Effect of the decentration of the treatment zone on visual quality and myopia control after overnight orthokeratology lens wear

In recent years, the incidence of myopia in adolescents has been increasing year by year, and how to effectively control the development of myopia has become a research hotspot in the field of public health.The orthokeratology lens has been widely used in myopia control because of its great safety, reliability, and little impact on daily life.The cornea after overnight orthokeratology lens wear can be divided into a relatively flat central treatment zone and a steep peripheral defocus zone.Decentration of the treatment zone is common in clinical practice and is mainly located in the inferior temporal quadrant.Studies have shown that the greater the asymmetry of the anterior corneal surface, the greater the degree of myopia at baseline, and the smaller the diameter of the lens, the greater the deviation of the treatment zone.In addition, decentration of the treatment zone is also related to the gravity of the lens, Bell phenomenon, eyelid, and so on.Large decentration of the treatment zone results in decreased visual quality, including clinical symptoms such as ghosting vision and glare, which may be caused by the increase in comatic aberration.Decentration of the treatment zone may have better myopia control, due to the increase of defocus in the pupil area.Obvious decentration of the treatment zone can be solved by increasing the sagittal height, adjusting the alignment curve, increasing the lens diameter and switching to toric lenses, etc.This article reviewed the factors that affect the decentration of the treatment zone after overnight orthokeratology wear, the influence of decentration on visual quality and myopia control, and the methods to help solve the problems caused by the decentration of the treatment zone, which can guide fitting and replacement of orthokeratology lenses.

Myopia; Therapy; Orthokeratologic procedures; Decentration of the treatment zone; Influencing factors; Visual quality