The efficacy of a device-based approach to microorganism disinfection and protein removal for orthokeratology lenses in varied clinical circumstances.

PURPOSE: RigidCare is an electrolysis-based device that recently obtained approval from the US's FDA to sterilise microorganisms and remove proteins for orthokeratology (O-K) lenses. The study was conducted to investigate the device's performance in varied clinical circumstances. METHODS: Trial lenses and private lenses were employed by O-K lens wearers from five hospitals for an evaluation of disinfection and sterilisation and an assessment of protein removal, respectively. Menicon multipurpose solution and protein remover were selected for use with the control group. Following the instructions, pre-cleaning lens samples, post-cleaning lens samples and residual solution samples of trial lenses of the experimental and control groups were collected for microorganism examinations by an experienced third-party testing organisation. The levels of protein deposition for these two approaches were rated by senior O-K experts. Categorical variables were analysed using statistical tests, such as the chi-squared test and Fisher's exact test. RESULTS: The microbial positive rate detected from the pre-cleaning and post-cleaning lens samples and the residual solution of the trial lenses for the experimental and control group was 4/76 vs 1/74 (P = 0.37), 1/76 vs 0/74 (P = 1.00) and 0/76 vs 8/74 (P = 0.006), respectively. Following protein removal, the experimental group exhibited a significantly higher overall proportion of lenses rated as 'clean' or with a 'mild deposit' (96.4 %, 79/82) compared to the control group (85.7 %, 66/77), with a significant difference (P < 0.05). CONCLUSION: This multi-center study demonstrated that RigidCare exhibited superior efficacy in disinfection, sterilisation and protein removal as compared to Menicon multipurpose solution and protein remover.

Relationship between myopia control and amount of corneal refractive change after orthokeratology lens treatment.

BACKGROUND: To evaluate the relationship between amount of corneal refractive change (CRC) after wearing orthokeratology (Ortho-K) lenses and axial length (AL) growth. METHODS: We retrospectively enrolled 77 patients (77 eyes) aged 8-14 years who wore Ortho-K lenses more than 12 months. We divided the patients into 2 subgroups: spherical equivalent (SE) ≤ -3.0 D and SE > -3.0 D subgroup. The sagittal and tangential curvature maps and corneal topographic data within the 8-mm diameter ring at the baseline and during follow-up visits after wearing Ortho-K lens were recorded in addition to the area, height, and volume of the CRC region. The AL data were recorded at the baseline and during follow-up visits. Multivariate linear regression was conducted to analyze associations between the area, height, and volume of the CRC region, AL elongation, and SE. RESULTS: The average change in the CRC region was 9.77 ± 0.60 D in height, 16.66 ± 3.61 mm2 in area, and 87.47 ± 8.96 D*mm2 in volume on the tangential diagram after wearing Ortho-K lenses for 3 months. The AL showed a change of 0.19 ± 0.14 mm after 1 year of Ortho-K lens wear (P < 0.05). At 1 year, AL elongation was negatively correlated with the area (P = 0.019) and volume (P < 0.001) of the CRC region. At 1 year, for every 1-mm2 increase in the area and every 1-D*mm2 increase in the volume of the CRC region, the average AL elongation decreased by 0.01 mm and 0.002 mm, respectively, in the multivariate analysis. In patients with SE ≤ -3.0 D, AL elongation was negatively correlated with the CRC-region volume (ß = -0.002, P = 0.018), and in patients with SE > -3.0 D, AL elongation was negatively correlated with the CRC-region area (ß = -0.017, P = 0.016). CONCLUSIONS: The AL elongation-control efficacy of Ortho-K lenses may be related to the area and volume of the CRC region.

The Relationship between Axis Length Difference and Refractive Error in Unilateral Myopic Anisometropic Children Treated with Orthokeratology.

