Doh Lee

Flap thickness reproducibility in laser in situ keratomileusis with a femtosecond laser: Optical coherence tomography measurement

PURPOSE: To compare ultrasound (US) pachymetry, Orbscan, and optical coherence tomography (OCT) measurements of the central corneal thickness (CCT) before laser in situ keratomileusis (LASIK) and evaluate the reproducibility of flaps created with the IntraLase femtosecond laser (IntraLase, Inc.) using OCT. SETTING: Department of Ophthalmology, IIsan Paik Hospital, Goyang, Korea. METHODS: Central corneal thickness was measured using OCT, US pachymetry, and Orbscan in 59 eyes of 30 patients before femtosecond laser LASIK. The postoperative corneal flap thickness, measured using OCT, was compared with the preoperative intended thickness. RESULTS: Optical coherence tomography, US pachymetry, and Orbscan measurements provided similar CCT values (P>.05). Corneal thickness values obtained using US or Orbscan correlated well with those obtained by OCT, with the correlation coefficient ranging from 0.804 to 0.889 (P<.05). The OCT measurements showed no significant difference between the postoperative flap thickness and the intended flap thickness (P>.05). CONCLUSIONS: Optical coherence tomography was comparable to US pachymetry and Orbscan in cornea thickness measurement. Optical coherence tomography was easy and relatively accurate to use preoperatively and in the early postoperative period. The femtosecond laser created highly reproducible flaps that corresponded with the preoperative intended thickness.

Corneal thickness measurement using Orbscan, Pentacam, Galilei, and ultrasound in normal and post-femtosecond laser in situ keratomileusis eyes.

Purpose: To compare corneal pachymetry assessment using slit scanning imaging (Orbscan), rotating Scheimpflug imaging (Pentacam), dual Scheimpflug system (Galilei), and ultrasound pachymetry in normal and post-femtosecond (FS) laser in situ keratomileusis (LASIK) eyes. Methods: Sixty eyes of 60 patients were enrolled for this study, which consisted of 30 unoperated eyes (normal corneas) and 30 eyes after FS-LASIK (post-LASIK corneas). Central corneal thickness was measured sequentially using Orbscan II, Pentacam, Galilei, and ultrasound pachymetry, and the average value of measurements obtained by the 4 different methods were compared in each group. Results: In normal corneas, corneal thickness measurements were not different by all 4 methods [P = 0.202, 1-way analysis of variance (ANOVA)]. In post-LASIK corneas, the measurement was significantly different among those achieved by 4 methods (P < 0.001, 1-way ANOVA). Orbscan measurement was thinner than those yielded by Galilei, Pentacam, or ultrasound pachymetry with average of 47.7, 38.5, and 34.4 &mgr;m, respectively (all P values < 0.001, 1-way ANOVA and the Tukey multiple comparisons test) in post-LASIK corneas. Orbscan, Pentacam, and Galilei measurements showed good agreement with ultrasound pachymetry data in both groups, except Orbscan data in post-LASIK corneas showed a statistically significant difference from ultrasound pachymetry measurements (P value = 0.001, 1-way ANOVA and the Tukey multiple comparisons test). Conclusions: Any of central corneal thicknesses obtained by all 4 measurement modalities might be acceptable before refractive surgery. However, in post-FS-LASIK eyes, measurements using Orbscan were thinner than those obtained with other modalities; in contrast, those with Pentacam or Galilei were comparable with ultrasound pachymetry.

New surgical strategy for corneal tattooing using a femtosecond laser.

Purpose: The purpose of this study was to describe a new method of femtosecond (FS) laser-assisted corneal tattooing and to report the results of this method in a case series. Methods: The study involved 6 eyes of 6 patients with total or partial corneal opacity. An FS laser was used for lamellar dissection and to make a side cut with a hinge, creating a corneal flap. Laser parameters were adjusted depending on ocular condition and the location of the corneal opacity. After lifting the corneal flap, further lamellar dissection with a diamond blade was performed up to the periphery of the limbal area. Using a cannula, dye was injected into the lamellar stromal bed and the space of the lamellar dissected pocket in the limbus, after which the flap was repositioned. Results: The design and application of the FS laser for dissection and flap creation were successful in all cases. There were no significant complications other than an incomplete cut under band keratopathy in 1 eye. The cosmetic effects were satisfactory in all cases. No patient complained of pain for more than 1 day after surgery. Conclusions: The advantages of the FS laser-assisted corneal tattooing include a customized design, speed, decreased pain, reduced risk of perforation, and good wound healing. This procedure provides improvements over current corneal tattooing techniques, although it is relatively expensive.

