Research Papers: General

Morphology, topography, and optics of the orthokeratology cornea

[+] Author Affiliations
Miguel Faria-Ribeiro, José Manuel González-Méijome

University of Minho, Clinical and Experimental Optometry Research Laboratory, Center of Physics, School of Sciences (Optometry), Campus de Gualtar, Braga 4710-057, Portugal

Rafael Navarro Belsue

Consejo Superior de Investigaciones Científicas and Universidad de Zaragoza, Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, P. Cerbuna, 12, Zaragoza 50009, Spain

Norberto López-Gil

Universidad of Murcia, Facultad de Óptica y Optometría, Edificio 35 (Campus de Espinardo), Murcia 30100, Spain

J. Biomed. Opt. 21(7), 075011 (Jul 19, 2016). doi:10.1117/1.JBO.21.7.075011
History: Received January 7, 2016; Accepted June 20, 2016
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Abstract.  The goal of this work was to objectively characterize the external morphology, topography, and optics of the cornea after orthokeratology (ortho-k). A number of 24 patients between the ages of 17 and 30 years (median=24  years) were fitted with Corneal Refractive Therapy® contact lenses to correct myopia between 2.00 and 5.00 diopters (D) (median=3.41  D). A classification algorithm was applied to conduct an automatic segmentation based on the mean local curvature. As a result, three zones (optical zone, transition zone, and peripheral zone) were delimited. Topographical analysis was provided through global and zonal fit to a general ellipsoid. Ray trace on partially customized eye models provided wave aberrations and retinal image quality. Monozone topographic description of the ortho-k cornea loses accuracy when compared with zonal description. Primary (C40) and secondary (C60) spherical aberration (SA) coefficients for a 5-mm pupil increased 3.68 and 19 times, respectively, after the treatments. The OZ area showed a strong correlation with C40 (r=0.49, p<0.05) and a very strong correlation with C60 (r=0.78, p<0.01). The OZ, as well as the TZ, areas did not correlate with baseline refraction. The increase in the eye’s positive SA after ortho-k is the major factor responsible for the decreased retinal optical quality of the unaccommodated eye.

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© 2016 Society of Photo-Optical Instrumentation Engineers

Citation

Miguel Faria-Ribeiro ; Rafael Navarro Belsue ; Norberto López-Gil and José Manuel González-Méijome
"Morphology, topography, and optics of the orthokeratology cornea", J. Biomed. Opt. 21(7), 075011 (Jul 19, 2016). ; http://dx.doi.org/10.1117/1.JBO.21.7.075011


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