The Effect of Lens Design on Corneal Power Distribution in Orthokeratology.

SIGNIFICANCE: This study will enhance our understanding of the effects of orthokeratology lens design on corneal profile, the results of which may be useful in developing future orthokeratology lens designs. PURPOSE: This study aimed to evaluate the effect of lens design on corneal power distribution after orthokeratology using mathematical methods. METHODS: Sixty-five subjects were enrolled in this prospective study and assigned to four groups: Euclid with 6.2-mm back optic zone diameter (aged <14 years), Euclid with 6.2-mm back optic zone diameter (aged ≥14 years), double tear reservoir lens with 5.0-mm back optic zone diameter, and double tear reservoir lens with 6.0-mm back optic zone diameter. Manifest refraction and corneal topography were checked at baseline and 1 day, 1 week, 2 weeks, and 1 month after lens wear. Relative corneal refractive power change was calculated by a polynomial function and a monomial function. The maximum relative corneal refractive power change (Ymax) and the corresponding distance from the corneal center (Xmax) were analyzed. Relative corneal refractive power change over time and between groups was compared using repeated-measures analysis of variance. RESULTS: Refractive reduction and central corneal flattening were seen at all follow-up visits after orthokeratology lens wear, being fastest in the 5.0-mm back optic zone diameter group (P < .001). The cornea steepened in an aspheric way toward the midperiphery and peaked at approximately 2 to 3 mm off the apex. Overall, Ymax was not different among the four groups, but Xmax was smallest in the 5.0-mm back optic zone diameter group (P < .001). At 1/2 Xmax, relative corneal refractive power change of the 5.0-mm back optic zone diameter design was significantly higher than that of the other three groups (P < .001). The power exponent of the monomial of the 5.0-mm back optic zone diameter design was greater than that of the other three groups (P < .001). CONCLUSIONS: An orthokeratology lens design with smaller back optic zone diameter might yield a faster myopic reduction and a smaller aspheric treatment zone.

Changes in Peripheral Refraction, Higher-Order Aberrations, and Accommodative Lag With a Radial Refractive Gradient Contact Lens in Young Myopes.

PURPOSE: To evaluate changes in the peripheral refraction (PR), visual quality, and accommodative lag with a novel soft radial refractive gradient (SRRG) experimental contact lens that produces peripheral myopic defocus. METHODS: 59 myopic right eyes were fitted with the lens. The PR was measured up to 30° in the nasal and temporal horizontal visual fields and compared with values obtained without the lens. The accommodative lag was measured monocularly using the distance-induced condition method at 40 cm, and the higher-order aberrations (HOAs) of the entire eye were obtained for 3- and 5-mm pupils by aberrometry. Visual performance was assessed through contrast sensitivity function (CSF). RESULTS: With the lens, the relative PR became significantly less hyperopic from 30° to 15° temporally and 30° nasally in the M and J0 refractive components (P<0.05). Cylinder foci showed significant myopization from 30° to 15° temporally and 30° to 25° nasally (P<0.05). The HOAs increased significantly, the CSF decreased slightly but reached statistical significance for 6 and 12 cycles per degree (P<0.05), and the accommodative lag decreased significantly with the SRRG lens (P=0.0001). There was a moderate correlation between HOAs and CSF at medium and high spatial frequencies. CONCLUSION: The SRRG lens induced a significant change in PR, particularly in the temporal retina. Tangential and sagittal foci changed significantly in the peripheral nasal and temporal retina. The decreased accommodative lag and increased HOAs particularly in coma-like aberration may positively affect myopia control. A longitudinal study is needed to confirm this potential.

Efficacy of a gas permeable contact lens to induce peripheral myopic defocus.