Korean Guidelines for the Diagnosis and Management of Dry Eye: Development and Validation of Clinical Efficacy

Purpose To evaluate the clinical efficacy of newly developed guidelines for the diagnosis and management of dry eye. Methods This retrospective, multi-center, non-randomized, observational study included a total of 1,612 patients with dry eye disease who initially visited the clinics from March 2010 to August 2010. Korean guidelines for the diagnosis and management of dry eye were newly developed from concise, expert-consensus recommendations. Severity levels at initial and final visits were determined using the guidelines in patients with 90 ± 7 days of follow-up visits (n = 526). Groups with different clinical outcomes were compared with respect to clinical parameters, treatment modalities, and guideline compliance. Main outcome measures were ocular and visual symptoms, ocular surface disease index, global assessment by patient and physician, tear film break-up time, Schirmer-1 test score, ocular surface staining score at initial and final visits, clinical outcome after three months of treatment, and guideline compliance. Results Severity level was reduced in 47.37% of patients treated as recommended by the guidelines. Younger age (odd ratio [OR], 0.984; p = 0.044), higher severity level at initial visit, compliance to treatment recommendation (OR, 1.832; p = 0.047), and use of topical cyclosporine (OR, 1.838; p = 0.011) were significantly associated with improved clinical outcomes. Conclusions Korean guidelines for the diagnosis and management of dry eye can be used as a valid and effective tool for the treatment of dry eye disease.

Novel technique of corneal biopsy by using a femtosecond laser in infectious ulcers.

Purpose: To describe femtosecond laser-assisted corneal biopsy and its use in assessing the causative organisms in 2 cases of infectious corneal ulcers. Methods: A 27-year-old man and a 65-year-old woman, both of whom showed uncertain symptoms, repeated negative test results for infectious organisms, and after no improvement despite empirical therapy, underwent diagnostic corneal biopsy by using a femtosecond laser. A corneal flap depth of 200 μm and a diameter of 3 mm were obtained from each patient. Results: The biopsy specimen from the male patient showed pseudohyphae, which led to a diagnosis of candidal keratitis. The biopsy specimen from the female patient showed positive Gram stain and no evidence of fungal ulcers and yielded a culture of Streptococcus viridans. No complications occurred during either procedure. Conclusions: Femtosecond laser-assisted corneal biopsy enabled identification of the infectious pathogen in both patients. This technique is easy, safe, and rapid, and it yields a biopsy specimen with a uniform depth and precise size. Femtosecond laser-assisted corneal biopsy can be used as an accurate diagnostic method in uncertain cases of corneal ulcers.

Creation of an extremely thin flap using IntraLase femtosecond laser.

A 43-year-old woman had laser in situ keratomileusis (LASIK) using the IntraLase femtosecond laser (IntraLASIK) to create 110 microm flaps. Despite uneventful flap formation, the flaps in both eyes were extremely thin, making it difficult to lift them. The flap in the right eye resembled an epi-LASIK epithelial flap. It was lifted uneventfully. The flap in the left eye was stretched and torn on lifting, and the procedure was therefore postponed. After 6 months, the IntraLASIK surgical procedure was repeated in the left eye using a thicker and smaller flap than in the first procedure. Despite the improvements associated with using an IntraLase femtosecond laser, thinner-than-intended corneal flaps can occur. Early recognition of such a flap can prevent further complications.

The Effect of Bevacizumab versus Ranibizumab in the Treatment of Corneal Neovascularization: A Preliminary Study

