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Helen A Swarbrick - One of the best experts on this subject based on the ideXlab platform.
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the impact of Orthokeratology Lens wear on binocular vision and accommodation a short term prospective study
Contact Lens and Anterior Eye, 2018Co-Authors: Pauline Kang, Kathleen Watt, Tina Chau, Jenny Zhu, Bruce John William Evans, Helen A SwarbrickAbstract:Abstract Purpose To investigate the effects of short-term Orthokeratology (OK) on accommodation and binocular visual function in young adults. Methods Twenty-four myopes (18 to 38 years) were fitted with OK Lenses in both eyes. Best corrected distance visual acuity (VA), subjective and objective refractions, corneal topography and a series of binocular vision tests were measured at baseline (BL) before Lens wear and then repeated after 28 nights of OK. Data from 15 subjects who demonstrated successful OK Lens fit are reported. Results Corneal flattening and hyperopic shifts in spherical equivalent refractive error (all p Conclusions Binocular vision remained unchanged after OK, although variability of phoria and stereoacuity measures reduced. This suggests that OK improves or maintains accommodative and binocular vision function in young adult myopes who achieve good vision with OK. Myopes with phorias outside normal ranges and/or poor distance accommodative facility may benefit most with OK, in binocular and accommodative function.
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discontinuation of long term Orthokeratology Lens wear and subsequent refractive surgery outcome
Contact Lens and Anterior Eye, 2017Co-Authors: Pauline Kang, Helen A SwarbrickAbstract:Abstract Purpose To report a case of Lens discontinuation in a long term Orthokeratology (OK) Lens wearer and describe regression in refraction, corneal topography, and corneal thickness over 408 days after Lens discontinuation. Furthermore, the outcome of subsequent LASIK treatment is also reported. Case report A 41 year old Caucasian female who had been previously wearing OK Lenses for 13 years discontinued Lens wear in the left eye to consider refractive surgery in that eye. The greatest changes in subjective and objective refractions, corneal topography and thickness occurred during the first 28 days after Lens discontinuation. Subjective refraction did not reach baseline values, but corneal topography parameters returned to pre-OK values after 408 days of no Lens wear. The patient then received successful refractive surgery treatment in that eye, achieving uncorrected visual acuity of 0.00 LogMAR units, and residual refractive error within ±0.50 D of emmetropia. Conclusion The period of Lens discontinuation required for long term OK Lens wearers before refractive surgery is likely to vary between individuals and the patient described in this case report required a significant period of Lens discontinuation of at least one year before being considered suitable for refractive surgery.
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reduced corneal sensitivity and sub basal nerve density in long term Orthokeratology Lens wear
Eye & Contact Lens-science and Clinical Practice, 2017Co-Authors: Edward Lum, Blanka Golebiowski, Helen A SwarbrickAbstract:To investigate changes in corneal sensitivity and nerve morphology in Orthokeratology (OK) contact Lens wear. In a cross-sectional study, 54 subjects (aged 18–45 years) were grouped into three categories: nonLens (NL), soft Lens (SCL), and OK Lens wearers. Corneal sensitivity was measured at the corneal apex and 2.5 mm temporal to the apex using the Cochet–Bonnet aesthesiometer. Corneal nerve morphology was assessed by sampling a 1 mm2 area of the corneal sub-basal nerve plexus using the Heidelberg Retinal Tomograph with Rostock Corneal Module at the corneal apex and 2.5 mm temporal to the apex. Nerve fiber density (NFD) was calculated by measuring the total length of nerve fibers per square millimeter using Image-Pro Analyser. Comparisons between groups were made using mixed analysis of variance and post hoc paired t tests with Bonferroni correction or the Kruskal–Wallis test and post hoc Mann–Whitney U tests as appropriate. There was a significant difference in corneal sensitivity between the three groups (P=0.027). Central threshold was significantly higher in the OK than NL group (0.69±0.42 g/mm2 vs. 0.45±0.12 g/mm2; P=0.048). Mid-peripheral threshold was not different between the three groups (P>0.05). There was a significant difference in NFD between the three groups (P 0.05). Long-term OK Lens wear is associated with a decrease in central corneal sensitivity and NFD. The mechanism underlying refractive change during OK treatment seems to impact both corneal sensitivity and nerve morphology.
