Sin-Wan Cheung1, Pauline Cho2. 1. School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China. Electronic address: orpeggy@gmail.com. 2. School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China.
Abstract
PURPOSE: To compare the effects of normal growth and longer term use of orthokeratology (ortho-k) on ocular biometric parameters in the anterior segment, including central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (CLT), and anterior segment length (ASL). METHODS: Baseline and six monthly data were retrieved from 78 subjects (aged 7-10 years, with myopia≤4.00D and astigmatism≤1.25D) who had completed a two-year randomized clinical trial using ortho-k for myopia control. They were randomly assigned to wear ortho-k lenses or single-vision spectacles (control). Anterior segment parameters were measured with the Pentacam after cycloplegia. RESULTS: No significant changes in CLT and ASL over time were observed in either group of subjects (37 ortho-k; 38 control). In the control group, CCT remained unchanged during the study period but in the ortho-k group, it was significantly reduced by an average of 0.009mm by the 6-month visit (p<0.001) and remained unchanged thereafter. No significant changes in ACD was found in the ortho-k group but it was significantly increased by an average of 0.04mm (p=0.001) in the control group. CONCLUSION:CLT nor ASL did not change over time in either control or ortho-k subjects. Although ACD significantly increased in the control subjects and CCT significantly reduced in the first six months of ortho-k lens wear, these changes were small and did not affect the overall ASL.
RCT Entities:
PURPOSE: To compare the effects of normal growth and longer term use of orthokeratology (ortho-k) on ocular biometric parameters in the anterior segment, including central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (CLT), and anterior segment length (ASL). METHODS: Baseline and six monthly data were retrieved from 78 subjects (aged 7-10 years, with myopia≤4.00D and astigmatism≤1.25D) who had completed a two-year randomized clinical trial using ortho-k for myopia control. They were randomly assigned to wear ortho-k lenses or single-vision spectacles (control). Anterior segment parameters were measured with the Pentacam after cycloplegia. RESULTS: No significant changes in CLT and ASL over time were observed in either group of subjects (37 ortho-k; 38 control). In the control group, CCT remained unchanged during the study period but in the ortho-k group, it was significantly reduced by an average of 0.009mm by the 6-month visit (p<0.001) and remained unchanged thereafter. No significant changes in ACD was found in the ortho-k group but it was significantly increased by an average of 0.04mm (p=0.001) in the control group. CONCLUSION: CLT nor ASL did not change over time in either control or ortho-k subjects. Although ACD significantly increased in the control subjects and CCT significantly reduced in the first six months of ortho-k lens wear, these changes were small and did not affect the overall ASL.
Authors: Jeffrey J Walline; Kristina B Lindsley; S Swaroop Vedula; Susan A Cotter; Donald O Mutti; Sueko M Ng; J Daniel Twelker Journal: Cochrane Database Syst Rev Date: 2020-01-13