Keisuke Kawana

Comparison of corneal thickness measurements using Orbscan II, non-contact specular microscopy, and ultrasonic pachymetry in eyes after laser in situ keratomileusis

Aims: To compare central corneal thickness measurements of three pachymetry devices in eyes after laser in situ keratomileusis (LASIK). Methods: Central corneal thickness was measured in 203 eyes after myopic LASIK. Orbscan II scanning slit topography (Bausch & Lomb), SP-2000P non-contact specular microscopy (Topcon), and ultrasonic pachymetry (Tomey) were used in this sequence. Results: Three devices gave significantly different corneal thickness readings (p<0.0001, repeated measure analysis of variance). The measurements of Orbscan II (445.6 (SD 60.0) μm) were significantly smaller than those of noncontact specular microscopy (467.9 (SD 40.2) μm; p<0.0001, Tukey multiple comparison) and ultrasonic pachymetry (478.8 (SD 41.9) μm; p<0.0001). The value obtained with SP-2000P non-contact specular microscopy was significantly smaller than that taken with ultrasonic pachymetry (p<0.001). There were significant linear correlations between scanning slit topography and non-contact specular microscopy (Pearson’s correlation coefficient r = 0.912, p<0.0001), non-contact specular microscopy and ultrasonic pachymetry (r = 0.968, p<0.0001), and ultrasonic pachymetry and scanning slit topography (r = 0.933, p<0.0001). Conclusion: In post-LASIK eyes, Orbscan II scanning slit topography significantly underestimated corneal thickness. Non-contact specular microscopy gave smaller thickness readings than ultrasonic pachymetry, but these two units showed an excellent linear correlation.

Visualization of sub-retinal pigment epithelium morphologies of exudative macular diseases by high-penetration optical coherence tomography.

PURPOSE To evaluate the clinical significance of the newly developed long-wavelength probe optical coherence tomography (LP-OCT) for the diagnosis of exudative macular diseases. METHODS Fourteen eyes of 13 participants were prospectively enrolled in the study. There were seven type I and five type II choroidal neovascularization (CNV) cases associated with age-related macular degeneration and idiopathic neovascularization and one case of polypoidal choroidal vasculopathy (PCV). A custom-built LP-OCT based on swept-source OCT (SS-OCT) technology was used. This new OCT uses a probe beam with a wavelength of 1060 nm that provides deeper penetration into the choroid and higher image contrast to the structures beneath the retinal pigment epithelium (RPE) and pathologic tissues than does conventional OCT. The depth resolution is 10.4 microm in tissue and the measurement speed is 28,000 depth scans/s. All the eyes were also examined by standard short wavelength probe OCT (SP-OCT). The image contrasts of the LP- and SP-OCT were qualitatively evaluated and analyzed by Wilcoxons paired signed rank test and Spearmans rank correlation test. RESULTS In 10 of 14 eyes, high-contrast visualization of the diseases beneath the RPE, CNV, or fibrin was attained. These diseases were almost invisible in the SP-OCT images. The LP-OCT of the remaining eyes also revealed significant improvement in the image contrasts beneath the RPE and CNV. Qualitative evaluation of the image contrasts and subsequent statistical test indicated statistically significant improvement in the image penetration to the choroid of LP-OCT to that of SP-OCT. CONCLUSIONS LP-OCT provided significant improvement in the image contrast of exudative macular diseases.

Evaluation of Trabeculectomy Blebs Using 3-Dimensional Cornea and Anterior Segment Optical Coherence Tomography

