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Optical coherence tomography (OCT) is a non-invasive, high-resolution and high-speed imaging modality that has enjoyed rapid growth in ophthalmology since its development 20 years ago. Contact lens fitting is traditionally based on trial lenses, which is expensive and time-consuming. Modern anterior segment OCT is capable of generating three-dimensional ocular surface maps of the cornea and sclera with potential application in contact lens fitting. This paper reviewed the history, the ophthalmic applications, and the most recent advancement in three-dimensional anterior segment OCT. There is very limited literature of OCT in contact lens fitting to date. This review anticipates an increase in this application in the near future. [ABSTRACT FROM AUTHOR]

Aim: To study the morphological pattern of pearl-like lesions in the anterior chambers of children before and after management using anterior segment spectral domain optical coherence tomography (SD-OCT). Patients and methods: This was a prospective, observational cross-sectional study of patients presenting with peculiar pearl-like lesions in the anterior chamber of their eyes. 1 mL of betamethasone sodium phosphate (2 mg/mL) and betamethasone dipropionate (5 mg/mL) was injected subconjunctivally. Follow-ups of all patients were conducted for a period of 6 weeks. Anterior segment imaging was done using SD-OCT and also photo slit lamp before and after management. Results: Twelve eyes of 12 patients were included in this study. These patients presented with pearl-like lesions in the anterior chamber with signs of anterior uveitis. There was no history of ocular injury or tuberculosis in any patients. Six weeks after subconjunctival steroid injection, all patients achieved mean best-corrected visual acuity, which changed from 0.2 (range 0.1-0.4) to 0.5 (range 0.4-0.8), and the severity of iritis decreased. SD-OCT showed that the lesions at presentation appeared as a globular noncystic mass attached to the back of the cornea, encroaching on the angle of the eye, and attached to the anterior surface of the iris at some points. Conclusion: SD-OCT for imaging the anterior segment allowed us to exclude the cystic nature of this pearly lesion. Some similarities may exist between these pearly lesions and superficial phlyctenular keratitis, which may support the immunological and inflammatory origin of these lesions. [ABSTRACT FROM AUTHOR]

Purpose: To study quantitative changes in anterior chamber angle (ACA) after laser peripheral iridotomy (LPI) in narrow-angle eyes using anterior segment optical coherence tomography (AS-OCT). Methods: Eighteen subjects with narrow angles were imaged with AS-OCT for determining test-retest variability. Forty-six participants with narrow angles were scanned with AS-OCT before LPI and 4 weeks after LPI. The presence of ACA closure by both AS-OCT imaging and gonioscopy was compared before and after LPI. Three ACA parameters by AS-OCT, angle opening distance at 500 μm (AOD), trabecular-ris space area at 500 μm (TISA) and angle recess area at 500 μm (ARA), at both nasal and temporal quadrants were incorporated for analysis. The increment of ACA parameters defined as exceeding the 95% confidence interval of test-retest variability was assessed after LPI. Results: All 3 parameters obtained from the 18 eyes showed good measurement reproducibility (intraclass correlation coefficient 0.850-0.979). Persistent angle closure was detected in 23.9% of eyes by gonioscopy, and in 34.8% of eyes by AS-OCT images at temporal quadrant after LPI. When assessed by measurement variability criteria, the percentage of eyes that showed no significant change in ACA parameters ranged from 23.9% to 45.7% after LPI. Conclusions: Overall, ACA parameters changed significantly after LPI; however, when assessed by AS-OCT, ACA remained unchanged in some narrow-angle eyes despite LPI. Our findings suggest that multiple causes other than pupillary block may contribute to narrow-angle closure following LPI. [ABSTRACT FROM AUTHOR]