Purpose: To explore the correlation between the axial length (AL) difference (myopic and nonmyopic eye) and the refractive error in children with unilateral myopia anisometropia (UMA) and to elucidate its clinical application in the process of Ortho-K lenses review following nonstop wearing. Methods: This study retrospectively analyzed the data of 70 children with UMA (age, 8-15 years) whose myopic eyes were treated with Ortho-K lenses. The spherical equivalent refractive errors (SERE) of the myopic eye ranged from -0.75 D to -4.25 D, and astigmatism was no less than -1.50 D. In addition, SERE of nonmyopic eyes were no less than -0.50 D. AL, and the refractive data of both eyes were measured at baseline. A multivariate linear regression was used to analyze the relationship between the AL difference and refractive error, and paired t-test was used to analyze the changes in AL in both eyes. Results: Every 1 mm axial length change corresponds to -1.627 D (95% CI: -1.921 D, -1.333 D; P < 0.001) change in refractive error in children. The association between the AL change and the degree of myopia did not change with age (P=0.751). Among the 70 subjects, 51 (72.86%) had myopia in the right eye, and the 95% confidence interval (CI) for myopia occurring in the right eye was 62.4%-83.3%. The paired t-test showed that the average AL growth was significantly slower in myopic eyes treated with Ortho-K lenses than in nonmyopic eyes (t = 9.805, P < 0.001). Conclusion: Every 1 mm AL change would cause an average refractive error increase. Age did not influence the association between AL changes and the degree of myopia. The right eye is more likely to be affected in children with UMA. The Ortho-K lens treatment slowed down the growth of AL in the myopic eye in children with UMA.

The effect of orthokeratology treatment zone decentration on myopia progression.

BACKGROUND: This study aimed to compare the changes in the axial length (AL) in myopic children that wear centered and decentered orthokeratology (Ortho-K). METHODS: This retrospective study included 217 subjects who were treated with an Ortho-K lens for >12 months. The subjects were divided into three groups based on the magnitude of the Ortho-K lens treatment zone decentration: mildly, moderately, and severely decentered groups. Distance and direction of treatment zone decentration were calculated using software that was developed in-house. The AL changes in different groups were compared. RESULTS: Based on the distance of the treatment zone decentration, 65 children (65 eyes) were included in the mildly decentered group, 114 children (114 eyes) in the moderately decentered group, and 38 children (38 eyes) in the severely decentered group. The mean decentration distance in the three groups was 0.35 ± 0.11 mm, 0.71 ± 0.13 mm, and 1.21 ± 0.22 mm, respectively. The mean AL increase in the three groups after 12 months of Ortho-K lens wear was 0.24 ± 0.21 mm, 0.23 ± 0.18 mm, and 0.19 ± 0.20 mm, respectively. There were no significant differences in AL changes among the three groups. CONCLUSIONS: Ortho-K lens decentration is common in clinical practice. The AL change after Ortho-K lens wear was not significantly different in subjects with different magnitudes of Ortho-K lens decentration. Fitting the Ortho-K lens in the properly centered zone is recommended to ensure the safety of Ortho-K lens wear and to maintain visual quality.

Distribution differences of macular cones measured by AOSLO: Variation in slope from fovea to periphery more pronounced than differences in total cones.

Large individual differences in cone densities occur even in healthy, young adults with low refractive error. We investigated whether cone density follows a simple model that some individuals have more cones, or whether individuals differ in both number and distribution of cones. We quantified cones in the eyes of 36 healthy young adults with low refractive error using a custom adaptive optics scanning laser ophthalmoscope. The average cone density in the temporal meridian was, for the mean±SD, 43,216±6039, 27,466±3496, 14,996±1563, and 12,207±1278cones/mm2 for 270, 630, 1480, and 2070µm from the foveal center. Cone densities at 630µm retinal eccentricity were uncorrelated to those at 2070µm, ruling out models with a constant or proportional relation of cone density to eccentricity. Subjects with high central macula cone densities had low peripheral cone densities. The cone density ratio (2070:630µm) was negatively correlated with cone density at 630µm, consistent with variations in the proportion of peripheral cones migrating towards the center. We modelled the total cones within a central radius of 7deg, using the temporal data and our published cone densities for temporal, nasal, superior, and inferior meridians. We computed an average of 221,000 cones. The coefficient of variation was 0.0767 for total cones, but higher for samples near the fovea. Individual differences occur both in total cones and other developmental factors related to cone distribution.