OBJECTIVE To investigate the internal structures of trabeculectomy blebs using 3-dimensional cornea and anterior segment optical coherence tomography (3-D CAS OCT). DESIGN Observational case series. PARTICIPANTS Thirty-eight filtering blebs in 31 patients who had undergone trabeculectomy examined retrospectively. METHODS Intrableb structures were examined using 3-D CAS OCT. The blebs were classified clinically as successful (intraocular pressure [IOP] <18 mmHg without glaucoma medication) or failed. MAIN OUTCOME MEASURES Bleb structures were assessed in terms of the visibility of the drainage route, scleral flap, and microcysts. The length and height of the internal fluid-filled cavity, maximum and minimum bleb wall thickness, total bleb height, volumes of the internal fluid-filled cavity and hyporeflective area, and number of microcysts were analyzed. RESULTS Intrableb drainage route, scleral flap, and microcysts were observed in 92.1%, 94.7%, and 86.8% eyes, respectively. The IOP showed a significant negative correlation with horizontal and vertical length of the fluid-filled cavity (Spearman correlation coefficient [r(s)] = -0.634; P<0.0001; and r(s) = -0.539; P = 0.0008, respectively), height of the fluid-filled cavity (r(s) = -0.334; P = 0.031), maximum bleb wall thickness (r(s) = -0.491; P = 0.0023), total bleb height (r(s) = -0.629; P<0.0001), volume of the internal fluid-filled cavity (r(s) = -0.480; P = 0.0029), volume of hyporeflective area (r(s) = -0.443; P = 0.0056), and number of microcysts (r(s) = -0.451; P = 0.0045). There were 26 successful (64.8%) and 12 failed (31.6%) blebs. Significant differences were observed between these groups in IOP (P<0.0001), horizontal and vertical length of the fluid-filled cavity (P<0.0001 and P = 0.0019, respectively), height of the fluid-filled cavity (P = 0.0046), maximum bleb wall thickness (P = 0.0029), total bleb height (P = 0.0003), volume of the internal fluid-filled cavity (P = 0.0006), volume of hyporeflective area (P = 0.0020), and number of microcysts (P = 0.0025). CONCLUSIONS The internal aqueous humor outflow channel and scleral flap could be visualized, and the 3-D volume of the intrableb cavity was calculated using 3-D CAS OCT. The successful blebs exhibited a large internal fluid-filled cavity, an extensive hyporeflective area, and thicker bleb walls with more microcysts. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Anterior Ocular Biometry Using 3-Dimensional Optical Coherence Tomography

PURPOSE To evaluate anterior ocular biometry by comparing the measurements of central corneal thickness (CCT) and anterior chamber depth (ACD) with 3-dimensional corneal and anterior segment optical coherence tomography (CAS-OCT) and other methods. DESIGN Cross-sectional study. PARTICIPANTS Forty eyes of 40 normal subjects. METHODS The CCT was measured by 4 methods (CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry), and the ACD was measured by 3 methods (CAS-OCT, Scheimpflug camera, and scanning-slit topography). The anterior chamber volume (ACV) was calculated with CAS-OCT. Repeatability and reproducibility of CAS-OCT measurements were evaluated. MAIN OUTCOME MEASUREMENTS The CCT and ACD were measured and compared between devices. The ACV was calculated with CAS-OCT. Coefficient of variation and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility of CAS-OCT measurements. RESULTS The mean CCT was 547.0+/-39.0, 590.0+/-39.8, 525.0+/-45.0, and 545.0+/-40.3 microm with CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry, respectively. Significant differences were observed among the 4 methods (P<0.0001; 1-way analysis of variance [ANOVA]). The CCT measured with Scheimpflug camera was significantly larger than those measured with the other methods (P<0.0001; Bonferroni multiple comparison), but there was no significant difference among the other 3 methods. The mean ACD was 3.01+/-0.47, 3.04+/-0.52, and 2.88+/-0.50 mm with CAS-OCT, Scheimpflug camera, and scanning-slit topography, respectively. There was no significant difference among the 3 methods (P = 0.678; 1-way ANOVA). A significant linear correlation in CCT and ACD were observed between CAS-OCT and other methods (all P<0.0001). The mean ACV calculated with CAS-OCT was 169.7+/-23.1 mm(3). The coefficient of repeatability and reproducibility of CCT and ACD measurements were <5% and ICCs were >0.98. CONCLUSIONS The CCT measurements were comparable among CAS-OCT, ultrasonic pachymetry, and scanning-slit topography, but Scheimpflug camera yielded a significantly higher CCT value. There was no significant difference in ACD measurements among CAS-OCT, Scheimpflug camera, and scanning-slit topography. The ACV was noninvasively measured by CAS-OCT. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any materials discussed in this article.

