Primary angle closure disease (PACD) is a major cause of blindness worldwide. It has a high prevalence in East Asia, especially in China, which leads to a higher incidence of blindness than open-angle glaucoma. The aim of this study was to directly observe the circumlental space (CLS) in laser peripheral iridotomized eyes with PACD and to determine whether this structure plays a role in the pathogenesis of PACD. Fifty eyes of 50 patients with PACD, who had received laser peripheral iridotomy performed with neodymium:yttrium-aluminum-garnet were recruited from glaucoma clinics from March 2021 to May 2022, including 17 primary angle closure suspect (PACS), 16 primary angle closure (PAC) and 17 primary angle closure glaucoma (PACG). They were classified into two groups based on whether the ciliary process and the crystalline lens equator were in contact using slit-lamp photograph: the attached group and the unattached group. The demographic, clinical characteristics and anterior segment parameters measured from ultrasound biomicroscopy were compared between the attached group and the unattached group. Thirty-three eyes were assigned to the attached group and 17 eyes belonged to the unattached group. In the unattached group, the mean CLS was 0.10 ± 0.07 mm. No significant differences were identified between the different diagnosis groups in age, sex, best-corrected visual acuity, intraocular pressure, white-to-white, axial length, central corneal thickness, anterior chamber depth, flat keratometry, steep keratometry or iridotomy diameter (p > 0.05). The unattached group had shorter trabecular-ciliary process distance (p = 0.021) and larger ciliary process area (p = 0.001) compared with the attached group. Small CLS and its potential effect (partial ciliary block) might be considered as one of the mechanisms of PACD.

Primary angle closure glaucoma is a visually debilitating disease that is under-detected worldwide. Many of the challenges in managing primary angle closure disease (PACD) are related to the lack of convenient and precise tools for clinic-based disease assessment and monitoring. Artificial intelligence (AI)- assisted tools to detect and assess PACD have proliferated in recent years with encouraging results. Machine learning (ML) algorithms that utilize clinical data have been developed to categorize angle closure eyes by disease mechanism. Other ML algorithms that utilize image data have demonstrated good performance in detecting angle closure. Nonetheless, deep learning (DL) algorithms trained directly on image data generally outperformed traditional ML algorithms in detecting PACD, were able to accurately differentiate between angle status (open, narrow, closed), and automated the measurement of quantitative parameters. However, more work is required to expand the capabilities of these AI algorithms and for deployment into real-world practice settings. This includes the need for real-world evaluation, establishing the use case for different algorithms, and evaluating the feasibility of deployment while considering other clinical, economic, social, and policy-related factors.

OBJECTIVE: To investigate longitudinal changes in the anterior segment (AS) using serial optical coherence tomography (OCT) images and determine the impact of these changes on the anterior chamber angle (ACA) in eyes with primary angle closure disease (PACD) treated with laser peripheral iridotomy (LPI).
METHODS: Retrospective clinical cohort study.
METHODS: This study included 103 patients with PACD who underwent LPI and were followed up by a mean 6.7 ± 1.7 AS-OCT examinations for a mean 6.5 ± 2.9 years. Temporal changes in AS-OCT parameters, including anterior chamber depth (ACD), angle opening distance (AOD750), angle recess area (ARA750), iris thickness (IT750), lens vault (LV), and pupil diameter (PD), were analyzed by multivariate linear mixed effects models (LMEMs).
RESULTS: Multivariate LMEMs showed that decrease in AOD750 was not significant (-1.59 µm/y, P = .222); however, ARA750 decreased over time (-2.3 × 103 µm2/y, P = .033) and SSA showed marginal significance (-0.20°/y, P = .098), and LV increased significantly (11.6 µm/y, P < .001) after LPI. Mean LV change was negatively associated with AOD750, ARA750, and SSA, whereas PD was negatively associated with ARA750 (P < .001 each). PD decreased with aging (-13.7 µm/y, P = .036), accompanied by thinning of IT750 (-1.7 µm/y, P = .063).
CONCLUSIONS: LV tends to increase with aging, which contributes to the shallowing of the anterior chamber and narrowing of ACA in PACD eyes treated with LPI. In the meantime, pupillary constriction and subsequent peripheral iris thinning associated with aging could possibly offset the effect of ACA narrowing.

