[Alterations in intraocular pressure and the CorVis parameters after LASIK].
BACKGROUND
The reduction of corneal thickness following laser-assisted in-situ keratomileusis (LASIK) requires a correction of intraocular pressure (IOP) measurements. The corneal visualization Scheimpflug technology (CorVis ST, Oculus, Wetzlar, Germany) not only measures the IOP and central corneal thickness (CCT) but also determines 10 additional corneal parameters, such as the time to first and second applanation and velocity. Besides CCT we compared various corneal parameters before and after LASIK in order to detect possible correlations and to correct IOP measurements.


METHODS
Measurements with CorVis ST were made before and after LASIK in 45 myopic patients (45 left eyes). We compared the IOP and CorVis ST parameters using a paired t‑test before and after LASIK and corrected for possible correlations in a multifactorial linear model. Finally, we correlated the changes in IOP to changes in biomechanical parameters.


RESULTS
We observed a direct correlation between the IOP measurements and the corneal thickness. The IOP was underestimated by 0.039 mm Hg per micrometer in reduction of corneal thickness. The multifactorial linear model showed a correlation of IOP change to A2 velocity and the radius of applanation.


CONCLUSIONS
Surgical thinning of the central cornea via LASIK demonstrated a direct correlation between corneal thickness and IOP measurements using the CorVis ST technique. Postoperative changes of the A2 velocity and the applanation radius also had a statistically significant influence on post-LASIK IOP measurements. Our findings could be useful to obtain more precise post-LASIK IOP measurements.
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland. alexandra.anton@uniklinik-freiburg.de.
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Anton
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.|Augenarztpraxis, Allerheiligenstr. 13, 77855, Achern, Deutschland.
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Neuburger
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.|Berufsausübungsgemeinschaft Vobig & Jordan, Hans-Thoma-Straße 24, 60596, Frankfurt am Main, Deutschland.
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Jordan
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Wecker
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Lübke
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Heinzelmann
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Lapp
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Böhringer
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Reinhard
Klinik für Augenheilkunde, Universitätsklinikum Freiburg, Medizinische Fakultät, Albert-Ludwigs-Universität Freiburg, Killianstraße 5, 79106, Freiburg, Deutschland.
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Maier
D003315:Cornea / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D063171:Corneal Pachymetry; D006801:Humans; D007429:Intraocular Pressure; D020731:Keratomileusis, Laser In Situ; D009216:Myopia / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014065:Tonometry, Ocular; D016896:Treatment Outcome
Corneal biomechanic; Corneal visualization Scheimpflug technology (CorVis ST); Intraocular pressure correction; Laser in situ keratomileusis (LASIK); Scheimpflug technology