Agreement of Anterior Segment Parameters Obtained From Swept-Source Fourier-Domain and Time-Domain Anterior Segment Optical Coherence Tomography.

PurposeTo assess the interdevice agreement between swept-source Fourier-domain and time-domain anterior segment optical coherence tomography (AS-OCT).MethodsFifty-three eyes from 41 subjects underwent CASIA2 and Visante OCT imaging. One hundred eighty-degree axis images were measured with the built-in two-dimensional analysis software for the swept-source Fourier-domain AS-OCT (CASIA2) and a customized program for the time-domain AS-OCT (Visante OCT). In both devices, we examined the angle opening distance (AOD), trabecular iris space area (TISA), angle recess area (ARA), anterior chamber depth (ACD), anterior chamber width (ACW), and lens vault (LV). Bland-Altman plots and intraclass correlation (ICC) were performed. Orthogonal linear regression assessed any proportional bias.ResultsICC showed strong correlation for LV (0.925) and ACD (0.992) and moderate agreement for ACW (0.801). ICC suggested good agreement for all angle parameters (0.771-0.878) except temporal AOD500 (0.743) and ARA750 (nasal 0.481; temporal 0.481). There was a proportional bias in nasal ARA750 (slope 2.44, 95% confidence interval [CI]: 1.95-3.18), temporal ARA750 (slope 2.57, 95% CI: 2.04-3.40), and nasal TISA500 (slope 1.30, 95% CI: 1.12-1.54). Bland-Altman plots demonstrated in all measured parameters a minimal mean difference between the two devices (-0.089 to 0.063); however, evidence of constant bias was found in nasal AOD250, nasal AOD500, nasal AOD750, nasal ARA750, temporal AOD500, temporal AOD750, temporal ARA750, and ACD. Among the parameters with constant biases, CASIA2 tends to give the larger numbers.ConclusionsBoth devices had generally good agreement. However, there were proportional and constant biases in most angle parameters. Thus, it is not recommended that values be used interchangeably

Detection of occludable angle with anterior segment optical coherence tomography and Pentacam as non-contact screening methods

Purpose To evaluate diagnostic capacity for occludable anterior chamber angle detection with anterior segment optical coherence tomography (AS-OCT) and Pentacam. Methods Observational cross-sectional study with AS-OCT and Pentacam. AS-OCT measures: angle opening distance from Schwalbe line (SL) perpendicular (AOD-SL-Perp) and vertical to iris (AOD-SL-Vert), and iridotrabecular angle (ITA). Pentacam measures: anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA). We analysed Spearman's correlation with gonioscopic classification. Area under receiver operating characteristic curves (AUCs) for occludable angle detection were compared. Agreement between iridocorneal values of methods was evaluated. Results Seventy-four left eyes of 74 patients. Correlation between temporal AS-OCT and gonioscopy: 0.83 (p < 0.0001) AOD-SL-Perp temporal, 0.82 (p < 0.0001) AOD-SL-Vert temporal, and 0.69 (p < 0.0001) ITA temporal. Correlation between AS-OCT nasal and gonioscopy: 0.74 (p < 0.0001) AOD-SL-Perp nasal, 0.74 (p < 0.0001) AOD-SL-Vert nasal, and 0.70 (p < 0.0001) ITA nasal. Correlation of Pentacam with temporal gonioscopy: 0.57 (p < 0.0001) ACD, 0.56 (p < 0.0001) ACV, and 0.63 (p < 0.0001) ACA. Correlation of Pentacam with nasal gonioscopy: 0.47 (IC 0.27-0.73, p < 0.0001) ACD, 0.49 (p < 0.0001) ACV, and 0.56 (CI 0.38-0.7, p < 0.0001) ACA. AS-OCT AUCs: AOD-SL-Perp temporal 0.89 (CI 0.80-0.95), AOD-SL-Vert 0.87 (CI 0.77-0.94), ITA temporal 0.88 (CI 0.78-0.94), AOD-SL-Perp nasal 0.83 (CI 0.72-0.91), AOD-SL-Vert nasal 0.87 (CI 0.77-0.94), and ITA nasal 0.91 (IC 0.81-0.96). Pentacam AUCs: ACD 0.76 (CI 0.64-0.85), ACV 0.75 (CI 0.63-0.84), and ACA 0.84 (CI 0.74-0.92). No statistical differences between different AUCs. Intraclass correlation coefficient (ICC) of ACA (Pentacam) with ITA temporal (AS-OCT) 0.59 and with nasal ITA nasal (AS-OCT) 0.65. Conclusion Both systems show high capacity for non-contact occludable angle detection. But agreement between methods is moderate or low