OBJECTIVE: To perform an in vivo evaluation of the changes in Schlemm\'s canal (SC) among patients with primary angle-closure disease (PACD) using swept-source optical coherence tomography (SS-OCT).
METHODS: Patients diagnosed with PACD who had not undergone surgery were recruited. The SS-OCT quadrants scanned herein included the nasal and temporal sections at 3 and 9 o\'clock, respectively. The diameter and cross-sectional area of the SC were measured. A linear mixed-effects model was performed to analyze the effects of parameters on the SC changes. The hypothesis of interest was related to the angle status (iridotrabecular contact, ITC/open angle, OPN), which was further explored with pairwise comparisons of the estimated marginal means (EMMs) of the SC diameter and SC area. In the ITC regions, the relationship between the trabecular-iris contact length (TICL) percentage and SC parameters was also studied by a mixed model.
RESULTS: A total of 49 eyes of 35 patients were included for measurements and analysis. The percentage of observable SCs in the ITC regions was only 58.5% (24/41), whereas it was 86.0% (49/57) in the OPN regions (χ2 = 9.44, p = 0.002). ITC was significantly associated with a decreasing SC size. The EMMs for the diameter and cross-sectional area of SC at the ITC and OPN regions were 203.34 μm versus 261.41 μm (p = 0.006) and 3174.43 μm2 versus 5347.63 μm2 (p = 0.022), respectively. Sex, age, spherical equivalent refraction, intraocular pressure, axial length, extent of angle closure, history of acute attack and treatment with LPI were not significantly associated with SC parameters. In the ITC regions, a larger TICL percentage was significantly associated with a decrease in SC diameter and area (p = 0.003 and 0.019, respectively).
CONCLUSIONS: The morphologies of SC could be affected by the angle status (ITC/OPN) in patients with PACD, and ITC was significantly associated with a decreasing SC size. These changes in SC as described by OCT scans might help to elucidate the progression mechanisms of PACD.

To determine the association of primary angle-closure disease (PACD) in patients with retinal vein occlusion (RVO) at a tertiary eye care center in North India.
It is a cross-sectional, observational study. Sixty consecutive patients with retinal vein occlusion within a period of one year from a single tertiary eye care center were enrolled. Detailed history, slit-lamp examination of the anterior segment, intraocular pressure measurement by applanation tonometry, gonioscopy and fundus examination were done. Anterior chamber depth and axial length were also measured.
Among the 60 patients, 29 were males (48.3%) and 31 females (51.6%). Twenty-seven (45%) of them had central retinal vein occlusion (CRVO) and 33 (55%) had branch retinal vein occlusion (BRVO). Forty percent of patients with RVO had PACD. Relative risk of PACD was 1.71 times in patients with CRVO as compared to BRVO. Risk of glaucoma was 49% more in CRVO than BRVO. Probability of PACD was more in patients of RVO who had diabetes and CAD as comorbidity.
The association between PACD and RVO is less known. PACD can be one of the risk factors for the development of RVO. A comprehensive examination and detailed angle evaluation of both of the eyes should be done in all cases of RVO, in addition to investigating for systemic risk factors. However, larger population-based studies would be required to prove it as an independent risk factor.

OBJECTIVE: To assess the clinical characteristics of comorbid retinal dystrophies and primary angle closure disease.
METHODS: Retrospective study from January 1992 to June 2020.
METHODS: This descriptive study included 92 eyes of 46 patients with comorbid retinal dystrophies and primary angle closure disease (PACD) that included eyes with primary angle closure suspect, primary angle closure and primary angle closure glaucoma. Demographic profile, clinical characteristics of PACD and its association with retinal dystrophies are described.
RESULTS: The study included 46 patients (92 eyes). Males were majority, 63%. Mean (± standard deviation) age when retinal dystrophy was diagnosed was 29.6 ± 9.4 years and PACD was diagnosed at 32.23 ± 7.92 years. Mean BCVA at presentation was 1.07 ± 0.87 log MAR [95% confidence interval (CI) 0.87, 1.26]. Mean Intraocular pressure at diagnosis of glaucoma was 27 ± 16 mmHg (95% CI 23.5, 31.5 mmHg). The most common retinal dystrophy associated with PACD was retinitis pigmentosa (RP) followed by RP with retinoschisis. The hospital-based prevalence of PACD among all patients with RP and retinoschisis was 0.19% and 0.15% respectively. Laser peripheral iridotomy was performed in 74 eyes (80.5%). Glaucoma was managed medically in majority of the eyes (58 eyes, 63.04%) and minority required surgical management with trabeculectomy (11, 11.9%).
CONCLUSIONS: Retinitis pigmentosa is the most common retinal dystrophy associated with PACD. Comorbid PACD in eyes with retinal dystrophies was observed in second to third decade of life. This calls for screening for angle closure in eyes with retinal dystrophies from second decade onwards to identify the comorbid PACD and treat or refer them appropriately.