Purpose To compare the short term effects of bevacizumab and ranibizumab injections on the regression of corneal neovascularization (NV). Methods Sixteen eyes of 16 patients with corneal NV were randomly assigned for an injection with 2.5 mg of bevacizumab (group 1, n = 8) or 1 mg of ranibizumab (group 2, n = 8) through subconjunctival and intrastromal routes. The patients were prospectively followed-up for one month after the injections. Corneal NV areas, as shown on corneal slit-lamp photographs stored in JPEG format, were calculated using Image J software before the injection, one week after the injection, and one month after the injection. The corneal NV areas were compared before and after the injections. Results Seven women and nine men, with an average age of 51 years, presented with corneal NV secondary to herpetic keratitis (7 cases), graft rejection (6), chemical burn (1), pemphigoid (1), and recurrent ulcer (1). In group I, the preoperative corneal NV area (8.75 ± 4.33%) was significantly decreased to 5.62 ± 3.86% one week after the injection and to 6.35 ± 3.02% one month after the injection (p = 0.012, 0.012, respectively). The corneal NV area in group 2 also exhibited a significant change, from 7.37 ± 4.33% to 6.72 ± 4.16% one week after the injection (p = 0.012). However, no significant change was observed one month after the injection. The mean decrease in corneal NV area one month after injection in group 1 (28.4 ± 9.01%) was significantly higher than in group 2 (4.51 ± 11.64%, p = 0.001). Conclusions Bevacizumab injection resulted in a more effective and stable regression of corneal NV compared to the ranibizumab injection. The potency and dose of these two drugs for the regression of corneal NV require further investigation.

The comparison of femtosecond laser-assisted penetrating keratoplasty with conventional surgery in terms of endothelial safety: ex vivo study using porcine eyes.

Purpose: To evaluate the effect of using femtosecond (FS) laser technology for penetrating keratoplasty (PK) in terms of corneal graft endothelial ultrastructure and viability in porcine eyes. Methods: Thirty-two freshly enucleated porcine eyes were divided into 4 equal groups (n = 8): group 1, incomplete penetration using the FS laser (a 100 μm-depth from the endothelial side remained); group 2, complete penetration using the FS; group 3, trephination using a vacuum trephine until the aqueous humor appeared; group 4, no treatment (control group). For groups 1 and 2, side cuts were performed using a 60-kHz FS laser (IntraLase FS Laser, Abbot Medical Optics, Abbott Park, IL). Preoperative ultrasound pachymetry was used to make measurements at 5 positions. Scanning electron microscopy (SEM) was used to determine morphological changes, and light microscopy with Alizarin red staining was used to determine the amount of cell death. Results: Preoperative corneal thicknesses were similar for all groups. All 4 groups showed similar corneal endothelial cell morphology and viability at the graft center (P = 0.15, Kruskal-Wallis test). At the graft border, endothelial cell damage was minor in group 1, moderate in group 2, and most severe and diffuse in group 3 (P = 0.009, Kruskal-Wallis test). Conclusions: FS laser use is safe for the endothelium at the graft center and has less harmful effects on the endothelium at the incision area than does conventional trephination. Therefore, FS laser-assisted corneal grafts with complete penetration seems to be the optimum choice for preserving endothelial cells during PK.

Different epithelial cleavage planes produced by various epikeratomes in epithelial laser in situ keratomileusis

PURPOSE: To determine the anatomic cleavage planes produced by various epikeratomes in epithelial laser in situ keratomileusis (epi‐LASIK). SETTING: Department of Ophthalmology, IIsan Paik Hospital, Goyang, Korea. METHODS: Sixteen eyes (8 patients) were included in this study. Three epikeratomes, the Moria Epi‐K, Centurion SES, and Amadeus II, were used to collect 4 epithelial flaps from 2 patients in the epi‐LASIK procedure. Four epithelial flaps from 2 patients were also obtained by laser‐assisted subepithelial keratectomy (LASEK). Immunohistochemical staining using monoclonal antibodies against integrin ß1, integrin ß4, laminin 5, and collagen type VII was performed. RESULTS: Immunohistochemical staining showed expression of integrin ß1 and integrin ß4 in all epithelial flaps. In epi‐LASIK, the expression of laminin 5 and collagen type VII had a linear or dotted pattern that differed based on the epikeratome used. In the epithelial flaps obtained using LASEK, the expression of laminin 5 and collagen type VII had a dotted pattern. CONCLUSIONS: Each epikeratome yielded reproducible but different cleavage planes of corneal epithelium. The results suggest that further study is needed to elucidate the wound‐healing process after epi‐LASIK because different cleavage planes produced by different epikeratomes may influence the process.

The analysis of predicted capsular bag diameter using modified model of capsule measuring ring in Asians

Background:  This study measured the capsular bag diameter (CBD) of Asian eyes using a modified capsular measuring ring (CMR) after cataract surgery, and identified preoperative predictive factors for postoperative CBD and the change of capsular bag diameter after surgery.