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dc.contributor.authorSuheimat, M.*
dc.contributor.authorVerkicharla, P.K.*
dc.contributor.authorMallen, Edward A.H.*
dc.contributor.authorRozema, J.J.*
dc.contributor.authorAtchison, D.A.*
dc.date.accessioned2016-09-21T17:19:34Z
dc.date.available2016-09-21T17:19:34Z
dc.date.issued2015
dc.identifier.citationSuheimat, M., Verkicharla, P. K., Mallen, E. A., Rozema, J. J. and Atchison, D. A. (2015) Refractive indices used by the Haag-Streit Lenstar to calculate axial biometric dimensions. Ophthalmic & Physiological Optics. 35(1): 90-96.
dc.identifier.urihttp://hdl.handle.net/10454/9410
dc.descriptionNo
dc.description.abstractPURPOSE: To estimate refractive indices used by the Lenstar biometer to translate measured optical path lengths into geometrical path lengths within the eye. METHODS: Axial lengths of model eyes were determined using the IOLMaster and Lenstar biometers; comparing those lengths gave an overall eye refractive index estimate for the Lenstar. Using the Lenstar Graphical User Interface, we noticed that boundaries between media could be manipulated and opposite changes in optical path lengths on either side of the boundary could be introduced. Those ratios were combined with the overall eye refractive index to estimate separate refractive indices. Furthermore, Haag-Streit provided us with a template to obtain 'air thicknesses' to compare with geometrical distances. RESULTS: The axial length estimates obtained using the IOLMaster and the Lenstar agreed to within 0.01 mm. Estimates of group refractive indices used in the Lenstar were 1.340, 1.341, 1.415, and 1.354 for cornea, aqueous, lens, and overall eye, respectively. Those refractive indices did not match those of schematic eyes, but were close in the cases of aqueous and lens. Linear equations relating air thicknesses to geometrical thicknesses were consistent with our findings. CONCLUSION: The Lenstar uses different refractive indices for different ocular media. Some of the refractive indices, such as that for the cornea, are not physiological; therefore, it is likely that the calibrations in the instrument correspond to instrument-specific corrections and are not the real optical path lengths.
dc.language.isoen
dc.subjectAxial length
dc.subjectEye
dc.subjectAnatomy & Histology
dc.subjectBiometry
dc.subjectHumans
dc.subjectLinear models
dc.subjectAnatomic refraction
dc.subjectOcular physiology
dc.subjectRefractometry
dc.subjectLenstar
dc.subjectThickness
dc.subjectAxial length
dc.subjectPartial coherence interferometry
dc.subjectRefractive index
dc.titleRefractive indices used by the Haag-Streit Lenstar to calculate axial biometric dimensions
dc.status.refereedYes
dc.date.Accepted2014-11-05
dc.date.application2014-12-03
dc.typeJournal Article
dc.type.versionNo full-text in the repository
dc.identifier.doihttps://doi.org/10.1111/opo.12182
dc.openaccess.statusclosedAccess


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