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C. Hebson, J. B. Randleman, M. Woodward, K. Rocha; A Comparison of Ocular Response Analyzer, Orbscan II, and Pentacam for Pre-Operative Refractive Surgery Screening. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4202.
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© ARVO (1962-2015); The Authors (2016-present)
To compare and correlate Corneal hysteresis (CH) and Cornea resistance factor (CRF) values generated from the Ocular Response Analyzer (ORA, Reichert Inc.) with tomographic indices generated by Orbscan II (Bausch & Lomb) and Pentacam (Oculus Inc.) and determine the ability of these measurements to synergistically assess corneal biomechanical properties.
Retrospective review of 40 eyes from 20 patients. ORA data included CH and CRF values. Orbscan II and Pentacam data included posterior elevation data (posterior float and posterior best-fit sphere) and corneal thickness (central and thinnest point). Pearson’s correlation coefficients were used to evaluate the relationship between CRF, CH, and these tomographic indices.
Mean ORA CH is 9.6 ± 1.8 mmHg (4.6 - 12.8 mmHg) and CRF is 9.3 ± 2.1 mmHg (4.8 - 14.9 mmHg). Average Orbscan II posterior float is 0.028 ± 0.007 mm (0.012 - 0.042 mm), posterior best-fit sphere is 6.61 ± 0.02 mm (6.25 - 7.17 mm), central thickness is 0.561 ± 0.341 mm (0.493 - 0.623 mm), and thinnest point is 0.552 ± 0.354 mm (0.482 - 0.615 mm). Average Pentacam posterior float is 0.011 ± 0.005 mm (0.005 - 0.033 mm), posterior best-fit sphere is 6.56 ± 0.21 mm (6.17 - 6.98 mm), central thickness is 0.543 ± 0.030 mm (0.485 - 0.599 mm), and thinnest point is 0.541 ± 0.030 mm (0.483 - 0.599 mm). There was no correlation between CRF or CH with any posterior elevation indices; however, there was a moderate correlation between corneal thickness measures with both CH and CRF [Table 1].
There was no significant correlation between CH and CRF with either Orbscan II or Pentacam posterior tomographic indices and only moderate correlation with corneal thickness measurements. Other more advanced ORA and tomographic indices may be necessary to further evaluate corneal biomechanical properties.
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