Screening for Narrow Angles in the Singapore Population: Evaluation of New Noncontact Screening Methods

doi:10.1016/j.ophtha.2008.03.015

Ophthalmology

Volume 115, Issue 10, October 2008, Pages 1720-1727.e2

https://doi.org/10.1016/j.ophtha.2008.03.015 Get rights and content

Purpose

To assess the screening effectiveness of 3 new noncontact devices, the scanning peripheral anterior chamber depth analyzer (SPAC) (Takagi, Nagano, Japan), which measures peripheral anterior chamber depth (ACD); IOLMaster (Carl Zeiss Meditec, Jena, Germany), which measures central ACD; and Visante anterior segment optical coherence tomography (AS-OCT) (Visante, Carl Zeiss Meditec, Dublin, CA), which images the angles, and to compare these instruments with gonioscopy in identifying people with narrow angles (NAs).

Design

Cross-sectional, observational, community-based study.

Participants

Phakic subjects aged ≥50 years without ophthalmic symptoms who were recruited from a community polyclinic in Singapore.

Methods

All subjects underwent examination with SPAC, IOLMaster, and AS-OCT in the dark by a single operator. Gonioscopy was performed by an ophthalmologist masked to the instruments' findings. The area under the curve (AUC) receiver operating characteristic (ROC) was generated to assess the performance of these tests in detecting people with a NA in either eye.

Main Outcome Measures

Eyes were classified as having NAs by gonioscopy if the posterior pigmented trabecular meshwork could be seen for ≤2 quadrants of the angle circumference with or without peripheral anterior synechiae.

Results

A total of 2052 subjects were examined and underwent all 3 tests. The prevalence of a NA in at least 1 eye diagnosed by gonioscopy was 20.4% (422 subjects). The AUC for the SPAC using a numeric grade <5 as a cutoff was 0.83 (95% confidence interval [CI], 0.82–0.85), with a sensitivity of 90.0% (95% CI, 86.8–92.7) and a specificity of 76.6% (95% CI, 74.4–78.6). The AUC for the IOLMaster at an ACD cutoff of <2.87 mm was 0.83 (95% CI, 0.81–0.85), with a sensitivity of 87.7% (95% CI, 84.2–90.7) and a specificity of 77.7% (95% CI, 75.6–79.7). The AUC for the AS-OCT was 0.76 (95% CI, 0.74–0.78), with a sensitivity of 88.4% (95% CI, 84.9–91.3) and a specificity of 62.9% (95% CI, 60.5–65.2).

Conclusions

The low specificity found with the SPAC, IOLMaster, and AS-OCT may limit the usefulness of these devices in screening for NAs.

Financial Disclosure(s)

Proprietary or commercial disclosure may be found after the references.

Section snippets

Study Population and Recruitment

The study had the approval of the ethics review board of the Singapore Eye Research Institute and was performed in accordance with the tenets of the Declaration of Helsinki. In this prospective cross-sectional study, subjects aged >50 years who did not have any ophthalmic symptoms were recruited from a government-run community polyclinic providing primary health care services. This polyclinic serves >10,000 people per month, mainly of lower to middle socioeconomic status with a high proportion

Results

A total of 2114 subjects were screened from December of 2005 to June of 2006. Twelve subjects were ineligible because they were pseudophakic in both eyes or were known to have glaucoma and were excluded. Approximately 90% of subjects were Chinese, with a mean age of 63.3±8.0 years, and 1085 (52.9%) were women (Table 1). Of the 2102 eligible subjects, 50 subjects could not complete the tests for various reasons: alignment errors (12); inability to follow instructions (16) or focus on the

Discussion

The ideal community-based screening test should be clinician-independent, quick, and noninvasive, and have a very high specificity. Although a high sensitivity is important, the choice of the specific thresholds used to trigger a referral for examination is as much a question of public health and health economics issue as a clinical one. The severity of the disease and its impact on the national economy and personal finances need to be balanced against individual and national costs of testing,

