The effect of corneal astigmatism on refractive outcomes of phacoemulsification
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Введение. Сочетание астигматизма и катаракты довольно часто встречаемое явление – по данным литературы, от 15 до 29 % пациентов с помутнение хрусталика имеют роговичный астигматизм более 1,5 дптр, а от 3 до 15 % – более 2,0 дптр. Область применения торических интраокулярных линз (ТИОЛ) с каждым годом расширяется и требует тщательного подбора параметров для снижения остаточного послеоперационного астигматизма и обеспечения наилучших значений некорригированной остроты зрения (НКОЗ).
Цель исследования: оценить влияние роговичного астигматизма на рефракционные исходы факоэмульсификации.
Пациенты и методы. Работа выполнена на основе анализа данных 366 пациентов (427 глаз). Пациенты были разделены на 9 подгрупп в соответствии с расположением оси крутого меридиана роговицы. Всем пациентам выполнялись стандартное офтальмологическое обследование, кератотопография, а также измерение длины ПЗО, ГПК, силы крутого и плоского меридианов роговицы, а также расположение их осей с последующим сравнением до- и послеоперационных результатов. Статистическая обработка производилась в программе Jamovi. Статистический анализ проводился с использованием методов параметрической и непараметрической статистики: критерия Шапиро-Уилка, критерия U Манна-Уитни, критерия Краскела-Уоллиса и метода попарного сравнения Двасс-Стил-Кричлоу-Флигнер, регрессионного анализа. Различия при p <0,05 расценивались как статистически значимые.
Результаты. Роговичный астигматизм менее 0,5 дптр наблюдался всего у 32,1%, наиболее часто астигматизм принимал значения от 0,51 до 1 дптр – почти у половины исследуемых (42,9%). Астигматизм свыше 1,0 дптр встречался у каждого четвертого (25,1%). Наиболее часто встречался астигматизм прямого типа 47,8%, обратный наблюдался у 39,6% пациентов, все остальные случаи приходились на астигматизм с косыми осями – 12,6%. Средний возраст в группе исследуемых с обратным астигматизмом выше (77,9±6,8 лет), чем у групп с прямым (73,0±9,3 лет) и косым (76,4±6,9 лет) астигматизмом. Была выявлена закономерность: чем больше остаточный астигматизм, тем ниже значения некорригированной остроты зрения. В группах с прямым астигматизмом значения послеоперационного астигматизма, в целом, были меньше, чем значения в группах с обратным. Разница между показателями в среднем составляла 0,3-0,4 дптр, что соотносится со средней величиной астигматизма задней поверхности – 0,24 дптр. Калькулятор Barret toric calculator (BTC) рекомендует имплантировать торическую ИОЛ на 9,6% чаще, чем формула Kane. BTC рекомендовал Т2 в 7 раз чаще, чем Kane, что обусловлено наличием у данной группы обратного роговичного астигматизма.
Заключение. Главным итогом работы было создание формулы, которая прогнозирует остаточный астигматизм при выполнении ФЭ с имплантацией монофокальной неторической ИОЛ. Таким образом, на дооперационном этапе возможен расчет остаточного астигматизма на основе минимальных диагностических данных, который позволяет принять решение о целесообразности имплантации ТИОЛ.
