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AIM: To evaluate the accuracy of the formulas, including Haigis, SRK/T, Holladay 1, and Holladay 2, in predicting the diopter of the intraocular lens implanted in high myopia cataract patients.METHODS: Prospective study. A total of 168 cases(168 eyes)of age-related cataract with an axial length(AL)≥26 mm who were treated in our hospital from August 2017 to November 2021 were selected. According to the preoperative AL measured by IOL Master 700, the patients were divided into five groups, including 37 cases(37 eyes)in group A with 26 mm≤AL<27 mm, 34 cases(34 eyes)in group B with 27 mm≤AL<28 mm, 42 cases(42 eyes)in group C with 28 mm≤AL<29 mm, 28 cases(28 eyes)in group D with 29 mm≤AL<30 mm, and 27 patients(27 eyes)in group E with AL ≥ 30 mm. Subjective refraction was performed at 3 mo postoperatively, and the mean numerical error(MNE)and mean absolute error(MAE)of each formula for predicting diopters were calculated.RESULTS: The MNE and MAE of the Haigis and Holladay 2 formulas were relatively less in each group, and MNE and MAE did not significantly increase with the growth of the axial length. However, the MAE and MNE of the SRK/T and Holladay 1 formulas significantly increased with the growth of the axial length, with the MNE and MAE of the Holladay 1 formula increasing more significantly in groups C, D, and E.CONCLUSION: For patients with age-related cataract, with an axial length of ≥26 mm, the accuracy of predicting the diopter of the intraocular lens using the Haigis and Holladay 2 formulas were higher.
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AIM: To compare the accuracy between Wang-Koch axial length adjustment formulas(SRK/TWK, Holladay ⅠWK)and SRK/T, Haigis, Holladay Ⅰ, Hoffer Q in calculating intraocular lens power of cataract patients with high myopia.METHODS: A total of 42 cataract patients with high myopia(57 eyes)were collected. All eyes underwent phacoemulsification combined with intraocular lens implantation surgery in our Hospital from September 2019 to March 2022. They were divided into two groups according to the axial length(AL): group A(27mm≤AL<30mm, 31 eyes)and group B(AL≥30mm, 26 eyes). Patients were followed up at 3mo. The actual postoperative diopter was recorded, and then the refractive mean numerical error(MNE)and mean absolute error(MAE)were calculated.RESULTS: MAE of each formulas was statistically different after surgery(P<0.01), among which the MAE of Holladay ⅠWK and SRK/TWK [0.31(0.08, 0.57), 0.34(0.17, 0.63)D] was lower than other formulas. However, there were no statistical difference between SRK/TWK, Holladay ⅠWK and SRK/T, Haigis formulas [0.61(0.27, 1.02), 0.63(0.22, 1.01)D](P>0.05). MAE were statistically different among the formulas in group A(27mm≤AL<30mm; P<0.01). The MAE of Holladay ⅠWK and SRK/TWK was lower than other formulas [0.18(0.05, 0.51), 0.28(0.16, 0.52)D], but there were no statistical difference with SRK/T and Haigis formulas [0.45(0.18, 0.65), 0.50(0.14, 0.75)D](P>0.05). In group B(AL≥30mm), the MAE of each formulas was statistically different after surgery(P<0.01), among which MAE of Holladay IWK and SRK/TWK was the lowest, followed by SRK/T and Haigis, whereas, Holladay I and Hoffer Q ranked the highest. Furthermore, there were statistical differences between MAE of SRK/TWK, Holladay ⅠWK [0.44(0.23, 0.67), 0.41(0.22, 0.66)D] and SRK/T, Haigis formulas [0.78(0.55, 1.07), 0.75(0.45, 1.25)D](all P<0.05).CONCLUSION: For cataract patients with AL ≥30mm, the Wang-Koch axial length adjustment formulas were relatively accurate in calculating diopter of intraocular lens, and had clinical application value to some extent.
