TY - JOUR
T1 - Characterisation of Schlemm's canal cross-sectional area
AU - Kagemann, Larry
AU - Nevins, Jessica E.
AU - Jan, Ninj Jiun
AU - Wollstein, Gadi
AU - Ishikawa, Hiroshi
AU - Kagemann, Janice
AU - Sigal, Ian A.
AU - Nadler, Zach
AU - Ling, Yun
AU - Schuman, Joel S.
PY - 2014/7
Y1 - 2014/7
N2 - Purpose: To compare three methods of Schlemm's canal (SC) cross-sectional area (CSA) measurement. Methods: Ten eyes (10 healthy volunteers) were imaged three times using spectral-domain optical coherence tomography (Cirrus HD-OCT, Zeiss, Dublin, California, USA). Aqueous outflow vascular structures and SC collector channel ostia were used as landmarks to identify a reference location within the limbus. SC CSA was assessed within a 1 mm segment (±15 frames of the reference, 31 frames in all) by three techniques. (1) Using a random number table, SC CSA in five random frames from the set of 31 surrounding the reference were measured and averaged. (2) The most easily visualised SC location (subjective) was measured, and (3) SC CSA was measured in all 31 consecutive B-scans, and averaged. (comprehensive average, gold standard). Subjective and random CSAs were compared with the comprehensive by general estimating equation modelling, and structural equation modelling quantified agreement. Results: The average from five random locations (4175 ±1045 μm2) was not significantly different than that obtained from the gold standard comprehensive assessment (4064±1308 μm2, p=0.6537). Subjectively located SC CSA (7614±2162 μm2) was significantly larger than the comprehensive gold standard SC CSA (p<0.0001). The average of five random frames produced significantly less bias than did subjective location, yielding a calibration line crossing the 'no-bias' line. Discussion: Subjectively located SC CSA measurements produce high estimates of SC CSA. SC assessed by measuring five random locations estimate CSA was similar to the gold standard estimate.
AB - Purpose: To compare three methods of Schlemm's canal (SC) cross-sectional area (CSA) measurement. Methods: Ten eyes (10 healthy volunteers) were imaged three times using spectral-domain optical coherence tomography (Cirrus HD-OCT, Zeiss, Dublin, California, USA). Aqueous outflow vascular structures and SC collector channel ostia were used as landmarks to identify a reference location within the limbus. SC CSA was assessed within a 1 mm segment (±15 frames of the reference, 31 frames in all) by three techniques. (1) Using a random number table, SC CSA in five random frames from the set of 31 surrounding the reference were measured and averaged. (2) The most easily visualised SC location (subjective) was measured, and (3) SC CSA was measured in all 31 consecutive B-scans, and averaged. (comprehensive average, gold standard). Subjective and random CSAs were compared with the comprehensive by general estimating equation modelling, and structural equation modelling quantified agreement. Results: The average from five random locations (4175 ±1045 μm2) was not significantly different than that obtained from the gold standard comprehensive assessment (4064±1308 μm2, p=0.6537). Subjectively located SC CSA (7614±2162 μm2) was significantly larger than the comprehensive gold standard SC CSA (p<0.0001). The average of five random frames produced significantly less bias than did subjective location, yielding a calibration line crossing the 'no-bias' line. Discussion: Subjectively located SC CSA measurements produce high estimates of SC CSA. SC assessed by measuring five random locations estimate CSA was similar to the gold standard estimate.
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U2 - 10.1136/bjophthalmol-2013-304629
DO - 10.1136/bjophthalmol-2013-304629
M3 - Article
C2 - 24590558
AN - SCOPUS:84905565731
SN - 0007-1161
VL - 98
SP - ii10-ii14
JO - British Journal of Ophthalmology
JF - British Journal of Ophthalmology
IS - SUPPL. 2
ER -