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

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


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.

Publication types

  • Observational Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Anterior Chamber / pathology*
  • Cornea / anatomy & histology*
  • Female
  • Fourier Analysis
  • Glaucoma, Angle-Closure / diagnosis*
  • Gonioscopy
  • Humans
  • Intraocular Pressure / physiology
  • Male
  • Prospective Studies
  • ROC Curve
  • Tomography, Optical Coherence*
  • Tonometry, Ocular
  • Trabecular Meshwork / pathology*
  • Visual Acuity / physiology