Comparison of accuracy of intraocular lens calculation formulas in cataract eyes with prior radial keratotomy and axial length longer than 28mm / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To compare the accuracy of different intraocular lens(IOL)calculation formulas in cataract patients with axial length longer than 28mm and a history of radial keratotomy(RK).METHODS: Retrospective study. The medical records of 19 cataract patients(29 eyes)after RK and with axial length longer than 28mm who underwent cataract surgery from January 2011 to July 2020 in Beijing Tongren Hospital were analyzed. The absolute error(AE)of the difference among three different formulas was calculated. AE refers to the absolute value between the actual spherical equivalent after cataract surgery and the spherical equivalent predicted by the IOL formula. The AE values of the three formulas and the percentages of eyes with AE≤0.5, 0.75, 1.0, and 2.0D were calculated and compared.RESULTS: The AE values of the three formulas were significantly different(χ2=8.759, P=0.013). The Barrett True-K formula had the smallest median AE, which was only 0.62(0.20, 1.15)D, followed by the Haigis formula 0.76(0.34, 1.26)D, and the Holladay 1(D-K)formula had the largest 1.01(0.49, 1.62)D. The percentages of affected eyes with AE ≤0.5, 0.75, 1.0, and 2.0D for the Barrett True-K formula were 48%, 59%, 69%, and 93%, which were equal to or higher than the other two formulas.CONCLUSION: The Barrett True-K formula is more recommended among the three formulas for cataract patients after RK and with axial length longer than 28 mm.

Selection of intraocular lens calculation formula for cataract surgery in glaucoma patients / 国际眼科杂志(Guoji Yanke Zazhi)

Glaucoma and cataracts are the leading causes of blindness, and surgery is an important treatment option. Patients with glaucoma have clinical characteristics such as high intraocular pressure, shallow anterior chamber and short axial length, and the ocular structure is often altered after anti-glaucoma surgery like trabeculectomy. These changes also lead to differences in the accuracy of intraocular lens(IOL)refractive calculation between cataract surgery after anti-glaucoma surgery or combined glaucoma and cataract surgery and alone cataract surgery. Meanwhile glaucoma patients' individual clinical characteristics and structural changes caused by anti-glaucoma surgery have shown differences in the impact on the predictive accuracy of IOL diopters and the type of refractive drift. This article reviews the latest research advances in the causes of refractive error(RE), the characteristics of refractive drift, and the selection of the most appropriate IOL formula for glaucoma patients undergoing cataract surgery or cataract surgery after anti-glaucoma surgery or combined glaucoma and cataract surgery.

Resultados del cálculo de la lente intraocular con fórmula Holladay 2 y Barret Universal 2 / Results of Intraocular Lens Calculation with Holladay 2 and Barret Universal 2 formula

Objetivo: Determinar los resultados refractivos con las fórmulas Holladay 2 y Barret Universal 2 a partir del cálculo de la lente intraocular en pacientes operados de catarata. Métodos: Se realizó un estudio descriptivo prospectivo y longitudinal con 60 ojos de 50 pacientes operados de catarata mediante la técnica de facoemulsificación. Se empleó para el cálculo de la lente el IOL Master 700 y el Pentacam AXL con la fórmula Holladay 2 y Barret Universal 2, respectivamente. Resultados: Predominó el sexo femenino y el grupo etario mayor de 60 años. Los ojos mayores de 26 mm mostraron la mayor diferencia entre el poder dióptrico de la lente intraocular que se implantó según Holladay y en menores de 22 mm según Barret Universal. Ambos grupos presentaron una disminución del equivalente esférico, siendo superior a 7 y 5 dioptrías en ojos mayores de 26 mm en el posoperatorio de ambas fórmulas. Posterior a la cirugía se observó una mejoría en la agudeza visual sin corrección y corregida de más de 4 líneas en la cartilla de Snellen, independiente de la longitud axial, para ambos grupos en estudio. Sin cambios significativos en el cilindro queratométrico. En el 70,0 por ciento de los casos, el resultado refractivo final estuvo en rango de la emetropía para el grupo Holladay 2 y el 66,7 por ciento para el grupo Barret Universal 2. Conclusiones: Ambas fórmulas resultan útiles para el cálculo de la lente intraocular en todos los rangos de longitud axial(AU)

