Sensors, Vol. 19, Pages 4046: Geometric Aberration Theory of Offner Imaging Spectrometers
Sensors, Vol. 19, Pages 4046: Geometric Aberration Theory of Offner Imaging Spectrometers Sensors doi: 10.3390/s19184046 Authors: Meihong Zhao Yanxiu Jiang Shuo Yang Wenhao Li A third-order aberration theory has been developed for the Offner imaging spectrometer comprising an extended source; two concave mirrors; a convex diffraction grating; and an image plane. Analytic formulas of the spot diagram are derived for tracing rays through the system based on Fermat’s principle. The proposed theory can be used to discuss in detail individual aberrations of the system such as coma, spherical aberration and astigmatism, and distortion together with the focal conditions. It has been critically evaluated as well in a comparison with exact ray tracing constructed using the commercial software ZEMAX. In regard to the analytic formulas, the results show a high degree of practicality.
Conclusions: Improved topographic and biomechanic indexes at 1 year after CXL suggest it‘s potential as first-line therapy for RKC, as it is for KC.
Conditions: Cataract; Astigmatism; Cornea Interventions: Procedure: 'Off the shelf' toric lens; Procedure: Tailored Toric lens Sponsors: Guy's and St Thomas' NHS Foundation Trust; City, University of London; King's College London Not yet recruiting
A team of University of Arizona researchers is studying whether glasses used to correct astigmatism in toddlers can improve language, cognitive and motor development. A $4.1 million grant from the National Institutes of Health will fund the study.
Authors: Zhang M, Qian D, Jing Q, Chen J, Deng M, Jiang Y Abstract Purpose: To clarify the distribution of corneal spherical aberrations (SAs) in cataract patients with different corneal astigmatism and axial length. Setting: Department of Ophthalmology and Vision Science of the Eye and ENT Hospital of Fudan University, Shanghai, China. Design: Retrospective case series. Methods: The axial length, corneal SAs, and other corneal biometrics were collected in cataract patients with Pentacam HR and IOLMaster 500. The statistical analysis of the corneal SAs was based on the stratification of axial length and...
Publication date: 5 October 2019Source: New Scientist, Volume 243, Issue 3250Author(s): I wear spectacles to correct for myopia and astigmatism. Is it possible to create a program to adjust the image of a TV, mobile or PC monitor using my optical prescription such that I could view it without spectacles?
Conclusions: This study reflects the preferences of cornea experts regarding primary pterygium treatment and may serve as a guide for the management of this pathology.
Conclusions: With long-term follow-up, late post-PK ectasia becomes an increasing problem. PALK can be a successful surgical option to reinforce the ectatic area while preserving a functional clear PK. By adding donor corneal tissue, PALK restores the ectatic area, improves visual acuity, keratometric values, and astigmatism, and preserves the functional graft while avoiding the higher risks of a larger diameter PK.
This study aimed to investigate the association between environmental exposure to tobacco smoke (ETS) during early life and astigmatism in Chinese preschool children. In this cross-sectional study, information concerning prenatal and postnatal ETS exposure at three stages of early life (during pregnancy, from birth to one year and from one to three years), visual problems of children and parents (including a confirmed diagnosis of astigmatism), socio-demographics and perinatal characteristics were obtained from 27,890 parent-reported questionnaires. Logistic regression analyses were undertaken to yield adjusted odds ratios...
CONCLUSIONS Inconspicuous IOL malpositioning is one of the reasons responsible for decreased vision acuity after cataract surgery, which may not be easily identified by slit-lamp examination. High astigmatism and ocular higher-order aberrations derived from malpositioned IOL can be important clues.
CONCLUSIONS: In this prospective study, WTW diameter had minimal effects on the SIA in uncomplicated small-incisional cataract surgery through a 2.2 mm temporal or superotemporal CCI with a single surgeon. Our findings suggest that corneal diameter does not play a clinically significant role in this population undergoing small-incisional cataract surgery. PMID: 31564344 [PubMed - in process]