PurposeTo compare the performance of anterior chamber volume (ACV) and anterior chamber depth (ACD) obtained using Scheimpflug imaging with angle opening distance (AOD500) and trabecular-iris space area (TISA500) obtained using spectral domain anterior segment optical coherence tomography (SD-ASOCT) in detecting narrow angles classified using gonioscopy.MethodsIn this prospective, cross-sectional observational study, 265 eyes of 265 consecutive patients underwent sequential Scheimpflug imaging, SD-ASOCT imaging, and gonioscopy. Correlations between gonioscopy grading, ACV, ACD, AOD500, and TISA500 were evaluated. Area under receiver operating characteristic curve (AUC), sensitivity, specificity, and likelihood ratios (LRs) were calculated to assess the performance of ACV, ACD, AOD500, and TISA500 in detecting narrow angles (defined as Shaffer grade ≤1 in all quadrants). SD-ASOCT images were obtained at the nasal and temporal quadrants only.ResultsTwenty-eight eyes (10.6%) were classified as narrow angles on gonioscopy. ACV correlated with gonioscopy grading (P<0.001) for temporal (r=0.204), superior (r=0.251), nasal (r=0.213), and inferior (r=0.236) quadrants. ACV correlated with TISA500 for nasal (r=0.135, P=0.029) and temporal (P=0.160, P=0.009) quadrants and also with AOD500 for nasal (r=0.498, P<0.001) and temporal (r=0.517, P<0.001) quadrants. For detection of narrow angles, ACV (AUC=0.935; 95% confidence interval (CI) =0.898-0.961) performed similar to ACD (AUC=0.88, P=0.06) and significantly better than AOD500 nasal (AUC=0.761, P=0.001), AOD500 temporal (AUC=0.808, P<0.001), TISA500 nasal (AUC=0.756, P<0.001), and TISA500 temporal (AUC=0.738, P<0.001). Using a cutoff of 113 mm3, ACV had 90% sensitivity and 88% specificity for detecting narrow angles. Positive and negative LRs for ACV were 8.63 (95% CI=7.4-10.0) and 0.11 (95% CI=0.03-0.4), respectively.ConclusionsACV measurements using Scheimpflug imaging outperformed AOD500 and TISA500 using SD-ASOCT for detecting narrow angles. [ABSTRACT FROM AUTHOR]

AimsTo report corneal endothelial cell loss and in vivo visualization of the Ahmed glaucoma valve implant in eyes with refractory glaucoma.MethodsTen eyes underwent Ahmed valve implant surgery and were followed-up for 12 months. Data collected included intraocular pressure (IOP), number of antiglaucoma medications and surgery-related complications. At 6 and 12 months postoperatively, the intracameral length of the drainage tube (ICL) and the distance between the tube and the cornea (T–C distance), and the iris (T–I distance) were assessed using anterior segment optical coherence tomography (AS-OCT). Heidelberg cornea tomograph II (HRT II) was used to measure the corneal endothelial cell density.ResultsMean (±SEM) preoperative IOP was 29.5±4 mmHg. Mean postoperative IOP was 11.6±2 at 12 months (P<0.01). Over a 6-month period, mean corneal endothelial loss was 7.9%±2.5 in the central and 7.5%±2.4 in the peripheral cornea (P<0.01). There was no correlation between central or peripheral corneal endothelial cell loss and the T–C, T–I distance or the ICL of the tube.ConclusionsCorneal endothelial cell loss occurs following Ahmed valve implant surgery, this appears to be multifactorial. AS-OCT and HRT II are promising methods for the follow-up of patients with a glaucoma drainage device. [ABSTRACT FROM AUTHOR]

The association between myopia control efficacy in children treated with orthokeratology and corneal epithelial thickness is still unknown. The aim of this study was to explore the corneal epithelial thickness and its association with axial length changes in children treated with orthokeratology. This retrospective cohort study enrolled children aged from 9 to 15 years who had received orthokeratology for myopia control and had been followed up for at least 1 year. Anterior segment optical coherence tomography was performed to generate wide epithelial thickness maps of the patients. Annual axial length changes were calculated from the axial length at 6 months after the initiation of orthokeratology lens wear and at final measurements. Corneal epithelial thickness data were obtained from 24 sectors and a central 2 mm zone of the wide epithelial thickness map. Associations between annual axial length changes and corneal epithelial thickness for each sector/zone of the wide epithelial thickness map, and orthokeratology treatment data were determined by generalized estimating equations. Finally, a total of 83 eyes of 43 patients (mean age 11.2 years) were included in the analysis. The mean annual axial length change was 0.169 mm; when regressing demographic and ortho-k parameters to mean annual axial length changes, age and target power were both negatively associated with them (β = −14.43, p = 0.008; β = −0.26, p = 0.008, respectively). After adjusting for age and target power, the annual axial length changes were positively associated with the corneal epithelium thickness of IT1, I1, SN2, and S2 sectors of the wide epithelial thickness map, and negatively with that of the I3 sector. In conclusion, we identified associations between annual axial length changes and the corneal epithelium thickness of certain sectors in children treated with orthokeratology. This may facilitate the design of orthokeratology lenses with enhanced efficacy for myopia control. [ABSTRACT FROM AUTHOR]