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myopia control during Orthokeratology Lens wear in children using a novel study design
Ophthalmology, 2015Co-Authors: Helen A Swarbrick, Ahmed Alharbi, Kathleen Watt, Pauline KangAbstract:Purpose To investigate the effect of overnight Orthokeratology (OK) contact Lens wear on axial length growth in East Asian children with progressive myopia. Design A prospective, randomized, contralateral-eye crossover study conducted over a 1-year period. Participants We enrolled 26 myopic children (age range, 10.8–17.0 years) of East Asian ethnicity. Methods Subjects were fitted with overnight OK in 1 eye, chosen at random, and conventional rigid gas-permeable (GP) Lenses for daytime wear in the contralateral eye. Lenses were worn for 6 months. After a 2-week recovery period without Lens wear, Lens–eye combinations were reversed and Lens wear was continued for a further 6 months, followed by another 2-week recovery period without Lens wear. Axial eye length was monitored at baseline and every 3 months using an IOLMaster biometer. Corneal topography (Medmont E300) and objective refraction (Shin-Nippon NVision-K 5001 autorefractor) were also measured to confirm that OK Lens wear was efficacious in correcting myopia. Main Outcome Measurements Axial length elongation and myopia progression with OK were compared with conventional daytime rigid contact Lens wear. Results After 6 months of Lens wear, axial length had increased by 0.04±0.06 mm (mean ± standard deviation) in the GP eye ( P = 0.011) but showed no change (−0.02±0.05 mm) in the OK eye ( P = 0.888). During the second 6-month phase of Lens wear, in the OK eye there was no change from baseline in axial length at 12 months (−0.04±0.08 mm; P = 0.218). However, in the GP eye, the 12-month increase in axial length was significant (0.09±0.09 mm; P Conclusions These results provide evidence that, at least in the initial months of Lens wear, overnight OK inhibits axial eye growth and myopia progression compared with conventional GP Lenses. Apparent shortening of axial length early in OK Lens wear may reflect the contribution of OK-induced central corneal thinning, combined with choroidal thickening or recovery due to a reduction or neutralization of the myopiogenic stimulus to eye growth in these myopic children.
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can manipulation of Orthokeratology Lens parameters modify peripheral refraction
Optometry and Vision Science, 2013Co-Authors: Pauline Kang, Paul Gifford, Helen A SwarbrickAbstract:Purpose To investigate changes in peripheral refraction, corneal topography, and aberrations induced by changes in Orthokeratology (OK) Lens parameters in myopes. Methods Subjects were fitted with standard OK Lenses that were worn overnight for 2 weeks. Peripheral refraction, corneal topography, and corneal surface aberrations were measured at baseline and after 14 nights of OK Lens wear. Subsequent to a 2-week washout period, subjects were refitted with another set of Lenses where one eye was randomly assigned to wear an OK Lens with a smaller optic zone diameter (OZD) and the other eye with a steeper peripheral tangent. Measurements were taken again at a second baseline and after 14 days of overnight wear of the second OK Lens set. Results Standard OK Lenses with a 6-mm OZD and 1/4 peripheral tangent caused significant changes in both peripheral refraction and corneal topography. Significant hyperopic shift occurred in the central visual field (VF) while a myopic shift was found at 35 degrees in the nasal VF. OK induced significant reductions in corneal power at all positions along the horizontal corneal chord except at 2.4 mm nasal where there was no significant change and at 2.8 mm nasal where there was an increase in corneal refractive power. A positive shift in spherical aberration was induced for all investigated Lens designs except for the 1/2 tangent design when calculated over a 4-mm pupil. Reducing OZD and steepening the peripheral tangent did not cause significant changes in peripheral refraction or corneal topography profiles across the horizontal meridian. Conclusions OK Lenses caused significant changes in peripheral refraction, corneal topography, and corneal surface aberrations. Modifying OZD and peripheral tangent made no significant difference to the peripheral refraction or corneal topography profile. Attempting to customize refraction and topography changes through manipulation of OK Lens parameters appears to be a difficult task.
Pauline Cho - One of the best experts on this subject based on the ideXlab platform.