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Purpose: To assess the prediction accuracy of intraocular lens (IOL) formulas and study the effect of axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), and lens thickness (LT) on the accuracy of formulas using optic biometry. Methods: This study was performed on 164 eyes of 164 patients who underwent uneventful cataract surgery. Ocular biometry values were measured using Lenstar?900, and intraocular lens (IOL) power was calculated using the SRK/T, SRK II, Hoffer Q, Holladay 2, and Barrett Universal II formulas. We evaluated the extent of bias within each formula for different ocular biometric measurements and explored the relationship between the prediction error and the ocular parameters by using various IOL formulas. Results: The summarization of refractive prediction error and absolute prediction error for each IOL formulation was performed after adjusting the mean refractive error to zero. The deviation in the error values was minimum for SRK/T (0.265) followed by Holladay 2 (0.327) and Barret (0.382). Further, SRK/T had the lowest median (0.15) and mean (0.198) absolute error as compared to other formulations. For the above formulations, 100% of the eyes were in the diopter range of ±1.0. It was observed that the overall distribution of error was closer to zero for SRK/T, followed by Holladay 2 and then Barrett. Conclusion: In summary, we found that accuracy was better in SRK/T formula. We achieved a better understanding of how each variable in the formulas is relatively weighed and the influencing factors in the refraction prediction.
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@#AIM:To evaluate the effect of keratometry on the calculation accuracy of intraocular lens(IOL)diopter in patients with normal axial cataract.METHODS:Totally 157 cases(157 eyes)with age related cataract were collected in Kaifeng Central Hospital from June 2020 to June 2021. Patients were divided into 3 groups according to keratometry: group A(53 eyes)(K<42D), group B(55 eyes)(42D≤K≤46D), group C(49 eyes)(K>46D). The IOL diopter was calculated by SRK/T, Hoffer Q, Holladay 2, Haigis, Kane and Barrett Ⅱ formulas respectively. Subjective optometry was performed after 1mo operation. The average refractive prediction error(RPE)and mean absolute error(MAE)were calculated, and their differences were compared and analyzed.RESULTS:There were significant difference between RPE of each formula and 0D in groups A and C(<i>P</i><0.05), and Barrett Ⅱ formula was significantly different with SRK/T, Hoffer Q, Holladay 2 and Haigis formula(<i>P</i><0.01), but was no significantly different with Kane formula in RPE(<i>P</i>>0.01). There was no significant difference in RPE between group B and 0D(<i>P</i>>0.05). The ratio of Barrett Ⅱ formula in MAE≤0.5D in group A was significantly higher than SRK/T, Hoffer Q, Holladay 2 and Haigis formula(all <i>P</i><0.01), but there was no significant difference compared with Kane formula(<i>P</i>>0.01). In group B, there was no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤0.5D and ≤1.0D(all <i>P</i> >0.01). In group C, the ratio of SRK/T and Hoff Q formula in MAE≤0.5D was lower than Barrett Ⅱ formula(all <i>P</i><0.01), and there were no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤1.0D(<i>P</i> >0.01).CONCLUSION:If K<42D or K>46D before operation, the commonly used formulas will produce refractive error, but the accuracy of Kane and Barrett Ⅱ formulas are still higher than other formulas.
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@#AIM:To observe the effect of combined surgery in cataract patients with pterygium.<p>METHODS:A prospective single centered study was performed on 22 patients(mean age: 59.05±8.70 years)of concurrent cataract and pterygium(size 2-5 mm in length), who attended the outpatient department during the study period of one year, and the minimum follow up was 3mo-1a for all patients. Mean keratometry(K<sub>mean</sub>), mean astigmatism, best corrected visual acuity(LogMAR), preoperatively and 3mo postoperatively had been determined. The corneal curvature, pterygium size and the prediction error(PE)were observed.<p>RESULTS: The amount of PE was <±0.50 D in 18 patients(81.8%)and ±0.50 D to ±1.00 D in 4 patients(18.2%). None of the patients had PE of >1.00 D. The mean axial length did not change significantly(<i>P</i>=0.77)postoperatively. The mean keratometric reading increased from 42.994±1.536 preoperatively to 43.324±1.479 postoperatively but this was not significant(<i>P</i>=0.105). The corneal astigmatism decreased significantly from 2.09±0.789 D preoperatively to 0.523±0.277 D postoperatively(<i>P</i><0.05). BCVA(LogMAR)significantly improved from 1.007±0.402 preoperatively to 0.024±0.062 postoperatively(<i>P</i><0.05). No correlation was found between changes in keratometry and PE(<i>r</i>=-0.29, <i>P</i>=0.19). And, there was no correlation was found between pterygium size and PE(<i>r</i>=0.2997, <i>P</i>=0.17). <p>CONCLUSION: Combined phacoemulsification+foldable intraocular lens(IOL)implantation and conjuctival autograft(CAG)application was safe and effective procedure.
