The clinical study of Orthokeratology and related issues

Objective:To assess visual,refractive and topographic changes in subjects undergoing overnight Orthokeratology and the predictability of the treatment.Methods:In this study of pre and post Orthokeratology on vision,refraction,apical corneal power and topographic changes were measured. Studies were also done to assess whether a correlation exists between refractive change and corneal shape,apical corneal power,intraocular pressure(IOP),and corneal thickness.Results:Uncorrected visual acuity improved significantly by day 7(P0.05). The mean subjective refraction,autorefraction and apical corneal power were significantly reduced(P0.05). A strong correlation was found between refractive change,apical corneal power change and corneal eccentricity(P0.05),and between refractive change and apical corneal power change(P0.05). A weaker correlation was found between IOP,corneal thickness and apical corneal power change.Conclusion:Overnight Orthokeratology is an effective means for temporarily reducing myopia. Corneal shape and corneal eccentricity can be used as a predictive tool to estimate the likely degree of myopia reduction with Orthokeratology.