Visante Anterior Segment Optical Coherence Tomography Research Articles

Central Corneal Thickness Among Filipino Patients in an Ambulatory Eye Surgery Center Using Anterior Segment Optical Coherence Tomography.

ObjectiveThe purpose of the study was to determine the central corneal thickness (CCT) among Filipino patients that may contribute to different glaucoma diagnosis using the anterior segment optical coherence tomography in an ambulatory eye surgery center.MethodsA single-center retrospective, cross-sectional study design including 1232 eyes of 641 patients of the Asian Eye Institute, Makati, Philippines from January 2019 to December 2019 who had their CCT measured with Visante anterior segment optical coherence tomography (AS-OCT). CCT was correlated with age, sex, presence of diabetes and/or hypertension, and glaucoma diagnosis.ResultsAmong 641 patients who had their CCT measured by Visante AS-OCT, 723 eyes of 369 patients were included. Nearly half of the study population were normal or glaucoma suspects. The mean CCT among Filipino patients was 535.59 ± 34.06 µm. Ocular hypertensive patients had the thickest CCT, while normal tension glaucoma patients had the thinnest CCT. After adjusting for multiple variables, CCT had a direct relationship with the presence of diabetes, IOP level and the diagnosis of ocular hypertension, while inverse relationship with age. Most of the patients presenting with angle closure glaucoma were females aged 60 and above.ConclusionVisante AS-OCT is a non-contact and non-aerosol generating instrument allaying the fear of disease transmission from contact or aerosolization of tears. Our study confirms similar relationships of CCT with age, presence of diabetes, IOP level, and diagnosis of ocular hypertension or normal tension glaucoma among Filipino patients with the available literature from other ethnicities.

Repeatability and agreement of two anterior segment OCT in myopic patients before implantable collamer lenses implantation.

To evaluate the intra-operator repeatability of time domain and swept-source Fourier domain anterior segment optical coherence tomography (AS-OCT), namely, Visante AS-OCT and Casia SS-1000 OCT, in measuring the preoperative parameters of implantable collamer lens (ICL) in myopic eyes, as well as the agreement between the two devices. A total of 97 eyes from 49 myopes were investigated in this prospective case series study. The anterior chamber depth (ACD), angle-to-angle distance (ATA), pupil diameter (PD) and crystalline lens rise (CLR) in all subjects were measured for three times during one session by the same operator. The repeatability was evaluated using the within-subject standard deviation (Sw), repeatability limits and intraclass correlation coefficients (ICC). The agreement between the two systems was evaluated using the Bland-Altman plots and 95% limits of agreement (LoA). The repeatability limits of Visante AS-OCT in measuring ACD, ATA, PD and CLR were 0.099, 0.141, 0.304, and 0.079 mm, respectively. The repeatability limits of Casia SS-1000 OCT in measuring ACD, ATA, PD, and CLR were 0.105, 0.127, 0.357, and 0.082 mm, respectively. Excellent repeatability could be attained in both devices, with the ICC>0.8 for all the measured variables. The interdevice agreement was excellent (P>0.05) for ACD and ATA, but poor (P<0.05) for PD and CLR. Good repeatability can be attained by time domain and swept-source Fourier-domain OCT for all the measured variables. Moreover, interdevice agreement analysis suggests that interchangeable measurements between two devices can be achieved for ACD and ATA, but not for PD and CLR; but the differences in measurements were not clinically significant.

