Angle Closure Assessment Research Articles

Novel hyperparallel optical coherence tomography for angle closure assessment: comparison with swept-source OCT and gonioscopy

AimTo evaluate reproducibility and agreement of angle closure assessment by a novel hyperparallel optical coherence tomography (OCT) system (HP-OCT, Cylite Optics, Melbourne, Australia), in comparison with swept-source OCT (SS-OCT, CASIA...

Automatic measurement of anterior chamber angle parameters in AS-OCT images using deep learning.

The early assessment of angle closure is of great significance for the timely diagnosis and treatment of primary angle-closure glaucoma (PACG). Anterior segment optical coherence tomography (AS-OCT) provides a fast and non-contact way to evaluate the angle close using the iris root (IR) and scleral spur (SS) information. The objective of this study was to develop a deep learning method to automatically detect IR and SS in AS-OCT for measuring anterior chamber (AC) angle parameters including angle opening distance (AOD), trabecular iris space area (TISA), trabecular iris angle (TIA), and anterior chamber angle (ACA). 3305 AS-OCT images from 362 eyes and 203 patients were collected and analyzed. Based on the recently proposed transformer-based architecture that learns to capture long-range dependencies by leveraging the self-attention mechanism, a hybrid convolutional neural network (CNN) and transformer model to encode both local and global features was developed to automatically detect IR and SS in AS-OCT images. Experiments demonstrated that our algorithm achieved a significantly better performance than state-of-the-art methods for AS-OCT and medical image analysis with a precision of 0.941, a sensitivity of 0.914, an F1 score of 0.927, and a mean absolute error (MAE) of 37.1±25.3 µm for IR, and a precision of 0.805, a sensitivity of 0.847, an F1 score of 0.826, and an MAE of 41.4±29.4 µm for SS, and a high agreement with expert human analysts for AC angle parameter measurement. We further demonstrated the application of the proposed method to evaluate the effect of cataract surgery with IOL implantation in a PACG patient and to assess the outcome of ICL implantation in a patient with high myopia with a potential risk of developing PACG. The proposed method can accurately detect IR and SS in AS-OCT images and effectively facilitate the AC angle parameter measurement for pre- and post-operative management of PACG.

Non-optical coherence tomography modalities for assessment of angle closure.

Primary angle closure glaucoma is a leading cause of irreversible blindness, particularly in Asia. Its pathophysiology is based in the closure of the anterior chamber angle (ACA). In addition to gonioscopy (current reference standard), in the past decade, anterior segment optical coherence tomography (AS-OCT) has been incorporated in routine ophthalmic practice to help assess the configuration of the ACA. Especially in nonspecialist ophthalmology practice, gonioscopy may be less frequently performed and AS-OCT may not be available, leading to the need of other anterior segment evaluation methods. Evaluating the anterior chamber depth (ACD) has long been recognized as screening tool for primary angle-closure glaucoma. It can be measured with several devices, such as Scheimpflug photography and the scanning peripheral ACD analyzer. It can also be estimated with the oblique flashlight test and van Herick technique (limbal ACD assessment). More recently, goniophotographic systems have been developed to produce images of the ACA similar to those seen with manual gonioscopy. NGS-1 automated gonioscope (NIDEK Co, Gamagori, Japan) and the RetCam (Natus Medical Incorporated, Pleasanton, CA) are commercially available. However, NGS-1 is the only one with a specialized software for ACA imaging. Several prototype devices are currently being developed, such as the GonioPEN and axicon lens assisted gonioscopy. This article aims to review different modalities of ACA assessment, beyond AS-OCT, and compare their relative advantages and disadvantages.

Understanding diagnostic disagreement in angle closure assessment between anterior segment optical coherence tomography and gonioscopy

Background/aimsAlthough being a more objective tool for assessment and follow-up of angle closure, reliability studies have reported a moderate diagnostic performance for anterior segment optical coherence tomography (OCT) technologies when...

Anterior Segment Imaging for Angle Closure

To summarize the role of anterior segment imaging (AS-imaging) in angle closure diagnosis and management, and the possible advantages over the current standard of gonioscopy. Literature review and perspective. Review of the pertinent publications with interpretation and perspective in relation to the use of AS-imaging in angle closure assessment focusing on anterior segment optical coherence tomography and ultrasound biomicroscopy. Several limitations have been encountered with the reference standard of gonioscopy for angle assessment. AS-imaging has been shown to have performance in angle closure detection compared to gonioscopy. Also, imaging has greater reproducibility and serves as better documentation for long-term follow-up than conventional gonioscopy. The qualitative and quantitative information obtained from AS-imaging enables better understanding of the underlying mechanisms of angle closure and provides useful parameters for risk assessment and possible prediction of the response to laser and surgical intervention. The latest technologies-including 3-dimensional imaging-have allowed for the assessment of the angle that simulates the gonioscopic view. These advantages suggest that AS-imaging has a potential to be a reference standard for the diagnosis and monitoring of angle closure disease in the future. Although gonioscopy remains the primary method of angle assessment, AS-imaging has an increasing role in angle closure screening and management. The test should be integrated into clinical practice as an adjunctive tool for angle assessment. It is arguable that AS-imaging should be considered first-line screening for patients at risk for angle closure.

A Population-Based Assessment of the Agreement Between Grading of Goniophotographic Images and Gonioscopy in the Chinese-American Eye Study (CHES).

