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Purpose: A multi-level model was used to analyse factors, including environmental factors, affecting the controlling effect of orthokeratology on myopia progression., Methods: A 2-year prospective study was conducted in the West China Hospital, Sichuan University. Age, sex, height, baseline spherical equivalent refraction, choroidal thickness, axial length and other biometric ocular parameters were collected. Additionally, data on the following environmental factors were obtained: near-work distance and time, sleep time and time spent outdoors. After the baseline measurements, participants were followed up every 3 months for 2 years of lens wear. The primary outcome measure was axial length elongation over 2 years of orthokeratology. All variables were included in a univariate, three-level analysis model with inclusion in the final multivariate multi-level model if statistically significant., Results: Thirty-three participants (average age 9.73 ± 1.55 years) were included in this study. During the 2-year period of lens wearing, binocular changes in axial length increased significantly from the ninth month and continued until the end of the follow-up. Changes in axial length after 2 years of lens wearing were 0.44 ± 0.30 mm and 0.37 ± 0.26 mm in the right and left eyes, respectively (both p < 0.001). Based on the 2-year multi-level model, age, sex, baseline spherical equivalent refraction, flatter keratometry meridian and near-work time influence the effect of orthokeratology., Conclusions: This is the first study to use a multi-level model to analyse factors, including environmental factors, that affect myopia control using orthokeratology. These results showed that younger age, being female, having lower myopia at baseline, a steeper flattest keratometry meridian and no more than 5 h of near work per day were associated with better myopia control effect using orthokeratology over a 2-year treatment period., (© 2022 College of Optometrists.)

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 <0.001; FC > 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 <  0.001), compared to those used for three months. Cases that were not rinsed (OR 3.44, CI 1.50-7.86, p =  0.003) or rinsed by other methods (OR 4.07, CI 1.67-9.92, p =  0.002) had significantly more contamination, compared to those rinsed with multipurpose solution. Lens cases, which were not dried (OR 11.36, CI 2.06-62.93, p =  0.005) or air-dried (OR 8.71, CI 1.16-65.56, p =  0.036), showed more contamination compared to those wiped with tissue daily., Conclusion: Case design (cylindrical), monthly replacement, daily rinsing with MPS, and wiping with tissue daily can effectively reduce biofilm formation in contact lens cases., (Copyright © 2019 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Purpose: The aim was to compare the impact of rigid gas-permeable (RGP) contact lenses on vision-related quality of life (VR-QOL) in keratoconic patients with different grades of severity., Methods: This comparative study was conducted from December 2012 to September 2013 on 46 patients with bilateral keratoconus. Patients were divided into three groups according to the average of the steep keratometry (K) readings in the two eyes of each patient. Main outcome measures included binocular visual acuity (VA), lens wearing time, the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25), foreign body (FB) sensation, comfort and overall satisfaction., Results: Patients with severe keratoconus showed significantly reduced wearing time compared with the other two groups (4.8 ± 2.5 hours per day). Regarding the subjective criteria, there was no significant difference on NEI-VFQ-25 scores, foreign body sensation, comfort and overall satisfaction between mild and moderate keratoconus groups but scores in the group with severe keratoconus were significantly lower than the other two groups. Binocular VA strongly correlated with NEI-VFQ-25 scores; however, NEI-VFQ-25 scores had no significant correlations with different disease severities., Conclusions: Appropriate correction with RGP lenses contributes to good VR-QOL for keratoconic patients; however, as the disease progresses to a steep keratometric value of more than 52 dioptres (6.50 mm), RGP lenses did not guarantee a relatively good VR-QOL. Other lens options with new designs might bring better life quality for these patients with severe keratoconus., (© 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometry Australia.)