A Deep Learning System for Automated Angle-Closure Detection in Anterior Segment Optical Coherence Tomography Images

Anterior segment optical coherence tomography (AS-OCT) provides an objective imaging modality for visually identifying anterior segment structures. An automated detection system could assist ophthalmologists in interpreting AS-OCT images for the presence of angle closure. Development of an artificial intelligence automated detection system for the presence of angle closure. A deep learning system for automated angle-closure detection in AS-OCT images was developed, and this was compared with another automated angle-closure detection system based on quantitative features. A total of 4135 Visante AS-OCT images from 2113 subjects (8270 anterior chamber angle images with 7375 open-angle and 895 angle-closure) were examined. The deep learning angle-closure detection system for a 2-class classification problem was tested by 5-fold cross-validation. The deep learning system and the automated angle-closure detection system based on quantitative features were evaluated against clinicians' grading of AS-OCT images as the reference standard. The area under the receiver operating characteristic curve of the system using quantitative features was 0.90 (95% confidence interval [CI] 0.891-0.914) with a sensitivity of 0.79 ± 0.037 and a specificity of 0.87 ± 0.009, while the area under the receiver operating characteristic curve of the deep learning system was 0.96 (95% CI 0.953-0.968) with a sensitivity of 0.90 ± 0.02 and a specificity of 0.92 ± 0.008, against clinicians' grading of AS-OCT images as the reference standard. The results demonstrate the potential of the deep learning system for angle-closure detection in AS-OCT images.

Post-phacoemulsification iris changes in eyes with glaucoma or glaucoma suspect status.

PurposeThis prospective study used anterior segment optical coherence tomography (AS-OCT) to determine how phacoemulsification (phaco) changes iris parameters in eyes with glaucoma or glaucoma suspect status.MethodsUsing Visante AS-OCT (Carl Zeiss Meditec AG), the following pre- and post-phaco parameters were measured: IT750 = iris thickness at 750 μm from the scleral spur; IT2000 = iris thickness 2000 μm from the scleral spur; ITCM = the maximum iris thickness at the middle one third of the iris; ICURV = iris curvature; IAREA = iris area; and pupil size = pupil diameter (mm). Only high-quality images with an identifiable scleral spur were included, and only the nasal quadrant was analyzed. A single glaucoma specialist analyzed the parameters according to the Zhongshan Angle Assessment Program (ZAAP, Guangzhou, China). Multivariate analysis was performed using mixed effects regression correcting for age, gender, and ethnicity.Results89 subjects and 110 eyes were included in this study. The mean age of subjects was 74.83 {+/-} 8.69 years old. Most common diagnoses were POAG and glaucoma suspect (23% and 52%, respectively), and 16% of subjects had an LPI. In multivariate analysis of AS-OCT parameters, decreases in IT750, IT2000, ITCM, ICURV, and pupil size were statistically significant (p<0.05).ConclusionsAfter phacoemulsification, eyes with glaucoma as well as glaucoma suspect eyes have thinner irises and smaller pupils. This may lead to less iris-mediated aqueous outflow obstruction, providing support for early phacoemulsification glaucoma treatment.Translational relevanceOur AS-OCT imaging findings may guide clinical practice as iris parameters become increasingly relevant in preoperative phaco planning.

Comparison of central corneal thickness measurements in corneal edema using ultrasound pachymetry, Visante anterior-segment optical coherence tomography, Cirrus optical coherence tomography, and Pentacam Scheimpflug camera tomography.

PurposeTo compare the central corneal thickness (CCT) measurements in subjects with corneal edema using ultrasound pachymetry, Visante anterior-segment optical coherence tomography (OCT), Cirrus OCT, and Pentacam Scheimpflug camera tomography.MethodsThis prospective cross-sectional study included 46 eyes of 33 patients with corneal edema and a CCT exceeding 550 μm evaluated by ultrasound pachymetry, Visante OCT, Cirrus OCT, and Pentacam. Two observers measured each eye twice. Intraobserver and interobserver reproducibility were determined and agreement among the devices calculated.ResultsCCT was measured in 40 eyes of 29 patients. Regardless of the CCT, the measurements obtained using Visante OCT, Cirrus CCT, and ultrasound pachymetry were well correlated. Interobserver and intraobserver reproducibility were high among the three devices. Pentacam overestimated the results compared with the other devices, and ultrasound pachymetry was unmeasurable in six (13%) eyes with very thick and opaque corneas. In eyes with mild corneal edema (CCT 551–650 μm), measurements from the four devices were comparable.ConclusionAll devices reliably measured the CCT <650 μm. In eyes with edema exceeding 650 μm, CCT measurements from the Visante OCT, Cirrus OCT, and ultrasound pachymetry devices showed good reproducibility and were well correlated, while the Pentacam overestimated the values compared to the other devices. Pentacam and ultrasound pachymetry should not be used in eyes with extreme corneal edema and opacity.