PURPOSE: The purpose of this work was to evaluate the potential of a novel custom-designed rigid gas permeable (RGP) contact lens to modify the relative peripheral refractive error in a sample of myopic patients. METHODS: Fifty-two right eyes of 52 myopic patients (mean [±SD] age, 21 [±2] years) with spherical refractive errors ranging from -0.75 to -8.00 diopters (D) and refractive astigmatism of 1.00 D or less were fitted with a novel experimental RGP (ExpRGP) lens designed to create myopic defocus in the peripheral retina. A standard RGP (StdRGP) lens was used as a control in the same eye. The relative peripheral refractive error was measured without the lens and with each of two lenses (StdRGP and ExpRGP) using an open-field autorefractometer from 30 degrees nasal to 30 degrees temporal, in 5-degree steps. The effectiveness of the lens design was evaluated as the amount of relative peripheral refractive error difference induced by the ExpRGP compared with no lens and with StdRGP conditions at 30 degrees in the nasal and temporal (averaged) peripheral visual fields. RESULTS: Experimental RGP lens induced a significant change in relative peripheral refractive error compared with the no-lens condition (baseline), beyond the 10 degrees of eccentricity to the nasal and temporal side of the visual field (p < 0.05). The maximum effect was achieved at 30 degrees. Wearing the ExpRGP lens, 60% of the eyes had peripheral myopia exceeding -1.00 D, whereas none of the eyes presented with this feature at baseline. There was no significant correlation (r = 0.04; p = 0.756) between the degree of myopia induced at 30 degrees of eccentricity of the visual field with the ExpRGP lens and the baseline refractive error. CONCLUSIONS: Custom-designed RGP contact lenses can generate a significant degree of relative peripheral myopia in myopic patients regardless of their baseline spherical equivalent refractive error.

Assessment of the Clinical Effectiveness of DRL Orthokeratology Lenses vs. Single-Vision Spectacles in Controlling the Progression of Myopia in Children and Teenagers: 2 Year Retrospective Study.

The purpose of this study was to assess the effect of orthokeratology treatment with DRL lenses on the control of myopia progression compared with single vision glasses users (monofocal glasses). It was also possible to analyze the clinical efficacy of orthokeratology treatment with DRL lenses for myopia correction in children and adolescents in a 2 year retrospective, multicenter study, performed in eight different ophthalmology centers in France. A total of 360 data records of children and adolescents with myopia between -0.50 D and -7.00 D at baseline visit, who completed treatment and had a centered outcome, were selected for the study from a database of 1271. The final sample included subjects undergoing orthokeratology treatment with DRL lenses (n = 211 eyes) and spectacle wearers (n = 149 eyes). After one year of treatment, the data analysis shows that the DRL lens has a refractive myopia progression control rate of 78.5% compared with the spectacle wearers (DRL M change = -0.10 ± 0.25 D, p < 0.001 Wilcoxon test and Glasses M change = -0.44 ± 0.38 D, p < 0.001 Wilcoxon test). Similar results were found after 2 years of treatment (80% with 310 eyes). This study showed the clinical efficacy of orthokeratology DRL lenses compared to monofocal spectacle wearers in controlling myopia progression in children and adolescents in a 2 year retrospective study.

Changes in Choroidal Thickness and Retinal Activity with a Myopia Control Contact Lens.

PURPOSE: The axial elongation in myopia is associated with some structural and functional retinal changes. The purpose of this study was to investigate the effect of a contact lens (CL) intended for myopia control on the choroidal thickness (ChT) and the retinal electrical response. METHODS: Ten myopic eyes (10 subjects, 18-35 years of age) with spherical equivalents from -0.75 to -6.00 diopters (D) were enrolled. The ChT at different eccentricities (3 mm temporal, 1.5 mm temporal, sub-foveal ChT, 1.5 mm nasal, and 3 mm nasal), the photopic 3.0 b-wave of ffERG and the PERG were recorded and compared with two material-matched contact lenses following 30 min of wear: a single-vision CL (SV) and a radial power gradient CL with +1.50 D addition (PG). RESULTS: Compared with the SV, the PG increased the ChT at all eccentricities, with statistically significant differences at 3.0 mm temporal (10.30 ± 11.51 µm, p = 0.020), in sub-foveal ChT (17.00 ± 20.01 µm, p = 0.025), and at 1.5 mm nasal (10.70 ± 14.50 µm, p = 0.044). The PG decreased significantly the SV amplitude of the ffERG photopic b-wave (11.80 (30.55) µV, p = 0.047), N35-P50 (0.90 (0.96) µV, p = 0.017), and P50-N95 (0.46 (2.50) µV, p = 0.047). The amplitude of the a-wave was negatively correlated with the ChT at 3.0T (r = -0.606, p = 0.038) and 1.5T (r = -0.748, p = 0.013), and the amplitude of the b-wave showed a negative correlation with the ChT at 1.5T (r = -0.693, p = 0.026). CONCLUSIONS: The PG increased the ChT in a similar magnitude observed in previous studies. These CLs attenuated the amplitude of the retinal response, possibly due to the combined effect of the induced peripheral defocus high-order aberrations impacting the central retinal image. The decrease in the response of bipolar and ganglion cells suggests a potential retrograde feedback signaling effect from the inner to outer retinal layers observed in previous studies.

