Elsevier

Ophthalmology

Volume 114, Issue 1, January 2007, Pages 33-39
Ophthalmology

Original Article
Detection of Primary Angle Closure Using Anterior Segment Optical Coherence Tomography in Asian Eyes

https://doi.org/10.1016/j.ophtha.2006.05.073Get rights and content

Objective

To evaluate noncontact anterior segment optical coherence technology (AS-OCT) as a qualitative method of imaging the anterior chamber angle and to determine its ability to detect primary angle closure when compared with gonioscopy in Asian subjects.

Design

Prospective observational case series.

Participants

Two hundred three subjects were recruited from glaucoma clinics in Singapore with diagnoses of primary angle closure, primary open-angle glaucoma, ocular hypertension, or cataract. Both eyes (if eligible) of each patient were included in the study. Exclusion criteria were pseudophakia or previous glaucoma surgery.

Methods

Images of the nasal, temporal, and inferior angles were obtained with AS-OCT in dark and then light conditions. Gonioscopic angle width was graded using the Spaeth classification for each quadrant in low lighting conditions.

Main Outcome Measures

Angle closure was defined by AS-OCT as contact between the peripheral iris and angle wall anterior to the scleral spur and by gonioscopy as a Spaeth grade of 0° (posterior trabecular meshwork not visible). Comparison of the 2 methods in detecting angle closure was done by eye and by individual. Sensitivities and specificities of AS-OCT were calculated using gonioscopy as the reference standard.

Results

Complete data were available for 342 eyes of 200 patients. Of the patients, 70.9% had a clinical diagnosis of treated or untreated primary angle closure. Angle closure in ≥1 quadrants was detected by AS-OCT in 142 (71%) patients (228 [66.7%] eyes) and by gonioscopy in 99 (49.5%) patients (152 [44.4%] eyes). The inferior angle was closed more frequently than the nasal or temporal quadrants using both AS-OCT and gonioscopy. When performed under dark conditions, AS-OCT identified 98% of those subjects found to have angle closure on gonioscopy (95% confidence interval [CI], 92.2–99.6) and led to the characterization of 44.6% of those found to have open angles on gonioscopy to have angle closure as well. With gonioscopy as the reference standard, specificity of AS-OCT in the dark was 55.4% (95% CI, 45.2–65.2) for detecting individuals with angle closure.

Conclusion

Anterior segment OCT is a rapid noncontact method of imaging angle structures. It is highly sensitive in detecting angle closure when compared with gonioscopy. More persons are found to have closed angles with AS-OCT than with gonioscopy.

Section snippets

Study Participants

Ethical approval was obtained from the ethical review board of the National University Hospital Singapore, and written informed consent was obtained from all subjects. The work was carried out in accordance with the World Medical Association’s Declaration of Helsinki. Subjects ≥40 years old were recruited from the glaucoma clinics at National University Hospital. We attempted to recruit as many patients as possible with suspected (e.g., with a shallow central or peripheral AC) or confirmed

Characteristics of Study Population

A total of 203 subjects were recruited, of whom 123 (60.6%) were female. The majority of subjects were Chinese (174 [85.7%]), Malay (9 [4.4]), and Indian (12 [5.9%]), and a small number of subjects were of other ethnic origins (8 [3.9%]). The median age of the sample was 62.5 years (range, 40–86). Diagnosis of all recruited subjects is shown in Table 1. A diagnosis of narrow angles or primary angle closure with or without glaucoma was present for 144 (70.9%) patients, some of whom had been

Discussion

Anterior segment OCT technology enables examiners to obtain detailed cross-sectional images of the ACA while avoiding contact with the globe. These images can be analyzed qualitatively. As a result, it is a quick and easily tolerated procedure for the patient. It also is likely that there is less distortion of angle morphology due to lack of globe manipulation.

In this study, AS-OCT identified almost all eyes as having closed angles that were found by gonioscopy to be closed. Using gonioscopy as

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Cited by (0)

Manuscript no. 2005-1034.

Financial support: National University of Singapore (grant nos.: R-191000007101, R-191000007112).

Technical support and loan of anterior segment optical coherence tomography machine from Carl Zeiss Meditec, Dublin, California.

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