Quantitative descriptors of corneal topography that influence soft toric contact lens fitting

Cornea
L B SzczotkaAshraf Mahmoud

Abstract

Empirical soft toric contact lens fitting based on manifest refraction and keratometry often presents unanticipated fitting and power errors upon initial lens dispensing. However, corneal topography may provide features that influence soft toric lens performance, flexure, and back vertex power in situ, which may assist in improved fitting guidelines. In this study, quantitative topographic descriptors were generated and analyzed as potential variables in predicting soft toric fitting success. One hundred five eyes of 54 patients were empirically fit with back surface toric, prism ballasted, soft contact lenses after videokeratography was performed with the EyeSys 2000 (v. 4.0) or Humphrey Atlas (v. A6) instrument. Custom software was written to generate 54 separate quantitative descriptors of shape and astigmatism from the raw data files. A logistic regression was used to determine which variables significantly contributed to a successful or failed fit. Two types of empirical fitting failures were identified: loose fit (n = 15) and power errors (n = 17). The following variables were associated with a fitting failure: flat simulated keratometry (SimKf2b) within the central 3 mm zone, steep simulated keratometry (SimKs2b) within ...Continue Reading

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Citations

Feb 3, 2009·Optometry and Vision Science : Official Publication of the American Academy of Optometry·Scott A Read, Michael J Collins
Apr 14, 2010·Optometry and Vision Science : Official Publication of the American Academy of Optometry·Graeme YoungSuzanne Efron
Aug 21, 2013·Contact Lens & Anterior Eye : the Journal of the British Contact Lens Association·Wishal D RamdasIsabel Bleyen
Aug 9, 2005·Clinical & Experimental Optometry : Journal of the Australian Optometrical Association·D Robert Iskander, Michael J Collins
Dec 14, 2011·Clinical & Experimental Optometry : Journal of the Australian Optometrical Association·Ka Yin ChanPauline Cho
May 13, 2017·Contact Lens & Anterior Eye : the Journal of the British Contact Lens Association·Stefan BandlitzJames Wolffsohn

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