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Purpose: To study topographic epithelial and total corneal thickness changes in myopic subjects undergoing successful orthokeratology treatment in connection with the objective assessment of contact lens decentration. Methods: A prospective-observational and non-randomized study in 32 Caucasian myopic eyes undergoing Ortho-k for 3 months. Total, epithelial, and stromal thicknesses were studied before and after Ortho-k treatment, using optical coherence tomography with anterior segment application software. Central, paracentral, and mid-peripheral values are taken along 8 semi-meridians. Results: The central average total corneal thickness was 4.72 ± 1.04 μm thinner after Ortho-K. The paracentral corneal thickness showed no significant changes (p = 0.137), while the mid-peripheral corneal thickness was increased by 3.25 ± 1.6 μm associating this increase exclusively to the epithelial plot (p<0.001). When lens centration was assessed, a lens fitting decentration less than 1.0 mm was found for the whole sample, predominantly horizontal-temporal (87.5%) and vertical-inferior (50%) decentring. Corneal topographical analysis revealed a horizontal and vertical epithelial thickness asymmetric change profile with paracentral temporal thinnest values, and mid-peripheral nasal thickest values. Conclusions: The present study found a central corneal thinning induced by Ortho-k lenses in subjects with moderate myopia, only associated with a change in epithelial thickness, as well as mid-peripheral thickening, that seems to be mainly epithelial in origin. The authors also found a tendency of contact lens decentration toward temporal and inferior areas conditioning an asymmetric epithelial redistribution pattern.(AU)
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Humanos , Masculino , Femenino , Visión Ocular , Miopía , Cristalino , Procedimientos de Ortoqueratología , Sustancia Propia , Tomografía de Coherencia Óptica , Estudios Retrospectivos , Optometría , Oftalmología , Estudios ProspectivosRESUMEN
PURPOSE: To investigate the relationship between patients' baseline biometric factors or lens parameters and the diameter of the treatment zone in young myopic children undergoing Corneal Refractive Therapy. METHODS: The data of patients undergoing Corneal Refractive Therapy lens treatment within two years were retrospectively reviewed. Baseline clinical data, including sex, age, refractive power, corneal topography readings, ocular optical biometric measurements, and Corneal Refractive Therapy lens parameters, were subjected to Pearson, Spearman, and partial correlation analyses to identify the potential factors that may influence treatment zone diameter on corneal topography. Logistic and linear regression analyses were used to predict the treatment zone size. RESULTS: The Right eyes of 309 patients were included in this study. The spherical refraction, flat keratometric reading, Reverse Zone Depth 2, Landing Zone Angle 1, and lens diameter were independent factors of treatment zone diameter. In the multivariate analyses, Landing Zone Angle 1 was positively correlated, while Reverse Zone Depth 2 and lens diameter were negatively correlated with the size of the treatment area. The accuracy of logistic regression in predicting the treatment zone size was 71.5%. CONCLUSION: Adjustments to Corneal Refractive Therapy lens parameters may influence the treatment zone diameter on corneal topography. A higher Reverse Zone Depth 2, smaller Landing Zone Angle 1, and larger lens diameter can lead to a smaller treatment zone for Corneal Refractive Therapy lens treatment.
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Procedimientos de Ortoqueratología , Niño , Humanos , Topografía de la Córnea , Estudios Retrospectivos , Córnea , Refracción Ocular , BiometríaRESUMEN
PURPOSE: Return zone depth (RZD) and landing zone angle (LZA) are important parameters of corneal refractive therapy (CRT) lenses. A new machine learning algorithm is proposed for prescribing CRT lens parameters in Chinese adolescents with myopia. METHODS: This is a retrospective study. In total, 1037 Chinese adolescents with myopia (1037 right eyes) were enrolled. A calculation model based on corneal elevation maps was constructed to calculate RZD and LZA for the four quadrants. Furthermore, multiple linear regression and optimized machine learning models were established to predict RZD and LZA values for different combinations of age, sex, and ocular parameters. The four methods (sliding card, linear regression, calculation and optimized machine learning) were then compared to the parameters of the final ordered lens. RESULTS: The optimized machine learning pipeline achieved the best performance. Age, sex, horizontal visible iris diameter (HVID), spherical equivalent refraction degree (SER), eccentricity (e), keratometric (K) readings, corneal astigmatism (CA), axial length (AL), AL/corneal curvature ratio (AL/MK), and anterior chamber depth (ACD) were significant to the machine learning model. The R values for the nasal, temporal, superior and inferior LZA based on machine learning were 0.843, 0.693, 0.866 and 0.762, respectively, and those for the RZD were 0.970, 0.964, 0.975 and 0.964, respectively. CONCLUSIONS: The feasibility and efficiency of an optimized machine learning method to predict LZA and RZD parameters has been demonstrated. The advantage of the proposed method is that it is more accurate, easier to use and faster to implement than the traditional sliding card method.