Objective: To determine refractive outcomes with the Holladay 2 and Barret Universal 2 formulas from intraocular lens calculation in cataract surgery patients. Methods: A prospective and longitudinal descriptive study was performed with 60 eyes of 50 patients who underwent cataract surgery by phacoemulsification. The IOL Master 700 and Pentacam AXL with the Holladay 2 and Barret Universal 2 formula, respectively, were used to calculate the lens. Results: Female gender and age group older than 60 years predominated. Eyes larger than 26 mm showed the greatest difference between the dioptric power of the intraocular lens implanted according to Holladay and those smaller than 22 mm according to Barret Universal. Both groups presented a decrease of the spherical equivalent, being higher than 7 and 5 diopters in eyes larger than 26 mm postoperatively in both formulas. Postoperatively, there was an improvement in uncorrected and corrected visual acuity of more than 4 lines in the Snellen chart, independent of axial length, for both groups under study. No significant changes in keratometric cylinder. In 70.0 percent of the cases, the final refractive result was in the emmetropia range for the Holladay 2 group and 66.7 percent for the Barret Universal 2 group. Conclusions: Both formulas are useful for the calculation of the intraocular lens in all axial length ranges(AU)

Optimización de las constantes para el cálculo preciso de cinco modelos de lente intraocular / Optimization of constants for accurate calculation of five intraocular lens models

Objetivo: Optimizar las constantes utilizadas por las fórmulas SRK/T, SRK/T2, Holladay 1 y Hoffer Q para cinco modelos de lentes intraoculares (LIO), implantados durante la cirugía de catarata en el Instituto Cubano de Oftalmología (enero/2006-octubre/2019). Método: Se estudiaron retrospectivamente 47341 pacientes. Las constantes se optimizaron ajustando a cero el error de predicción promedio (EPm) y obteniendo el valor que arrojó el máximo número de ojos con error de predicción absoluto -EP- ≤; 0,25, tanto para la biometría ultrasónica como para la óptica. La eficacia de las constantes optimizadas se verificó mediante el análisis de los errores absolutos medio y mediano (EAM/EAMed) más bajos y el porcentaje de ojos en un intervalo determinado de error de predicción en función del valor de las constantes. También se analizaron el índice de rendimiento de la fórmula de Haigis y un nuevo índice introducido. Resultados: Las constantes optimizadas fueron significativamente diferentes de los valores del fabricante. Los valores obtenidos para EPm = 0 fueron diferentes a los mínimos de EAM y EAMed. El porcentaje de ojos con -EP- ≤ 0,25 y 0,50 D difirió cuando los criterios de optimización fueron diferentes. SRK/T y SRK/T2 mostraron los mejores rendimientos, según ambos índices. Conclusiones: Las constantes optimizadas mejoran los resultados postoperatorios para cada combinación LIO-fórmula. Diferentes criterios de optimización conducen a diferentes resultados. El EAM, el EAMed y el porcentaje de ojos con -EP- ≤; 0,50 D son parámetros válidos para comprobar el rendimiento de las fórmulas, hasta disponer de un índice único, fiable y consensuado(AU)

Objective: To optimize the constants used by the SRK/T, SRK/T2, Holladay 1 and Hoffer Q formulas for five intraocular lens (IOL) models implanted during cataract surgery at the Cuban Institute of Ophthalmology (January/2006-October/2019). Methods: 47341 patients were retrospectively studied. The constants were optimized by adjusting the average prediction error (EPm) to zero and obtaining the value that showed the maximum number of eyes with absolute prediction error -EP- ≤ 0.25, for both ultrasonic and optical biometry. The effectiveness of the optimized constants was verified by analyzing the lowest average and median absolute errors (EAM/EAMed) and the percentage of eyes in a given range of prediction error as a function of the value of the constants. The Haigis formula performance index and a newly introduced index were also analyzed. Results: The optimized constants were significantly different from the manufacturer's values. The values obtained for EPm = 0 were different from the EAM and EAMed minima. The percentage of eyes with -EP- ≤ 0.25 and 0.50 D differed when the optimization criteria were different. SRK/T and SRK/T2 showed the best performances, according to both indexes. Conclusions: Optimized constants improve postoperative outcomes for each IOL-formula combination. Different optimization criteria lead to different results. The EAM, the EAMed and the percentage of eyes with -EP- ≤ 0.50 D are valid parameters to check the performance of the formulas, until a single, reliable and consensual index is available(AU)