Central corneal thickness measurements using orbscan II scanning slit topography, noncontact specular microscopy, and ultrasonic pachymetry in eyes with keratoconus

Purpose: To compare corneal thickness measurements using Orbscan II scanning slit topography, Topcon SP-2000P noncontact specular microscopy, and ultrasonic pachymetry in eyes with keratoconus. Methods: Central corneal thickness was measured in 22 eyes with keratoconus. Eyes with apparent corneal opacity were excluded. Scanning slit topography, noncontact specular microscopy, and ultrasonic pachymetry were used in this sequence. The acoustic equivalent correlation factor (0.92) was used for Orbscan readings. Results: Three devices gave significantly different corneal thickness readings (P < 0.001, repeated-measure analysis of variance). Measurements with Orbscan scanning slit topography (449.5 ± 43.2 [SD] μm) were significantly smaller than those of ultrasonic pachymetry (485.0 ± 29.3 μm; P < 0.001, Tukey multiple comparison) and SP-2000P noncontact specular microscopy (476.7 ± 28.3 μm; P = 0.002). There were significant linear correlations between ultrasonic pachymetry and scanning slit topography (Pearson correlation coefficient r = 0.741, P < 0.001), between scanning slit topography and noncontact specular microscopy (r = 0.880, P < 0.001), and between noncontact specular microscopy and ultrasonic pachymetry (r = 0.811, P < 0.001). Conclusion: In eyes with keratoconus, Orbscan II scanning slit topography system gave significantly smaller corneal thickness readings than the other 2 devices. Measurements taken by noncontact specular microscopy and ultrasonic pachymetry were comparable. Three devices showed significant linear correlations with one another.

Three-dimensional anterior segment optical coherence tomography of filtering blebs after trabeculectomy.

PurposeTo evaluate trabeculectomy blebs by using 3-dimensional anterior segment optical coherence tomography (OCT). MethodsWe prospectively examined 4 eyes of 4 patients who developed filtering blebs after trabeculectomy. A 1310-nm high-speed OCT prototype was used to image the 3-dimensional structure of the filtering blebs. ResultsThe 3-dimensional structure of the filtering blebs was clearly observed in the OCT images. Three types of filtering blebs were observed: diffuse blebs in 2 eyes, an encapsulated bleb in 1 eye, and a nonfunctioning cystic bleb in 1 eye. The volume of each bleb was 9.97, 1.10, 0.76, and 0.88 mm3, respectively. En-face OCT images clearly showed the aqueous outflow channels at the margins of the scleral flaps. ConclusionThree-dimensional OCT allows objective and noninvasive assessment of filtering blebs after trabeculectomy.

Investigation of post-glaucoma-surgery structures by three-dimensional and polarization sensitive anterior eye segment optical coherence tomography

A sequential case series of post-glaucoma-surgery structures examined by three-dimensional corneal and anterior eye segment optical coherence tomography (3D-CASOCT) and 3D polarization sensitive CASOCT (PS-CASOCT) is presented. A total of 5 patients who underwent glaucoma surgery were included in this study. Of these, 1, 1, and 3 patient underwent trabeculotomy, laser iridotomy, and trabeculectomy respectively. One patient each who had undergone trabeculotomy or laser iridotomy was examined using a prototype 3D-CASOCT. This prototype is based on swept-source OCT technology, uses a probe beam with a center wavelength of 1.31 microm, and has an axial resolution of 11.6 microm and a scanning speed of 20,000 A lines/s. All 3 patients who underwent trabeculectomy were examined by PS-CASOCT, which has similar specifications to those of 3DCASOCT, measures the depth-resolved birefringence of a specimen, and yields conventional OCT images. Detailed 3D visualization of the incision site of trabeculotomy and the ablation site of laser iridotomy was achieved using 3D-CASOCT. PS-CASOCT revealed, in addition to the structural details, the birefringent properties of the tissues of the trabeculectomy bleb. Some blebs showed abnormal birefringence in the conjunctiva and in a remnant fluid pool. This may indicate the existence of fibrosis in these regions. Both 3D-CASOCT and PS-CASOCT provide clinically significant information for the postoperative assessment of structures created during glaucoma surgery. Interactive 3D datasets of all cases are provided for interactive clinical review. Complex raw 3D OCT volumes are also provided as a reference dataset for the development of PS-OCT algorithms.