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Cited by (92)

Performance of anterior segment OCT-based algorithms in the opportunistic screening for primary angle-closure disease
2024, Heliyon
This study aimed to investigate the performance of deep learning algorithms in the opportunistic screening for primary angle-closure disease (PACD) using combined anterior segment parameters.
This was an observational, cross-sectional hospital-based study. Patients with PACD and healthy controls who underwent comprehensive eye examinations, including gonioscopy and anterior segment optical coherence tomography (ASOCT) examinations under both light and dark conditions, were consecutively enrolled from the Department of Ophthalmology at the Beijing Tongren Hospital between November 2020 and June 2022. The anterior chamber, anterior chamber angle, iris, and lens parameters were assessed using ASOCT. To build the prediction models, backward logistic regression was utilized to select the variables to discriminate patients with PACD from normal participants, and the area under the receiver operating characteristic curve was used to evaluate the efficacy of the opportunistic screening.
The data from 199 patients (199 eyes) were included in the final analysis and divided into two groups: PACD (109 eyes) and controls (90 eyes). Angle opening distance at 500 μm, anterior chamber area, and iris curvature measured in the light condition were included in the final prediction models. The area under the receiver operating characteristic curve was 0.968, with a sensitivity of 91.74 % and a specificity of 91.11 %.
ASOCT-based algorithms showed excellent diagnostic performance in the opportunistic screening for PACD. These results provide a promising basis for future research on the development of an angle-closure probability scoring system for PACD screening.
Progressive Changes in the Anterior Segment and Their Impact on the Anterior Chamber Angle in Primary Angle Closure Disease
2024, American Journal of Ophthalmology
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).
Retrospective clinical cohort study.
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).
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).
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.
Assessment of Iris Trabecular Contact in Eyes with Gonioscopic Angle-Closure
2023, Ophthalmology
To investigate the extent of iris trabecular contact (ITC) measured by anterior segment OCT (AS-OCT) and its association with primary angle-closure (PAC) and PAC glaucoma (PACG) in eyes with gonioscopic angle-closure and to determine the diagnostic performance of ITC for detection of gonioscopic angle-closure.
Multicenter, prospective study.
A total of 119 healthy participants with gonioscopic open-angle and 170 patients with gonioscopic angle-closure (94 with PAC suspect and 76 with PAC/PACG) were included.
One eye of each subject was randomly selected for AS-OCT imaging. Angle-opening distance (AOD500) and trabecular iris space area (TISA500) were measured every 10° for 360°. Two criteria of ITC500 were examined: (1) AOD500 = 0 mm and (2) TISA500 = 0 mm². The association between the extent of ITC500 and PAC/PACG in eyes with gonioscopic angle-closure was analyzed with logistic regression analysis.
Sensitivity and specificity of ITC500 for detection of gonioscopic angle-closure; odds ratio (OR) of PAC/PACG.
The sensitivity of ITC500 ≥ 10° for detection of gonioscopic angle-closure ranged from 82.4% (AOD500 = 0 mm) to 84.7% (TISA500 = 0 mm²), and the specificity was 85.7% (for both AOD500 = 0 mm and TISA500 = 0 mm²). The extent of ITC500 determined by AS-OCT, not cumulative gonioscopy score (i.e., the sum of the modified Shaffer grades over 4 quadrants), was associated with the odds of PAC/PACG in eyes with gonioscopic angle-closure; the odds of PAC/PACG increased by 5% for every 10° increase in ITC500 (OR, 1.051, 95% confidence interval [CI], 1.022–1.080 for AOD500 = 0 mm; OR, 1.049, 95% CI, 1.022–1.078 for TISA500 = 0 mm²). Axial length and anterior chamber depth were not associated with PAC/PACG in eyes with gonioscopic angle-closure (P ≥ 0.574).
A greater extent of ITC measured by AS-OCT, not angle-closure determined by gonioscopy, was associated with a greater odds of PAC/PACG in eyes with gonioscopic angle-closure.
Evaluation of the Diagnostic Performance of Swept-Source Anterior Segment Optical Coherence Tomography in Primary Angle Closure Disease
2022, American Journal of Ophthalmology
Citation Excerpt :
ACD is a parameter that has been extensively studied and found to be a significant risk factor of PACD.20-28 However, using ACD to diagnose PACD, as defined by gonioscopy, has yielded only moderate performance in the literature—sensitivity and specificity are often around 70% to 80%.24,26,29-33 ACD measured from SS-OCT, on the other hand, provides much higher diagnostic power with >85% sensitivity and specificity.
To evaluate the diagnostic performance of swept-source anterior segment optical coherence tomography (SS-OCT) in differentiating eyes with primary angle closure disease (PACD) from eyes of control subjects, as well as eyes with PAC and PAC glaucoma (PACG) from eyes with PAC suspect (PACS) disease.