Changes in the limbal microvasculature following a chemical eye injury are essential for prognosis and management. At the slit lamp, it can be difficult to assess, here using fluorescein and indocyanine green angiography we show that anterior segment angiography may be informative to assess objectively the limbal microvascular changes over the follow-up period. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate graft detachment after Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes and DMEK combined with cataract surgery (triple DMEK)., Design: Analysis of 3 single-center prospective cohort studies and 1 randomized controlled trial., Participants: Participants with Fuchs' endothelial corneal dystrophy., Methods: A validated neural network for image segmentation quantified graft detachment on anterior segment OCT (AS-OCT) images 3 days after DMEK and at the 2-week postoperative visit. Area and volume of graft detachment were compared between DMEK only and triple DMEK using generalized estimating equation models and adjusting for participant age and the size of the air bubble., Main Outcome Measures: Area and volume of DMEK graft detachment., Results: Among 207 participants with 270 eyes included, 75 pseudophakic eyes had DMEK only and 195 eyes had triple DMEK. A total of 147 eyes had less than one third of detachment at day 3. In 139 of these eyes (95%), detachment was still less than one third at the 2-week scan, indicating that postoperative graft detachment at 2 weeks occurred mainly in eyes with early detachment. When superimposing all 3-dimensional maps from 2 weeks after surgery, the central graft was mainly attached and detachment was located at the graft margin. The mean area of graft detachment decreased from 28% in DMEK only and 38% in triple DMEK to 16% in DMEK only and 25% in triple DMEK at the 2-week postoperative visit. At 2 weeks, the mean area of detachment was 1.85-fold higher (95% confidence interval [CI], 1.34-2.56) and the mean volume was 2.41-fold higher (95% CI, 1.51-3.86) in triple DMEK compared with DMEK. A total of 46 eyes received rebubbling procedures, with 7 eyes (9%) in the DMEK group and 39 eyes (20%) in the triple DMEK group (adjusted risk ratio, 3.1; 95% CI, 1.3-7.1), indicating that rebubbling was more common in eyes undergoing triple DMEK., Conclusions: Automated segmentation of AS-OCT images allowed precise quantification of graft detachment over time and identified DMEK combined with cataract surgery as a risk factor. Frequency of operative follow-up might be guided by extent of detachment in the first postoperative days after DMEK., (© 2022 by the American Academy of Ophthalmology.)

Aim: To compare the simulated safe distance (SSD) preoperatively versus real safe distance (RSD) postoperatively in patients with iris-claw phakic intraocular lens (pIOL) implantation according to iris configuration., Methods: Totally 60 eyes of 60 patients underwent pIOL implantation for surgical correction of myopia. Anterior chamber depth (ACD) was measured with the IOLMaster 700, and nasal and temporal safety distances (SD) were measured pre- and postoperatively using Anterior Segment Visante-OCT. SD was defined as a line measured between the edge of the optic or its simulated image to the endothelium. Eyes were divided into 3 groups: convex, concave, and plane according to preoperatory iris configuration. Statistical analysis was performed using the R program, for the comparison of independent groups and multiple comparisons, the Kruskal-Wallis test and the Dunn test were used respectively., Results: Mean difference between nasal preoperative SSD and postoperative RSD was -0.36±0.38, -0.29±0.48, and -0.18±0.30 mm in the concave, convex, and plane group, respectively. Mean difference between temporal SSD and RSD was -0.36±0.37, -0.14±0.38, and -0.24±0.33 mm in the concave, convex, and plane group, respectively. There were statistically significant differences between SSD and RSS for both nasal and temporal sides in the concave and plane group ( P <0.002)., Conclusion: Preoperative SSD and postoperative RSD for iris-claw pIOL shows significant differences in patients with concave and plane iris., (International Journal of Ophthalmology Press.)

