Post-Orthokeratology Changes in the Corneal Epithelium Induced by an Orthokeratology Lens: An Anterior-Segment Optical Coherence Tomography Assessment.

Objective: To evaluate detailed regional changes in corneal epithelial thickness after orthokeratology treatment according to the targeted refractive power.

Methods: This retrospective study included a total of 63 eyes of 44 patients who underwent overnight orthokeratology for the correction of myopia. Corneal epithelial thickness was segmentally measured using anterior segment optical coherence tomography before and after treatment.

Results: In the central zone (0-2 mm), the corneal epithelial thickness was significantly decreased by 7.54±5.46 μm ( P <0.05). In the paracentral zone (2-4 mm), it was also significantly decreased in all sectors, with the greatest thinning found in the temporal area. In the midperipheral zone (4-6 mm), it was significantly increased especially in the superior superonasal area, whereas in the peripheral zone (6-7 mm), it was also significantly increased especially in the inferior temporal area. The changes in the epithelial thickness within the central 4-mm area was significantly correlated with the amount of the target refractive power in both low- and high-correction groups. The geography pattern of corneal epithelial redistribution was in accordance with the overall trend of the orthokeratology lens fitting decentration.

Conclusions: Orthokeratology induces central epithelial thinning and peripheral thickening with an asymmetric redistribution, presumably due to inferior temporal lens decentration. Eyes with higher refractive correction showed greater changes in the corneal epithelial thickness.