[Orbscan: a new device for iridocorneal angle measurement].
OBJECTIVE
To evaluate the accuracy and reproducibility of iridocorneal angle measurement obtained with a slit-lamp method (Orbscan).


METHODS
The iridocorneal angle was measured in 100 normal eyes of 50 patients using the Orbscan II device. Angles were measured in eight meridians using both the "plane" and "polynomial" modes. For each eye, two exams were taken successively and the reproducibility was calculated by analyzing the difference between both measurements. Angle value was correlated with subjective spherical equivalent and other biometric measurements obtained by Orbscan (i.e., anterior chamber depth, axial length, corneal diameter).


RESULTS
Reproducibility of the angle measurement was significantly better with the plane mode than with the polynomial mode (5.4%+/-4.7 versus 7.2%+/-6.2; p<0.001). Reproducibility significantly varied with localization (p<0.001). Significant differences were found between reconstruction modes (49.3 degrees +/-4.6 degrees for plane mode versus 42.8 degrees +/-6.7 degrees for the polynomial mode; p<0.001) and according to localization (p=0.02). Correlation with the other biometric measurements was higher for the plane mode than for the polynomial mode. Angle measurement with the plane mode showed significant correlation with subjective spherical equivalent (r(s)=-0.59; p<0.001), the anterior chamber depth measurement (r(s)=-0.74; p<0.001), the axial length measurement (r(s)=-0.34; p<0.002), and the corneal diameter measurement (r(s)=-0.34; p<0.002).


CONCLUSIONS
The iridocorneal angle measure obtained with the plane mode showed high reproducibility and it significantly correlated with clinical parameters. It appears to be useful for clinical application.
Allouch
C
C
Pôle Saint Antoine, CHNO des Quinze-Vingts, 28 rue de Charenton, 75571 Paris Cedex 12, France.
Touzeau
O
O
Borderie
V
V
Puech
M
M
Ameline
B
B
Scheer
S
S
Laroche
L
L
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000033:anatomy & histology; D001699:Biometry; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005123:Eye / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000175:diagnosis; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D009216:Myopia / Q000175:diagnosis; D009885:Ophthalmology / Q000295:instrumentation*; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis*