Purpose
To report the long-term results of combined same-day intrastromal corneal ring segment placement and corneal collagen cross-linking (CXL) for postoperative laser in situ keratomileusis (LASIK) ectasia.
Design
Retrospective, interventional case series.
Method
This retrospective, interventional cases series was performed in Turkiye Hospital Eye Clinic and the Department of Ophthalmology, Fatih University Medical Faculty Hospital, Istanbul, Turkey. Sixteen eyes of 14 patients with postoperative ectasia after LASIK were enrolled. All consecutive patients were treated with femtosecond laser-assisted intrastromal corneal ring segment implantation and followed by same-day corneal collagen cross-linking for ectasia occurring after LASIK. Main outcome measures included uncorrected distance visual acuity, corrected distance visual acuity, spherical and cylindrical refraction, and simulated keratometry values.
Results
The mean age ± standard deviation of the 10 women and 4 men was 33.0 ± 6.5 years (range, 23 to 44 years), and the mean follow-up was 43 months (range, 36 to 62 months). The uncorrected distance visual acuity improved significantly from 1.18 ± 0.42 logarithm of the minimal angle of resolution (logMAR) units to 0.44 ± 0.22 logMAR ( P < .001), and the corrected distance visual acuity improved significantly from 0.46 ± 0.26 logMAR to 0.21 ± 0.14 logMAR ( P < .001). The mean spherical and cylindrical refraction decreased significantly ( P < .001 for both). The maximum keratometry value decreased from baseline by 49.3 ± 4.9 diopters (D) to 43.9 ± 2.8 D at the last visit, and the minimum keratometry value decreased from 44.3 ± 4.7 D to 41.5 ± 3.5 D ( P < .001 for both). No serious complications were shown during follow-up.
Conclusions
Implantation of intrastromal corneal ring segment implantation combined with same-day corneal collagen cross-linking was a safe and effective treatment for ectasia occurring after LASIK. It also significantly improved the visual acuity, refraction, and keratometry values.
The treatment of ectasia occurring after laser in situ keratomileusis (LASIK) remains a therapeutic challenge for refractive surgeons. At present, several treatment options, including rigid gas-permeable contact lenses, corneal collagen cross-linking (CXL), topography-guided photorefractive keratectomy with simultaneous CXL, intrastromal corneal ring segment (ICRS) implantation, and corneal transplantation, have been described. However, there is still a lack of consensus regarding the best indication for each technique.
Although the main goal of treatment of ectasia occurring after LASIK is to arrest the progression of the disease, from a patient’s perspective, the regaining of visual quality is very important. CXL was introduced as a new treatment method to arrest the ectasia occurring after LASIK. Previous studies also have reported improvements in visual acuity and keratometry values after CXL in patients with ectasia occurring after LASIK. However in some cases, satisfactory results cannot be obtained with CXL only treatment, especially in advanced stages of the disease.
Intrastromal corneal ring segments can be used in combination with CXL for corneal ectatic disorders. This improves the refractive error and visual acuity and decreases the possibility of continued progression of the ectasia. This study evaluated the outcomes of combined same-day ICRS and CXL treatment for ectasia occurring after LASIK with a mean follow-up of 43 months.
Methods
Study Design and Subjects
The study was approved by the local institutional review board and adhered to the tenets of the Declaration of Helsinki. All patients provided written informed consent. This was a retrospective study of all consecutive patients treated with combined same-day ICRS implantation and CXL for iatrogenic corneal ectasia occurring after LASIK at the Turkiye Hospital Eye Clinic and the Department of Ophthalmology, Fatih University Medical Faculty Hospital, Istanbul, Turkey, between 2006 and 2010.
A diagnosis of corneal ectasia was made when patients demonstrated progressive central or inferior corneal steepening, an increase in myopia, an increase in astigmatism, loss of uncorrected distance visual acuity (UDVA), and often loss of corrected distance visual acuity (CDVA). Exclusion criteria included patients with a history of corneal surgery (except LASIK), corneal pachymetry less than 400 μm, maximum keratometry value (K max ) higher than 60 diopters (D), central corneal opacity, and pregnancy.
Examination and Study Measurements
All patients underwent a comprehensive ophthalmologic examination including Snellen and logMAR visual acuity assessment, manifest refraction (sphere and cylinder), slit-lamp biomicroscopy, Goldmann tonometry, and fundus evaluation. All patients also underwent central corneal thickness measurement by ultrasonic pachymetry (Tomey AL-3000; Tomey Corp., Nagoya, Japan) and corneal topography measurement (Orbscan II, Bausch & Lomb, Orbtek, Inc.; Salt Lake City ,Utah, USA).
Surgical Procedure
Intrastromal corneal ring segment (KeraRing; Mediphacos, Belo Horizonte, Brazil) implantation was performed in an operating room under sterile conditions using topical proparacaine 0.5% (Alcaine; Alcon Laboratories, Inc, Fort Worth, Texas, USA) by 2 surgeons (H.C. and A.Y.). The Purkinje reflex was chosen as the central point and was marked under a biomicroscopy (VISX S4; Advanced Medical Optics, Inc.; Santa Ana, California, USA). During surgery, corneal thickness was measured along the ring location markings using ultrasonic pachymetry (Tomey AL-3000). Tunnel depth was set at 80% of the thinnest corneal thickness on the tunnel location. The arc length and thickness were chosen according to the manufacturer’s nomogram. In this nomogram, the segment distribution and thickness were selected based on the area of ectasia and spherical equivalent value. To define the distribution of the ectasia, the cornea was divided in half using the steepest meridian. A 30-kHz femtosecond laser (IntraLase; Advanced Medical Optics, Inc) was used to create the ring channels. The channel’s inner diameter was set to 4.8 mm and the outer diameter was set to 5.6 mm. Each of the ring’s energy for channel creation and the energy for the entry cut was 1.30 mJ; this was completed in approximately 15 seconds. The entry incision had a length of 1 mm in all cases and was placed on the steepest corneal topographic axis. The ICRS was implanted immediately after the channel was created. After ring implantation, the CXL procedure was performed according to the Dresden protocol by the same surgeons (A.Y. and H.C.) on the same day. The epithelium was debrided mechanically with a Desmarres blade over an 8-mm diameter. The cornea was saturated with a photosensitizing solution of riboflavin 0.1% with 20% dextran T500 (Ricrolin; SOOFT, Montegiorgio, Italy) by corneal instillation at a rate of 1 drop per 3 minutes for 30 minutes. The presence of riboflavin in the anterior chamber, demonstrating the complete impregnation of the cornea, was observed using the slit lamp of the operative microscope, visible as a yellowish flare. The corneal thickness was measured before surgery, after epithelial removal, and during ultraviolet A irradiation. If the cornea was less than 400 μm, hypotonic riboflavin was administered. After verification of the ultraviolet A laser source unit’s calibration using an ultraviolet A power meter, the corneal collagen was polymerized for 30 minutes (Vega CBM x-linker LED-UVA single 370-nm beam, 3 mW/cm 2 , 5.4 J/cm 2 ). The ultraviolet beam’s focus was checked initially with an aiming beam produced by 2 centering LED (644 nm). During this second step, riboflavin was instilled regularly so as to maintain its stromal concentration.
After abundant rinsing with balanced salt solution and instillation of 1 drop of moxifloxacin (Vigamox; Alcon Laboratories, Inc), a bandage lens (Focus Night & Day; CIBA Vision, Duluth, Georgia, USA) was placed. Postoperative treatment included oral analgesics (paracetamol 500 mg 4 times daily for 3 days), 7 days of topical moxifloxacin, and topical ketorolac 0.5% (Acular; Allergan, Inc, Irvine, California, USA) followed by 7 days of topical dexamethasone (Maxidex; Alcon Laboratories, Inc). All patients were seen again on day 3 to assess the quality of epithelial healing, to check whether infectious complications existed, and to remove the bandage lens.
Mean Outcome Measures and Follow-up
Mean outcome measures were UDVA, CDVA, spherical and cylindrical refraction, simulated keratometry values (minimum keratometry [K min ] and K max ), and the thinnest corneal thickness values, which were recorded before surgery and at 3, 6, and 12 months and at the last visit (mean, 43 months) after surgery.
Statistical Analysis
SPSS statistical software version 16.0 for Windows (SPSS, Inc, Chicago, Illinois, USA) was used for statistical analysis. The Wilcoxon matched-pairs test was performed for all parameter comparisons between preoperative and postoperative examinations. Differences with a value of P < .05 were considered statistically significant.