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@#AIM: To compare the accuracy of Barrett Universal Ⅱ, Haigis and modified Wang-Koch SRK/T formulas in calculating intraocular lens(IOL)power in eyes with long axial length(AL).<p>METHODS: Eyes were divided into three AL groups as follows: 26.0 to 28.0mm(group A), 28.0 to 30.0mm(group B), and 30.0mm or more(group C). All eyes underwent phacoemulsification cataract surgery. In the 3mo after operation, IOL powers that would have resulted in emmetropia were calculated according to results of subjective refraction. The predictive error(PE)and absolute error(AE)of each formulas were calculated and compared and the factors(AL, keratometry value, the anterior chamber depth)associated with PEs were analyzed.<p>RESULTS: The average PE of Barrett Universal Ⅱ, Haigis and modified Wang-Koch SRK/T formulas were 0.37±0.78D, 0.77±0.88D and 0.36±0.82D respectively. In groups A and B, the PEs and AEs of three formulas were not statistically significant(<i>P</i>>0.05). However, in group C, the PEs and AEs of Barrett Universal Ⅱ and modified Wang-Koch SRK/T formula were significantly less than Haigis formula(<i>P</i><0.05). The PEs of Haigis formula in cataract eyes with long AL was affected by AL and keratometry value, whereas the PEs of Barrett Universal Ⅱ and modified Wang-Koch SRK/T formula was not affected by AL.<p>CONCLUSION: In eyes with an AL of 26.0 to 30.0mm, all three formulas are acceptable. In eyes with AL of 30.0mm or more, the accuracy of Barrett Universal Ⅱ and modified Wang-Koch SRK/T formula are better than Haigis formula.
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@#The good effect of refractive cataract surgery depends on a variety of factors, mainly including accuratebiometrics before surgery and accurate calculation of intraocular lens(IOL)power. The accuracy of intraocular biometrics with abnormal eyes axis before surgery is lower. Moreover, compared with the normal eyes axis, the error of postoperative refractive state prediction is larger, which brings great challenges to obtaining the best postoperative visual quality. Recently, new optical biometrics have been used clinically, and individualized IOL power calculation formulas have been developed and applied, which makes the choice of intraocular lens power more accurate. This article reviews the latest research progress on the measurement of eye parameters and the selection of IOL power calculation formula in patients with abnormal axial cataract in the past 3a, in order to provide reference for clinical application.
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@#AIM: To evaluate the effect of pupil dilation on ocular biometry and IOL power in cataract patients with high myopia, and the difference between cataract patients with high myopia and cataract patients with normal axial length(AL).<p>METHODS:Measurements of AL, corneal curvature(K including K1 and K2), anterior chamber depth(ACD)were performed using IOLmaster in 22 cataract patients with high myopia(34 eyes)(group A)and 23 cataract patients with normal AL(39 eyes)(group B)before and after pupil dilation. SRK-T and Haigis were used to caculate pre- and post-cycloplegic IOL power.<p>RESULTS:ACD after dilation(3.84±0.58mm)significantly increased comparing with ACD before dilation(3.61±0.35mm)in group A(<i>P</i><0.01). ACD after dilation(3.30±0.70mm)also significantly increased comparing with ACD before dilation(3.13±0.63mm)in group B(<i>P</i><0.01). But the difference of pre- and post-cycloplegic ACD between the two groups was not statistically significant(<i>P</i>>0.05). Pre- and post-cycloplegic AL and K(including K1 and K2)were not significantly different in two groups(<i>P</i>>0.05). The differences between pre- and post-cycloplegic IOL power were not statistically significant using the SRK-T and Haigis formula(<i>P</i>>0.05), but the IOL power changed by over 1D after pupil dilation using the SRK-T and Haigis formula respectively in 15% and 27% of eyes in group A,in 3% and 5% in group B.<p>CONCLUSION:ACD increases after pupil dilation in cataract patients with high myopia, which is not different from cataract patients with normal AL. Pupil dilation does not affect AL, K and the IOL power(using SRK-T and Haigis)in cataract patients with high myopia. But the IOL power may change greater than in cataract patients with normal AL, so we suggest IOL power should be measured and calculated without mydriasis.