Advances in intraocular lens power calculation formulas in high myopia / 中华实验眼科杂志

As the number of cataract patients with high myopia increases, and the cataract surgery shifts from a rehabilitation procedure to a refractive procedure, achieving a good postoperative visual acuity has been the target of cataract patients with high myopia.Because of inaccurate axial length measurement, unpredictable effective lens position and improper selection of intraocular lens (IOL) calculation formulas, the precision of refractive prediction in cataract patients with high myopia remains low, which affects the visual acuity and satisfaction of patients.With the development of IOL calculation formulas, SRK/T, Holladay1 and other thin-lens vergence formulas have been modified in axial length, corneal curvature and other parameters, and the thick-lens vergence formulas such as Barrett Universal Ⅱ have been widely put into use.Meanwhile, new formulas including artificial intelligence-based formulas such as Hill-RBF, ray tracing formulas such as Olsen and OKULIX, and theoretical formulas such as Kane and EVO formulas have been developed.More choices and guarantees are available for refractive prediction after cataract surgery.This paper summarized the optimization and advance of different types of IOL calculation formulas so as to provide different available choices to improve the accuracy of IOL power calculation in cataract patients with high myopia.

Comparación entre las fórmulas SRK/T, Hoffer Q, Barrett Universal y HRBF para el cálculo del lente intraocular / Comparison of the formulas SRK/T, Hoffer Q, Barrett Universal and HRBF for intraocular lens calculation

Objetivo: Comparar la exactitud de las fórmulas SRK/T, Hoffer Q, Barrett Universal y HRBF en el cálculo del lente intraocular. Métodos: Se realizó un estudio descriptivo longitudinal prospectivo de 70 ojos de 70 pacientes operados de cirugía de catarata con implante de lente intraocular, de junio del año 2018 a junio del 2019, utilizando el IOL Master 700, en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Se determinó la exactitud de cada fórmula respecto al error de predicción del equivalente esférico y se compararon entre sí. Resultados: Los pacientes entre 60 y 80 años constituyeron el 70,00 por ciento de los casos y el sexo femenino representó el 61,43 por ciento. Los ojos de tamaño medio representaron el 91,43 por ciento del total. No hubo diferencias en el error de predicción absoluto medio entre de las fórmulas analizadas para el rango total de longitudes axiales. La fórmula de Barrett tuvo el 65,71 por ciento de ojos con un error de predicción dentro de ± 0,50 D. El mayor porcentaje de ojos con un error mayor a 1 dioptría recayó sobre la Hoffer Q (10,00 por ciento). Conclusiones: El grupo etario más representado está entre 60 y 80 años y el sexo femenino es mayoritario. Predominan los ojos de tamaño medio y las mensuraciones biométricas dentro de los valores promedio estándar. Las fórmulas HRBF, SRK/T, Hoffer Q y Barrett predicen el resultado refractivo posoperatorio con una exactitud similar para el rango total de longitudes axiales. La fórmula de Barrett logra el mayor porcentaje de ojos con errores de predicción posoperatorios dentro del rango de la emetropía(AU)