Measurement of and Factors Associated with the Anterior Chamber Volume in Healthy Chinese Adults

Purpose. To measure the anterior chamber volume (ACV) and determine factors associated with the ACV in healthy Chinese adults. Methods. In this cross-sectional study, we used swept-source optical coherence tomography (SS-OCT) to measure ACV and other anterior segment parameters. Factors associated with ACV were also determined. Results. A total of 313 healthy Chinese adults were enrolled. The anterior segment parameters, including ACV, could be measured by SS-OCT with excellent repeatability and reproducibility. There was a significant difference between the horizontal and vertical anterior chamber widths (ACW) (P<0.05), with a mean difference of 390 μm. The ACV (mean 153.83±32.42 mm3) was correlated with most of the anterior segment parameters, especially anterior chamber depth (ACD), which accounted for about 85% of the variation of ACV. Most of the anterior segment parameters were significantly correlated with age, and the relative changes in ACV and ACD were greatest in subjects aged 41–50 years. Conclusion. ACV was correlated with most of the anterior segment parameters measured in this study, particularly ACD. The relatively large difference between horizontal and vertical ACW suggests that the ACV could and should be measured using multiple OCT scans

스펙트럼영역 빛간섭단층촬영기를 이용한 홍채각막각과 근위 누관의 해부학적 구조 평가

학위논문(박사) -- 서울대학교대학원 : 수의과대학 수의학과, 2022. 8. 서강문.본 연구에서는 눈의 전안부 구조 및 부속기를 조사하기 위해 빛간섭단층촬영기를 이용하여 홍채각막각과 눈물관을 포함한 눈의 미세구조를 평가하였다. 제1장에서는 임상 환경에서 홍채각막각 척도의 영상화 가능성을 조사하였다. 빛간섭단층촬영기 및 초음파 생체 현미경을 이용하여 개의 외측 안륜부에서 총 47개의 눈을 검사하였다. 이에 따라 획득한 영상으로부터 홍채각막각(ICA)과 각개방거리(AOD)를 측정하였다. 관찰자 내 및 관찰자 간 재현성은 급내 상관 계수를 사용하여 평가하였다. 관찰자 내 재현성을 평가하기 위해 첫 번째 검사자의 첫 번째 및 두 번째 등급 측정값을 비교하였다. 관찰자 간 재현성을 평가하기 위해 두 검사자 간의 측정값을 비교하였다. 빛간섭단층촬영기 및 초음파 생체현미경에 대한 홍채각막각과 각개방거리 간의 일치는 Bland-Altman plot을 사용하여 평가하였다. 첫 번째 평가에서 빛간섭단층촬영기에 대한 평균 홍채각막각 및 각개방거리는 각각 31.4 ± 6.4°및 641.4 ± 270.8 μm였다. 초음파 생체현미경에 대한 평균 홍채각막각과 각개방거리는 각각 32.0 ± 4.8°와 700.4 ± 238.8 μm였다. 홍채각막각 및 각개방거리 측정의 경우 두 기기 모두에서 관찰자 내 재현성이 우수한 반면 빛간섭단층촬영기에서는 관찰자 간 재현성이 우수하고 초음파 생체현미경에서는 양호했다. 빛간섭단층촬영기와 초음파 생체현미경 사이의 홍채각막각의 평균 차이는 0.6o였으며, 일치 한계 범위는 18.9o였다. 빛간섭단층촬영기와 초음파 생체현미경 사이의 각개방거리 평균 차이는 58.9 μm였고 일치 한계는 804.4 μm였다. 빛간섭단층촬영기는 임상 환경에서 홍채각막각 척도의 평가를 위한 효과적인 비접촉 영상 기법이다. 빛간섭단층촬영기로 얻은 측정 값의 재현성은 초음파 생체현미경과 비슷하거나 우수하지만, 각개방거리 값은 초음파 생체 현미경으로 측정한 값과 교차하여 사용할 수 없었다. 제2장에서는 빛간섭단층촬영기를 사용하여 상부 및 하부 근위 누관 영상화 가능성을 확인하였다. 정상 비글견 4마리에서 8개의 눈이 실험에 포함되었다. 