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Purpose: To prospectively evaluate the biometric changes in Indian pediatric cataract and postoperative refractive status. Methods: A total of 147 patients were recruited into three groups: age <6 months, age between 7 months and 18 months, and age between 19 and 60 months and prospectively observed for 6 months. Exclusion criteria were preterm birth, microphthalmia, microcornea, megalocornea, uveitis, glaucoma, and traumatic or complicated cataract. Axial length and keratometry, the primary outcome measures, were taken preoperatively under general anesthesia before surgery. These children were followed up for 6 months to look for refractive and biometric changes. T-test and linear regression with the logarithm of independent variables were done. Results: All unilateral cataractous eyes (n = 25) and randomly selected bilateral cases (n = 122) were included in the analysis, for a total of 147 eyes. Mean age was 17.163 ± 13.024 months; axial length growth was 0.21, 0.18, 0.06 mm/month, and keratometry decline was 0.083, 0.035, 0.001 D/month in age groups 0–6, 7–18, and 19–60 months, respectively. The visual acuity improved in log MAR from 1.020 to 0.745 at 6 months postoperatively. There was statistically significant (Spearman's correlation coefficient = –0.575, P < 0.001) between age and postoperative refraction. There were no intraocular lens (IOL)-related complications seen in the immediate postoperative period. Peripheral opacification was seen in 102 eyes and central opacification in 1 eye at a 6-month follow-up. Conclusion: Indian eyes have a lower rate of axial length growth and keratometry change in comparison with western eyes implying smaller undercorrection in emmetropic IOL power for Indian pediatric eyes to achieve a moderate amount of hyperopia.
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Purpose: Our study was conducted to evaluate and compare the accuracy of the refractive prediction determined by the calculation formulas for different intraocular lens (IOL) powers for high myopia. Methods: This study reviewed 217 eyes from 135 patients who had received cataract aspiration treatment and IOL implantation. The refractive mean numerical error (MNE) and mean absolute error (MAE) of the IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) were examined and compared. The MNE and MAE at different axial lengths (AL) were compared, and the percentage of every refractive error absolute value for each formula was calculated at ±0.25D, ±0.50D, ±1.00D, and ±2.00D. Results: In all, 98 patients were recruited into this study and 98 eyes of them were analyzed. We found that Barrett Universal II formula had the lowest MNE and MAE, SRK/T and Haigis formulas arrived at similar MNE and MAE, and the MNE and MAE calculated by Holladay and Hoffer Q formula were the highest. Barrett Universal II formulas have the lowest MAE among different AL patients, whereas it reached the highest percentage of refractive error absolute value within 0.5D in this study. The MAE of each formula is positively correlated with AL. Conclusion: Barrett Universal II formula rendered the lowest predictive error compared with SRK/T, Haigis, Holladay, and Hoffer Q formulas. Thus, Barrett Universal II formula may be regarded as a more reliable formula for high myopia.