Results
Demographic Results
Sixteen eyes of 14 patients (10 male, 4 female) with corneal ectasia after LASIK were included. The mean patient age ± standard deviation at ICRS implantation and CXL treatment was 33.0 ± 6.5 years (range, 23 to 44 years). Mean follow-up ± standard deviation was 43 ± 9 months (range, 36 to 62 months). Risk factors before LASIK included 7 eyes with a deep stromal ablation (> 75 μm), 4 eyes with a thin cornea (< 500 μm), 3 eyes with forme fruste keratoconus, 2 eyes with a steep cornea, and 1 eye with undiagnosed pellucid marginal degeneration. In 4 cases, no risk factor was determined. ICRS were implanted as 1 segment (inferiorly) in 13 (81.2%) eyes and as 2 segments in 3 (18.8%) eyes.
Clinical Outcomes
Demographic and clinical findings of each patient at baseline and at the last visit after the treatment are summarized in Table 1 . Also, mean values for mean outcome measures at baseline and after treatment are shown in Table 2 . The mean logMAR UDVA and logMAR CDVA values were significantly lower at all postoperative visits compared with preoperative values ( P < .05 for all). At the last visit, UDVA increased (increase of ≥ 1 Snellen line) in 15 eyes and remained stable (change of < 1 Snellen line) in 1 eye. No eyes showed deterioration (lost ≥ 1 line). CDVA increased in 13 eyes and remained stable in 3 eyes ( Figure 1 ). Patients had a mean posttreatment UDVA gain of 2.9 ± 1.5 lines (range, 0.5 to 6 lines) and had a mean posttreatment CDVA gain of 2.3 ± 2.2 lines (range, 0.5 to 8 lines).
| Patient No. | Age (y) | Sex | Eye | Baseline | After ICRS (Last Visit) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UDVA | CDVA | Sphere | Cylinder | K min | K max | Pachymeter | UDVA | CDVA | Sphere | Cylinder | K min | K max | Pachymeter | ||||
| 1 | 32 | M | R | 6/300 | 6/20 | –3.75 | –3.50 | 36.6 | 40.8 | 411 | 6/60 | 6/15 | –3.75 | –2.75 | 35.9 | 39.8 | 405 |
| 2 | 44 | F | R | 6/150 | 6/38 | –6.0 | –7.50 | 51.7 | 58.3 | 409 | 6/10 | 6/6.6 | 0 | –3.0 | 48.7 | 50.4 | 420 |
| 3 | 24 | M | R | 6/126 | 6/8.5 | –5.0 | –2.0 | 42.7 | 47.1 | 467 | 6/15 | 6/8.5 | –1.5 | –1.0 | 41.5 | 42.5 | 466 |
| 4 | 23 | M | R | 6/190 | 6/30 | –12.0 | –2.0 | 46.8 | 47.4 | 424 | 6/20 | 6/8.5 | –1.50 | –2.0 | 37.2 | 39.9 | 398 |
| L | 6/150 | 6/30 | –10.0 | –2.0 | 46.0 | 48.3 | 453 | 6/20 | 6/8.5 | –2.0 | –2.0 | 43.7 | 45.3 | 412 | |||
| 5 | 38 | M | L | 6/60 | 6/30 | –1.0 | –3.0 | 40.5 | 43.3 | 460 | 6/30 | 6/20 | 0 | –1.25 | 40.3 | 42.5 | 462 |
| 6 | 33 | M | L | 6/190 | 6/30 | –15.0 | –3.0 | 54.5 | 59.1 | 401 | 6/20 | 6/15 | –3.0 | –3.0 | 40.0 | 43.5 | 380 |