Efficacy of the DRL orthokeratology lens in slowing axial elongation in French children.

Background: This study aims to assess and compare the impact of Orthokeratology Double Reservoir Lens (DRL) versus Single Vision Lenses (SVL) on axial elongation and anterior chamber biometric parameters in myopic children over a 6- and 12-month treatment period in France. Methods: A retrospective study involving 48 patients aged 7 to 17 years, who underwent either orthokeratology treatment or single-vision spectacle correction, was conducted. Changes in refractive error, axial length, and anterior chamber depth were examined. Results: Twenty-five patients comprised the Orthokeratology (OK) group, while twenty-three were in the control group (single-vision spectacle group). Significant increases in mean axial length were observed over time in both the control (0.12 ± 0.13 mm and 0.20 ± 0.17 mm after 6 and 12 months, respectively; F (2,28.9) = 27.68, p < 0.001) and OK groups (0.02 ± 0.07 mm and 0.06 ± 0.13 mm after 6 and 12 months, respectively; F (2,29.1) = 5.30, p = 0.023). No statistically significant differences in axial length were found between male and female children (p > 0.620). Age-specific analysis revealed no significant axial elongation after 12 months in the 14-17 years group in the OK group. Anterior biometric data analysis at 6 and 12 months showed statistical significance only for the DRL group. Conclusion: Orthokeratology resulted in an 86 and 70% reduction in axial elongation after 6 and 12 months of lens wear, respectively, compared to the single-vision spectacles group. Myopia progression was more pronounced in younger children, underscoring the importance of initiating myopia control strategies at early ages.

Toric double tear reservoir contact lens in orthokeratology for astigmatism.

OBJECTIVES: This study aimed at assessing the performance of a double tear reservoir toric reverse geometry contact lens design for the correction of myopic and astigmatic refractive errors through overnight orthokeratology (Ortho-K). METHODS: Consecutive records of a total of 32 patients with refractive astigmatism greater than 1.25 D at any orientation, best corrected distance monocular visual acuity ≥ 1.00 (decimal) before Ortho-K treatment and stable ocular refraction for at least 1 month at the time of the last visit were retrospectively examined. Preorthokeratology and postorthokeratology information included noncycloplegic subjective refraction, best-corrected visual acuity, pupil diameter, corneal topography, and ocular aberrometry. The associations between the achieved myopic and cylinder reduction and the modifications in various corneal topographic parameters were investigated. Right eyes were chosen for data analysis. RESULTS: A statistically significant difference (Z=-4.805; P<0.001) was encountered between initial refractive sphere and final residual refractive sphere, with a dioptric change of -2.05 ± 1.46 D (median: -1.88; -5.25 to 0.50), accounting for a change of 106% of the initial myopia. Similarly, differences between pretreatment and posttreatment refractive cylinders were significant (Z=-4.945; P<0.001), with a dioptric change of -1.80 ± 1.06 D (median: -1.50; -5.25 to -0.50), that is, a change of 85% of the initial astigmatism. Changes in topographic Best Fit Sphere and Best Fit Toric presented a strong positive correlation with the accomplished myopic and astigmatic refractive changes, respectively. CONCLUSIONS: The results of this investigation suggest that the correction of astigmatic errors with toric orthokeratology lens designs may have a promising future.

Efficacy, predictability and safety of long-term orthokeratology: An 18-year follow-up study.

PURPOSE: To determine the efficacy, predictability and safety of long-term orthokeratology in children and adults. METHODS: Case histories of 300 orthokeratology patients (596 eyes; 34.3% children; 65.7% adults) were reviewed to collect information on demographics, corneal and refractive parameters, visual acuity, residual refraction and adverse effects. Predictability was defined as the percentage of eyes with absolute values of spherical equivalent refraction ≤ 0.5 D of emmetropia, and efficacy as the ratio of post-orthokeratology uncorrected and pre-orthokeratology corrected distance visual acuity. RESULTS: Median duration of treatment was 37 and 28.5 months in children and adults, respectively (p = 0.022). During the first year, 17.2% of children and 33% of adults ceased lens wear (p < 0.001). For children and adults with a successful ortho-k treatment of at least one year of duration, 88.7% and 95.9% of eyes had a predictable refractive outcome, and efficacy was 0.98 and 1.01, respectively. A larger percentage of children (65.7%) were free of complications than of adults (55.4%) (p = 0.015). One event of microbial keratitis occurred in adults (6.8 cases per 10,000 patient-years) and none in children. Corneal staining was the most frequent complication, with a higher incidence in adults (p = 0.007) and in higher myopia (p < 0.001), higher anterior corneal eccentricity (p = 0.019) and smaller anterior horizontal radius (p = 0.027). CONCLUSION: Orthokeratology is a safe and predictable long-term procedure in children and adults, with a low incidence of serious adverse effects. Corneal staining episodes are relatively frequent throughout the course of the treatment, thus highlighting the relevance of education of experienced users.