Introduction. The combination of astigmatism and cataract is a fairly common occurrence. According to literature, 15 to 29% of patients with cataract have corneal astigmatism of more than 1.5 D, and 3 to 15% have more than 2.0 D. The use of toric intraocular lenses (TIOL) is expanding every year and requires thorough selection of parameters to reduce residual postoperative astigmatism and provide the best values of uncorrected distance visual acuity (UCDVA). Objective: To evaluate the influence of corneal astigmatism on refractive outcomes after phacoemulsification. Patients and methods. The study was based on the analysis of data from 366 patients (427 eyes). Patients were divided into 9 subgroups according to the axis of the corneal steep meridian. All patients underwent standard ophthalmologic examination, corneal topography, as well as measurement of axial length, anterior chamber depth, power of the steep and flat meridians of the cornea and their axes, followed by comparison of pre- and postoperative results. Statistical processing was performed using the Jamovi program. Statistical analysis was carried out using parametric and non-parametric statistics: Shapiro-Wilk test, Mann-Whitney test, Kruskal-Wallis test, and the pairwise comparison method of Dwass-Steel-Krichlow-Fligner, linear regression analysis. Differences at p <0.05 were considered statistically significant. Results. Astigmatism of less than 0.5 diopters was observed in 32.1%, with the most common cylindrical component values ranging from 0.51 to 1 D - 42.9%. Astigmatism of more than 1.0 D was observed in every fourth patient (25.1%). Astigmatism with-the-rule (WTR) was the most common, at 47.8%, while astigmatism against-the-rule (ATR) was observed in 39.6% of patients, and all other cases were due to oblique astigmatism component - 12.6%. The average age in the group with ATR astigmatism was higher (77.9±6.8 years) than in groups with WTR (73.0±9.3 years) and oblique (76.4±6.9 years) astigmatism. A regularity was revealed: the higher the residual astigmatism, the lower the values of uncorrected visual acuity, which worsens the patient's quality of life. In groups with WTR astigmatism, postoperative astigmatism values were generally lower than those in groups with ATR astigmatism. The difference between the indicators averaged 0.3-0.4 D, which corresponds to the mean value of astigmatism of the posterior surface - 0.24 D. Barrett toric calculator (BTC) recommended implanting a toric IOL 9.6% more often than the Kane formula. BTC recommended T2 implantation 7 times more often than Kane, which is due to this group having inverse corneal astigmatism. Conclusion. The main outcome of the study was the creation of a formula that predicts residual astigmatism when performing phacoemulsification with implantation of a monofocal non-toric IOL. Thus, during the preoperative stage, it is possible to calculate residual astigmatism based on minimal diagnostic data, which allows for a decision regarding the feasibility of toric IOL implantation.
Introduction. The combination of astigmatism and cataract is a fairly common occurrence. According to literature, 15 to 29% of patients with cataract have corneal astigmatism of more than 1.5 D, and 3 to 15% have more than 2.0 D. The use of toric intraocular lenses (TIOL) is expanding every year and requires thorough selection of parameters to reduce residual postoperative astigmatism and provide the best values of uncorrected distance visual acuity (UCDVA). Objective: To evaluate the influence of corneal astigmatism on refractive outcomes after phacoemulsification. Patients and methods. The study was based on the analysis of data from 366 patients (427 eyes). Patients were divided into 9 subgroups according to the axis of the corneal steep meridian. All patients underwent standard ophthalmologic examination, corneal topography, as well as measurement of axial length, anterior chamber depth, power of the steep and flat meridians of the cornea and their axes, followed by comparison of pre- and postoperative results. Statistical processing was performed using the Jamovi program. Statistical analysis was carried out using parametric and non-parametric statistics: Shapiro-Wilk test, Mann-Whitney test, Kruskal-Wallis test, and the pairwise comparison method of Dwass-Steel-Krichlow-Fligner, linear regression analysis. Differences at p <0.05 were considered statistically significant. Results. Astigmatism of less than 0.5 diopters was observed in 32.1%, with the most common cylindrical component values ranging from 0.51 to 1 D - 42.9%. Astigmatism of more than 1.0 D was observed in every fourth patient (25.1%). Astigmatism with-the-rule (WTR) was the most common, at 47.8%, while astigmatism against-the-rule (ATR) was observed in 39.6% of patients, and all other cases were due to oblique astigmatism component - 12.6%. The average age in the group with ATR astigmatism was higher (77.9±6.8 years) than in groups with WTR (73.0±9.3 years) and oblique (76.4±6.9 years) astigmatism. A regularity was revealed: the higher the residual astigmatism, the lower the values of uncorrected visual acuity, which worsens the patient's quality of life. In groups with WTR astigmatism, postoperative astigmatism values were generally lower than those in groups with ATR astigmatism. The difference between the indicators averaged 0.3-0.4 D, which corresponds to the mean value of astigmatism of the posterior surface - 0.24 D. Barrett toric calculator (BTC) recommended implanting a toric IOL 9.6% more often than the Kane formula. BTC recommended T2 implantation 7 times more often than Kane, which is due to this group having inverse corneal astigmatism. Conclusion. The main outcome of the study was the creation of a formula that predicts residual astigmatism when performing phacoemulsification with implantation of a monofocal non-toric IOL. Thus, during the preoperative stage, it is possible to calculate residual astigmatism based on minimal diagnostic data, which allows for a decision regarding the feasibility of toric IOL implantation.
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факоэмульсификация, астигматизм, торические ИОЛ, формула расчета ИОЛ, биометрия, задняя поверхность роговицы, Barrett toric calculator, Kane formula, phacoemulsification, astigmatism, toric intraocular lenses, IOL calculation formula, biometry, posterior corneal surface, Barrett toric calculator, Kane formula.