Dataset Information

Association between long-term orthokeratology responses and corneal biomechanics.

ABSTRACT: Myopia is very prevalent worldwide, especially among Asian populations. Orthokeratology is a proven intervention to reduce myopia progression. The current study investigated association between baseline corneal biomechanics and orthokeratology responses, and changes of corneal biomechanics from long-term orthokeratology. We fitted 59 adult subjects having myopia between -4.00D to -5.00D with overnight orthokeratology. Corneal biomechanics was measured through dynamic bidirectional corneal applanation (in terms of corneal hysteresis, CH and corneal resistance factor, CRF) and corneal indentation (in terms of corneal stiffness, S and tangent modulus, E). Subjects with poor orthokeratology responses had lower E (mean 0.474?MPa) than subjects with good orthokeratology responses (mean 0.536?MPa). Successful orthokeratology for 6 months resulted in reducing CH (reduced by 5.8%) and CRF (reduced by 8.7%). Corneal stiffness was stable, but E showed an increasing trend. Among subjects with successful orthokeratology, a higher baseline S resulted in greater myopia reduction (Pearson correlation coefficient, r?=?0.381, p?=?0.02).

SUBMITTER: Lam AKC

PROVIDER: S-EPMC6715748 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Association between long-term orthokeratology responses and corneal biomechanics.

Lam Andrew K C AKC Hon Ying Y Leung Stanley Y Y SYY Shu-Ho Lu L Chong Jones J Lam David C C DCC

Scientific reports 20190829 1

Myopia is very prevalent worldwide, especially among Asian populations. Orthokeratology is a proven intervention to reduce myopia progression. The current study investigated association between baseline corneal biomechanics and orthokeratology responses, and changes of corneal biomechanics from long-term orthokeratology. We fitted 59 adult subjects having myopia between -4.00D to -5.00D with overnight orthokeratology. Corneal biomechanics was measured through dynamic bidirectional corneal applan ...[more]

PMID: 31467346

Similar Datasets

Project description: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, P < 0.001) and steeper in the steeper meridian (0.06 ± 0.34 D, P=0.032) after cessation of ortho-k lens wear, resulting in a significant increase in corneal toricity (0.28 ± 0.43 D, P < 0.001), which is associated with an increase in refractive astigmatism (0.57 ± 0.57 D, r=0.465, P < 0.001). The amount of residual corneal flattening in the flatter meridian is significantly affected by the length of ortho-k treatment (t=-2.965, P=0.004) and the baseline age of subject (t=-2.841, P=0.005), but not by the baseline spherical or cylindrical refractive error (both P > 0.05). In the historical control group, there is no significant change in the corneal curvature over two years in children wearing spectacle lenses (both meridians, P > 0.05). Change of corneal toricity was more significant in the ortho-k group than in the spectacle control group (P=0.001). 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).

Project description:To determine the risk-adjusted mortality of intentionally injured patients within 7 to 9 years postinjury, compared with unintentionally injured patients.Violent injury contributes significantly to trauma mortality in the United States. Homicide is the second leading killer of American youth, aged 15 to 24 years. Long-term survival among intentionally injured patients has not been well studied. It is also unknown whether intentionally injured patients have worse long-term survival compared with unintentionally or accidentally injured patients with equivalent injuries.Adult trauma patients admitted for 24 hours or more and discharged alive from the Johns Hopkins Hospital from January 1, 1998, to December 31, 2000, were included. The primary outcome was mortality within 7 to 9 years postinjury. Long-term patient survival was determined using the National Death Index. The association between injury intentionality and mortality was investigated using a Cox proportional hazard regression model, adjusted for confounders such as injury severity and patient race, socioeconomic status, and comorbid conditions. Overall differences in survival between those with intentional versus unintentional injury were also determined by comparing adjusted Kaplan-Meier survival curves.A total of 2062 patients met inclusion criteria. Of these, 56.4% were intentionally injured and 43.6% were unintentionally injured. Compared with unintentionally injured patients, intentionally injured patients were younger and more often male and from a zip code with low median household income. Approximately 15% of all patients had died within 7 to 9 years of follow-up. Older age and presence of comorbidities were associated with this outcome; however, intentional injury was not found to be significantly associated with long-term mortality rates. There was also no significant difference in survival curves between groups; intentionally injured patients were much more likely to die of a subsequent injury, whereas those with unintentional injury commonly died of noninjury causes.There was no significant difference in mortality between intentionally injured and unintentionally injured patients within 7 to 9 years postinjury. These results confirm the long-term effectiveness of lifesaving trauma care for those with intentional injury. However, given that patients with intentional injuries were more likely to suffer a subsequent violent death, interventions focused on breaking the cycle of violence are needed.

Project description:Corneal wound healing is an enormously complex process that requires the simultaneous cellular integration of multiple soluble biochemical cues, as well as cellular responses to the intrinsic chemistry and biophysical attributes associated with the matrix of the wound space. Here, we document how the biomechanics of the corneal stroma are altered through the course of wound repair following keratoablative procedures in rabbits. Further we documented the influence that substrate stiffness has on stromal cell mechanics. Following corneal epithelial debridement, New Zealand white rabbits underwent phototherapeutic keratectomy (PTK) on the right eye (OD). Wound healing was monitored using advanced imaging modalities. Rabbits were euthanized and corneas were harvested at various time points following PTK. Tissues were characterized for biomechanics with atomic force microscopy and with histology to assess inflammation and fibrosis. Factor analysis was performed to determine any discernable patterns in wound healing parameters. The matrix associated with the wound space was stiffest at 7days post PTK. The greatest number of inflammatory cells were observed 3days after wounding. The highest number of myofibroblasts and the greatest degree of fibrosis occurred 21days after wounding. While all clinical parameters returned to normal values 400days after wounding, the elastic modulus remained greater than pre-surgical values. Factor analysis demonstrated dynamic remodeling of stroma occurs between days 10 and 42 during corneal stromal wound repair. Elastic modulus of the anterior corneal stroma is dramatically altered following PTK and its changes coincide initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Factor analysis demonstrates strongest correlation between elastic modulus, myofibroblasts, fibrosis and stromal haze thickness, and between edema and central corneal thickness. STATEMENT OF SIGNIFICANCE:Tissue biomechanics during the course of corneal wound healing is documented for the first time through atomic force microscopy, and is correlated with advanced clinical imaging and immunohistochemistry. Parameters obtained from the study are applied in a multivariate statistical model to cluster the data for better classification and monitor the wound repair process. Elastic modulus of the anterior corneal stroma is dramatically altered following wounding and correlates initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Importantly, the occurrence of myofibroblasts is preceded by changes in tissue mechanics, which is important to consider in light of crosslinking procedures applied to treat corneal diseases.

Dataset Information

Association between long-term orthokeratology responses and corneal biomechanics.

Publications

Association between long-term orthokeratology responses and corneal biomechanics.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets