Swept-source Anterior Segment Optical Coherence Tomography Research Articles

Anterior Vitreous Objective Assessment in Uveitis: An Anterior Segment Swept Source Optical Coherence Tomography Study

ABSTRACT Purpose To assess inflammatory changes in the anterior vitreous (AV) using a swept source anterior segment optical coherence tomography (SS-ASOCT) and to correlate them with uveitis features and clinical grading of intraocular inflammation. Methods 140 eyes from 96 patients were included in this observational, cross-sectional study: 40 ACTIVE uveitis, 40 INACTIVE uveitis and 60 CONTROLS. All eyes underwent intraocular inflammation clinical grading (anterior chamber (AC) cells counting and vitreous haze evaluation) and AV imaging with SS-ASOCT. Cells seen in the AV on OCT were manually counted using imageJ. Vitreous reflectivity variation was indirectly measured by calculating the vitreous/iris pigment epithelium (VIT/IPE) relative intensity. These OCT-based parameters were compared across the groups and correlated with inflammation clinical grading. Results The mean [SD] number of AV OCT cells was significantly higher (both p < 0.001) in ACTIVE uveitis (12[9.8]) compared to INACTIVE uveitis (4.5[3.5]) and CONTROLS (4[3.1]). In ACTIVE uveitis the number of AV OCT cells was significantly and positively correlated with the AC cells (p = 0.04), the VIT/IPE relative intensity (p = 0.0002), the uveitis anatomical classification (INTERMEDIATE UVEITIS, p = 0.02) and the vitreous haze clinical grading (p < 0.0001). The mean[SD] VIT/IPE relative intensity of the AV increased from CONTROLS (0.12[0.01]) to INACTIVE uveitis (0.15[0.01]) to ACTIVE uveitis (0.17[0.02]), but with no statistically significant differences. Conclusions We were able to visualize and objectively evaluate changes occurring in the AV in eyes with uveitis by means of a commercially available SS-ASOCT. OCT-cells in the AV could represent an adjunctive tool in the objective evaluation of intraocular inflammation.

Assessment of Changes in Cap and Residual Stromal Thickness Values during a 6-Month Observation after Refractive Lenticule Extraction Small Incision Lenticule Extraction.

Background: In this study, the changes in corneal cap and residual stromal thickness (RST) values during a 180-day observation period after refractive lenticule extraction small incision lenticule extraction (ReLEx SMILE) were assessed. Methods: Fifty patients underwent ReLEx SMILE using the VisuMax 500 femtosecond laser, with corneal imaging conducted pre and post procedure via anterior segment optical coherence tomography (AS-OCT). Cap thickness in the center and 1.5 mm from the center in four meridians was measured at various intervals. Results: The results showed a significant decrease in cap thickness 180 days post procedure compared to earlier intervals (p < 0.05). Similarly, RST decreased gradually and significantly post procedure (p < 0.05). Notably, changes in cap thickness within the central 1.5 mm area were more dynamic than RST changes during the 6-month observation period following SMILE. Conclusions: The corneal cap thickness measured with swept-source AS-OCT within the central 1.5 mm area underwent more dynamic changes than the residual stromal thickness during the 6-month observation following SMILE.

Establishing the Normative Data Set Necessary for Imaging-Based Childhood Uveitis Surveillance: A Cross-Sectional Study.

Anterior segment optical coherence tomography (AS-OCT) is an emerging diagnostic and monitoring tool for anterior uveitis. We investigated AS-OCT findings in the eyes of a large, diverse population of children free of uveitis to establish its potential to "rule out" accurately those without disease. In this cross-sectional observational study, image acquisition was performed with swept source AS-OCT (Heidelberg Anterion), using a protocol of 13 B-scans per volume, from 217 children (434 eyes) aged 5 to 15years, with analysis of acquired images (identification of apparent inflammatory cells, or "cell events") by multiple graders. Outcomes of interest were median and maximum cell event count (MEDCC, MAXCC) per B-scan from each eye and the total cell event count (TCC) per volume scan. At least one cell event was detected in volume scans of 76% of eyes (329/434) and 87% of children (189/217). The maximum number (MAXCC) per scan ranged from 0 to 6 (median, 2). There was a strong positive association between increasing age (years) and the number of cell events detected within a volume scan following adjustment for gender and iris color (adjusted regression coefficient for TCC 0.5; P < 0.0001; 95% confidence interval, 0.4-0.7). Our findings demonstrate that apparent inflammatory cells are detectable on AS-OCT in the apparently healthy eyes of children and furthermore suggest early life developmental changes in blood-iris barrier stability that merit further exploration. We provide the foundation for the normative data set necessary for establishing the clinical utility of AS-OCT for surveillance of children with inflammatory eye diseases.