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one year results of the variation of Orthokeratology Lens treatment zone voltz study a prospective randomised clinical trial
Ophthalmic and Physiological Optics, 2021Co-Authors: Biyue Guo, Sin Wan Cheung, Randy Kojima, Pauline ChoAbstract:Purpose To present the 1-year results of the Variation of Orthokeratology Lens Treatment Zone (VOLTZ) Study, which aims to investigate the myopia control effect of Orthokeratology (ortho-k) Lenses with different back optic zone diameters (BOZD). Method Children, aged 6 to Results The 1-year results of 34 and 36 subjects (right eye only) in the 6-MM and 5-MM groups, respectively, are presented. No significant differences in baseline demographics were found between the groups (p > 0.05). The first-fit success rates, based on satisfactory centration at the 1-month visit, were 100% and 94% respectively. Horizontal TZ size was 0.92 mm and 0.72 mm smaller in the 5-MM group at the 6-month and 12-month visits, respectively (p 0.05). Axial elongation was slower in the 5-MM group (0.04 ± 0.15 mm) than the 6-MM group (0.17 ± 0.13 mm) (p = 0.001). A significant positive correlation was observed between the horizontal TZ size and axial elongation (r = 0.36, p = 0.006). Conclusion Clinical performance of the two ortho-k Lenses was similar, indicating that a smaller BOZD (5 mm) did not affect Lens performance or ocular integrity. However, a smaller BOZD led to a reduced TZ, with retardation of axial elongation by 0.13 mm compared to conventional 6 mm BOZD ortho-k Lenses after one year of Lens wear.
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corneal thickness changes in myopic children during and after short term Orthokeratology Lens wear
Ophthalmic and Physiological Optics, 2021Co-Authors: Kin Wan, Sin Wan Cheung, Hing Tuen Yau, Pauline ChoAbstract:Purpose To evaluate thickness changes in the central and mid-peripheral cornea (CCT and mPCT), corneal epithelium (CET and mPET) and stroma (CST and mPST) of myopic children during and after short-term Orthokeratology (ortho-k) Lens wear, with conventional (CCF, 0.75 D) and increased compression factors (ICF, 1.75 D). Methods This was a self-controlled case series study. Subjects wore a CCF Lens in one eye and an ICF Lens in the other. Anterior segment optical coherence tomography images were captured weekly for 1 month during Lens wear and for 2 weeks after discontinuing Lens wear. CCT and CET (central 3-mm cornea) and mPCT and mPET (within a 4-6 mm diameter annulus) were measured. Stromal thickness (ST) was determined by subtracting epithelium thickness (ET) from corneal thickness (CT). The repeatability of the analytical software was also investigated on age-matched spectacle-wearing subjects (n = 98). Results Excluding three outliers (>3 S.D.s), the coefficient of repeatability and intraclass correlation coefficients of 98 spectacle-wearing subjects ranged from 2.63 to 4.64 μm and from 0.90 to 0.99, respectively. For the weekly-change study, CCT and CET in both eyes were significantly thinner after Lens wear (p 0.20) in either eye. CT (all sublayers) rebounded to baseline values 2 weeks after discontinuing Lens wear (0.99 > p > 0.12). Conclusions Significant reductions in CT and ET, but not ST, were observed within 1 month of ortho-k Lens wear. Wearing ICF Lenses resulted in a higher reduction in CET. Corneal thickness changes were reversible after discontinuing Lens wear.
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effect of povidone iodine contact Lens disinfecting solution on Orthokeratology Lens and Lens case contamination and organisms in the microbiome of the conjunctiva
Contact Lens and Anterior Eye, 2021Co-Authors: Sin Wan Cheung, M V Boost, Pauline ChoAbstract:Abstract Purpose To compare Lens cleaning routines using a povidone iodine-based rigid Lens disinfecting solution and its effect on conjunctival colonisation, and Lens and Lens case contamination. Methods Participants, aged 6–10 years, receiving Orthokeratology treatment were randomised to four Lens cleaning routines: with and without the use of daily and/or weekly cleaners, which were performed by their parents. Conjunctival colonisation was compared before Lens wear and at 1-, 3-, and 6-month after commencement of Lens wear. Contamination of Lenses and Lens cases was investigated at these times. Organisms were identified using MALDI-TOF mass spectrometry. Results Of the 76 participants who completed the study, conjunctival colonization was present in 24 (32 %) at baseline. Of the remaining 52 participants, 34 consistently yielded no growth. Participants positive at baseline were statistically more likely to be colonized after commencement of Lens wear (p = 0.020). Overall, colonization rate was reduced to 15 % (11/72) after 6-month Lens wear, which reached significance for initially colonized participants (p Conclusions Disinfection for rigid and ortho-k Lens wearers may be effectively achieved with the use of povidone iodine-based solution, apparently regardless of cleaning routine adopted in the current study. The absence of pathogens in the conjunctiva, Lenses, and Lens cases in the great majority of samples indicates that it can improve the safety of overnight Lens wear.