상안검의 누관 근위부 영상을 얻기 위해 영상화하고자 하는 눈의 내측 방향으로 머리를 돌리고 상안검의 내측 부분을 외번하여 상누관 근위부를 노출시켰다. 하누관 근위부 이미지를 얻기 위해 누점 바로 아래에서 하안검을 외번하였다. "각도 모드"를 사용하여 촬영 기준선을 누관의 장축에 평행하게 배치하여 누관 근위부 입구 폭을 측정했다. 인공눈물을 점안하고, 인공눈물 점안 전과 후의 누관 근위부 폭을 비교하였다. 또한 누관이 확장된 후 초기 누관 근위부 입구 폭으로 되돌아오는 시간인 회귀 시간을 기록했다. 인공눈물 점적 전에는 상누관과 하누관 근위부 폭 사이에 유의한 차이가 있었다(각각 91.8 ± 3.2 및 110.1 ± 8.4 μm). 인공눈물 점적 후 평균 상누관 및 하누관 근위부 폭는 각각 236.9 ± 27.7 및 238.4 ± 30.4 μm였다. 상누관 및 하누관 근위부 폭은 인공눈물 점적 전후의 누관 근위부 폭과 유의한 차이가 관찰되었다. 인공눈물 점적 후 상부 및 하부 누관 근위부 폭의 초기 너비로의 평균 회귀 시간은 4분 이내였다. 빛간섭단층촬영기는 상부 및 하부 누관 근위부를 고해상도 이미지로 촬영 할 수 있는 효과적인 방법이었다. 이 방법을 사용하여 수의학 임상에서 점안액 점안 후 누관 근위부 변화를 관찰할 수 있었다. 본 연구 결과, 빛간섭단층촬영기는 안구 미세구조를 평가하는데 유용한 방법으로 판단되며 이를 통해 안구의 전안부 및 부속기의 미세구조의 병태생리학적 정보를 잘 확인할 수 있을 것으로 사료된다.This study was to evaluate the microstructures of the eye including iridocorneal angle and lacrimal canaliculi (LC) by spectral-domain optical coherence tomography (SD-OCT). In chapter 1, the feasibility of imaging the canine iridocorneal angle parameters in a clinical setting was investigated. A total of 47 eyes of dogs were scanned at the temporal limbus using SD-OCT and UBM. Iridocorneal angle (ICA) and angle opening distance (AOD) were measured from the obtained images accordingly. The intra-observer and inter-observer reproducibility were evaluated using the intraclass correlation coefficient. To evaluate intra-observer reproducibility, measurements of the first and second grading from the first examiner were compared. To evaluate inter-observer reproducibility, measurements between the two examiners were compared. Bland-Altman plots were used to evaluate agreement between ICA and AOD for SD-OCT and ultrasound biomicroscopy (UBM). In the first grading, ICA and AOD for SD-OCT were 31.4 ± 6.4° and 641.4 ± 270.8 µm (mean ± SD), respectively. ICA and AOD for UBM were 32.0 ± 4.8° and 700.4 ± 238.8 µm (mean ± SD), respectively. For ICA and AOD measurements, intra-observer reproducibility was excellent for both devices, whereas inter-observer reproducibility was excellent for SD-OCT and good for UBM. The mean difference in ICA between SD-OCT and UBM was 0.6° with a limit of agreement (LoA) span of 18.9°. The mean difference in AOD between SD-OCT and UBM was 58.9 µm with a LoA span of 804.4 µm. SD-OCT is an effective non-contact imaging modality for the evaluation of canine iridocorneal angle parameters in a clinical setting. Reproducibility of measurements obtained is comparable or superior to UBM, but values obtained by SD-OCT and UBM for AOD are not interchangeable between devices. In chapter 2, the feasibility of visualizing upper and lower proximal LC using SD-OCT was confirmed. Eight eyes of four normal Beagle dogs were included. To obtain an upper proximal LC image, the head was turned in the opposite direction to the eye being imaged, and the medial part of the upper eyelid was everted to expose the LC. To obtain a lower LC image, the lower eyelid was everted just below the punctum. Using “angle mode”, the scan line was placed parallel on the long axis of the LC. The inlet LC width (LCW) was measured. Artificial tears (AT) were instilled, and LCW was compared before and after AT instillation. Additionally, the return time to the initial LCW inlet width was recorded. Before AT instillation, there was a significant difference between the mean upper and lower LCW (91.8 ± 3.2 and 110.1 ± 8.4 µm, respectively). After AT instillation, the mean upper and lower LCW were 236.9 ± 27.7 and 238.4 ± 30.4 µm, respectively. Significant differences in the LCW before and after AT instillation in both the upper and lower LCWs were observed. The mean return time of the upper and lower LCW to their initial widths after AT instillation was within 4 min. SD-OCT could be one option for providing high-resolution images of the upper and lower proximal LC. This method enables observation of LC changes after instillation of eyedrops in veterinary clinical practice. In conclusion, SD-OCT would be an useful method for evaluating the ocular microstructures and the pathophysiological information of anterior segment of the eye and adnexa could be well confirmed.GENERAL INTRODUCTION 1 CHAPTER I Comparison of Iridocorneal Angle Parameters Measured by Spectral Domain Optical Coherence Tomography and Ultrasound Biomicroscopy in Dogs ABSTRACT 5 INTRODUCTION 6 MATERIALS AND METHODS 1. Animals studied 8 2. Procedures 9 3. Image analyses 12 4. Statistical analyses 15 RESULTS 1. Intra-observer reproducibility 16 2. Inter-observer reproducibility 18 3. Agreement between SD-OCT and UBM 20 DISCUSSION 22 CONCLUSION 28 CHAPTER II Evaluation of the Upper and Lower Lacrimal Canaliculus Using Spectral Domain Optical Coherence Tomography in Normal Beagle Dogs ABSTRACT 30 INTRODUCTION 31 MATERIALS AND METHODS 1. Animals studied 33 2. Imaging device 33 3. Scanning procedures and image analyses 34 4. Statistical analyses 39 RESULTS 40 DISCUSSION 43 CONCLUSION 47 GENERAL CONCLUSIONS 48 REFERENCES 50 ABSTRACT IN KOREAN 58박