Segmentation and Quantification for Angle-Closure Glaucoma Assessment in Anterior Segment OCT.

Angle-closure glaucoma is a major cause of irreversible visual impairment and can be identified by measuring the anterior chamber angle (ACA) of the eye. The ACA can be viewed clearly through anterior segment optical coherence tomography (AS-OCT), but the imaging characteristics and the shapes and locations of major ocular structures can vary significantly among different AS-OCT modalities, thus complicating image analysis. To address this problem, we propose a data-driven approach for automatic AS-OCT structure segmentation, measurement, and screening. Our technique first estimates initial markers in the eye through label transfer from a hand-labeled exemplar data set, whose images are collected over different patients and AS-OCT modalities. These initial markers are then refined by using a graph-based smoothing method that is guided by AS-OCT structural information. These markers facilitate segmentation of major clinical structures, which are used to recover standard clinical parameters. These parameters can be used not only to support clinicians in making anatomical assessments, but also to serve as features for detecting anterior angle closure in automatic glaucoma screening algorithms. Experiments on Visante AS-OCT and Cirrus high-definition-OCT data sets demonstrate the effectiveness of our approach.

Distortion Correction of Visante Optical Coherence Tomography Cornea Images.

Quantitative biometry measurements from uncorrected anterior segment optical coherence tomography (AS-OCT) images are inaccurate because of spatial and optical distortions. Prior reported distortion correction equations for the Visante AS-OCT were not reproducible. The goal was to calculate the distortions and provide equations to correct corneal parameters for the Visante AS-OCT to get a central corneal radius of curvature from young and older subjects. Five contact lenses (CLs) of known front and back radii of curvature and central thickness were imaged using the Visante AS-OCT (Carl Zeiss, Dublin, CA). Contact lens surface coordinates from Visante images were identified and fitted with a circle using custom Matlab image analysis software. Spatial and optical distortions of the Visante image of the CL radii of curvature and thickness were calculated and corrected. Visante images were also captured from 24 younger (aged 21 to 36 years) and 30 older (aged 36 to 48 years) human subjects. Corneal radii of curvature and thickness measurements from these subjects were corrected, and intrasession and intersession repeatabilities of the corneal parameters were calculated. Root mean square error of radius and power of the CL surfaces after distortion correction were 0.02 mm and 0.18D for the front and 0.011 mm and 0.11D for the back, respectively. Intraclass correlation coefficient for intrasession and intersession repeatability for all the corneal parameters from the human subjects was greater than 0.88 in both age groups. A distortion correction algorithm was developed for the Visante AS-OCT and applied to extract human corneal radius of curvature measurements.

Imaging of filtering blebs after implantation of the Ex-PRESS shunt with the use of the Visante optical coherence tomography.

To analyze the features of the filtering blebs following implantation of the Ex-PRESS glaucoma device (model P-50) with the aid of the Visante anterior segment optical coherence tomography (AS-OCT). Five patients with open angle glaucomas were included in the study. They all underwent implantation of the Ex-PRESS device under a scleral flap. The surgical procedure was augmented with the use of mitomycin C subconjunctivally. The filtering blebs were analyzed with the Visante AS-OCT with the scans taken along the axis of the implantation of the glaucoma device. All filtering blebs were graded as diffuse functioning. The morphological characteristics of the blebs were similar to those of the trabeculectomy. However the use of the Ex-PRESS implant tend to form a characteristic episcleral lake at the site of the plate of the implant. The use of the Ex-PRESS implant produces filtering blebs similar to those of the trabeculectomy with the formation of a characteristic episcleral lake at the site of the plate of the implant.