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. [ABSTRACT FROM AUTHOR]

Purpose: To compare anterior segment and angle parameters between pseudoexfoliation syndrome (PEX) and PEX glaucoma (PEXG) and normal control subjects using anterior segment optical coherence tomography (AS-OCT) imaging., Design: Cross-sectional study., Methods: One hundred and two subjects with PEXG, PEX, and normal eyes as the control group were recruited from an academic referral institution. All subjects underwent a complete ophthalmologic examination, axial length measurement, and AS-OCT imaging. Anterior segment and angle parameters were evaluated., Results: After excluding 4 eyes because of poor imaging of the scleral spur, data from 34 eyes with PEXG, 33 eyes with PEX, and 31 eyes of normal control subjects were analyzed. Anterior chamber depth was significantly shallower in eyes with PEXG compared with eyes of control subjects (P < .001). The differences in anterior chamber angle parameters (AOD500, AOD750, TISA500,and TISA750) were significant among study groups, with lower values in the PEXG group compared with the PEX and control subject groups. Lens vault (mean [mm]±SD) was higher in the PEXG (0.46 ±0.21) and PEX (0.427 +0.28) groups compared with the control group (0.305+ 0.20)., Conclusions: PEXG eyes have the narrowest anterior chamber angle parameters. There is a progressive decrease in angle parameters from control subjects to the PEX group to the PEXG group. Narrow anterior chamber angle and anterior chamber depth may have a role in the progression of PEX to PEXG. Detection of narrow angle in these patients may help clinicians manage the disease more properly., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A 14-year-old female presented with complaint of nonprogressive whitish opacity over cornea of right eye since birth. Cycloplegic refraction found refractive error of -12.0 D sphere and -3.0 D cylinder @150° in right eye and +3.50 D sphere and +1.50 D cylinder @20° in left eye. We found localized defect in the posterior layers of cornea of right eye in anterior segment optical coherence tomography (OCT) [Figure 4]. [Extracted from the article]

An 81-year-old patient was referred for an intraocular lens (IOL) exchange surgery because of a presumed IOL opacification. Using diagnostic imaging techniques such as anterior segment optical coherence tomography (OCT) and Scheimpflug imaging, we revealed that the presumed IOL opacification was in fact a liquefied aftercataract. As a result, an intraocular surgery was avoided and the patient was successfully treated with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy., Competing Interests: Grants and personal fees from OCULUS (GUA, RK), grants from 10.13039/501100010313Heidelberg Engineering (GUA, RK). No conflict of interest (TN, CSM)., (© 2022 The Authors.)

Purpose: To develop and apply a neural network for quantification of endothelial corneal graft detachment using anterior segment (AS) OCT., Design: Training and validation of a neural network and application within a prospective cohort., Participants: Patients two weeks after Descemet membrane endothelial keratoplasty., Methods: Investigators manually labeled the posterior cornea and the graft in cross-sectional images of rotational AS OCT scans. Neural networks for image segmentation were trained to identify the area of graft detachment on cross-sectional images. The best-performing neural network with the lowest misclassification (Youden index) and highest spatial overlap with the ground truth (Dice coefficient) was selected and evaluated in a separate dataset. Three-dimensional maps of the area and volume of graft detachment were calculated. For application, the neural network's rating on the detachment was compared with slit-lamp-based ratings of cornea specialists on the same day as the AS OCT imaging took place., Main Outcome Measures: Youden index and Dice coefficient., Results: Neural networks were trained on 27 AS OCT scans with 6912 labeled images. Among 48 combinations of probability thresholds and epoch states, the best-performing neural network showed a Youden index of 0.99 and a Dice coefficient of 0.77, indicating low misclassification and good spatial overlap on individual image segmentation. In the validation set unknown to the neural network with 20 scans (5120 images), the Youden index was 0.85 and the Dice coefficient was 0.73, and a high overall performance compared with the manually labeled ground truth ( R 2  = 0.90). In the application set with 107 eyes, the neural network estimated the mean percent detachment larger than the cornea specialist (mean difference, 8.2 percentage points; 95% confidence interval, 6.2-10.2). Masked review of 42 AS OCTs with more than ±10 percentage points difference in ratings showed that clinicians underestimated the true detachment in cases with significant detachment requiring intervention., Conclusions: Deep learning-based segmentation of AS OCT images quantified the percent and the volume of DMEK graft detachment with high precision. Fully automated 3-dimensional quantification of graft detachment is highly sensitive, particularly in corneas with a significant amount of detachment, and may support decision making., (© 2021 by the American Academy of Ophthalmology.)