Optical coherence tomography and optical coherence tomography angiography in uveitis : a review

Optical coherence tomography (OCT) has dramatically changed the understanding and management of uveitis and other ocular conditions. Currently, OCT angiography (OCTA) combines structural information with the visualization of blood flow within the imaged area. The aim of this review is to present the basic principles of OCT and OCTA interpretation and to investigate the role of these imaging techniques in the diagnosis and management of uveitis. Common complications of intraocular inflammation such as macular oedema and inflammatory choroidal neovascularization are often diagnosed and followed with OCT/OCTA scans. However, uveitis specialists can obtain much more information from tomographic scans. This review provides a comprehensive description of typical OCT/OCTA findings characterizing different ocular structures in uveitis, proceeding from the cornea to the choroid. A careful interpretation of OCT/OCTA images can help in the differential diagnosis, the prediction of clinical outcomes, and the follow-up of patients with uveitis

A laser-induced mouse model with long-term intraocular pressure elevation

Purpose: To develop and characterize a mouse model with intraocular pressure (IOP) elevation after laser photocoagulation on the trabecular meshwork (TM), which may serve as a model to investigate the potential of stem cell-based therapies for glaucoma. Methods: IOP was measured in 281 adult C57BL/6 mice to determine normal IOP range. IOP elevation was induced unilaterally in 50 adult mice, by targeting the TM through the limbus with a 532-nm diode laser. IOP was measured up to 24 weeks post-treatment. The optic nerve damage was detected by electroretinography and assessed by semiautomatic counting of optic nerve axons. Effects of laser treatment on the TM were evaluated by histology, immunofluorescence staining, optical coherence tomography (OCT) and transmission electron microscopy (TEM). Results: The average IOP of C57BL/6 mice was 14.5±2.6 mmHg (Mean ±SD). After laser treatment, IOP averaged above 20 mmHg throughout the follow-up period of 24 weeks. At 24 weeks, 57% of treated eyes had elevated IOP with the mean IOP of 22.5±2.5 mmHg (Mean ±SED). The difference of average axon count (59.0%) between laser treated and untreated eyes was statistically significant. Photopic negative response (PhNR) by electroretinography was significantly decreased. CD45+ inflammatory cells invaded the TM within 1 week. The expression of SPARC was increased in the TM from 1 to 12 weeks. Histology showed the anterior chamber angle open after laser treatment. OCT indicated that most of the eyes with laser treatment had no synechia in the anterior chamber angles. TEM demonstrated disorganized and compacted extracellular matrix in the TM. Conclusions: An experimental murine ocular hypertension model with an open angle and optic nerve axon loss was produced with laser photocoagulation, which could be used to investigate stem cell-based therapies for restoration of the outflow pathway integrity for ocular hypertension or glaucoma. Copyright

A review of artificial intelligence applications in anterior segment ocular diseases

Background: Artificial intelligence (AI) has great potential for interpreting and analyzing images and processing large amounts of data. There is a growing interest in investigating the applications of AI in anterior segment ocular diseases. This narrative review aims to assess the use of different AI-based algorithms for diagnosing and managing anterior segment entities. Methods: We reviewed the applications of different AI-based algorithms in the diagnosis and management of anterior segment entities, including keratoconus, corneal dystrophy, corneal grafts, corneal transplantation, refractive surgery, pterygium, infectious keratitis, cataracts, and disorders of the corneal nerves, conjunctiva, tear film, anterior chamber angle, and iris. The English-language databases PubMed/MEDLINE, Scopus, and Google Scholar were searched using the following keywords: artificial intelligence, deep learning, machine learning, neural network, anterior eye segment diseases, corneal disease, keratoconus, dry eye, refractive surgery, pterygium, infectious keratitis, anterior chamber, and cataract. Relevant articles were compared based on the use of AI models in the diagnosis and treatment of anterior segment diseases. Furthermore, we prepared a summary of the diagnostic performance of the AI-based methods for anterior segment ocular entities. Results: Various AI methods based on deep and machine learning can analyze data obtained from corneal imaging modalities with acceptable diagnostic performance. Currently, complicated and time-consuming manual methods are available for diagnosing and treating eye diseases. However, AI methods could save time and prevent vision impairment in eyes with anterior segment diseases. Because many anterior segment diseases can cause irreversible complications and even vision loss, sufficient confidence in the results obtained from the designed model is crucial for decision-making by experts. Conclusions: AI-based models could be used as surrogates for analyzing manual data with improveddiagnostic performance. These methods could be reliable tools for diagnosing and managing anterior segmentocular diseases in the near future in remote areas. It is expected that future studies can design algorithms thatuse less data in a multitasking manner for the detection and management of anterior segment diseases