The Role of Back Optic Zone Diameter in Myopia Control with Orthokeratology Lenses.

We compared the efficacy of controlling the annual increase in axial length (AL) in myopic Caucasian children based on two parameters: the back optic zone diameter (BOZD) of the orthokeratology (OK) lens and plus power ring diameter (PPRD) or mid-peripheral annular ring of corneal steepening. Data from 71 myopic patients (mean age, 13.34 ± 1.38 years; range, 10-15 years; 64% male) corrected with different BOZD OK lenses (DRL, Precilens) were collected retrospectively from a Spanish optometric clinic. The sample was divided into groups with BOZDs above or below 5.00 mm and the induced PPRD above or below 4.5 mm, and the relation to AL and refractive progression at 12 months was analyzed. Three subgroups were analyzed, i.e., plus power ring (PPR) inside, outside, or matching the pupil. The mean baseline myopia was -3.11 ± 1.46 D and the AL 24.65 ± 0.88 mm. Significant (p < 0.001) differences were found after 12 months of treatment in the refractive error and AL for the BOZD and PPRD. AL changes in subjects with smaller BOZDs decreased significantly regarding larger diameters (0.09 ± 0.12 and 0.15 ± 0.11 mm, respectively); in subjects with a horizontal sector of PPRD falling inside the pupil, the AL increased less (p = 0.035) than matching or outside the pupil groups by 0.04 ± 0.10 mm, 0.10 ± 0.11 mm, and 0.17 ± 0.12 mm, respectively. This means a 76% lesser AL growth or 0.13 mm/year in absolute reduction. OK corneal parameters can be modified by changing the OK lens designs, which affects myopia progression and AL elongation. Smaller BOZD induces a reduced PPRDs that slows AL elongation better than standard OK lenses. Further investigations should elucidate the effect of pupillary diameter, PPRD, and power change on myopia control.

Visual Performance and High-Order Aberrations with Different Contact Lens Prototypes with Potential for Myopia Control.

Purpose: Contact lenses (CLs) used for myopia control incorporate variable power distribution across the optic zone potentially creating degradation of the high-order aberrations. The present study aims to evaluate the retinal image quality and visual performance in three prototypes of CLs intended to control axial elongation of the eye before they are considered for clinical trials.Methods: This is a non-dispensing cross-over, double-blind study where 30 right eyes of myopic subjects worn 3 multifocal test lenses and 1 monofocal control lens in random order. Lens 1 was a radial refractive gradient design (center distance) and Lens 2 and 3 center-near with an additional annular ring for near. Nominal add power was 2.00D, 1.50D, and 2.00D, respectively. Subjects had an age 21.96 ± 2.23 years [18-30] and mean spherical equivalent refraction M = -2.23 ± 1.50D [-0.75 to -5.50] with refractive astigmatism below -0.75D. Higher-order aberrations (HOA), glare formation (halo), high- and low-contrast LogMAR visual acuity (VA), and contrast sensitivity function (CSF) was measured under monocular conditions.Results: All individual terms of HOA and total root mean square from 3rd to 8th order increased significantly with the 3 test lenses compared to control. Between test lenses, Lens 1 increased significantly the higher HOA compared with Lens 2 and Lens 3. Halo size was significantly larger with test lenses compared with control, with Lens 1 showing the largest. VA under high-contrast conditions was similar for all lenses. Under low-contrast conditions, Lens 1 and Lens 2 performed significantly worse than control (Bonferroni post hoc correction, p < 0.001). CSF was below normal limits with Lens 1 for 3 and 6 cpd spatial frequency but was not significantly different between test lenses and control.Conclusions: Lenses with larger stabilized areas for distance vision interfere less with VA and induce lower values of HOA and image degradation.