Background: penetrating keratoplasty (PKP) is performed for a wide spectrum of corneal disorders. Glaucoma due to pupillary block or synechial angle closure or aqueous misdirection is a major complication after keratoplasty. Peripheral anterior synechia (PAS) is recognized as one of the risk factors for graft rejection and may occasionally cause intraocular pressure (IOP) elevation, it is important to evaluate anterior chamber (AC) angle in eyes after PKP Aim of the Work: to document OCT changes in the anterior chamber angle after PKP for different pathologies. Patients and Methods: this prospective non-randomized study included 10 eyes of 10 patients undergoing penetrating keratoplasty (PKP) for a variety of indications. The patients age ranged from 20 to 60 years. Results: the mean postoperative IOP was higher (15.4 ± 4.03mmHg) than preoperative IOP (12.5 ± 2.46mmHg), but this difference was not statistically significant [P value = 0.088]. The postoperative mean Temporal TISA was lower (0.24 ± 0.08 mm²) than preoperative Temporal TISA (0.3 ± 0.1mm²). This difference was statistically significant [P value = 0.015]. The postoperative mean Nasal TISA was lower (0.26 ± 0.1 mm²) than preoperative Nasal TISA (0.34 ± 0.15 mm²). This difference was statistically significant [P value = 0.010]. The postoperative mean IOP in infectious keratitis was higher (16.14 ± 4.63mmHg) than postoperative mean IOP in keratoconus (13.67 ± 1.53mmHg), but this difference was not statistically significant [P value = 0.565]. Conclusion: there is an increase in IOP post PKP but the difference was not statistically significant. There is narrowing in angle post PKP. The difference was statistically significant in temporal and nasal angles but not statistically significant in superior and inferior angles. The mean IOP was higher in infectious keratitis than keratoconus but the difference was not statistically significant. There is no correlation between corneal diameter and the changes in IOP and angle measurements. [ABSTRACT FROM AUTHOR]

Background: Keratoconus, the most common primary corneal ectasia, is a bilateral asymmetric corneal degeneration accompanied with local corneal thinning and occurs mostly in the inferior and central part of the cornea, it usually causes high myopia and irregular astigmatism which results in poor quality of vision. Based on disease severity, many treatment modalities exist including glasses and contact lenses for mild to moderate disease, while corneal graft preserved for more advanced disease. In advent of alternative treatments, intrastromal ring implantation have been introduced which improves visual acuity and optical aberrations and also corrects refractive errors and mean keratometric data, anterior segment Optical cohehernce Tomography epithelial mapping is anew modality to assess epithelial thickness. Objective: To investigate epithelial thickness changes in keratoconic patients before and after intracorneal ring segment implantation using AS OCT. Methods: Thirty eyes with early to moderate keratoconus were included in this prospective interventional case series study which has been conducted at patients from Ain shams university hospitals, after the approval of the research ethical committee in the Faculty of Medicine, Ain Shams University between March to October. All cases underwent a Complete ophthalmological examination before surgery. the examination included Visual acuity assessment and Best corrected visual acuity. Slit Lamp Biomicroscopy examination with fundus examination through dilated pupil using D lens & Corneal Topography, Anterior segment Optical cohehernce Tomography Epithelial mapping(- zeiss). Results: we found that epithelial thickness showing statistically significant change comparing pre and post operative epithelial mapping especially in certain areas in the map, area (_),(_) mm. Conclusion: There is increase in epithelium thickness in keratoconic corneas after intracorneal ring segment implantation to compensate for stromal irregularities in patients with keratoconus. [ABSTRACT FROM AUTHOR]

