Contribution of posterior corneal astigmatism to total corneal astigmatism

2012 ◽  
Vol 38 (12) ◽  
pp. 2080-2087 ◽  
Author(s):  
Douglas D. Koch ◽  
Shazia F. Ali ◽  
Mitchell P. Weikert ◽  
Mariko Shirayama ◽  
Richard Jenkins ◽  
...  
2018 ◽  
Vol 3 ◽  
pp. 40-40
Author(s):  
Diana Silva ◽  
Mafalda Mota ◽  
Catarina Pedrosa ◽  
Peter Pêgo ◽  
Sara Pinto ◽  
...  

2021 ◽  
Author(s):  
Mohamed Mohamed ◽  
Mahmood Khan ◽  
Amritha Kanakamedala ◽  
Isha Gupta ◽  
Li Wang ◽  
...  

Abstract PURPOSE To assess the repeatability and comparability of the Galilei G4 versus the Cassini topographer in post-refractive eyes and in normal eyes, including older patients representative of an initial cataract evaluation. METHODS Simulated keratometric (simK), total corneal and posterior corneal power and astigmatism were evaluated in both post-refractive and normal eyes. Repeatability was measured by calculating within-subject standard deviation (Sw), coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Vector analyses and Bland-Altman plots were employed to assess agreement between devices. RESULTS We studied 32 subjects with a history of refractive surgery and 32 subjects without a history of refractive surgery undergoing cataract surgery. The mean age was 55 ± 18.5 years and the age range was 21.5 to 91.5 years. In non-refractive and post-refractive eyes, the ICC was > 0.9 (P < .001) for all corneal powers and for simK and total corneal astigmatism for both analyzers. The ICC for posterior corneal astigmatism magnitude using the Galilei was 0.62 and 0.67 and for the Cassini 0.55 and 0.38 in normal and post-refractive eyes, respectively. CONCLUSIONS In both post-refractive and normal eyes, the Galilei G4 and Cassini analyzers have high repeatability in simK, total, and posterior corneal power and low repeatability for posterior corneal astigmatism.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuanfeng Jiang ◽  
Ying Qin ◽  
Shaochong Bu ◽  
Hong Zhang ◽  
Xiaomin Zhang ◽  
...  

AbstractThe aim of the study is to explore the distribution patterns and internal correlations of the morphological parameters of the cornea in patients with age-related cataract. The Pentacam HR was used to measure anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), total corneal astigmatism (TCA) and keratometric corneal astigmatism (KCA). With age, the proportion of with-the-rule (WTR) ACA decreased from 65.31% to 23.63%, while the against-the-rule (ATR) ACA increased from 26.53% to 56.20%. PCA exceeded 0.50 D in 9.14% of eyes, while 76.35% of them were ATR. The magnitude of ACA was positively correlated with PCA in the whole sample, with a more significant correlation in WTR eyes (sr = 0.349, P < 0.001). The vector summation effect of PCA to ACA changed from compensation to augmentation with aging. In 57.53% of WTR eyes, KCA was overestimated by an average of 0.21 ± 0.17 D, while it was underestimated by 0.38 ± 0.27 D in 87.62% of ATR eyes. In conclusion, among age-related cataract patients, ACA and TCA gradually shifted from WTR to ATR with aging, while most PCA remained as ATR. Ignoring the age-related changes and real PCA might cause overestimation of WTR astigmatism and underestimation of ATR astigmatism.


2020 ◽  
Vol Volume 14 ◽  
pp. 3325-3330
Author(s):  
Mohamed Hosny ◽  
Alaa Badawy ◽  
Lobna Khazbak ◽  
Mohamed Anis ◽  
Sarah Azzam

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohamed Mohamed ◽  
Mahmood Khan ◽  
Amritha Kanakamedala ◽  
Isha Gupta ◽  
Li Wang ◽  
...  

AbstractTo assess the repeatability and comparability of the Galilei G4 versus the Cassini topographer in post-refractive eyes and in normal eyes, including older patients representative of an initial cataract evaluation. Simulated keratometric (simK), total corneal and posterior corneal power and astigmatism were evaluated in both post-refractive and normal eyes. Repeatability was measured by calculating within-subject standard deviation (Sw), coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Vector analyses and Bland–Altman plots were employed to assess agreement between devices. We studied 32 subjects with a history of refractive surgery and 32 subjects without a history of refractive surgery undergoing cataract surgery. The mean age was 55 ± 18.5 years and the age range was 21.5–91.5 years. In non-refractive and post-refractive eyes, the ICC was > 0.9 (P < 0.001) for all corneal powers and for simK and total corneal astigmatism for both analyzers. The ICC for posterior corneal astigmatism magnitude using the Galilei was 0.62 and 0.67 and for the Cassini 0.55 and 0.38 in normal and post-refractive eyes, respectively. In both post-refractive and normal eyes, the Galilei G4 and Cassini analyzers have high repeatability in simK, total, and posterior corneal power and low repeatability for posterior corneal astigmatism.


Cornea ◽  
2018 ◽  
Vol 37 (6) ◽  
pp. 720-726 ◽  
Author(s):  
David P. Piñero ◽  
María T. Caballero ◽  
Juan M. Nicolás-Albujer ◽  
Dolores de Fez ◽  
Vicent J. Camps

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