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risk factors associated with contamination of Orthokeratology Lens cases
Contact Lens and Anterior Eye, 2020Co-Authors: Jianglan Wang, Longqian Liu, M V Boost, Maurice Yap, Pauline ChoAbstract:Abstract Purpose To evaluate the risk factors associated with contamination of Lens cases in a group of Orthokeratology (ortho-k) Lens wearers. Method Ortho-k patients attending the Contact Lens Clinic of the Hospital were required to complete a checklist about their routine daily care and handling of Lens cases. Their cases were then collected for analysis. Contamination was evaluated by determining the optical density (OD) of crystal violet stained biofilm present in the cases. OD values were divided into three groups, lower, middle, and upper tertiles, and associations between risk factors were determined by multivariate analysis. Results A total of 194 subjects were recruited. Twenty-five subjects used cylindrical Lens cases (CC), 98 flat cases with ridges (FCR), and 71 flat cases without ridges (FC). FCRs were the most heavily contaminated and CC showed least contamination (FCR > FC, OR 2.16, CI 1.11–4.18, p = 0.023; FCR > CC, OR 8.86, CI 2.97–26.44, p CC, OR 2.33, CI 1.35–12.45, p = 0.013). Replacing Lens cases monthly significantly reduced the risk of high contamination (OR 0.013, CI 0.06-0.30, p Conclusion Case design (cylindrical), monthly replacement, daily rinsing with MPS, and wiping with tissue daily can effectively reduce biofilm formation in contact Lens cases.
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prevalence of antiseptic resistance genes in staphylococci isolated from Orthokeratology Lens and spectacle wearers in hong kong
Contact Lens and Anterior Eye, 2018Co-Authors: Guangsen Shi, M V Boost, Pauline ChoAbstract:Purpose To compare isolation of staphylococci from periorbital tissues and accessories of Orthokeratology (ortho-k) Lens and spectacle wearers and investigate prevalence of antiseptic-resistance (QAC) genes. To determine minimum inhibitory concentrations (MIC) of antiseptics and antibiotic susceptibility of isolates. Methods Staphylococci were isolated from eyelids, eyelashes, and conjunctival sacs of 23 ortho-k Lens wearers and 20 spectacle wearers. Samples were also collected from ortho-k Lenses, Lens cases, and spectacle frames. Isolations of Staphylococcus aureus were compared between ortho-k subjects and controls for all samples and for coagulase-negative staphylococci (CNS) from conjunctival sacs. QAC genes were amplified in 110 S. aureus and 59 CNS isolates and prevalence compared in isolates from ortho-k Lens and spectacle wearers. Associations were assessed between presence of QAC genes and antibiotic and antiseptic susceptibility. Results Although isolation of S. aureus did not differ significantly in periorbital samples from ortho-k and control subjects, QAC genes were significantly more common in both S. aureus and CNS from ortho-k subjects (odds ratio 4.4 and 10.74, respectively). Overall, qacA/B was the predominant gene detected, being present in 26.5% CNS and 11% S. aureus. smr and qacH were present in 12% of CNS, but were less common in S. aureus. QAC gene-positive isolates had higher MICs to benzalkonium chloride and chlorhexidine digluconate. Conclusions Our results suggest that long-term use of multipurpose solutions containing quaternary ammonium compounds may select for carriage of organisms harboring QAC genes. As these genes are associated with antibiotic resistance, their increased prevalence in isolates from contact Lens wearers is a concern.
Xingtao Zhou - One of the best experts on this subject based on the ideXlab platform.