OBJECTIVE: To develop deep learning classifiers and evaluate their diagnostic performance in detecting the static gonioscopic angle closure and peripheral anterior synechia (PAS) based on swept source optical coherence tomography (SS-OCT) images.
METHODS: Subjects were recruited from the Glaucoma Service at Zhongshan Ophthalmic Center of Sun Yat-sun University, Guangzhou, China. Each subject underwent a complete ocular examination, such as gonioscopy and SS-OCT imaging. Two deep learning classifiers, using convolutional neural networks (CNNs), were developed to diagnose the static gonioscopic angle closure and to differentiate appositional from synechial angle closure based on SS-OCT images. Area under the receiver operating characteristic (ROC) curve (AUC) was used as outcome measure to evaluate the diagnostic performance of two deep learning systems.
RESULTS: A total of 439 eyes of 278 Chinese patients, which contained 175 eyes of positive PAS, were recruited to develop diagnostic models. For the diagnosis of static gonioscopic angle closure, the first deep learning classifier achieved an AUC of 0.963 (95% CI, 0.954-0.972) with a sensitivity of 0.929 and a specificity of 0.877. The AUC of the second deep learning classifier distinguishing appositional from synechial angle closure was 0.873 (95% CI, 0.864-0.882) with a sensitivity of 0.846 and a specificity of 0.764.
CONCLUSIONS: Deep learning systems based on SS-OCT images showed good diagnostic performance for gonioscopic angle closure and moderate performance in the detection of PAS.

BACKGROUND: To determine the prevalence of zonulopathy in a large cohort of eyes with primary angle closure disease (PACD) that underwent cataract surgery.
METHODS: Retrospective consecutive case series of PACD eyes (including primary angle closure suspect, primary angle closure, and primary angle closure glaucoma) that underwent phacoemulsification cataract surgery or clear lens extraction between 2009 and 2020 at a single ophthalmology centre. Those with risk factors for zonulopathy such as history of trauma, pseudoexfoliation syndrome, intraocular surgery, retinitis pigmentosa or connective tissue disorders were excluded. The primary outcomes included the prevalence of zonulopathy assessed intraoperatively and secondary pigment dispersion syndrome.
RESULTS: In our cohort of 806 consecutive PACD eyes, the prevalence of zonulopathy was 7.3% (59 of 806 eyes) - significantly greater than the 0.46%-2.6% range reported for the general population (p < 0.001). Intraoperative signs of zonular weakness included floppy capsular bag (29 eyes, 3.6%), zonular laxity (25 eyes, 3.1%) and zonular dehiscence (11 eyes, 1.4%). Among these eyes, capsular tension ring was used in 23 eyes (39.0%), six eyes (10.2%) experienced vitreous prolapse intraoperatively and underwent anterior vitrectomy, and two eyes (3.4%) experienced posterior capsular rupture, one of which required a scleral-fixated intraocular lens. Secondary pigment dispersion syndrome was observed in 141 eyes (17.5%).
CONCLUSIONS: This study evidenced a high prevalence of zonulopathy among a large cohort of PACD eyes and suggests zonulopathy as a possible under-recognised cause of angle closure. Until more sophisticated imaging modalities become available, awareness about the prevalence of zonulopathy in angle closure disease coupled with careful preoperative examinations can help minimise or prevent the complications of zonulopathy.

BACKGROUND: Primary angle closure disease (PACD) is a type of glaucoma in which the intraocular pressure (IOP) is increased because of the blockage of the anterior chamber angle. Medications contraindicated for patients with PACD, such as anticholinergics, cause mydriasis, and can elevate IOP. However, anticholinergics are currently contraindicated only for primary angle closure glaucoma (PACG) in Japanese package inserts. In this study, we investigated the prescription status of medications contraindicated for PACD, such as anticholinergics, in patients with PACD scheduled for eye surgeries.
METHODS: Forty-three Japanese patients diagnosed with PACD at Kobe City Eye Hospital, Japan, and scheduled hospitalization for eye surgeries between December 2017 and July 2018, were included. Data, including sex, age, diagnosis, IOP, anterior chamber depth, and patients\' regular medications prior to hospitalization, were collected for each patient from the electronic medical records.
RESULTS: The number of patients with chronic primary angle closure (CPAC) and acute primary angle closure (APAC) was 35 (81.4%) and 8 (18.6%), respectively. Among all the 43 patients with PACD, 8 (18.6%) received 15 medications that are potentially contraindicated for PACD by non-ophthalmologist. According to medication categories, benzodiazepine hypnotics were the most commonly prescribed. Among the 8 patients with APAC, 2 (25.0%) had routinely received medications contraindicated for PACD. The median number of all kinds of prescriptions on the day of hospitalization was significantly higher for patients who received medications contraindicated for PACD than for those who did not receive them (p = 0.010).
CONCLUSIONS: About 20% of patients with PACD received medications potentially contraindicated for PACD, such as anticholinergics. Attention should be paid to patients prescribed multiple drugs for adverse events, such as increase in intraocular pressure.

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.
Cross-sectional study.
Patients with primary angle closure disease (PACD) were identified from the Chinese American Eye Study, a population-based study in Los Angeles, California.
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.
Averaged and sectoral measurements of biometric parameters.
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).
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.