Measurement centration and zone diameter in anterior, posterior and total corneal astigmatism in keratoconus

Fredriksson, Anneli; Behndig, Anders

doi:10.1111/aos.13517

Cited by 8 publications

(4 citation statements)

References 29 publications

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“…Newer technologies, such as Scheimpflug camera imaging (Koch et al 2012;Savini et al 2014;Tonn et al 2015;Naeser et al 2017), optical coherence tomography (Ueno et al 2014) and specular reflections (Klijn et al 2016), measure keratometric astigmatism (KA) and posterior corneal astigmatism (PCA) separately. These methods may also provide a total corneal astigmatism (TCA), based on Snell 0 s law (Koch et al 2012;Savini et al 2014;Tonn et al 2015;Klijn et al 2016;Fredriksson & Behndig 2017;Nae et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Age‐related changes in with‐the‐rule and oblique corneal astigmatism

Næser

Savini

Bregnhøj

2018

Acta Ophthalmologica

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Corneal astigmatism is stable until the age of 50 years; thereafter both keratometric and total corneal astigmatism show a 0.25 D ATR change per 10 years. The average 0.25 D ATR PCA compensates the predominant keratometric WTR astigmatism in the younger patients and increases the TCA in the elderly with keratometric ATR astigmatism. The gender-based differences in age-related astigmatism require further studies.

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Section: Introductionmentioning

confidence: 99%

Age‐related changes in with‐the‐rule and oblique corneal astigmatism

Næser

Savini

Bregnhøj

2018

Acta Ophthalmologica

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“…The corneal apex is found as a better reference center for toric IOL surgical planning according to our data. Choosing the inappropriate reference center may reduce the prediction accuracy, especially when there is a certain distance between the two reference centers (19). Previously, some studies recommended the pupil center as the reference center in this context, because the researchers considered that the entrance pupil controls what the patient sees (20,21).…”

Section: Discussionmentioning

confidence: 99%

The Influence of Analysis Mode Selection on Prediction Accuracy of Corneal Astigmatism Using Pentacam

Meng

et al. 2021

Front. Med.

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Purpose: To evaluate the influence of analysis mode selection on prediction accuracy of corneal astigmatism using Pentacam.Methods: Fifty-nine eyes of 59 patients implanted with toric intraocular lenses (IOLs) were included in the retrospective study. Preoperative corneal astigmatism (total refractive power) measured with Pentacam was analyzed based on 2-, 3-, 4-, or 5-mm ring or zone mode either centered on corneal apex or pupil center. Actual corneal astigmatism was calculated based on residual astigmatism on the corneal plane, surgical-induced astigmatism, and effective toric power on the corneal plane. Prediction error, the difference between actual corneal astigmatism and measured astigmatism, was compared among different analysis modes. Influences of local topography on prediction error were also evaluated.Results: Based on the zone mode, prediction error was lower when centered on corneal apex than on pupil center at different diameters, whereas based on the ring mode, this difference was only seen at 2-mm cornea (all P < 0.05). When centered on the corneal apex, the zone mode showed lower prediction error than the ring mode at 4- and 5-mm corneas (both P < 0.001), regardless of asymmetric or symmetric astigmatism. In symmetric bowtie, the zone mode showed lower prediction error than the ring mode at 2-mm cornea of the small bowtie, and 4- and 5-mm corneas of the large bowtie (all P < 0.05).Conclusions: For toric IOL planning, the corneal apex may be a better reference center. At a cornea diameter ≥4 mm, the zone mode is more accurate than the ring mode. Local topography affects prediction accuracy in the symmetric bowtie.

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“…(4,(16)(17)(18)(19)(20)(21) Com relação às aberrações de alta ordem, elas podem ser rastreadas por meio do OPD Scan, o qual auxilia o oftalmologista a medir as irregularidades ópticas, dentre elas, as da córnea. (2,3,4,10,(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) Já a classificação ABCD de Belin-Ambrósio é uma das mais utilizadas como critério diagnóstico do ceratocone. (9)(10)(11)(12)14,(25)(26)(27) Diante disso, destaca-se a importância do diagnóstico do ceratocone o mais precocemente possível, para que sejam adotadas estratégias de tratamento menos invasivas e para melhorar o prognóstico da população em geral.…”

Section: Introductionunclassified