, Chittcharus A, Lindstrom RL. Long term analysis of LASIK for the correction of refractive errors after penetrating keratoplasty. Cornea 2004; 23:479–489 24. Forseto AS, Nose´ RAM, Francesconi CM, Nose´ W. Laser in situ keratomileusis for undercorrection after radial keratotomy. J Refract Surg 1999; 15:424–428 25. Yong L, Chen G, Li W, et al. Laser in situ keratomileusis enhancement after radial keratotomy. J Refract Surg 2000; 16:187–190 26. Francesconi CM, Nose´ RAM, Nose´ W. Hyperopic laser-assisted in situ keratomileusis for radial keratotomy-induced hyperopia. Ophthalmology 2002; 109:602–605 27. Agarwal A, Agarwal A, Agarwal T, et al. Laser in situ keratomileusis for residual myopia after radial keratotomy and photorefractive keratectomy. J Cataract Refract Surg 2001; 27:901–906 28. Clausse MA, Boutros G, Khanjian G, et al. A retrospective study of laser in situ keratomileusis after radial keratotomy. J Refract Surg 2001; 17: S200–S2001 29. Lipshitz I, Man O, Shemesh G, et al. Laser in situ keratomileusis to correct hyperopic shift after radial keratotomy. J Cataract Refract Surg 2001; 27:273–276 30. Attia WH, Alio´ JL, Artola A, et al. Laser in situ keratomileusis for undercorrection and overcorrection after radial keratotomy. J Cataract Refract Surg 2001; 27:267–272 31. Shah SB, Lingua RW, Kim CH, Peters NT. Laser in situ keratomileusis to correct residual myopia and astigmatism after radial keratotomy. J Cataract Refract Surg 2000; 26:1152–1157 32. Lazaro C, Castillo A, Hernandez-Matamoros JL, et al. Laser in situ keratomileusis enhancement after photorefractive keratectomy. Ophthalmology 2001; 108:1423–1429; discussion by SN Rao, PA Majmudar, 1429 33. Forseto AS, Francesconi CM, Nose´ RAM, Nose´ W. Laser in situ keratomileusis to correct refractive errors after keratoplasty. J Cataract Refract Surg 1999; 25:479–485 34. Nassaralla BR, Nassaralla JJ. Laser in situ keratomileusis after penetrating keratoplasty. J Refract Surg 2000; 16:431–437 35. Rashad KM. Laser in situ keratomileusis for correction of high astigmatism after penetrating keratoplasty. J Refract Surg 2000; 16:701–710 36. Webber SK, Lawless MA, Sutton GL, Rogers CM. LASIK for post penetrating keratoplasty astigmatism and myopia. Br J Ophthalmol 1999; 83:1013–1018

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