Low_resolution_Thesis_CDD_221009_public - Visual Optics and ...

ANTERIOR AND POSTERIOR CORNEAL ELEVATION MAPS AFTER REFRACTIVE SURGERY
7.1. ABSTRACT
Purpose: To check whether myopic LASIK induces changes on the
posterior corneal surface.
Methods: Scheimpflug imaging (Pentacam, Oculus) was used to
measure pre- and post-operative posterior corneal topography in 27
eyes (14 subjects) that had undergone standard myopic LASIK
surgery (attempted corrections between -1.25 and -8.50 D) and on
18 non-operated eyes (9 subjects). Longitudinal displacement of the
posterior corneal apex and changes of the apical radius of curvature
and asphericity were computed.
Results: The measurements on patients show that, on average, the
only relevant (although clinically unimportant) change in radius of
curvature and asphericity occurred the first day after surgery (R = -
28 ± 34 m and Q = -0.06 ± 0.06). No statistically significant
change was observed afterwards. The change in radius is more
pronounced in the vertical direction than in the horizontal direction.
On average, there was no significant displacement of the posterior
corneal apex. Individual changes over time do not show a systematic
trend across patients, and control subjects experience changes of the
same order of magnitude.
Conclusions: There is no evidence of surgically-induced changes in
the corneal posterior surface beyond one week after surgery.
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