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Objetivo: evaluar la aplicación de un factor corrección en el cálculo del lente intraocular en pacientes con cámara anterior estrecha y grosor del cristalino aumentado. Métodos: se realizó un estudio experimental donde se aplicó un factor de corrección y se comparó con dos grupos de control. Resultados: predominó el sexo femenino con el 71 por ciento de los casos. La edad fue de 70 años y más. El 48,4 por ciento de los pacientes presentó una esfera posoperatoria entre ± 0,50 dioptrías; el 19,4 por ciento estuvo por debajo de -0,50 dioptrías y el 32,3 por ciento de los pacientes por encima de + 0,50 dioptrías. El grupo 3 (grosor del cristalino mayor que 4,60 mm si factor de corrección) tuvo el mayor porcentaje de esfera posoperatoria ± 0,50 dioptrías (58,3 por ciento). El grupo 2 tuvo el mayor porcentaje de pacientes con esfera obtenida mayor de 0,50 dioptrías (38,2 por ciento). Conclusiones: los pacientes a quienes se les aplica el factor de corrección obtienen una esfera posoperatoria cercana a la emetropía a pesar de que la muestra no es homogénea y no se obtienen esferas por encima de 1 dioptría(AU)
Objective: Evaluate the application of a correction factor for intraocular lens power calculation in patients with a narrow anterior chamber and augmented crystalline lens thickness. Methods: An experimental study was conducted in which a correction factor was applied and compared with two control groups. Results: Female sex prevailed with 71 percent of the cases. Age was 70 years and over. 48.4 percent of the patients had a postoperative sphere between ± 0.50 diopters; 19.4 percent were below - 0.50 diopters and 32.3 percent were above + 0.50 diopters. Group 3 (crystalline lens thickness above 4.60 mm without correction factor) had the highest postoperative sphere percentage of ± 0.50 diopters (58.3 percent). Group 2 had the highest percentage of patients with an achieved sphere above 0.50 diopters (38.2 percent). Conclusions: Patients to whom the correction factor was applied achieved a postoperative sphere close to emmetropia, despite the fact that the sample was not homogeneous and spheres above 1 diopter were not obtained(AU)
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Humans , Female , Aged , Lenses, Intraocular/adverse effectsABSTRACT
Background: Global advances in ophthalmology have created a greater need for ocular parameters in differentclinical and diagnostic fields. One important ophthalmic parameter is the curvature of cornea which is commonlyneeded for intraocular lens power calculation before cataract and refractive surgery and helps ophthalmologistsin contact lens fitting, diagnosis of several eye conditions such as keratoconus, keratoglobus and Marfan’ssyndrome.Subjects and Methods: The data for the study were retrospectively collected from the case files of patients whohad undergone cataract surgery from January 2017 to July 2017 in a private eye hospital Raipur, Chhattisgarh.The data collected were horizontal & Vertical curvature of cornea which was done by manual keratometer forcalculating intraocular lens power (after applying various formulas) to be implanted during cataract surgery.Then by using various statistical methods the results were interpreted.Results: The total number of patients taken for the study were 600 and the total number of eyes were 600, out ofwhich 300 (50%) were males and 300 (50%) females, with the age ranging from 45 to 80 years. The mean cornealrefractive power for the total sample were K1 (vertically) 44.18±1.89D, K2 (horizontally) 44.74± 1.88D, rangesfrom 39 D to 51 D. Although corneal refractive power was slightly higher in female as compared to male but thedifference was not significant. The values were almost similar in right and left eyes.Conclusion: The analysis might provide normative data for curvature of cornea required for IOL calculation incataract patients of Chhattisgarh region. Data of the range will be useful as reference values in case the surgeryis to be done at high volumes in surgical camps in rural areas where biometry equipment may not be available.There were no significant differences noted between male and female, right and left eyes in central Indianpopulation.