A program to analyse optical coherence tomography images of the ciliary muscle.

To describe and validate bespoke software designed to extract morphometric data from ciliary muscle Visante Anterior Segment Optical Coherence Tomography (AS-OCT) images. Initially, to ensure the software was capable of appropriately applying tiered refractive index corrections and accurately measuring orthogonal and oblique parameters, 5 sets of custom-made rigid gas-permeable lenses aligned to simulate the sclera and ciliary muscle were imaged by the Visante AS-OCT and were analysed by the software. Human temporal ciliary muscle data from 50 participants extracted via the internal Visante AS-OCT caliper method and the software were compared. The repeatability of the software was also investigated by imaging the temporal ciliary muscle of 10 participants on 2 occasions. The mean difference between the software and the absolute thickness measurements of the rigid gas-permeable lenses were not statistically significantly different from 0 (t=-1.458, p=0.151). Good correspondence was observed between human ciliary muscle measurements obtained by the software and the internal Visante AS-OCT calipers (maximum thickness t=-0.864, p=0.392, total length t=0.860, p=0.394). The software extracted highly repeatable ciliary muscle measurements (variability ≤6% of mean value). The bespoke software is capable of extracting accurate and repeatable ciliary muscle measurements and is suitable for analysing large data sets.

Reproducibility of Angle Metrics Using the Time-Domain Anterior Segment Optical Coherence Tomography: Intra-Observer and Inter-Observer Variability

Purpose: To evaluate the reproducibility of anterior chamber angle measurements obtained by the Zeiss Visante anterior segment optical coherence tomography (AS-OCT).Methods: Twenty eyes from 20 normal subjects with open anterior chamber angles were studied. The anterior chamber angle was imaged using the Visante AS-OCT. The angle-opening distance (AOD 500, AOD 750), trabercular iris space area (TISA 500, TISA 750) and scleral spur angle (SS angle) at the inferior angle location were measured. All the subjects underwent imaging in a darkened room (1 foot candles measured at the eye). Images were graded in a masked fashion by certified Doheny Image Reading Center graders. For intra-grader reproducibility assessments, images were re-graded by the same grader 1 week later after random sorting of images. For inter-grader assessments, a second masked grader independently reviewed the images. Intraclass correlation coefficients (ICC) were used to assess reproducibility.Results: Inferior angle measurements of AOD (500, 750), TISA (500, 750) and SS angle for 20 normal eyes were calculated. The intra-observer ICC calculations showed excellent reproducibility for all measurements (AOD 500 = 0.95, AOD 750 = 0.97, TISA 500 = 0.93, TISA 750 = 0.94, SS = 0.96; p < 0.001 for all). The inter-observer ICC calculations showed lower reproducibility for all measurements (AOD 500 = 0.71, p < 0.001; AOD 750 = 0.82, p < 0.001; TISA 500 = 0.49, p = 0.08; TISA 750 = 0.61, p = 0.02; SS = 0.75).Conclusion: Determination of anterior chamber angle measurements was possible with the time-domain AS-OCT, but only modest inter-observer reproducibility was found even among experienced graders.

Anterior Segment Biometry Using Spectral-Domain Optical Coherence Tomography

To compare the anterior chamber and anterior chamber angle measurements obtained with spectral-domain anterior segment optical coherence tomography (AS-OCT) and time-domain AS-OCT. The anterior chamber of healthy participants was imaged with spectral-domain AS-OCT (Casia SS-1000; Tomey, Nagoya, Japan) and time-domain AS-OCT (Visante; Carl Zeiss Meditec, Dublin, CA). Central corneal thickness (CCT), anterior chamber depth (ACD), angle opening distance at 500 and 750 μm (AOD 500 and AOD 750), trabecular iris space area at 500 and 750 μm (TISA 500 and TISA 750), and scleral spur angle were measured. The intraclass correlation coefficients (ICCs) were calculated. The Pearson correlation test was used to evaluate the correlation between the measurements and Bland-Altman plots to evaluate the agreement. One hundred one eyes of 101 healthy participants were analyzed. Excellent repeatability was found with both devices for CCT, AOD 500, AOD 750, TISA 750, and scleral spur angle (ICC = 0.90 to 0.98 and 0.89 to 0.97, respectively) and excellent to moderate repeatability was found for TISA 500 (ICC = 0.68 to 0.97 and 0.70 to 0.93, respectively). For all parameters, Casia and Visante measurements were significantly correlated (r = 0.76 to 0.98; P < .02). ACD measured with the Casia was significantly larger (mean difference = 0.12 ± 0.08 mm; P < .0001), and the scleral spur angle measured with the Casia was significantly lower (mean difference = 4.85° ± 5.30°; P < .01). There were nonsignificant differences between the devices for the other parameters (P > .06). Both Casia and Visante AS-OCT demonstrate high repeatability. Except for the ACD and scleral spur angles, the two devices show good agreement.

Anterior segment OCT imaging in mucopolysaccharidoses type I, II, and VI

To describe the anterior segment optical coherence tomography (AS-OCT) characteristics of patients with ocular manifestations of mucopolysaccharidoses type I (Hurler), II (Hunter), and VI (Maroteaux-Lamy). Prospective, observational study of nine consecutive patients with variants of mucopolysaccharidosis (MPS) attending the Paediatric Ophthalmology service at Manchester Royal Eye Hospital, UK. All patients underwent Visante AS-OCT imaging as part of their ophthalmic assessment. Ocular involvement tended to be symmetrical. Angle-to-angle distance was significantly lower in MPS VI than in MPS I (P=0.04). Anterior chamber depth, angle opening distance, trabecular-iris space area, and scleral spur angle tended to be lower in MPS VI than in MPS I, but did not reach statistical significance. Corneal thickness in the central 0-2 mm zone was greater in MPS VI than in MPS I, approaching but not attaining statistical significance (P=0.07). The 2-5 and 5-7 mm zones were significantly thicker in MPS VI than MPS I (P=0.04, P=0.04). There was no difference in corneal thickness between MPS I and MPS VI in the peripheral 7-10 mm zone (P=0.57). Measurements of the patient with MPS II resembled the mean values of the MPS I group. AS-OCT is valuable in quantifying anterior segment pathology in MPS. It suggests more crowded anterior segments and greater corneal thickness in patients with MPS VI than MPS I. AS-OCT is useful in evaluating the risk and mechanism of glaucoma in MPS patients, and may improve our assessment of the efficacy of systemic treatment.

Application of anterior segment optical coherence tomography in glaucoma

Optical coherence tomography (OCT) is a cross-sectional, three-dimensional, high-resolution imaging modality that uses low coherence interferometry to achieve axial resolution in the range of 3–20 μm. Two OCT platforms have been developed: time domain (TD-OCT) and spectral (or Fourier) domain (SD/FD-OCT). Visante anterior segment OCT (Carl Zeiss Meditec) is a TD-OCT widely used for anterior segment imaging. The SD-OCT systems with both posterior and anterior segment imaging capabilities include the RTVue, iVue (Optovue), the Cirrus (Carl Zeiss Meditec), and the Spectralis (Heidelberg Engineering, Inc.). Each of the SD-OCTs has a wavelength in the range of 820–879 nm. Anterior segment OCT is a non-contact method providing high resolution tomographic cross-sectional imaging of anterior segment structures. Anterior segment OCT provides qualitative and quantitative assessment of the anterior segment structures important to the pathogenesis and the anatomical variations of glaucoma, and the approach to and success of treatment. We summarize the clinical applications of anterior segment OCT in glaucoma.

