Influence of Anterior Segment Swept-source Optical Coherence Tomographic Profiles in the Temporal Decentration of Orthokeratology Treatment Zone

Abstract

Purpose: This study aims to elucidate the factors contributing to the temporal decentration of the orthokeratology lens (OK lens) treatment zone, employing profiles obtained from anterior segment swept-source optical coherence tomography (AS SS-OCT).Methods: The measurements prior to treatment were taken using AS SS-OCT (Anterion; Heidelberg, Germany) in subjects who had worn OK lenses for at least 2 weeks. The collected data encompassed anterior corneal refractive profiles, corneal thickness profiles, anterior corneal elevation profiles, and anterior corneal aberrations. A comparison was drawn between two groups: the temporal decentration (TD) group and the control (no decentration [ND]) group, based on the presence of temporal decentration of the treatment zone.Results: The analysis included a total of 63 eyes (48 eyes in the ND group and 15 eyes in the TD group) from 33 patients (10.6 ± 2.2 y). No significant differences were observed in axial length, spherical equivalent, and horizontal corneal diameter between groups. However, the TD group exhibited higher values in terms of anterior SimK_mean (D), central K (D), and anterior K at temporal and nasal 3.0, 2.0, and 1.0 mm points. Moreover, the TD group displayed a higher horizontal meridian to vertical meridian ratio (H/V K ratio at 4.0 mm diameter) of anterior corneal K at 4.0 mm diameter ring. The ND group showed a higher vertical distance to the maximum corneal power (K_max y) compared to the TD group. Although high order root mean square aberrations were relatively higher in the ND group, statistical significance was marginally attained (<i>p</i> = 0.047).Conclusions: The temporal decentration of the OK lens treatment zone was determined to be linked with steeper corneal curvature at the central and horizontal meridians, an augmented relative steepness of the horizontal meridian at the 4.0 mm diameter, and a vertical displacement in K_max on AS SS-OCT.