Purpose: To describe the effective use of only 50% air fill of the anterior chamber for rebubbling partially detached Descemet Membrane Endothelial Keratoplasty (DMEK) grafts at the slit lamp at a time of restricted operating theatre access during the COVID-19 pandemic., Methods: We present two cases of patients who underwent rebubbling of a partially detached DMEK grafts at the slit lamp following DMEK surgery without peripheral iridotomy. The rebubbling was performed with a 27-gauge needle attached to a 1ml syringe and the patients seated at the slit lamp. Air was injected into the anterior chamber until a 50% air fill was achieved. The patients were instructed to lie supine for 30 min in clinic and the remainder of the day at home., Results: We performed two rebubbling procedures at the slit lamp using the standard needle and syringe. Both cases achieved 50% air fills without any complications. At 3 days post-procedure the air bubble had resolved and the graft appeared attached centrally and at day 14 post-procedure the two patients had a clear and attached corneal graft with corrected visual acuity of 6/7.5 and 6/9, respectively., Conclusion: Rebubbling of detached DMEK grafts at the slit lamp with 50% air fill in the anterior chamber is a relatively simple and effective procedure. This provides an alternative approach for managing the complication of partially detached DMEK grafts in the era of COVID-19 with limited operating theatre access and avoids the risk of complications such as pupillary block in 'PI-less' DMEK.

