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J. Wasielica-Poslednik, F. Berisha, S. Aliyeva, N. Pfeiffer, E. M. Hoffmann; Inter- and Intraobserver Reproducibility of Corneal-Compensated Intraocular Pressure, Corneal Resistance Factor and Corneal Hysteresis Measurements Performed With the Ocular Response Analyzer. Invest. Ophthalmol. Vis. Sci. 2008;49(13):714.
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To evaluate the inter- and intraobserver variability of ocular response analyzer (ORA) measurements, namely corneal-compensated intraocular pressure (IOPcc), corneal resistance factor (CRF) and corneal hysteresis (CH).
One randomly chosen eye of 46 healthy volunteers and glaucoma patients was included in this study. Inclusion criteria were best-corrected visual acuity of at least 20/40, clear media, no corneal pathologies and no history of ocular surgery. Three clinical observers performed three consecutive measurements with the ORA with an interval of 1 minute between measurements. In addition, central corneal thickness (CCT) was measured with the Haag-Streit OLCR Pachymeter. The inter- and intraobserver reproducibility for IOPcc, CRF and CH were assessed by ANOVA based intraclass correlation coefficient (ICC) and coefficient of variation (CV).
The mean ICC for interobserver reproducibility was 0.94 for IOPcc, 0.90 for CRF, and 0.86 for CH. The corresponding CV values were 12.8%, 10.3%, and 13.6% respectively.The intraobserver ICC values for IOPcc were 0.86 for the first examiner, 0.84 for the second, and 0.89 for the third. CV was 11.7%, 11.9%, and 11.0% respectively. For CRF the intraobserver ICC values were 0.69, 0.81, and 0.63, and corresponding CV values were 9.6%, 8.1, and 10.8%. The intraobserver ICC for CH was 0.66 for the first observer, 0.71 for the second, and 0.61 for the third examiner. The respective CV values were 12.7%, 11.8%, and 13.9%. There was a significant correlation between CCT and CRF (Rsq=0.13, p=0.02). The correlations between CCT and IOPcc, and CH were not significant (p>0.05).
The interobserver reproducibility of ORA measurements was almost perfect for IOPcc, CRF, and CH. The intraobserver short-term reproducibility was almost perfect for IOPcc and substantial for CRF and CH for all observers. In conclusion, to our knowledge the present study is the first evaluation of the reproducibility of the ORA measurements. This device might be useful in glaucoma diagnosis and management.
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