Correlation of central corneal thickness measurements using Topcon TRK‐1P, Zeiss Visante AS‐OCT and DGH Pachmate 55 handheld ultrasonic pachymeter

BackgroundCorneal pachymetry is an important aspect of modern eye care. This study aims to compare the measurement of central corneal thickness (CCT) using automated optical pachymetry, anterior segment optical coherence tomography (AS-OCT) and ultrasound.MethodsFifty volunteers participated in this study. Central corneal thickness was measured using the Topcon TRK-1P (Topcon, Tokyo, Japan) automated optical pachymeter, the Visante AS-OCT (Carl Ziess Meditec, Dublin, CA, USA) and the Pachmate 55 handheld ultrasonic pachymeter (DGH, Exton, PA, USA). Pearson correlation coefficients were calculated to compare automated optical pachymetry and AS-OCT with ultrasound. Bland–Altman plots were generated and limits of agreement (LOA) calculated.ResultsFifty eyes were measured for comparison. The mean and standard deviation of the CCT measured by optical pachymetry was 523.7 ± 42.3 μm (range: 412 to 594), 536.0 ± 36.9 μm (range: 425 to 607) for AS-OCT and 553.4 ± 40.7 μm (range: 431 to 630) for ultrasound. Comparison of optical pachymetry and AS-OCT with ultrasound, generated Pearson correlation coefficients of 0.96 and 0.98, respectively. Measurements using optical pachymetry and AS-OCT were consistently lower than when measuring with ultrasound. Bland–Altman plots revealed mean differences of 29.7 μm between optical pachymetry and ultrasound (LOA ‐5.4 to ‐54.1) and of 17.4 μm (LOA +0.9 to ‐35.7) between and ultrasound.ConclusionDue to AS-OCT and automated optical pachymetry consistently measuring lower than ultrasound, it should be noted that these devices are not interchangeable in clinical practice.

Factors Affecting Corneoscleral Topography

To evaluate factors affecting corneoscleral profile (CSP) using anterior segment optical coherence tomography (AS-OCT) in combination with conventional videokeratoscopy. OCT DATA WERE COLLECTED FROM 204 SUBJECTS OF MEAN AGE 34.9 YEARS (SD: ±15.2 years, range 18-65) using the Zeiss Visante AS-OCT and Medmont M300 corneal topographer. Measurements of corneal diameter (CD), corneal sagittal height (CS), iris diameter (ID), corneoscleral junction angle (CSJ), and scleral radius (SR) were extracted from multiple OCT images. Horizontal visible iris diameter (HVID) and vertical palpebral aperture (PA) were measured using a slit lamp graticule. Subject body height was also measured. Associations were then sought between CSP variables and age, height, ethnicity, sex, and refractive error. Significant correlations were found between age and ocular topography variables of HVID, PA, CSJ, SR, and ID (P < 0.0001), while height correlated with HVID, CD, and ID, and power vector terms with vertical plane keratometry, CD, and CS. Significant differences were noted between ethnicities with respect to CD (P = 0.0046), horizontal and vertical CS (P = 0.0068 and P = 0.0095), and horizontal ID (P = 0.0010). The same variables, with the exception of vertical CS, also varied with sex; horizontal CD (P = 0.0018), horizontal CS (P = 0.0018), and ID (P = 0.0012). Age accounted for the greatest variance in topography variables (36%). Age is the main factor influencing CSP; this should be taken into consideration in contact lens design, IOL selection, and in the optimization of surgical procedures. Ocular topography also varied with height, sex, ethnicity, and refractive error.

Assessment of the Anterior Chamber Angle in Patients with Nanophthalmos: An Anterior Segment Optical Coherence Tomography Study

