[Orbscan: a new device for iridocorneal angle measurement].

Area of Science:

• Ophthalmology and optometry.
• Biomedical optics and instrumentation.

Background:

• Accurate measurement of the iridocorneal angle is crucial for diagnosing and managing various ocular conditions, including glaucoma.
• Slit-lamp based devices offer a non-invasive method for angle assessment, but their reproducibility and accuracy require thorough evaluation.

Purpose of the Study:

• To assess the accuracy and reproducibility of iridocorneal angle measurements using the Orbscan II slit-lamp based device.
• To compare the performance of different measurement modes (plane vs. polynomial) and their correlation with ocular biometric parameters.

Main Methods:

• Iridocorneal angle measurements were performed on 100 normal eyes using the Orbscan II, employing both "plane" and "polynomial" reconstruction modes across eight meridians.
• Reproducibility was determined by successive measurements on the same eye, and angle values were correlated with subjective spherical equivalent, anterior chamber depth, axial length, and corneal diameter.

Main Results:

• The "plane" mode demonstrated significantly better reproducibility (5.4%+/-4.7) compared to the "polynomial" mode (7.2%+/-6.2) (p<0.001).
• Significant differences in angle measurements were observed between the "plane" (49.3°+/-4.6°) and "polynomial" (42.8°+/-6.7°) modes (p<0.001).
• The "plane" mode exhibited stronger correlations with clinical parameters, including anterior chamber depth (r(s)=-0.74) and spherical equivalent (r(s)=-0.59).

Conclusions:

• Iridocorneal angle measurement using the "plane" mode of the Orbscan II offers high reproducibility.
• This method shows significant correlation with key clinical parameters, suggesting its utility in routine ophthalmological practice.
• The "plane" mode appears to be a reliable tool for clinical assessment of the iridocorneal angle.