Objective: Compare the accuracy of the formulas SRK/T, Hoffer Q, Barrett Universal and HRBF for intraocular lens calculation. Methods: A prospective longitudinal descriptive study was conducted of 70 eyes of 70 patients undergoing cataract surgery with intraocular lens implantation from June 2018 to June 2019 at Ramón Pando Ferrer Cuban Institute of Ophthalmology. In all cases IOL Master 700 was used for lens calculation. Determination of the accuracy of each formula in error prediction of the spherical equivalent was followed by a comparison of the formulas. Results: Patients aged 60-80 years were 70.00 percent of the cases; female sex represented 61.43 percent. Medium sized eyes were 91.43 percent of the total eyes examined. Mean absolute prediction error did not show any difference between the formulas analyzed for the total range of axial lengths. The Barrett formula spotted 65.71 percent of the eyes with a prediction error within ± 0.50 D. The highest percentage of eyes with an error greater than 1 diopter corresponded to the Hoffer Q formula (10.00 percent ). Conclusions: The best represented age group was 60-80 years; female sex prevailed. A predominance was found of medium size and biometric measurements within standard mean values. The formulas HRBF, SRK/T, Hoffer Q and Barrett predict the postoperative refractive result with similar accuracy throughout the total range of axial lengths. The Barrett formula achieves the highest percentage of eyes with postoperative prediction errors within the range of emmetropia(AU)

Fórmula Barrett True K en pacientes con catarata operados de cirugía refractiva corneal / The Barrett True-K formula in cataract patients undergoing corneal refractive surgery

Objetivo: Determinar los resultados refractivos en pacientes operados de catarata con cirugía refractiva corneal, según el cálculo del poder dióptrico de la lente intraocular con la fórmula Barrett True K. Métodos: Se realizó un estudio pre-experimental, del tipo antes y después, en el cual fueron incluidos 18 pacientes (31 ojos). En ellos se analizaron variables demográficas y clínicas. La principal variable de salida fue la predictibilidad del componente esférico ± 0,50 D, ± 1,0 D según la longitud axial. Resultados: Fueron estudiados pacientes con un promedio de edad de 59,4 años, predominantemente del sexo femenino (66,7 por ciento). El 77,4 por ciento fue operado con queratotomía radial. Con la cirugía de catarata se produjo una mejora ostensible de la agudeza visual no corregida (mediana preoperatoria: 0,12 y mediana posoperatoria: 0,60). Solo el 9,7 por ciento de los ojos analizados presentó una agudeza visual sin corregir de 20/20 y el 90,3 por ciento de 20/40 o más. La cantidad de ojos con un equivalente esférico de ± 0,50 disminuyó en la medida en que aumentó la longitud axial (corta: 100 por ciento; normal: 57,1 por ciento; larga: 22,7 por ciento), no así la predictibilidad del componente esférico de ± 0,50, que aumentó (corta: 50,0 por ciento; normal: 57,1 por ciento; larga: 63,6 por ciento). Conclusiones: La fórmula Barrett True K resulta útil para el cálculo de la lente intraocular en pacientes operados de catarata y cirugía refractiva corneal previa(AU)

Objective: Determine refractive outcomes in patients undergoing cataract corneal refractive surgery based on intraocular lens dioptric power calculation with the Barrett True-K formula. Methods: A pre-experimental before/after study was conducted of 18 patients (31 eyes). Demographic and clinical variables were analyzed. The main output variable was spherical component predictability ± 0.50 D, ± 1.0 D according to axial length. Results: Mean age was 59.4 years; female sex prevailed (66.7 percent). Of the patients studied, 77.4 percent underwent radial keratotomy. Cataract surgery led to notable uncorrected visual acuity improvement (preoperative mean: 0.12; postoperative mean: 0.60). Only 9.7 percent of the eyes examined had an uncorrected visual acuity of 20/20, whereas 90.3 percent had 20/40 or more. The number of eyes with a spherical equivalent of ± 0.50 fell as axial length rose (near: 100 percent; normal: 57.1 percent; far: 22.7 percent), unlike ± 0.50 spherical component predictability, which rose from near: 50.0 percent; normal: 57.1 percent; far: 63.6 percent. Conclusions: The Barrett True-K formula is useful for intraocular lens calculation in patients undergoing previous cataract and corneal refractive surgery(AU)

Research progress on influencing factors of refractive error after cataract surgery for high myopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#High myopia is one of the major blinding diseases in China and even in the world, and high myopia with cataract is a kind of complex cataract with a high risk of blindness. At present, surgery is the only treatment. Because high myopia can lead to a series of complex changes in the eye, compared with the normal axial eye, it is easier to produce the refractive error and refractive drift after surgery. In this paper, the influencing factors of refractive error after cataract surgery for high myopia are reviewed, including the accuracy of preoperative biological measurement, the choice of intraocular lens calculation formula, and the change of effective intraocular lens position.