ABSTRACTPurpose: To quantitatively assess the parameters of anterior chamber and angle dimensions by anterior segment optical coherence tomography (AS-OCT) in nanophthalmos.Methods: In this prospective, cross-sectional and comparative study, 34 eyes of 34 healthy individuals (control group) and 37 eyes of 37 patients with nanophthalmos (study group) were enrolled. A single experienced ophthalmologist imaged and measured the right eye with the Visante AS-OCT. The anterior chamber angle (ACA), angle opening distance (AOD) at 500 and 750 µm from the scleral spur, and trabecular–iris space area (TISA) at 500 and 750 µm at the nasal and temporal angles were measured.Results: Mean nasal/temporal ACA was 44.90 ± 9.09/47.07 ± 8.69° in the control group and 32.15 ± 10.30/29.77 ± 10.57° in the study group (p < 0.001). Mean nasal/temporal AOD500 and AOD750 was 0.52 ± 0.18/0.53 ± 0.15 mm and 0.71 ± 0.26/0.71 ± 0.23 mm in the control group. The mean nasal/temporal AOD500 and AOD750 were 0.33 ± 0.12/0.31 ± 0.15 mm and 0.48 ± 0.16/0.47 ± 0.22 mm in the study group. Mean nasal/temporal TISA500 and TISA750 were 0.16 ± 0.06/0.17 ± 0.05 mm2 and 0.31 ± 0.11/0.33 ± 0.09 mm2 in the control group. Mean nasal/temporal TISA500 and TISA750 were 0.11 ± 0.04/0.09 ± 0.05 mm2 and 0.20 ± 0.07/0.20 ± 0.10 mm2 in the study group. All values were significantly lower in the study group compared with the control group.Conclusion: Determination of angle parameters using AS-OCT is a rapid noncontact method that is useful in patients with nanophthalmos. The findings demonstrated that nanophthalmic eyes had lower ACA parameters including ACA, AOD500, AOD750, TISA500 and TISA750 at the nasal and temporal angles.

Analysis of iris structure and iridocorneal angle parameters with anterior segment optical coherence tomography in Fuchs’ uveitis syndrome

To evaluate the differences in the biometric parameters of iridocorneal angle and iris structure measured by anterior segment optical coherence tomography (AS-OCT) in Fuchs' uveitis syndrome (FUS). Seventy-six eyes of 38 consecutive patients with the diagnosis of unilateral FUS were recruited into this prospective, cross-sectional and comparative study. After a complete ocular examination, anterior segment biometric parameters were measured by Visante(®) AS-OCT. All parameters were compared between the two eyes of each patient statistically. The mean age of the 38 subjects was 32.5 ± 7.5 years (18 female and 20 male). The mean visual acuity was lower in eyes with FUS (0.55 ± 0.31) than in healthy eyes (0.93 ± 0.17). The central corneal thickness did not differ significantly between eyes. All iridocorneal angle parameters (angle-opening distance 500 and 750, scleral spur angle, trabecular-iris space (TISA) 500 and 750) except TISA 500 in temporal quadrant were significantly larger in eyes with FUS than in healthy eyes. Anterior chamber depth was deeper in the eyes with FUS than in the unaffected eyes. With regard to iris measurements, iris thickness in the thickest part, iris bowing and iris shape were all statistically different between the affected eye and the healthy eye in individual patients with FUS. However, no statistically significant differences were evident in iris thickness 500 μm, thickness in the middle and iris length. There were significant difference in iris shape between the two eyes of patients with glaucoma. AS-OCT as an imaging method provides us with many informative resultsin the analysis of anterior segment parameters in FUS.

Accommodative changes in anterior chamber depth in patients with high myopia

To study the accommodative changes in the central anterior chamber depth (ACD) in patients with high myopia using anterior segment optical coherence tomography (AS-OCT). Cataract Surgery Department and Clinical & Functional Diagnostics Department, S. Fyodorov Eye Microsurgery Complex-Federal State Institution, Moscow, Russian Federation. Prospective case-control study. The ACD measurements were obtained in the nonaccommodative state (baseline) and during accommodation using the Visante AS-OCT device. Thirty-six myopic eyes (36 patients; mean age 27 years; mean spherical equivalent (SE) -12.52 diopters [D]) and 31 emmetropic eyes (31 subjects; mean age 26 years; mean SE -0.39 D) were examined. At baseline, the mean ACD in both groups was similar. During accommodation, the mean maximum changes in the ACD were significantly less pronounced in the myopia group (-0.14 mm ± 0.07 [SD]; range -0.03 to -0.29 mm) than in the emmetropia group (-0.22 ± 0.08 mm; range -0.04 to -0.35 mm) (P<.0001). Ten patients in the myopia group had a critically shallow anterior chamber (ACD <2.8 mm) in the state of accommodation. Accommodative changes in the ACD were significantly less pronounced in eyes with high myopia than in emmetropic eyes. Still, the anterior chamber might become critically shallow during accommodation in some myopic eyes, and this should be taken into account when planning phakic intraocular lens implantation to correct high myopia. No author has a financial or proprietary interest in any material or method mentioned.