Purpose: To evaluate scleral thickness in central serous chorioretinopathy (CSC) using anterior segment (AS) OCT., Design: Retrospective, comparative study., Participants: Forty-seven eyes of 40 patients with CSC and 53 eyes of 47 age- and gender-matched normal control participants., Methods: Spherical equivalent, axial length, subfoveal choroidal thickness, and scleral thickness were compared between the CSC and control groups. Scleral thickness was measured by AS OCT 6 mm posterior to the scleral spur in 4 directions., Main Outcome Measure: Scleral thickness in CSC eyes., Results: No differences were found between the 2 groups in age, gender, spherical equivalent, or axial length. Subfoveal choroidal thickness was significantly greater in CSC eyes than in normal control eyes (424.0 ± 101.4 μm vs. 324.3 ± 91.8 μm; P < 0.001). Scleral thickness was significantly greater in CSC eyes than in normal control eyes at the superior (429.4 ± 50.3 μm vs. 395.2 ± 55.4 μm; P = 0.005), temporal (447.7 ± 45.7 μm vs. 396.5 ± 64.1 μm; P < 0.001), inferior (455.7 ± 81.2 μm vs. 437.8 ± 46.9 μm; P = 0.022), and nasal (454.9 ± 44.7 μm vs. 416.6 ± 51.2 μm; P = 0.001) points., Conclusions: Scleral thickness measured by AS OCT was significantly greater in CSC eyes than in normal control eyes, although no differences were found in spherical equivalent or axial length. Thick sclera may have a role in the pathogenesis of CSC., (Copyright © 2020 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess differences in ocular biometric measurements between primary angle closure suspect (PACS) eyes and primary angle closure (PAC) and primary angle closure glaucoma (PACG) eyes., Design: Cross-sectional study., Participants: Patients with primary angle closure disease (PACD) were identified from the Chinese American Eye Study, a population-based study in Los Angeles, California., Methods: Patients previously underwent complete ocular examinations including gonioscopy and anterior segment (AS)-OCT imaging with the Tomey CASIA SS-1000 (Tomey Corporation). Four AS-OCT images were analyzed per eye. Averaged and sectoral measurements of biometric parameters, including angle recess area (ARA), trabecular iris space area (TISA), iris area, iris curvature, lens vault, anterior chamber depth, and anterior chamber area, were compared between early PACD (PACS) and late PACD (PAC and PACG) groups. Machine learning classifiers that attempt to differentiate between early and late PACD eyes were developed by applying different regression algorithms to a training dataset of sectoral parameter measurements. Classifier performance was assessed using an independent test dataset., Main Outcome Measures: Averaged and sectoral measurements of biometric parameters., Results: Two hundred ninety-eight eyes (231 PACS, 67 PAC or PACG) of 298 patients were analyzed. No difference was found in averaged biometric measurements between the 2 groups before (P > 0.09) or after (P > 0.14) adjusting for age and gender. Differences (P < 0.04) between the 2 groups were found for 11 sectoral parameter measurements, including ARA and TISA. The performance of machine learning classifiers developed using sectoral parameter measurements was poor on the independent test dataset for all regression algorithms (area under the receiver operating characteristic curve, 0.529-0.628)., Conclusions: Differences in biometric measurements between subtypes of PACD eyes were small in a population-based cohort of Chinese Americans. The poor performance of classifiers based on these measurements highlights potential challenges of developing quantitative methods to detect late PACD., (Copyright © 2020 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Purpose: To assess the repeatability and agreement of ocular biometric parameters measured using the Tomey CASIA SS-1000 and Heidelberg ANTERION anterior segment optical coherence tomography (AS-OCT) devices., Methods: Both eyes of subjects 18 years of age or older were scanned three times with the CASIA and ANTERION under standardized dark lighting. One AS-OCT image along the horizontal (temporal-nasal) meridian was analyzed per eye and per scan. Pupillary diameter (PD) was within 15% for all pairwise comparisons. Anterior chamber depth, lens vault, anterior chamber width, angle opening distance, trabecular iris space area, and scleral spur angle (SSA500) were measured using manufacturer-provided image analysis software. Intraclass correlation (ICC), Wilcoxon signed-rank, and Bland-Altman analyses were performed to assess intradevice repeatability and interdevice agreement of measurements., Results: Thirty-two eyes of 21 subjects were analyzed. There was excellent agreement (ICC >0.98) and no significant difference ( P > 0.05) in PD across all comparisons. Intradevice measurement repeatability was excellent for both the CASIA (ICC range 0.93-0.99) and ANTERION (ICC range 0.97-0.99). Interdevice measurement agreement was also excellent (ICC range 0.85-0.96). Measurements within and between devices were similar ( P > 0.06) for all parameters except SSA500 ( P = 0.03). Linear regression and Bland-Altman plots showed the relationship was consistent across the entire range of measurements., Conclusions: Intradevice measurement repeatability is excellent for the CASIA and ANTERION. Interdevice measurement agreement between the two devices exceeds metrics reported by previous comparison studies., Translational Relevance: Modern swept-source AS-OCT devices produce highly repeatable measurements of ocular biometric parameters that are nearly interchangeable across devices., Competing Interests: Disclosure: A.A. Pardeshi, None; A.E. Song, None; N. Lazkani, None; X. Xie, None; A. Huang, Heidelberg Engineering (F); B.Y. Xu, Heidelberg Engineering (F), (Copyright 2020 The Authors.)