Repeatability and reproducibility of anterior ocular biometric measurements with 2-dimensional and 3-dimensional optical coherence tomography

PURPOSE: To evaluate the repeatability and reproducibility of central corneal thickness (CCT), anterior chamber depth (ACD), and anterior chamber width (ACW) measurements using 3‐dimensional (3‐D) corneal and anterior segment optical coherence tomography (CAS‐OCT) and 2‐dimensional (2‐D) anterior segment OCT (AS‐OCT). SETTING: Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan. DESIGN: Nonrandomized clinical trial. METHODS: The CCT, ACD, and ACW were measured in normal eyes using a prototype 3‐D swept‐source CAS‐OCT device and a 2‐D time‐domain AS‐OCT device (Visante). The coefficient of repeatability and reproducibility and the intraclass correlation coefficient (ICC) were calculated to evaluate the repeatability and reproducibility of the measurements. RESULTS: Eighty‐five eyes (85 subjects) were evaluated. The mean CCT measurement was 557.5 μm ± 40.5 (SD) with CAS‐OCT and 556.4 ± 39.4 μm with AS‐OCT; the mean ACD measurement, 3.13 ± 0.40 mm and 3.16 ± 0.39 mm, respectively; and the mean ACW, 11.80 ± 0.47 mm and 11.79 ± 0.49 mm, respectively. There was no statistically significant difference in CCT or ACW measurements between the 2 devices (P>.05, Wilcoxon signed rank test). Although the ACD measurements were significantly different (P<.0001), the difference was small (0.03 mm). Significant linear correlations were found between the measurements of the 2 devices (P<.0001). The ICC was greater than 0.99 for CAS‐OCT and greater than 0.96 for AS‐OCT. CONCLUSION: Corneal and anterior segment OCT and AS‐OCT provided comparable and well‐correlated anterior ocular biometric measurements, with sufficient repeatability and reproducibility. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Wound Architecture of Clear Corneal Incision With or Without Stromal Hydration Observed With 3-Dimensional Optical Coherence Tomography

PURPOSE To evaluate wound architectures of a clear corneal incision and the duration of stromal edema caused by intentional hydration in cataract surgery using 3-dimensional (3-D) cornea and anterior segment optical coherence tomography (OCT). DESIGN Prospective, randomized study. METHODS On 30 eyes of 23 patients, cataract surgery was performed through a clear corneal incision created with a 2.4-mm blade. After confirming the water tightness of the clear corneal incision at the end of surgery, 15 randomly selected eyes received stromal hydration, and the remaining 15 eyes did not. Using the 3-D cornea and anterior segment optical coherence tomography, wound architecture was assessed 1 day, 1 week, and 2 weeks after surgery. RESULTS There was a statistically significant difference in corneal thickness at the clear corneal incision between eyes with and without stromal hydration 1 day and 1 week after surgery (P < .001 and P < .05, Mann-Whitney U test), but not at 2 weeks after surgery. On day 1, gaping at the epithelial side was seen in 6.7% (2 eyes), gaping at the endothelial side in 30% (9 eyes), misalignment of the roof and floor of incision in 40% (12 eyes), and local detachment of Descemet membrane in 36.7% (11 eyes). These imperfections improved with time. CONCLUSIONS Using the 3-D cornea and anterior segment optical coherence tomography, detailed architectures of the clear corneal incision were investigated. It was found that the effect of stromal hydration lasted for at least 1 week after surgery.

Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography

Polarization-sensitive optical coherence tomography (PS-OCT) is known to be advantageous because of its additional tissue-specific contrast of the anterior eye. So far, this advantage has been shown only qualitatively. We evaluate the improved visibility afforded by 3-D PS corneal and anterior eye segment OCT (PS-CAS-OCT) in visualizing the trabecular meshwork (TM) based on statistical evidences. A total of 31 normal subjects participated in this study. The anterior eye segments of both the eyes of the subjects are scanned using a custom-made PS-CAS-OCT and the standard-scattering OCT (S-OCT) and polarization-sensitive phase-retardation OCT (P-OCT) images are obtained. Three graders grade the visibility of the TM using a four-leveled grading system. The intergrader agreement, intermodality differences, and interquadrant dependence of visibility are statistically examined. All three of three combinations of graders show substantial agreement in visibility with P-OCT (ρ = 0.74, 0.70, and 0.68, Spearmans correlation), while only one of three shows substantial agreement with S-OCT (ρ = 0.72). Significant dependence of the visibility on the modality (S-OCT versus P-OCT) and quadrants are found by the analysis of variance. A subsequent Wilcoxon signed-rank test reveals significantly improved visibility. PS-CAS-OCT may become a useful tool for screening angle-closure glaucoma.