Multicenter cross-sectional study.
Chinese patients were classified into control, PACS, and PAC/PACG groups. The area under the receiving operating characteristic curve (AUC) from logistic regression models was used to evaluate discriminating ability. Sensitivity and specificity were calculated, and performance of the models was validated using an independent dataset.
A total of 2928 SS-OCT images from 366 eyes of 260 patients were recruited to develop diagnostic models. The validation dataset included 1176 SS-OCT images from 147 eyes of 143 patients. For distinguishing PACD from control eyes, average anterior chamber depth had the highest AUC (0.94). With a cutoff of 2.2 mm for average anterior chamber depth, the sensitivity and specificity were 90.2% and 85.2% in the training set. For distinguishing PAC/PACG from PACS, a multivariate model had an AUC of 0.83, with sensitivity and specificity of 82.0% and 62.8% in the training set. The validation set confirmed the findings.
SS-OCT of the anterior segment showed excellent diagnostic performance distinguishing PACD from normal eyes and moderate diagnostic ability distinguishing eyes with PAC/PACG from eyes with PACS. ACD alone may provide a simple and effective way to diagnose PACD from control subjects. As ACD can be obtained using other more available modalities, this has implications for the early diagnosis of PACD.
Spectral domain - Optical coherence tomography (SD-OCT) as a monitoring tool for alterations in mouse lenses
2020, Experimental Eye Research
The eye lens displays a variety of phenotypes in the wake of genetic modifications or environmental influences. Therefore, a high-resolution in vivo imaging method for the lens is desirable. Optical coherence tomography (OCT) has become a powerful imaging tool in ophthalmology, especially for retinal imaging in small animal models such as mice. Here, we demonstrate an optimized approach specifically for anterior eye segment imaging with spectral domain OCT (SD-OCT) on several known murine lens cataract mutants. Scheimpflug and histological section images on the same eye were used in parallel to assess the observed pathologies. With SD-OCT images, we obtained detailed information about the different alterations from the anterior to the posterior pole of the lens. This capability makes OCT a valuable high-resolution imaging modality for the anterior eye segment in mouse.
Update on the usefulness of optical coherence tomography in assessing the iridocorneal angle
2019, Archivos de la Sociedad Espanola de Oftalmologia
El ángulo iridocorneal por sus implicaciones en la fisiopatología del drenaje del humor acuoso es una estructura fundamental de la cámara anterior. La tomografía de coherencia óptica de segmento anterior es una técnica rápida y no invasiva que obtiene imágenes de los tejidos vivos con una alta resolución permitiendo conocer la anatomía normal del ángulo, sus alteraciones y los cambios que se producen en el mismo tras diferentes intervenciones terapéuticas. La tecnología de la tomografía de coherencia óptica de segmento anterior ha ido evolucionando hasta ofrecer imágenes que permiten identificar y cuantificar estructuras angulares claves en sujetos sanos y en pacientes con glaucoma, especialmente la malla trabecular y el canal de Schlemm, lo que puede contribuir a ampliar el conocimiento de la fisiopatología del glaucoma. Además, permite cuantificar la abertura angular con unos parámetros objetivos descritos en los últimos años, entre los que destacan el ángulo iridotrabecular, la distancia de abertura angular y el área iridotrabecular. La tomografía de coherencia óptica de segmento anterior presenta múltiples utilidades en el estudio de los distintos mecanismos del cierre angular, la evaluación de los cambios angulares tras la realización de una iridotomía láser o iridoplastia, cirugía de la catarata o el implante de lentes fáquicas.
The iridocorneal angle, due to its implications in the physiopathology of aqueous humour drainage, is a fundamental structure of the anterior chamber. Anterior segment optical coherence tomography is a rapid and non-invasive technique that obtains images in vivo. The high resolution allows it to analyse the normal anatomy of the angle, any alterations, and the changes that occur after different therapeutic interventions. Anterior segment optical coherence tomography technology has evolved to provide images that allow the identification and quantification of the angular structures in healthy subjects and in glaucoma patients, and especially the trabecular meshwork and the Schlemm's canal. It also enables the angle width to be quantified, with some objective parameters that have been standardised in recent years, such as the trabecular-iris angle, the angle opening distance, and the trabecular-iris area. This technique has multiple uses in the study of the different mechanisms of angle closure, the evaluation of changes after a laser peripheral iridotomy or iridoplasty after cataract surgery, as well as after the implantation of phakic lenses.

View all citing articles on Scopus

: Manuscript no. 2007–1464.

: Financial Disclosure(s): Dr Kashiwagi has a Japanese patent on the SPAC (Japanese patent No. 3878164). Dr Friedman has been a paid consultant to Carl Zeiss-Meditec. Dr Foster has received honoraria and travel support from Carl Zeiss Meditec. Dr Aung has received research funding and travel support from Carl Zeiss Meditec.

: Supported by a grant from Singhealth Foundation, Singapore. The authors' work was independent of the funders (the funding source had no involvement).

: These authors (R.L. and P.J.F.) contributed equally to this work.

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Original articleScreening for Narrow Angles in the Singapore Population: Evaluation of New Noncontact Screening Methods

Purpose

Design

Participants

Methods

Main Outcome Measures

Results

Conclusions

Financial Disclosure(s)

Section snippets

Study Population and Recruitment

Results

Discussion

Ophthalmology

Ophthalmology

Am J Ophthalmol

Am J Ophthalmol

J Cataract Refract Surg

Ophthalmology

Ophthalmology

Ophthalmology

Number of people with glaucoma worldwide

Br J Ophthalmol

Global data on blindness

Bull World Health Organ

The epidemiology of age related eye diseases in Asia

Br J Ophthalmol

Glaucoma in Mongolia: a population-based survey in Hovsgol Province, northern Mongolia

Arch Ophthalmol

The prevalence of glaucoma in Chinese residents of Singapore: a cross-sectional population survey of the Tanjong Pagar district

Arch Ophthalmol

Prevalence of primary glaucoma in an urban south Indian population

Indian J Ophthalmol

Prevalence and clinical characteristics of glaucoma in adult Chinese: a population-based study in Liwan district, Guangzhou

Invest Ophthalmol Vis Sci

YAG laser iridotomy treatment for primary angle closure in East Asian eyes

Br J Ophthalmol

A population-based evaluation of glaucoma screening: the Baltimore Eye Survey

Am J Epidemiol

Primary angle closure glaucoma: oculometry, epidemiology, and genetics in a high risk population

Acta Ophthalmol Suppl

Anterior chamber depth and primary angle closure glaucoma I An epidemiological study in Greenland Eskimos

Acta Ophthalmol (Copenh)

Aetiology of the anatomical basis for primary angle closure glaucoma: biometrical comparisons between normal eyes and eyes with primary angle-closure glaucoma

Br J Ophthalmol

Original article
Screening for Narrow Angles in the Singapore Population: Evaluation of New Noncontact Screening Methods