Epithelial Ingrowth After Descemet Stripping Automated Endothelial Keratoplasty: Description of Cases and Assessment With Anterior Segment Optical Coherence Tomography

To describe 5 cases of epithelial ingrowth after Descemet stripping automated endothelial keratoplasty (DSAEK) and the use of anterior segment optical coherence tomography (AS-OCT) to describe the areas of ingrowth. Five cases with epithelial ingrowth after DSAEK were examined with commercially available AS-OCT and/or a novel custom-built ultrahigh resolution (UHR) AS-OCT. Argon laser photocoagulation was also used to confirm epithelial ingrowth on the iris surface. Pathological evidence of epithelial ingrowth was noted in an eye that underwent corneoscleral grafting for extensive ingrowth through a fistulous tract. Epithelial ingrowth was solely in the graft-host interface in 1 case and in both the interface and retrocorneal and iris surfaces in 4 cases. Argon laser photocoagulation on the iris confirmed epithelial ingrowth in 4 cases. The areas of epithelial ingrowth were imaged in 1 case with the Visante AS-OCT and in 3 cases with an UHR-OCT. In 1 case, block excision with corneoscleral grafting was required. Epithelial ingrowth can occur after DSAEK. This series reports 5 cases of epithelial ingrowth into the interface and/or the retrocorneal surface after DSAEK. Imaging with AS-OCT, specifically the UHR-OCT, and argon laser photocoagulation can help confirm the diagnosis. UHR-OCT imaging of the interface and retrocorneal surfaces can provide clues to the origin of epithelial ingrowth. Four cases were observed. One case underwent corneoscleral grafting with histological confirmation of epithelial ingrowth.

Laser in situ keratomileusis flap measurements: Comparison between observers and between spectral-domain and time-domain anterior segment optical coherence tomography

To evaluate the between-observer (interobserver) and between-instrument (intraobserver) variability in flap thickness measurements after laser in situ keratomileusis (LASIK) using spectral-domain and time-domain anterior segment optical coherence tomography (AS-OCT). Singapore National Eye Centre. Evaluation of diagnostic test or technology. Two independent masked observers measured flap thickness 1 month after LASIK using spectral-domain (RTVue) or time-domain (Visante) AS-OCT. The measurements were taken at central (0.0 mm), -1.5 mm, and +1.5 mm locations. Measurements were repeated to assess between-instrument variability. There was no statistically significant difference in mean flap thickness between the 2 observers at -1.5 mm, 0.0 mm, and +1.5 mm on spectral-domain AS-OCT and at -1.5 mm and +1.5 mm on time-domain AS-OCT (P < .01). There was a statistically significant difference between the 2 observers in the central (0.0 mm) values on time-domain AS-OCT (P=.0008). There was stronger interobserver correlation for spectral-domain AS-OCT at -1.5 mm (r = 0.82), 0.0 mm (r = 0.88), and +1.5 mm (r = 0.88) than for time-domain AS-OCT (r = 0.73, r = 0.62, and r = 0.79, respectively). There was no statistically significant difference in between-instrument measurements. There was stronger between-instrument correlation with spectral-domain AS-OCT than with time-domain AS-OCT at all locations. The mean standard deviation (measure of instrument repeatability) for spectral-domain AS-OCT was 4.19 μm. Spectral-domain AS-OCT had closer agreement in between-observer and between-instrument measurements than time-domain AS-OCT and provided more consistent measurements of post-LASIK flap thickness.