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Miopía , Adolescente , China , Córnea/diagnóstico por imagen , Topografía de la Córnea , Humanos , Aprendizaje Automático , Miopía/diagnóstico , Miopía/terapia , Refracción Ocular , Estudios RetrospectivosRESUMEN
PURPOSE: To determine whether orthokeratology (OK) induced treatment zone (TZ) diameter can be reduced by altering OK lens design, and if so the impact of modifying TZ diameter on relative peripheral refraction (RPR). METHODS: 16 subjects (mean age 23.4⯱â¯1.5 years; 8 female) completed the study. Standard (Control) OK lens design (PJ, Capricornia, Australia) or a modified version (Test) where the back optic zone diameter was reduced, and back optic zone asphericity and intermediate lens curves were altered, were worn overnight only for 7-nights in a randomised double masked order, with a minimum 1-week wash out (no lens wear) between lens designs. Full correction of refractive error was targeted. Refraction; best corrected visual acuity (BCVA); RPR (Shin-Nippon NVision-k 5001) along the horizontal and vertical meridians; and corneal topography (Medmont E300) were measured before starting lens wear and in the morning after lens removal after the seventh night of lens wear for both lens designs. TZ diameter and decentration was calculated from corneal topography. RESULTS: After 7-nights of wear both lens designs created -2.00D refraction effect with no significant difference in refractive effect or change to BCVA between the designs. The Test design created a significantly smaller horizontal (4.78⯱â¯0.37 vs 5.70⯱â¯0.37â¯mm, pâ¯<â¯0.001) and vertical (5.09⯱â¯0.51 vs 5.92⯱â¯0.51â¯mm pâ¯<â¯0.001) TZ diameter. The TZ was decentered inferior temporal with no significant difference between designs. There was no significant difference between the lens designs in RPR along the horizontal and vertical meridians at any measurement period. CONCLUSIONS: OK induced TZ diameter can be reliably reduced by altering OK lens design without detrimentally effecting lens centration or refractive effect. Reducing TZ diameter did not alter RPR, though measurement artifacts could be responsible for masking an effect. Longitudinal studies are needed to assess whether smaller TZ OK lens designs increase efficacy for slowing progression of myopia.
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Lentes de Contacto , Miopía/terapia , Procedimientos de Ortoqueratología , Diseño de Prótesis , Refracción Ocular/fisiología , Adulto , Topografía de la Córnea , Femenino , Humanos , Masculino , Miopía/fisiopatología , Ajuste de Prótesis , Agudeza Visual/fisiología , Adulto JovenRESUMEN
BACKGROUND: The aim of this study was to monitor refractive, topographic and biometric changes in Singaporean myopic children fitted with orthokeratology over a period of 12 months. METHODS: Data from 62 myopic eyes from an Asian population corrected with orthokeratology were retrospectively collected from an optometric clinic in Singapore. Anterior segment parameters were analysed with a Pentacam. Axial length was measured using the IOLMaster and refraction was assessed by subjective examination before the treatment and after one night, one week, and one, three, six and 12 months. A logistic regression model was built to evaluate the probability of slower (< 0.10 mm/year) or faster eye growth (≥ 0.10 mm/year). RESULTS: Subjects had a mean age of 12.2 ± 3.9 years (range 5-19 years), and 71 per cent were female. Baseline myopia was -3.95 ± 1.59 D (range -1.50 and -8.75 D). Statistically significant differences were found after 12 months of treatment for refractive error, parameters of the central anterior corneal surface (curvature and elevation) and central corneal thickness. Topographic and thickness changes stabilised after one week of treatment. During 12 months of orthokeratology treatment there was a significant increase of axial length (difference = 0.11 ± 0.18 mm, p < 0.001) while refraction remained stable. Changes in axial length of subjects above 11 years were not statistically significantly independent of the baseline myopia, and in subjects with baseline myopia greater than 4.00 D. Logistic regression showed that each additional year of age and each additional dioptre of baseline myopia decreased the probability of faster axial elongation (odds ratio [OR] = 1.23, 2.19 95% CI; OR = 1.08, 3.47 95% CI, respectively). CONCLUSION: Corneal parameters in orthokeratology treatment were stable after one week, particularly for myopes under 4.00 D. Axial length did not change significantly in children older than 11 years of age or in subjects with myopia above 4.00 D undergoing orthokeratology treatment.