PurposeTo compare grading of goniophotographic images and gonioscopy in assessing the iridocorneal angle.MethodsIn a population-based, cross-sectional study, participants underwent gonioscopy and goniophotographic imaging during the same visit. The iridocorneal angle was classified as closed if the posterior trabecular meshwork could not be seen. A single masked observer graded the goniophotographic images, and each eye was classified as having angle closure based on the number of closed quadrants. Agreement between the methods was analyzed by calculating kappa (κ) and first-order agreement coefficient (AC1) statistics and comparison of area under receiver operating characteristic curves (AUC).ResultsA total of 4149 Chinese Americans (3994 eyes) were included in this study. The agreement for angle closure diagnosis between gonioscopy and EyeCam was moderate to excellent (κ = 0.60, AC1 0.90, AUC 0.76–0.80).ConclusionsDetection of iridocorneal angle closure based on goniophotographic imaging shows moderate to very good agreement with angle closure assessment using gonioscopy.

The plateau iris component of primary angle closure glaucoma: Developmental or acquired

Primary angle closure glaucoma has been called the most common form of glaucoma in the world, and the leading cause of bilateral blindness. Pupillary block is felt to be the main mechanism of outflow obstruction in this condition. Recent advances in morphologic assessment of angle closure, specifically by means of ultrasound biomicroscopy, have revealed that plateau iris in eyes with angle closure glaucoma is more common than had previously been thought. The most characteristic finding in this disease is thicker and more anteriorly positioned lens. This induces the pupillary block that relives by laser iridotomy. Residual angle closure after laser iridotomy is due to the plateau iris. Peripheral iridoplasty, the standard treatment of plateau iris, tights the peripheral iris and opens the angle but has no effect on the ciliary processes configuration. The ciliary processes are positioned posteriorly after lens extraction but dose not disappears completely. Considering these facts we hypothesized that the plateau iris in primary angle closure glaucoma is a developmental entity that reaches to a critical stage with aging owing to the thickening and forward movement of the lens. Cataract surgery deeps the anterior chamber, widens the irido-corneal angle and reposits the ciliary processes posteriorly, so it can prevents synechia formation and progressive lens-induced angle narrowing and plateau iris progression, the acquired component, with aging.

Comparison of the Scanning Peripheral Anterior Chamber Depth Analyzer and the Modified van Herick Grading System in the Assessment of Angle Closure

To compare the performance of the scanning peripheral anterior chamber depth analyzer (SPAC) and the modified van Herick grading system in the assessment of angle closure, using gonioscopy as the reference standard. Prospective comparative study. One hundred twenty phakic subjects (53 with primary angle closure and 67 with open angles) with no history of laser or intraocular surgery. The modified van Herick grading system was used to grade the peripheral anterior chamber depth (ACD) clinically. The SPAC was used to assess ACD, and this was graded categorically as S (suspect angle closure), P (potential angle closure), or N (normal) and numerically from 1 to 12. One randomly selected eye of each subject underwent examination with the modified van Herick grading, SPAC, Goldmann applanation tonometry, optic disc examination, and gonioscopy. The SPAC measurements, modified van Herick grades (0%, 5%, 15%, 25%, 40%, 75%, and > or =100% of corneal thickness), and gonioscopy (graded as narrow or open) were correlated using the Spearman correlation coefficient. The receiver operating characteristics of the 2 methods to detect angle closure also were compared. Grading of ACD by the SPAC, the modified van Herick system, and gonioscopic grading of the angle. The SPAC results correlated well with the modified van Herick grading system (categorical grade, r = 0.527; numerical grade, r = 0.542; P<0.0001). For eyes graded as having narrow angles by gonioscopy, the area under the curve (AUC) for SPAC categorical grade S or P was 0.790; sensitivity and specificity were 84.9% and 73.1%, respectively. For the modified van Herick grading system, using a cutoff of peripheral ACD < or = 25% corneal thickness, the AUC was 0.872 and sensitivity and specificity were 84.9% and 89.6%. Compared with gonioscopy that found 53 of 120 cases of narrow angles, the SPAC graded more eyes as having narrow angles (63/120) than the modified van Herick system (52/120). The SPAC correlated well with the modified van Herick system in grading peripheral ACD. However, the SPAC appeared to overestimate the proportion of eyes with narrow angles relative to gonioscopy and the modified van Herick grading system.

Lens-induced uveitis: Further immunological studies in an experimental model

Primary angle closure glaucoma has been called the most common form of glaucoma in the world, and the leading cause of bilateral blindness. Pupillary block is felt to be the main mechanism of outflow obstruction in this condition. Recent advances in morphologic assessment of angle closure, specifically by means of ultrasound biomicroscopy, have revealed that plateau iris in eyes with angle closure glaucoma is more common than had previously been thought. The most characteristic finding in this disease is thicker and more anteriorly positioned lens. This induces the pupillary block that relives by laser iridotomy. Residual angle closure after laser iridotomy is due to the plateau iris. Peripheral iridoplasty, the standard treatment of plateau iris, tights the peripheral iris and opens the angle but has no effect on the ciliary processes configuration. The ciliary processes are positioned posteriorly after lens extraction but dose not disappears completely. Considering these facts we hypothesized that the plateau iris in primary angle closure glaucoma is a developmental entity that reaches to a critical stage with aging owing to the thickening and forward movement of the lens. Cataract surgery deeps the anterior chamber, widens the irido-corneal angle and reposits the ciliary processes posteriorly, so it can prevents synechia formation and progressive lens-induced angle narrowing and plateau iris progression, the acquired component, with aging.