Documentation of capsular block syndrome with swept-source anterior segment optical coherence tomography

A turbid white fluid was noticed in the retrolental space in the right eye of a 57-year-old male who had undergone cataract surgery 4 years ago. With clinical suspicion of capsular block syndrome (CBS), a swept-source anterior segment optical coherence tomography (SS-ASOCT) was conducted. Hyperreflective echo was detected between the posterior surface of the intraocular lens and the posterior capsule. Prompt relief from CBS was achieved through Nd: YAG laser treatment. The advent of SS-ASOCT allows rapid and detailed assessment of the eye’s anterior segment owing to its deeper ocular tissue penetration and better axial resolution within a few seconds.

Study 3: Anterior segment optical coherence tomography-guided surgical approach in slipped medial rectus muscle.

To discuss the novel swept-source anterior segment optical coherence tomography (SS-ASOCT)-guided surgical approach in slipped medial rectus muscles. Prospectively (between February 2020 and July 2022), six patients with a clinical suspicion of slipped medial rectus muscle were recruited. After complete ophthalmic and orthoptic evaluation, the missing medial rectus muscle is screened using Anterior Segment Optical Coherence Tomography (ASOCT). In presence of a traceable muscle, its morphology, depth, and distance from a fixed anatomical landmarks were noted; in its absence, the status of other recti was noted. Intraoperatively, the features were confirmed and the intended intervention was performed. The mean age of six patients was 25.66 ± 9.72 years, two with surgical trauma and four with penetrating trauma (66.66%). In five patients, the ASOCT traced the slipped medial rectus muscle successfully (83.33%); intraoperatively, the same was confirmed (within 1-2 millimeters) with favorable outcomes. ASOCT made a significant contribution in all subjects by reducing the number of interventions and muscle surgeries. In eyes with slipped medial rectus muscle, especially those which are within a finite distance from the angle can be traced using ASOCT. This approach impacts the outcomes in many ways.

Efficacy and safety of laser peripheral iridoplasty with different energy levels and locations in the treatment of primary angle closure disease assessed by swept-source anterior segment optical coherence tomography

BackgroundTo explore the efficacy and safety of laser peripheral iridoplasty (LPIp) with different energy levels and locations in the treatment of primary angle closure disease (PACD) assessed by swept-source anterior segment optical coherence tomography (AS-OCT).MethodsWe enrolled patients with PACD following best-corrected visual acuity (BCVA), intraocular pressure (IOP), anterior chamber gonioscopy, ultrasound biomicroscopy(UBM), optic disc OCT, and visual field examinations. After Pentacam and AS-OCT measurements, the patients were randomly divided into four treatment groups for LPIp with two different energy levels (high vs. low energy) and two locations (far from the periphery vs. near the periphery) and combined with laser peripheral iridotomy. BCVA, IOP, pupil diameter, central anterior chamber depth, anterior chamber volume, anterior opening distance (AOD)500, AOD750, trabecular iris angle (TIA)500, and TIA750 in four quadrants before and after laser treatment were compared.ResultsWe followed up 32 patients (64 eyes; average age, 61.80 ± 9.79 years; 8 patients/16 eyes per group) for up to 2 years. The IOP of all enrolled patients was decreased after surgery compared to that before (t = 3.297, P = 0.002), the volume of the anterior chamber was increased (t=-2.047, P = 0.047), and AOD500, AOD750, TIA500, and TIA750 were increased (all P < 0.05). Within-group comparisons showed that BCVA in the low-energy/far-periphery group was improved after surgery (P < 0.05). After surgery, the IOP was decreased in the two high-energy groups, whereas the volume of the anterior chamber, AOD500, AOD750, TIA500, and TIA750 were increased in all groups (all P < 0.05). However, when comparing every two groups, the high-energy/far-periphery group showed a stronger effect on pupil dilation than the low-energy/near-periphery group (P = 0.045). The anterior chamber volume in the high-energy/near-periphery group was larger than that in the high-energy/far-periphery group (P = 0.038). The change in TIA500 was for 6 points smaller in the low-energy/near-periphery group than in the low-energy/far-periphery group (P = 0.038). Other parameters showed no significant group differences.ConclusionLPIp combined with iridotomy can effectively reduce IOP, increase anterior chamber volume, increase chamber angle opening distance, and widen the trabecular iris angle. Intraoperatively, high-energy laser spots positioned one spot diameter from the scleral spur can obtain the best effect and safety. Swept-source AS-OCT can safely and effectively quantify the anterior chamber angle.

Imaging of anterior vitreous inflammation with swept-source anterior segment OCT

A 54-year-old male with panuveitis presented with 2+ vitreous haze, 2+ vitreous cells and vitreous opacities (A). Swept-source anterior segment optical coherence tomography (AS-OCT) (ANTERION, Heidelberg Engineering) imaging demonstrated hyperreflective foci suggestive of vitreous cells and vitreous opacities (white arrows, A-B) in the anterior vitreous. Following treatment with prednisone, exam demonstrated resolved vitreous opacities, 0.5+ vitreous haze, and 0.5+ vitreous cells (C), corresponding to a decrease in hyperreflective areas seen with AS-OCT (D). Despite posterior synechiae, swept source AS-OCT permitted high-resolution visualization of the anterior vitreous. With further image processing and analysis, this suggests a potential utility of AS-OCT for the objective longitudinal evaluation and monitoring of anterior vitreous inflammation.

Swept-source optical coherence tomography detects anterior-chamber changes in patients with angle-closure after laser peripheral iridotomy

Purpose: This study aimed to compare anterior-chamber parameters acquired by a swept-source anterior-segment optical coherence tomography before and after laser peripheral iridotomy. Methods: This study prospectively evaluated 14 patients with primary-angle closure and six patients with primary-angle closure glaucoma. Gonioscopy and anterior-segment optical coherence tomography using the DRI OCT Triton® were performed before and after laser peripheral iridotomy. Anterior-segment optical coherence tomography parameters were studied using scleral spur as reference: angle opening distance at 250, 500, and 750 µm, trabecular-iris space at 500 µm, trabecular-iris angle, trabecular-iris contact length, and iris curvature. Result: Anterior-segment optical coherence tomography identified 61% of the patients with two or more quadrants closed. Gonioscopy identified more closed angles than anterior-segment optical coherence tomography before laser peripheral iridotomy. In angle parameters, only the angle opening distance of 250 µm at the nasal quadrant was not significantly increased after laser peripheral iridotomy. The iris curvature and trabecular-iris contact length showed a significant reduction induced by the laser procedure. Even in eyes in which gonioscopy did not identify angular widening after laser peripheral iridotomy (n=7), the angle opening distance of 750 µm increased (nasal, 0.15 ± 0.10 mm to 0.27 ± 0.16 mm, p=0.01; temporal, 0.14 ± 0.11 mm to 0.25 ± 0.12 mm, p=0.001) and the iris curvature decreased (nasal, 0.25 ± 0.04 mm vs. 0.11 ± 0.07 mm, p=0.02; temporal, 0.25 ± 0.07 mm vs. 0.14 ± 0.08 mm, p=0.007). Conclusion: Anterior-chamber changes induced by laser peripheral iridotomy could be quantitatively evaluated and documented by DRI OCT Triton®.

Crystalline lens decentration and tilt in eyes with different axial lengths and their associated factors.

To analyze crystalline lens decentration and tilt in eyes with different axial lengths (ALs) using a swept-source anterior segment optical coherence tomography (SS-AS-OCT). Patients with normal right eyes who visited our hospital between December 2020 and January 2021 were included in this cross-sectional study. Data on crystalline lens decentration and tilt, AL, aqueous depth (AD), central corneal thickness (CCT), lens thickness (LT), lens vault (LV), anterior chamber width (ACW), and angle κ were collected. A total of 252 patients were included and divided into normal (n = 82), medium-long (n = 89), and long (n = 81) AL groups. The average age of these patients was 43.63 ± 17.02 years. The crystalline lens decentration (0.16 ± 0.08, 0.16 ± 0.09, and 0.20 ± 0.09 mm, P = 0.009) and tilt (4.58° ± 1.42°, 4.06° ± 1.32°, and 2.84° ± 1.19°, P < 0.001) were significantly different among the normal, medium, and long AL groups. Crystalline lens decentration was correlated with AL (r = 0.466, P = 0.004), AD (r = 0.358, P = 0.006), ACW (r = -0.004, P = 0.020), LT (r = -0.141, P = 0.013), and LV (r = -0.371, P = 0.003). Crystalline lens tilt was correlated with age (r = 0.312, P < 0.001), AL (r = -0.592, P < 0.001), AD (r = -0.436, P < 0.001), ACW (r = -0.018, P = 0.004), LT (r = 0.216, P = 0.001), and LV (r = 0.311, P = 0.003). Crystalline lens decentration was positively correlated with AL, and tilt was negatively correlated with AL.

Anterior Segment and Macular OCT in Alport Syndrome

The authors examined a 48-year-old White man with genetically confirmed diagnosis of X-linked Alport syndrome. His vision was 20/25 Snellen in both eyes, while anterior segment examination revealed bilateral anterior lenticonus (Fig A). High-resolution swept-source anterior segment OCT (Anterion, Heidelberg Engineering) showed anterior bulging of the lens in greater detail (Fig B). Fundus photography documented peri-macular dot-and-fleck retinopathy giving rise to the typical “lozenge-sign” (Fig C, Eidon, Centervue) caused by the hyperreflectivity and thickening of the internal limiting membrane.

Anterior segment characteristics in normal and keratoconus eyes evaluated with a new type of swept-source optical coherence tomography.

This study aimed to evaluate and compare the discriminating ability of corneal elevation maps generated using a swept-source optical coherence tomography (SS-OCT) (SS-OCT ANTERION, Heidelberg Engineering, Heidelberg, Germany), which was estimated with different reference surfaces, to distinguish normal corneas from those with keratoconus and keratoconus suspect. A total of 126 eyes of patients, which comprised 43, 37, and 46 keratoconus, keratoconus suspects, and normal controls, respectively, were included in this study. The anterior and posterior elevations at the thinnest point under the best-fit sphere (BFS) and toric-ellipsoid (BFT), respectively, and other corneal parameters were measured using the SS-OCT. In addition, the receiver operating characteristic (ROC) curve analysis and cut-off value were calculated to evaluate the diagnostic ability of the corneal elevation values in differentiating keratoconus and keratoconus suspects from normal eyes. The mean total keratometric and corneal elevation values were significantly higher in the keratoconus group than in the other groups. Pachymetric parameters exhibited the lowest values for keratoconus. In addition, ROC curve analyses showed a high accuracy of the thinnest point anterior and posterior BFT for both keratoconus and keratoconus suspects and normal controls (area under the ROC were 0.969 and 0.961, respectively). Furthermore, the optimal cut-off point of the posterior elevation at the thinnest point under BFT was 16.44 μm (sensitivity and specificity of 86% and 98%, respectively) for differentiating keratoconus from normal and keratoconus suspect eyes. The elevation map using the BFS and BFT references measured with the anterior segment SS-OCT is considered an effective indicator for keratoconus diagnosis. Therefore, the anterior segment SS-OCT can effectively differentiate keratoconus from suspected keratoconus and normal corneas by measuring parameters such as posterior and anterior elevations, pachymetry, and keratometry.

Comparative study of decentration, tilt and visual quality after implantation of aspherical intraocular lenses

Objective: To compare the difference of decentration and tilt among 4 kinds of aspherical intraocular lenses (IOLs), and to analyze their objective visual quality. Methods: Prospective non-randomized controlled clinical trial. Age-related cataract patients who planned to undergo phacoemulsification and IOL implantation in the Affiliated Hospital of North Sichuan Medical College from April to June in 2020 were divided into ZCB00 group, SN60WF group, A1-UV group, and AO group according to IOL types. Thirty right eyes and thirty left eyes were selected in each group. Before operation and at 1 day, 1 week and 1 month postoperatively, decentration and tilt values were measured by a new swept-source anterior-segment optical coherence tomography device (CASIA2), and wavefront aberrations, objective scatter index (OSI), modulation transfer function cut off frequency (MTF cut off) and Strehl ratio (SR) were also examined. Values of decentration, tilt and visual quality compared among 4 groups were took from the right eye. One-way analysis of variance was used for inter-group comparison, and repeated measurement one-way analysis of variance was used for intra-group comparison. Data between right eyes and left eyes from all the individuals were compared by independent sample t-test. Results: A total of 181 patients (240 eyes) were enrolled, and 169 patients (224 eyes) completed the follow-up (114 right eyes and 110 left eyes). There were 77 males and 92 females, with an age of (69±9) years. There was no significant difference in gender, age, axial length, decentration and tilt of crystalline lens and IOL power among 4 groups (all P>0.05). At 1 day, 1 week and 1 month postoperatively, there was significant difference in decentration value among 4 groups (F=7.11, 6.12, 4.66; all P<0.05). For further pairwise comparison, the decentration value of SN60WF group was higher than that of the other 3 groups at 1 day and 1 week postoperatively, and the decentration value of SN60WF group was (0.259±0.101) mm at 1 month postoperatively, which was higher than that of ZCB00 group (0.177±0.099) mm and AO group (0.163±0.122) mm, and the differences were statistically significant (using SNK-q test, both P<0.05). The IOL tilt value in the ZCB00 group, SN60WF group, A1-UV group, and AO group at 1 month postoperatively were (4.806±1.129)°, (5.080±1.309)°, (4.586±1.338)°, (5.112±1.406)°, respectively. No significant difference in tilt value among 4 groups was found at any time after surgery (all P>0.05). In each group, there was no significant difference in decentration and tilt value at different postoperative time points (all P>0.05). At 1 month postoperatively, there was no significant difference in decentration and tilt at horizontal and vertical directions respectively among 4 groups (all P>0.05), and in each group, there was no significant difference in decentration and tilt value between right eyes and left eyes (all P>0.05), and IOLs tended to tilt towards the inferonasal or inferotemporal direction in both eyes. With 4-mm and 6-mm pupil diameter, there was significant difference in internal (F=131.32, 85.17) and ocular (F=46.64, 47.55) spherical aberration among 4 groups (all P<0.01). For further pairwise comparison, the spherical aberration of AO group was higher than that of the other 3 groups, and the difference was statistically significant (using SNK-q test, all P<0.05). There was no significant difference in OSI, MTF cut off and SR among 4 groups (all P>0.05). Conclusions: The four types of IOLs show decentration and tilt in varying degrees after implantation in the capsular bag, but this difference do not lead to clinical significance. Human eyes have tolerance to mild decentration and tilt of aspheric IOLs, showing good visual quality.

Incidence and Risk Factors for Berger's Space Development after Uneventful Cataract Surgery: Evidence from Swept-Source Optical Coherence Tomography.

Background: This study investigates the incidence and risk factors for the development of Berger’s space (BS) after uneventful phacoemulsification based on swept-source optical coherence tomography (SS-OCT). Methods: Cataractous eyes captured using qualified SS-OCT images before and after uneventful phacoemulsification cataract surgery were included. Six high-resolution cross-sectional anterior segment SS-OCT images at 30° intervals were used for BS data measurements. BS width was measured at three points on each scanned meridian line: the central point line aligned with the cornea vertex and two point lines at the pupil’s margins. Results: A total of 223 eyes that underwent uneventful cataract surgery were evaluated. Preoperatively, only two eyes (2/223, 0.9%) were observed to have consistent BS in all six scanning directions. BS was observed postoperatively in 44 eyes (44/223, 19.7%). A total of 13 eyes (13/223, 5.8%) with insufficient image quality, pupil dilation, or lack of preoperative image data were excluded from the study. A total of 31 postoperative eyes with BS and 31 matched eyes without BS were included in the final data analysis. The smallest postoperative BS width was in the upper quadrant of the vertical meridian line (90°), with a mean value of 280 μm. The largest BS width was observed in the opposite area of the main clear corneal incision, with a mean value >500 μm. Conclusions: Uneven-width BS is observable after uneventful phacoemulsification. Locations with a much wider BS (indirect manifestation of Wieger zonular detachment) are predominantly located in the opposite direction to the main corneal incisions.

Iridian anterior segment OCT in rubella uveitis syndrome and cytomegalovirus anterior uveitis: a comparative study.

To compare iris affectation in cytomegalovirus anterior uveitis (CMVAU), rubella virus-associated uveitis (RVU), and healthy contralateral eyes, using swept-source anterior segment optical coherence tomography (SS-AS-OCT). A comparative, transversal, retrospective study examining 60 eyes from 30 patients-18 eyes (17 patients) with CMVAU, 14 eyes (13 patients) with RVU, and 28 healthy eyes-was performed. Six-millimeter cross-sectional SS-AS-OCT B-scans were obtained in each iris quadrant. Images were exported to ImageJ®. Qualitative and quantitative analyses were done: stromal thickness (ST), smooth index (SI), and optical density (OD) of pigment epithelium. Comparisons between measurements and clinical-demographic parameters were performed using SPSS®. Qualitative analysis showed extensive damage in iris stroma but was unable to differentiate between both uveitis. RVU eyes had a lower mean ST (315.72μm ± 42.4) compared to those with CMVAU (348.6μm ± 46) (p = 0.047) and a lower ST in the upper (338.9μm ± 38.52)/(386.25μm ± 47.2) (p = 0.005) and temporal (281.5μm ± 57.3)/(326.43μm ± 62.3) (p = 0.016) quadrants. Mean (0.94 ± 0.02)/(0.9 ± 0.03) (p = 0.001), temporal (0.94 ± 0.02)/(0.89 ± 0.03) (p < 0.001), and nasal SI (0.094 ± 0.02)/(0.9 ± 0.04) (p = 0.005) were higher in RVU. OD was similar in both uveitis. In healthy eyes, mean ST (376.8μm ± 39.7) was higher and mean SI was lower (0.87 ± 0.04) than in RVU (p < 0.001) and CMVAU eyes (p = 0.032). Mean OD was higher in healthy eyes (911 ± 130) than in CMVAU eyes (800 ± 200) (p = 0.037). The quantitative analysis of the SS-AS-OCT iris images allows for the differentiation between healthy eyes and those with CMVAU and RVU, as well as between both uveitis.

Tilt and decentration of posterior and anterior iris-claw intraocular lenses: a pilot study using anterior segment optical coherence tomography

BackgroundInformation on the centration and tilt of iris-claw intraocular lenses (IC-IOLs) is limited. In this study, we tested the capacity of an anterior segment optical coherence tomography (AS-OCT) instrument to measure decentration and tilt of anterior and posterior IC-IOLs through an integrated software.MethodsThe present observational, cross-sectional study was conducted at University Eye Clinic of Parma (Parma, Italy). The CASIA2 swept-source AS-OCT (Tomey Corp.) was used to measure the tilt and decentration of posterior and anterior IC-IOLs in patients implanted at least 6 months in advance. After failure with full-automation, semi-manual IOL tracing was applied. In-the-bag (IB) contralateral IOLs, when present, were measured automatically. The Bland-Altman method was used to evaluate the agreement between repeated measurements (2 images for each study eye). The amount and direction of tilt and decentration were recorded and plotted into polar charts for evaluation.ResultsA total of 21 patients were included: 14 with posterior and 7 with anterior IC-IOL fixation. In 17 eyes (81%), the AS-OCT provided a repeatable measurement of tilt and decentration. All contralateral eyes with IB IOL were automatically measured. The median decentration was 0.67 mm, 0.24 mm, and 0.24 mm in posterior IC-IOLs, anterior IC-IOLs, and IB IOLs group, respectively. The median tilt was 5.0°, 5.6°, and 5.6° for posterior IC-IOLs, anterior IC-IOLs, and IB IOLs, respectively. Tilt direction was mainly temporal, while decentration was inferior-temporal with posterior IC-IOLs and scattered with anterior IC-IOLs and IB IOLs.ConclusionsThe semi-manual tracing function of the CASIA2 AS-OCT provides repeatable and affordable measurements of the decentration and tilt of IC-IOLs in both the anterior and posterior chamber. Data from the former group were similar to the IB group.

Reproducibility of deep learning based scleral spur localisation and anterior chamber angle measurements from anterior segment optical coherence tomography images

AimsTo apply a deep learning model for automatic localisation of the scleral spur (SS) in anterior segment optical coherence tomography (AS-OCT) images and compare the reproducibility of anterior chamber angle...

Effect of Pterygium Removal Combined with Conjunctival Autograft on Corneal Parameters in Swept-Source Imaging.

Background: Both pterygium ingrowth and excision determine alterations in corneal topography. The aim of this study was to evaluate the influence of pterygium removal combined with conjunctival autografts in addition to the use of human fibrin tissue glue on changes in corneal parameters as measured by 3-D swept-source anterior segment optical coherence tomography (AS-OCT) imaging. Methods: Sixteen eyes (16 patients) with pterygium that qualified for surgical treatment were enrolled in this study. Eye examination, slit lamp, and 3-D AS-OCT (CASIA 2) assessment were performed before the surgery and 7 days, 1 month, and 6 months after pterygium excision. Topographic parameters of both anterior and posterior surfaces of the cornea were analysed at each follow-up visit. Results: The gradual decrease in total astigmatism power from preoperative median 2.75 (6.15) D to 1.2 (1.1) D at 6-month follow-up (p = 0.034) was noted from the day 7 visit. Values were strongly influenced by variations of anterior cornea astigmatism. In contrast, a gradual total HOA reduction at the 1-month (from median 0.79 (1.3) D to 0.44 (0.27) D; p = 0.038) and at 6-month visits (0.25 (0.09); p = 0.001) was observed. Similarly, values were strongly influenced by variations of the anterior. Additionally, total average keratometry values increased from preoperative 44.05 (2.25) D to 44.6 (1.9) (p = 0.043) 1 month after the surgery. Conclusions: Significant steepening of the anterior cornea and a reduction in both astigmatism and HOA were observed after pterygium excision. The anterior corneal surface was an essential component of the total postoperative corneal topography values. Three-dimensional swept-source AS-OCT imaging seems to be a valuable tool for monitoring both the progression of the disease and postoperative effects in pterygium eyes.

Lens Biometry in Congenital Lens Deformities: A Swept-Source Anterior Segment OCT Analysis.

Aims: To investigate the lens biometric parameters in congenital lens deformities, using a novel technique of swept-source anterior segment optical coherence tomography (SS-ASOCT).Methods: This prospective study included patients with microspherophakia (MSP), coloboma lentis (CL), and posterior lenticonus (PL). For this cohort, 360-degree high-resolution lens images were obtained using the latest SS-ASOCT (CASIA2, Tomey Corp, Nagoya, Japan). The lens biometric parameters were calculated by the CASIA2 built-in software for anterior lens radius (ALR), posterior lens radius (PLR), anteroposterior distance (APD), anterior chamber depth (ACD), equatorial diameter (Eq Dia), rear projection length (RPL), and maximum diameter of the lesion (MDL).Results: This study included two eyes each with MSP and CL and one eye with PL. The lens of MSP was spherical and posteriorly dislocated, with decreased ALR and PLR, Eq Dia, but increased APD. In patients with CL, the coloboma was isolated, bilateral, inferior, and located toward the maldeveloped ciliary body. High astigmatism was mainly lenticular, and this was calculated by the ALR and PLR. Regarding the site of coloboma, a significant decrease in ALR was observed, while the PLR and APD were not affected. The PL eyes had a cone-shaped protrusion of the posterior lens surface with a subtle cataractous region around the apex. An extremely high posterior surface curvature was observed with a mean PLR of 1.67 mm. The RPL and MDL were about 1.80 and 0.4 mm, respectively, which were homogenous at different sections.Conclusions: The CASIA2 is a valuable option for in vivo crystalline lens measurement for congenital lens deformities, enabling the accurate diagnosis and providing illuminating insights into the pathogenesis of MSP, CL, and PL

Segmentation Errors in the Measurement of Volumetric Parameters by Swept-Source Anterior Segment Optical Coherence Tomography.

Purpose: To investigate the error rate of segmentation in the automatic measurement of anterior chamber volume (ACV) and iris volume (IV) by swept-source anterior segment optical coherence tomography (SS-ASOCT) in narrow-angle and wide-angle eyes.Methods: In this study, fifty eyes from 25 narrow-angle subjects and fifty eyes from 25 wide-angle subjects were enrolled. SS-ASOCT examinations were performed and each SS-ASOCT scan was reviewed, and segmentation errors in the automatic measurement of ACV and IV were classified and manually corrected. Error rates were compared between the narrow-angle and the wide-angle groups, and ACV and IV before and after manual correction were compared.Results: A total of 12,800 SS-ASOCT scans were reviewed. Segmentation error rates of angle recess, iris root, posterior surface of the iris, pupil margin, and anterior surface of the lens were 84.06, 93.30, 13.15, 59.21, and 25.27%, respectively. Segmentation errors of angle recess, iris root, posterior surface of the iris, and pupil margin occurred more frequently in narrow-angle eyes, while more segmentation errors of the anterior surface of the lens were found in wide-angle eyes (all P < 0.001). ACV decreased and IV increased significantly after manual correction of segmentation errors in both groups (all P < 0.01).Conclusion: Segmentation errors were prevalent in the volumetric measurement by SS-ASOCT, particularly in narrow-angle eyes, leading to mismeasurement of ACV and IV.

Assessment of anterior chamber angle changes after phacoemulsification with swept-source OCT.

To assess the changes of anterior chamber angle in patients with shallow anterior chamber after phacoemulsification combined with intraocular lens (IOL) implantation, based on anterior segment swept-source optical coherence tomography (AS-SS-OCT) measurements. This was a prospective case control study; sixty eyes of sixty case were scheduled for cataract surgery with normal intraocular pressure (IOP). Based on anterior chamber depth (ACD) and gonioscopy findings, the eyes were divided into two groups: group of shallow anterior chamber and narrow angle (SAC group, 30 eyes); and group of normal anterior chamber group with wide angle (NAC group, 30 eyes). Measurements of ACD, anterior chamber volume (ACV), iris volume (IV), lens vault (LV), angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), and trabecular iris angle (TIA) were conducted in each group before and 3mo after surgery. There was no significant difference in age, axial length (AL), corneal curvature, corneal diameter, intraocular pressure, and IV between two groups before surgery, except for the LV (P=0.000). ACD and ACV were prominently larger in the NAC group than the SAC group 3mo after operation (3.69±0.38 vs 3.85±0.39 mm, P=0.025; 161.37±19.47 vs 178.26±20.30 mm3, P=0.002). AOD750, ARA750 in nasal and inferior quadrants, TISA750 in all quadrants except temporal, and TIA750 in all quadrants in SAC group were significantly smaller than those in NAC group after operation (all P<0.05). Cataract surgery can deepen anterior chamber and increase the width of anterior chamber angle in Chinese subjects, but the angle related parameters including AOD750, ARA750, TISA750, TIA, TISA750, and ACV in patients with shallow anterior chamber and narrow angle do not reach the normal level.