Comparison of the Aberrometry parameters of iTrace and Zywave in Patients with Keratoconus

Document Type : Original article

Authors

1 MSc Student of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran

2 MSc of Optometry, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran

3 Professor of Ophthalmology, School of Medicine, Tehran University of medical Sciences, Tehran, Iran

4 PhD of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

Abstract

Background and Aim: To determine agreement between the aberrometry parameters of iTrace and Zywave in patients with keratoconus.
Materials and Methods: In the present cross-sectional, comparative, and observational study, optical aberrations of 51 eyes of 40 patients with keratoconus, aged between 19 to 27 years old, refering to Farabi Eye Hospital in Tehran, were measured using iTrace and Bausch & Lomb Zywave II at a single visit without pupil dilation. The results were compared and analyzed with regards to the sphere, cylinder, as well as lower and higher order aberrations of the two devices considering for 0.5 mm pupils. The statistical analyses used included paired t-test, Pearson correlation coefficient, and the Bland-Altmann plot.
Results: The results obtained from Zywave and iTrace showed no significant differences when paired t-test was used (except of Trefoil (3, 3)) and the Bland-Altmann agreement range was (LoA = -0.51 to 0.53) in the sphere and (LoA = -1.29 to 1.19) in cylinder. Also, the agreement on lower order aberrations, including defocus (2, 0) (LoA = -2.5 to 3.07), astigmatism (2, 2) (LoA = -1.22 to 1.56), and oblique astigmatism (2, -2) (LoA = -1.11 to 0.92). Also, higher order aberrations included horizontal coma (3, 1) (LoA = -0.48 to 0.48), vertical coma (3, -1) (LoA = -0.77 to 0.92), Trefoil (3, -3) (LoA = - 0.57 to 0.49), spherical aberration (LoA = -0.41 to 0.33), total higher order aberration (LoA = -0.73 to 0.64), and total aberration (tRMS) (LoA = -3.11 to 2.87). The findings of the two devices in lower and higher order aberrations showed good correlation, except in Trefoil (3, 3) that showed a weak correlation.
Conclusion: In both iTrace and Zywave devices, agreement was observed in lower order and higher order aberrations in patients with keratoconus. These results can prove the reliability of iTrace device findings compared with B & L Zywave II.

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The Scientific Journal of Rehabilitation Medicine
Volume 5, Issue 4
January and February 2017
Pages 190-197

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History

  • Receive Date: 07 November 2015
  • Revise Date: 19 February 2016
  • Accept Date: 09 March 2016
  • First Publish Date: 21 December 2016

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