Resultados del cálculo de la lente intraocular con la fórmula Holladay 2 en pacientes con catarata / Results of intraocular lens calculation with the Holladay 2 formula in cataract patients

RESUMEN Objetivo: Determinar los resultados refractivos en pacientes operados de catarata, según el cálculo del poder dióptrico de la lente intraocular con la fórmula Holladay 2. Métodos: Se realizó un estudio descriptivo prospectivo y longitudinal en 222 ojos de 173 pacientes operados de catarata mediante la técnica de facoemulsificación. Se empleó para el cálculo de la lente el IOL Master 700 y la fórmula Holladay 2. Resultados: Predominó el sexo femenino y el grupo etario mayor de 60 años. En el posoperatorio se observó una mejoría en la agudeza visual sin corrección y corregida de más de 4 líneas en la cartilla de Snellen, independiente de la longitud axial, sin cambios significativos en el cilindro queratométrico. En 69,0 por ciento de los casos el resultado refractivo final estuvo en el rango de la emetropía. Los ojos mayores de 26 mm presentaron una disminución del equivalente esférico superior a 6 dioptrías en el posoperatorio; los menores de 22 mm mostraron la mayor diferencia entre el poder dióptrico de la lente intraocular que se implantó y el que sugiere la fórmula convencional. Conclusiones: La fórmula Holladay 2 resulta útil para el cálculo de la lente intraocular en todos los rangos de longitud axial(AU)

ABSTRACT Objective: Determine refractive results in patients undergoing cataract surgery based on intraocular lens dioptric power calculation with the Holladay 2 formula. Methods: A prospective longitudinal descriptive study was conducted of 222 eyes of 173 patients undergoing cataract surgery by phacoemulsification technique. IOL Master 700 and the Holladay 2 formula were used for lens calculation. Results: There was a predominance of the female sex and the over-60 years age group. The postoperative period was characterized by improvement in visual acuity without correction and corrected of more than 4 lines on the Snellen chart, regardless of axial length, with no significant changes in the keratometric cylinder. In 69.0 percent of the cases, the final refractive result was within the range of emmetropia. Eyes larger than 26 mm displayed a spherical equivalent reduction above 6 diopters postoperative, whereas eyes smaller than 22 mm showed the greatest difference between the dioptric power of the intraocular lens implanted and the one suggested by the conventional formula. Conclusion: The Holladay 2 formula is useful for intraocular lens calculation in all axial length ranges(AU)

Effects of intraocular pressure on the selection of intraocular lens calculation formulas for cataract and glaucoma surgery / 眼科新进展