Purpose: To develop a deep neural network that detects the scleral spur in anterior segment optical coherence tomography (AS-OCT) images., Methods: Participants in the Chinese American Eye Study, a population-based study in Los Angeles, California, underwent complete ocular examinations, including AS-OCT imaging with the Tomey CASIA SS-1000. One human expert grader provided reference labels of scleral spur locations in all images. A convolutional neural network (CNN)-based on the ResNet-18 architecture was developed to detect the scleral spur in each image. Performance of the CNN model was assessed by calculating prediction errors, defined as the difference between the Cartesian coordinates of reference and CNN-predicted scleral spur locations. Prediction errors were compared with intragrader variability in detecting scleral spur locations by the reference grader., Results: The CNN was developed using a training dataset of 17,704 images and tested using an independent dataset of 921 images. The mean absolute prediction errors of the CNN model were 49.27 ± 42.07 µm for X-coordinates and 47.73 ± 39.70 µm for Y-coordinates. The mean absolute intragrader variability was 52.31 ± 47.75 µm for X-coordinates and 45.88 ± 45.06 µm for Y-coordinates. Distributions of prediction errors for the CNN and intragrader variability for the reference grader were similar for X-coordinates ( P = 0.609) and Y-coordinates ( P = 0.378). The mean absolute prediction error of the CNN was 73.08 ± 52.06 µm and the mean absolute intragrader variability was 73.92 ± 60.72 µm., Conclusions: A deep neural network can detect the scleral spur on AS-OCT images with performance similar to that of a human expert grader., Translational Relevance: Deep learning methods that automate scleral spur detection can facilitate qualitative and quantitative assessments of AS-OCT images., Competing Interests: Disclosure: B.Y. Xu, None; M. Chiang, None; A.A. Pardeshi, None; S. Moghimi, None; R. Varma, Allegro Inc. (C), Allergan (C), Bausch Health Companies, Inc. (C), (Copyright 2020 The Authors.)

Objective: To assess if anterior segment optical coherence tomography (AS-OCT) is a noninvasive diagnostic method suitable to differentiate benign corneo-conjunctival lesions (pterygium) from premalignant lesions (corneo-conjunctival intraepithelial neoplasia, CIN)., Material and Methods: An observational, analytical and cross-sectional study was conducted in 22 eyes with conjunctival lesions clinically suspicious for pterygium and CIN during two years. Morphological differences between both lesions were studied with AS-OCT; epithelial thicknesses (EE) and extension length on corneal surface (GIC) were compared between both groups. A surgical excision of the lesion was performed for histopathological diagnosis., Results: Mean age of patients with pterygium (n=18) was 52.67±15 y.o and 74±12 y.o in subjects with CIN (n=4) (p<0.021). In pterygia, AS-OCT showed typical features (normal, thinning or slightly thickened EE; 77.4±26μm), in addition to an increase in wedge-shaped subepithelial tissue. Patients with CIN had a mean thickened EE (262.5±124μm) and strongly hyperreflective, with abrupt transition between normal and pathological epithelium. Analysis of EE between subjects with pterygium and CIN revealed statistically significant differences (p<0.002). ROC curve revealed a 100% sensitivity and specificity of OCT-SA in differentiation between CIN and pterygium, using 141μm as cutoff point of EE., Conclusion: AS-OCT is a useful tool for the differentiation between pterygium and CIN able to provide typical morphological characteristics. An EE greater than 141μm in AS-OCT suggests a sensitivity and specificity of 100% for the diagnosis of CIN., (Copyright © 2020 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.)

Introduction: To propose an objective method of quantifying pterygium thickness using AS-OCT. Methods: Anterior segment imaging was performed using Enhanced High Resolution Corneal (EHRC) of Visante™ OCT in 68 primary pterygium eyes. Prior to imaging, corneal topography assessment was performed on each pterygium eye in order to identify its topographic location. Based on topography mapping, three meridians (in degrees) were selected as close as possible to the pterygium border, which signify the demarcation of pterygium from the cornea. Reliability testing between intra and inter-observer on OCT imaging modality was examined using Intraclass correlation (ICC) and scatter plot. Results: The overall (n = 68) mean and SD of pterygium thickness via OCT modality were 0.48 ± 0.10 mm (CI: 0.45 - 0.50). OCT imaging also showed excellent intra and intergrader reliability in measuring pterygium thickness with ICC of 0.997 (CI: 0.994 - 0.998). Conclusions: We have described and demonstrated the use of EHRC as an objective measurement for pterygium thickness. This tool proved could eliminate the variability of human inter-graders in assessing thickness of pterygium with its promising ICC. This study had proved that anterior segment OCT imaging is a better choice in assessing pterygium compared to traditional slit-lamp biomicroscopy. We suggest that this tool is applicable for future work such as to understand the role thickness in pterygium morphology and its progression. Better understanding of pterygium morphology is important for future clinical decision, especially on prediction of induced corneal astigmatism and visual impairment due to pterygium. [ABSTRACT FROM AUTHOR]