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increased corneal toricity after long term Orthokeratology Lens wear
Journal of Ophthalmology, 2018Co-Authors: Zhi Chen, Feng Xue, Jiaqi Zhou, Xingtao ZhouAbstract:Purpose. To investigate the change in corneal toricity and associated refractive astigmatism after discontinuation of long-term Orthokeratology (ortho-k) Lens wear. Methods. This study investigated 136 subjects aged between 6 and 14 (9.1 ± 1.5) years old at the commencement of ortho-k treatment, who had been undergoing overnight ortho-k treatment for 24 to 72 (37.4 ± 11.9) months. Corneal refractive power and manifest refraction were measured and compared before ortho-k and 1 month after discontinuation of ortho-k Lens wear. Changes in corneal curvature were analyzed. Corneal curvature data from a historical longitudinal study were used as control. Results. Compared to pre-ortho-k values, the corneal curvature became significantly flatter in the flatter meridian (−0.22 ± 0.27 D, ) and steeper in the steeper meridian (0.06 ± 0.34 D, ) after cessation of ortho-k Lens wear, resulting in a significant increase in corneal toricity (0.28 ± 0.43 D, ), which is associated with an increase in refractive astigmatism (0.57 ± 0.57 D, ,). The amount of residual corneal flattening in the flatter meridian is significantly affected by the length of ortho-k treatment (,) and the baseline age of subject (,), but not by the baseline spherical or cylindrical refractive error (both ). In the historical control group, there is no significant change in the corneal curvature over two years in children wearing spectacle Lenses (both meridians, ). Change of corneal toricity was more significant in the ortho-k group than in the spectacle control group ().Conclusions. Long-term ortho-k Lens wear increases corneal toricity after discontinuation of the treatment, which is associated with an increase in refractive astigmatism. A more pronounced change in corneal toricity was found in subjects who were younger to start ortho-k and have been in a longer period of treatment. This trial is registered with http://www.chictr.org.cn (ChiCTR-TNRC-11001210).
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prediction of Orthokeratology Lens decentration with corneal elevation
Optometry and Vision Science, 2017Co-Authors: Zhi Chen, Feng Xue, Jiaqi Zhou, Xingtao ZhouAbstract:SIGNIFICANCELens decentration is common and unavoidable to some extent during ortho-k treatment. By using a simplified method, we are able to predict the magnitude and direction of ortho-k Lens decentration, which provides useful insights in screening for ideal ortho-k candidates and to make a quick
Dennis S.c. Lam - One of the best experts on this subject based on the ideXlab platform.
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Good visual outcome after prompt treatment of acanthamoeba keratitis associated with overnight Orthokeratology Lens wear.
Eye & Contact Lens-science and Clinical Practice, 2007Co-Authors: Victoria W. Y. Wong, Stanley C C Chi, Dennis S.c. LamAbstract:Purpose. To describe a patient with a good visual outcome after prompt treatment of Acanthamoeba keratitis as a complication of overnight Orthokeratology Lens wear. Methods. Interventional case report. Results. A 9-year-old boy experienced pain, photophobia, and redness in his right eye 3 days after visiting a swimming pool. He had been wearing overnight Orthokeratology Lenses for 5 months for the correction of moderate myopia in both eyes. On examination, best-corrected visual acuity in the right eye was 20/40. A diagnosis of Acanthamoeba keratitis with the presence of the classic feature of perineural infiltrates was made. The patient responded well to treatment with polyhexamethylene biguanide and propamidine isethionate (Brolene). Culture of corneal scrapings and contact Lens solution showed heavy growth of Acanthamoeba. Treatment was tapered gradually during the next 4 months, and the final best-corrected visual acuity was 20/25. Conclusions. Acanthamoeba keratitis may be a vision-threatening complication associated with overnight Orthokeratology Lens wear. It is essential for eye care professionals to fully explain and warn parents of the potential downsides that may be associated with Orthokeratology. Ophthalmologists should have a high level of suspicion of this complication because prompt diagnosis and treatment can result in good visual outcome.
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Orthokeratology Lens related corneal ulcers in children a case series
Ophthalmology, 2004Co-Authors: Alvin L Young, Alfred T S Leung, Lulu L Cheng, Angus K K Wong, Ricky W K Law, Dennis S.c. LamAbstract:Abstract Objective Orthokeratology is a process by which the corneal curvature is flattened by sequentially fitting rigid gas permeable contact Lenses of decreasing central curvature. There has been a resurgence of interest with the recent introduction of reverse geometry Lenses. Although promising results have been described in reducing the myopic refractive error, the use of these Lenses can be associated with corneal problems, as reported in this case series. Design Observational case series. Participants Six children with Orthokeratology-related corneal ulcers. Methods Consecutive cases of Orthokeratology Lens (OKL)–related corneal ulcers in children presented to a tertiary referral center (March 1999–June 2001) were reviewed. Main outcome measures Preinfection and postinfection visual acuity, refraction, any organisms identified. Results Six children between the ages of 9 and 14 years (mean = 12.1) were treated. The male:female ratio was 1:5. All cases were unilateral, with equal numbers of left and right eyes. All children wore the OKL at night for a duration of 8 to 12 hours, with the onset of infection between 3 and 36 months (mean = 16.6) of OKL wear. All of the patients suffered a resultant best-corrected visual acuity loss. Five of the 6 cases were culture positive for Pseudomonas aeruginosa . Conclusions In view of the temporary benefits of Orthokeratology, together with a known increased risk of infection associated with overnight Lens wear, parents of children considering Orthokeratology must be informed and warned of the potential for permanent loss of vision. The ophthalmic community should have a heightened awareness of the associated complications.
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Orthokeratology Lens related pseudomonas aeruginosa infectious keratitis
Cornea, 2003Co-Authors: Alvin L Young, Alfred T S Leung, Eva Y Y Cheung, Lulu L Cheng, Angus K K Wong, Dennis S.c. LamAbstract:Purpose.To report a case of Orthokeratology Lens-related Pseudomonas corneal ulcer in an adult.Methods.Case report.Results.A 37-year-old man presented with a 1-day history of painful red eye. He was a soft contact Lens wearer before he started on nocturnal Orthokeratology Lens wear of 8 to 10 hours
Zhikuan Yang - One of the best experts on this subject based on the ideXlab platform.
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two dimensional peripheral refraction and retinal image quality in Orthokeratology Lens wearers
Biomedical Optics Express, 2020Co-Authors: Zhenghua Lin, Raul Duartetoledo, Silvestre Manzanera, Weizhong Lan, Pablo Artal, Zhikuan YangAbstract:Orthokeratology (O-K) is a common procedure that uses rigid contact Lenses to reshape the cornea while worn overnight. Beyond the correction of refractive error, it has been suggested that this approach can also be used to reduce myopia progression, possibly because it induces changes in peripheral optics. As this hypothesis remains unproven, the aim of the present study was to explore changes in peripheral retinal optical quality in a group of myopic children following O-K treatment. We provide a comprehensive description of optical characteristics in a group of myopes before and after achieving stable corneal reshaping using overnight O-K Lenses. These characteristics extended across the central visual field (60° horizontal x 36° vertical) as measured with a custom Hartmman-Shack wavefront sensor. After corneal reshaping, peripheral refraction was found to be asymmetrically distributed, with a myopic relative refraction of approximately 3D in the temporal retina. Astigmatism and higher order aberrations also increased in the temporal side. Based on corneal topography following treatment, subjects were divided into two groups: Centred Treatment (CT, decentration ∈ [−0.5 + 0.5] mm) and Slightly Decentred Treatment (subjects with more decentred Lenses). The process was also modelled by ray-tracing simulation. The results indicate that increased myopia in the temporal retina is caused by the decentration of Lenses towards the temporal side. Peripheral optics differ significantly following O-K Lens treatment, but further research is required to determine whether this is likely to affect myopia progression.
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influence of treatment zone decentration on corneal higher order wavefront aberrations and axial length elongation after Orthokeratology
Chinese Journal of Optometry & Ophthalmology, 2017Co-Authors: Linlin Wang, Zhao Chen, Zhikuan YangAbstract:Objective: To study the dynamic effects of treatment zone decentration on corneal higher-order wavefront aberrations and axial length elongation after Orthokeratology. Methods: This prospective study assessed corneal topography and wavefront aberrations before Orthokeratology treatment and at 1 week, 6 months, and 1.5 years after overnight Orthokeratology Lens wear. Axial length elongation was evaluated before and after 1.5 years of treatment. Data were analyzed using Pearson correlation, repeated measurements ANOVA and paired t tests. Results: Decentration was located mainly in the inferior temporal quadrant. The magnitudes of decentration at 1 week, 6 months, and 1.5 years after Orthokeratology were located principally within 0.5-1.0 mm. There were no significant differences in the decentration magnitudes at the different follow-up visits after Orthokeratology. The root mean squares (RMS) of the total corneal higher-order aberration, third-order aberration, and coma-like aberration were significantly increased by Orthokeratology at 1 week, 6 months, and 1.5 years (F=4.491, 5.297, 2.927, P<0.05). Changes of aberrations were not correlated with the decentration at 1.5 years after Orthokeratology. Axial length elongation was increased significantly at 1.5 years after Orthokeratology (t=-0.725, P<0.05), but there was no significant correlation with the decentration. Conclusions: Decentration of the treatment zone became stable 1 week after Orthokeratology, and it increased the corneal higher-order aberrations at an early stage. However, Orthokeratology-induced decentration had no effect on axial length elongation up to 1.5 years. Key words: Orthokeratology procedures; myopia; decentration; corneal higher-order aberrations; axial length