Objective To clarify the effects of intraocular pressure (IOP) on the selection of intraocular lens (IOL) calculation formulas for cataract and glaucoma surgery in order to provide reference for avoiding refractive error (RE) in clinical.Methods The clinical data of 72 patients (80 eyes) with primary angle-closure glaucoma (PACG) and cataract undergoing combined cataract and glaucoma surgery in our department were enrolled from May 2015 to April 2017.The subjects were divided into normal IOP (10-21 mmHg,1 kPa =7.5 mmHg,n =28) and high IOP group (＞ 21 mm-Hg,n =52) based on preoperative mean IOP.Then the differences between the postoperative actual spherical equivalence (PASE) measured 3 months after operation and the predicted preoperative spherical equivalence (PPSE) of 4 kinds of IOL calculation formulas by IOL Master (SRK/T,Holladayl,Hoffer Q,and Haigis) were compared so as to evaluate the effects of IOP on the postoperative absolute refractive error (ARE) and refractive error (RE) of IOL formulas.Results The postoperative IOP for 3 months of all patients was significantly lower than that of preoperative data(t =9.96,P =0.000),and the decrease level was positively correlated with preoperative mean IOP (r =0.974,P =0.000).There were significant differences in the median ARE from SRK/T,Holladayl,Hoffer Q and Haigis formula in the normal and high IOP groups (P =0.008,0.004),while there was no significant difference in RE (RE ＞ 0) from SRK/T,Holladayl,Hoffer Q and Haigis formulas between the two groups (P =0.633,0.422).In the normal IOP group,there was significant difference in RE (RE ＜ 0) from the four formulas (P =0.000),and LSD comparison showed that the SRK/T formula had the smallest RE (all P＜0.01),and Haigis formula had the largest RE than the other formulas (all P ＜ 0.05).In the high IOP group,there was significant difference in RE (RE ＜ 0) from the four formulas (P =0.000),and LSD comparison showed that the Hoffer Q formula had the smallest RE (all P ＜ 0.01),and there was no significant difference in RE from other formulas (all P ＜ 0.05).Conclusions Combination of cataract and glaucoma surgery can improve visual acuity and intraocular pressure in patients,and the decreased level of postoperative IOP is positively correlated with preoperative mean IOP.As for calculation of the degree of IOL,the SRK/T formula shows a good accuracy when preoperative mean IOP is normal,and Hoffer Q formula should be chosen for patients with high preoperative mean IOP.

Recent progress on study of the selection of intraocular lens in the bilateral sequential cataract surgery / 中华实验眼科杂志

Bilateral sequential cataract surgery is very common in clinical,but the ophthalmologists often ignore how to choose the timing of operation and whether the first eye can be used to improve the intraocular lens (IOL) power calculation for the second one.Despite the refinements in IOL selection with the use of third-generation IOL formulas,5％ of eyes still result in a postoperative refractive surprise of ± 1.00 D or more.This paper introduced the methods of using refraction error of the first eye to improve the IOL power calculation for the second eye,and the refractive error of the second eye can be improved by modifying the IOL power to correct up to 50％ of the error from the first eye in details.Because of the variation of the postoperative refractive surprise within a month,the interval of three to four weeks between two eyes cataract surgery is highly recommended.These conclusions may provide the advantageous guidance for us in the selection of IOL in bilateral cataract surgery.

Personalización de las constantes en las fórmulas de cálculo de la lente intraocular / Personalization of constants in the intraocular lens calculation formulas

Objetivo: personalizar las constantes A, factor cirujano y profundidad de la cámara anterior para las fórmulas de cálculo de la lente intraocular en la cirugía de catarata en el Instituto Cubano de Oftalmología Ramón Pando Ferrer de mayo de 2007 a enero de 2011...

Objective: to personalize the A, surgeon factor and anterior chamber depth constants for intraocular lens calculation formulas in the cataract surgery at the Ramón Pando Ferrer Cuban Ophthalmological Institute from May 2007 to January 2011...

Comparison of Formulas for Intraocular Lens Power Calculation Installed in a Partial Coherence Interferometer

PURPOSE: To evaluate the accuracy of various formulas installed in IOLMaster software which uses partial coherence interferometry for axial length measurement. METHODS: This retrospective comparative study included 81 eyes of consecutive patients who had uneventful cataract surgery with implantation of Acrysof single piece (SA60AT) IOL. Axial length was measured with IOLMaster and IOL power was calculated using various formulas, including SRK II, SRK/T, Holladay 1, Haigis, and Hoffer Q. Subjects were stratified by axial length into Groups A (axial length or = 25.00 mm). Target refractions of the five formulas were compared to the postoperative manifest refraction at 1 month. RESULTS: The five formulas showed no difference in predicting postoperative refractive errors among all of the groups. CONCLUSIONS: Five formulas installed in IOLMaster software provided equivalent predictions of postoperative refractive error regardless of axial length.