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Biometría/métodos , Córnea/diagnóstico por imagen , Topografía de la Córnea/métodos , Miopía/terapia , Procedimientos de Ortoqueratología , Refracción Ocular/fisiología , Adolescente , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Masculino , Miopía/diagnóstico , Estudios Retrospectivos , Factores de Tiempo , Adulto JovenRESUMEN
PURPOSE: To describe the stabilization of early adult-onset myopia in three university students after initiating orthokeratology treatment with corneal refractive therapy contact lenses. METHODS: Three Caucasian early adult-onset progressing myopic subjects (1 male, 2 females) were fitted with corneal refractive therapy lenses to correct myopia between -1.50 and -2.50 D of sphere using Paragon CRT (Paragon Vision Sciences, Mesa, AZ) lenses for overnight orthokeratology. The pre-treatment refractive history from 2005 as well as refraction and axial length after treatment onset are reported over a period of 3 years between December 2009 and January 2013 with an additional year of follow-up after treatment discontinuation (January-December 2013). The peripheral refractive patterns and topographic changes are also reported individually. RESULTS: Treatment was successful in all three subjects achieving uncorrected visual acuity of 20/20 or better monocularly. During a period of 3 years of follow-up the subjects did not experience progression in their refractive error, nor in their axial length (measured during the last 2 years of treatment and 1 year after discontinuation). Furthermore, the subjects recovered to their baseline refraction and did not progressed further over the following year after lens wear discontinuation. CONCLUSIONS: We cannot attribute a causative effect to the orthokeratology treatment alone as underlying mechanism for myopia stabilization in this 3 patients. However, the present report points to the possibility of stabilization of early adult-onset myopia progression in young adults using corneal refractive therapy treatment.
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Lentes de Contacto , Córnea/patología , Miopía/terapia , Procedimientos de Ortoqueratología/métodos , Refracción Ocular/fisiología , Adolescente , Adulto , Topografía de la Córnea , Femenino , Estudios de Seguimiento , Humanos , Masculino , Miopía/diagnóstico , Miopía/fisiopatología , Estudios Retrospectivos , Adulto JovenRESUMEN
PURPOSE: To assess long-term intraocular straylight changes induced by corneal refractive therapy (CRT) and to determine whether these changes persist after cessation of CRT lens wear. METHODS: A single-center, prospective, longitudinal study was performed in 22 subjects (group 1) undergoing overnight corneal refractive therapy for 1 year. Ten right eyes of 10 subjects (group 2) with emmetropia served as controls. In each subject, high contrast visual acuity (HCVA), manifest refraction and intraocular straylight were determined at several time points during treatment and 1 month after discontinuing treatment. Straylight was measured using the van den Berg straylight meter (third generation). EDTRS charts (logMAR units) were used to assess HCVA. For both groups, only data for the right eyes were analyzed. RESULTS: Straylight (mean ± standard deviation) significantly fell from baseline (0.98 ± 0.13) to values recorded after 1 month (0.88 ± 0.13, p=0.011), 3 months (0.88 ± 0.13, p=0.004), 6 months (0.88 ± 0.13, p=0.000) and 12 months (0.76 ± 0.12, p=0.003) of treatment. One month after discontinuing CRT lens wear, straylight was still significantly lower than baseline (0.89 ± 0.13, p=0.003). No correlations were observed between intraocular straylight and HCVA. CONCLUSIONS: Good refractive outcomes and reductions in straylight were observed in response to corneal refractive therapy for myopia. The reduction in straylight observed after discontinuing CRT warrents further investigation.