Journal of cataract and refractive surgery · 2012
New method of quantifying corneal topographic astigmatism that corresponds with manifest refractive cylinder.
СтатьяНазвание и аннотация: Перевод пока не подготовлен
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Alpins Noel, Ong James K Y, Stamatelatos George
Аннотация
PURPOSE: To derive a method of quantifying corneal topographic astigmatism (CorT) that accurately represents manifest refractive cylinder.
SETTING: Private practice, Melbourne, Australia.
DESIGN: Retrospective study.
METHOD: Axial power measurements obtained using topography in right eyes and left eyes were analyzed. For each Placido ring, an astigmatism value was calculated. The ring astigmatism values were combined via vector summation to create a new measure termed CorT. This parameter was assessed against other commonly used measures of corneal astigmatism using the ocular residual astigmatism (ORA) and its standard deviation (SD) on how closely each measure matched manifest refractive cylinder. The flat meridian of the CorT can also be used to conceptually divide the cornea into 2 hemidivisions and a CorT value subsequently calculated for each hemidivision of the cornea.
RESULTS: The CorT was assessed against other commonly used measures of corneal astigmatism using the ORA (0.62 diopters [D] ± 0.33 [SD]) and had better correlation with manifest refractive cylinder than manual keratometry (K) (ORA 0.68 ± 0.38 D), simulated K (ORA 0.70 ± 0.35 D), corneal wavefront (ORA 0.74 ± 0.36 D), and paraxial curvature matching (ORA 0.85 ± 0.48 D). The SD of the ORA for CorT was significantly less than the other measures of astigmatism (P<.001).
CONCLUSIONS: An alternative measure of corneal astigmatism, known as CorT, corresponded better to manifest refractive cylinder than other commonly used measures. A hemidivisional CorT can also represent the nonorthogonal asymmetrical astigmatism in irregular corneas.
FINANCIAL DISCLOSURE: Dr. Alpins and Mr. Stamatelatos have a financial interest in the ASSORT software program used to support the planning and analysis of astigmatic correction. Dr. Ong is an employee of ASSORT.
SETTING: Private practice, Melbourne, Australia.
DESIGN: Retrospective study.
METHOD: Axial power measurements obtained using topography in right eyes and left eyes were analyzed. For each Placido ring, an astigmatism value was calculated. The ring astigmatism values were combined via vector summation to create a new measure termed CorT. This parameter was assessed against other commonly used measures of corneal astigmatism using the ocular residual astigmatism (ORA) and its standard deviation (SD) on how closely each measure matched manifest refractive cylinder. The flat meridian of the CorT can also be used to conceptually divide the cornea into 2 hemidivisions and a CorT value subsequently calculated for each hemidivision of the cornea.
RESULTS: The CorT was assessed against other commonly used measures of corneal astigmatism using the ORA (0.62 diopters [D] ± 0.33 [SD]) and had better correlation with manifest refractive cylinder than manual keratometry (K) (ORA 0.68 ± 0.38 D), simulated K (ORA 0.70 ± 0.35 D), corneal wavefront (ORA 0.74 ± 0.36 D), and paraxial curvature matching (ORA 0.85 ± 0.48 D). The SD of the ORA for CorT was significantly less than the other measures of astigmatism (P<.001).
CONCLUSIONS: An alternative measure of corneal astigmatism, known as CorT, corresponded better to manifest refractive cylinder than other commonly used measures. A hemidivisional CorT can also represent the nonorthogonal asymmetrical astigmatism in irregular corneas.
FINANCIAL DISCLOSURE: Dr. Alpins and Mr. Stamatelatos have a financial interest in the ASSORT software program used to support the planning and analysis of astigmatic correction. Dr. Ong is an employee of ASSORT.