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J Glaucoma. 2013 Dec;22(9):684-8. doi: 10.1097/IJG.0b013e318264b921.

Anterior chamber angle measurements using Schwalbe's line with high-resolution fourier-domain optical coherence tomography.

Author information

1
*Department of Ophthalmology, Eye and ENT Hospital, Fudan University, Shanghai, China †Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA.

Abstract

PURPOSE:

To use Fourier-domain optical coherence tomography (OCT) to measure the angle opening distance at Schwalbe's line (AOD-SL) and determine its value in anterior chamber angle assessment.

METHODS:

Horizontal scans of the nasal and temporal anterior chamber angles in glaucoma subjects were performed at 830 nm wavelength Fourier-domain OCT. Images were graded by 2 ophthalmologists who assessed the visibility of Schwalbe's line (SL), anterior limbus (AL), scleral spur (SS), and angle recess (AR). AOD-SL was measured with computer calipers. SL was manually identified by the termination of the corneal endothelium. Gonioscopy was used to classify anterior chamber angles according to a modified Shaffer system. Spearman ρ analysis was performed to assess correlation between AOD-SL and modified Shaffer grade. A cutoff value of AOD-SL for diagnosing occludable angles (modified Shaffer grade ≤ 1) was determined by receiver operating characteristic (ROC) analyses.

RESULTS:

Thirty-five glaucoma subjects (65 eyes) were enrolled. SL, AL, AR, and SS were visible by OCT in 97.7%, 99.2%, 87.3%, and 80.8% of eyes, respectively. Nasal and temporal AOD-SLs were 322.6 ± 200.2 µm and 341.4 ± 197.4 µm, respectively. Correlation coefficients between AOD-SL and modified Shaffer grade were 0.80 (nasal) and 0.81 (temporal). The diagnostic cutoff value of AOD-SL for occludable angles was 290 µm. The areas under the ROC curve, sensitivity, specificity values were 0.90, 0.80, 0.87 (nasal) and 0.90, 0.85, 0.77 (temporal), respectively.

CONCLUSIONS:

The measurement of AOD-SL by Fourier-domain OCT is highly correlated with gonioscopy and may be a useful noncontact method for assessing angle closure risk.

PMID:
22827999
PMCID:
PMC3496838
DOI:
10.1097/IJG.0b013e318264b921
[Indexed for MEDLINE]
Free PMC Article

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