| 7 | 28 | M | L | 6/15 | 6/10 | 0 | –5.0 | 44.8 | 50.9 | 493 | 6/7.5 | 6/7.5 | 0 | –2.0 | 43.2 | 45.4 | 495 |
| 8 | 32 | F | L | 6/60 | 6/15 | 0 | –4.0 | 45.9 | 50.4 | 484 | 6/20 | 6/15 | 0 | –1.75 | 45.0 | 45.9 | 475 |
| 9 | 31 | F | L | 6/60 | 6/10 | –2.0 | –3.0 | 46.0 | 52.2 | 457 | 6/15 | 6/7.5 | –1.50 | –1.00 | 45.5 | 47.5 | 460 |
| 10 | 35 | M | R | 6/20 | 6/7.5 | –3.0 | –3.0 | 42.0 | 45.0 | 467 | 6/15 | 6/7.5 | 0 | –2.0 | 37.5 | 41.5 | 470 |
| 11 | 40 | M | R | 6/600 | 6/20 | –3.0 | –6.0 | 40.3 | 49.9 | 403 | 6/20 | 6/8.5 | 0 | –2.50 | 39.7 | 45.0 | 397 |
| 12 | 29 | M | R | 6/126 | 6/20 | –3.0 | –3.0 | 48.2 | 53.6 | 404 | 6/20 | 6/10 | 0 | –2.0 | 43.4 | 45.4 | 400 |
| 13 | 44 | F | L | 6/38 | 6/8.5 | 0 | –4.50 | 38.6 | 44.3 | 467 | 6/8.5 | 6/8.5 | 0 | –2.25 | 37.4 | 40.7 | 465 |
| 14 | 29 | M | R | 6/126 | 6/38 | –0.50 | –6.50 | 43.4 | 50.7 | 446 | 6/20 | 6/12 | 0 | –2.50 | 44.2 | 44.7 | 440 |
| L | 6/38 | 6/8.5 | 0 | –5.0 | 42.0 | 47.3 | 456 | 6/8.5 | 6/7.5 | 0 | –1.50 | 41.3 | 43.50 | 460 | |||
| Measure | Baseline | 3 Months | 6 Months | 12 Months | Last Visit |
|---|---|---|---|---|---|
| Visual acuity (logMAR) | |||||
| UDVA | 1.18 ± 0.42 (0.40 to 2.0) | 0.52 ± 0.29 (0.15 to 1.3) | 0.53 ± 0.26 (0.15 to 1.0) | 0.50 ± 0.22 (0.15 to 1,0) | 0.44 ± 0.22 (0.1 to 1.0) |
| P value a | 0.000 | 0.000 | 0.000 | 0.000 | |
| CDVA | 0.46 ± 0.26 (0.1 to 0.82) | 0.21 ± 0.11 (0.1 to 0.4) | 0.25 ± 0.15 (0.1 to 0.52 | 0.24 ± 0.14 (0.1 to 0.52) | 0.21 ± 0.14 (0.05 to 0.52) |
| P value a | 0.000 | 0.001 | 0.000 | 0.001 | |
| Refraction (D) | |||||
| Spherical | –4.0 ± 4.6 (–15.0 to 0.0) | –1.1 ± 1.7 (–6.0 to 0.0) | –1.0 ± 1.4 (–4.0 to 0.0) | –0.93 ± 1.35 (–4.0 to 0.0) | –0.82 ± 1.2 (–3.75 to 0.0) |
| P value a | 0.005 | 0.006 | 0.006 | 0.006 | |
| Cylindrical | –3.9 ± 1.6 (–7.5 to 2.0) | –2.0 ± 0.66 (–3.25 to 0.75) | –2.0 ± 0.68 (–3.0 to 0.75) | –1.9 ± 0.56 (–2.75 to 0.75) | –2.0 ± 0.63 (–3.0 to 1.0) |
| P value a | 0.000 | 0.000 | 0.000 | 0.000 | |
| Keratometry (D) | |||||
| Minimum | 44.3 ± 4.7 (36.6 to 54.5) | 41.2 ± 3.5 (35.8 to 48.6) | 41.6 ± 3.3 (35.7 to 48.9) | 41.4 ± 3.5 (35.7 to 49.0) | 41.5 ± 3.5 (35.9 to 48.7) |
| P value a | 0.005 | 0.008 | 0.008 | 0.017 | |
| Maximum | 49.3 ± 4.9 (40.8 to 59.1) | 43.7 ± 2.9 (39.8 to 50.1) | 44.1 ± 2.7 (39.5 to 50.5) | 43.9 ± 2.9 (39.4 to 50.4) | 43.9 ± 2.8 (39.8 to 50.4) |
| P value a | 0.000 | 0.000 | 0.000 | 0.000 | |
| Pachymetry (μm) | 444 ± 35 (401 to 493) | 411 ± 33 (340 to 455) | 422 ± 35 (365 to 475) | 432 ± 36 (370 to 490) | 439 ± 35 (380 to 495) |
| P value a | 0.000 | 0.000 | 0.018 | 0.275 | |
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