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Se estima que aproximadamente un millón o más de pacientes se realizan cirugía refractiva al año. Es por eso que con el envejecimiento son cada día más frecuentes los pacientes con catarata, a quienes previamente se les ha efectuado cirugía refractiva. El cálculo inexacto de la potencia dióptrica de la lente a implantar en la intervención de estos es también un problema de importancia creciente y con él la sorpresa refractiva. Este es mucho más complejo de lo normal, ya que existen dos fuentes de error: la incorrecta predicción de la posición efectiva de la lente por parte de la fórmula y la determinación errónea de la potencia de la córnea por parte de la queratometría. La corrección de estos dos factores permitirá realizar un cálculo correcto en estos ojos. De ahí la motivación para realizar una búsqueda actualizadas de los últimos diez años de diversos artículos publicados, con el objetivo de describir los principios para el cálculo de la lente intraocular tras cirugía refractiva corneal. Se utilizó la plataforma Infomed, específicamente la Biblioteca Virtual de Salud, con todos sus buscadores(AU)
It is considered that approximately one million or more patients undergo refractive surgery every year. Due to aging, the number of patients with cataract, who had previously undergone refractive surgery, is increasingly higher. The inaccurate calculation of the dioptric power of the lens to be implanted is also a growing significant problem and thus the refractive surprise. This is a much more complex situation since two error sources exist: the incorrect prediction of the effective position of the lens based on the formula and the wrong determination of the corneal power through keratometry. The correction of these two factors will allow making a suitable power calculation. Hence the motivation for updated search of several articles published in the last ten years, with the objective of describing the principles for intraocular lens power calculation after corneal refractive surgery. The Infomed platform, mainly the Virtual Library of Health, was fully used(AU)
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Humans , Keratectomy, Subepithelial, Laser-Assisted/methods , Lenses, Intraocular/statistics & numerical data , Refractive Surgical Procedures/methods , Electronic Data Processing/statistics & numerical dataABSTRACT
Abstract?AIM: To investigate the effect of pupillary dilation on intraocular lens power calculation.?METHODS: This prospective study included 52 eyes of 45 patients diagnosed with cataract and indicated for phacoemulsification with intraocular lens ( IOL ) implantation at the Faculty of Medicine of Mersin University. For each patient, preoperative corneal topography, autokeratometric measurements and biometric measurements were performed before and after pupil dilation.?RESULTS: Kh ( horizontal ) values obtained through autokeratometry and anterior chamber depth measured by biometric ultrasonography were significantly greater when pupils were dilated compared with values obtained when pupils were undilated. Implanting IOLs with power calculated using measurements taken during pupillary dilation resulted in a significantly higher rate of emmetropia. Comparison of emmetropic eyes and ametropic eyes showed significantly larger anterior chamber depth in emmetropic eyes.? CONCLUSION: Keratometric and biometric measurements are more important in IOL power calculation than the formula used. If biometric ultrasonography is performed using contact technique, care must be taken to avoid corneal compression. Anterior chamber depth should be followed during measurement, and the margin of error can be minimized by using the highest value obtained in IOL power calculation.
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?AIM: To evaluate the refractive predictability achieved with an aspheric intraocular lens ( IOL ) and to develop a preliminary optimized algorithm for the calculation of its power ( PIOL ) .?METHODS:This study included 65 eyes implanted with the aspheric IOL LENTIS L-313 ( Oculentis GmbH ) that were divided into 2 groups:12 eyes (8 patients) with PIOL≥23. 0 D (group A), and 53 eyes (35 patients) with PIOL<23. 0 D ( group B ). The refractive predictability was evaluated at 3mo postoperatively. An adjusted IOL power ( PIOLadj ) was calculated considering a variable refractive index for corneal power estimation, the refractive outcome obtained, and an adjusted effective lens position ( ELPadj ) according to age and anatomical factors.?RESULTS: Postoperative spherical equivalent ranged from -0. 75 to +0. 75 D and from -1. 38 to +0. 75 D in groups A and B, respectively. No statistically significant differences were found in groups A (P=0. 64) and B (P=0. 82 ) between PIOLadj and the IOL power implanted ( PIOLReal ) . The Bland and Altman analysis showed ranges of agreement between PIOLadj and PIOLReal of +1. 11 to -0. 96 D and +1. 14 to -1. 18 D in groups A and B, respectively. Clinically and statistically significant differences were found between PIOLadj and PIOL obtained with Hoffer Q and Holladay I formulas (P<0. 01).?CONCLUSION: The refractive predictability of cataract surgery with implantation of an aspheric IOL can be optimized using paraxial optics combined with linear algorithms to minimize the error associated to the estimation of corneal power and ELP.
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Background The incidence of dry eye is gradually increasing,and the aging of population is one of factors.Researches showed that the change of tear film stability leads to shift of corneal refractive power, which probably affects the measurement of intraocular lens (IOL) power.The influence of dry eye on the calculation of IOL power is worth paying close attention.Objective This study was to investigate the influence of dry eye on the accuracy of IOL power calculation in age-related cataractous patients.Methods A non-randomized controlled clinical study was performed.Two hundred and sixteen eyes of 216 cataract patients were enrolled in Yanbian Eye Ear Nose and Throat Hospital from May 2013 to February 2014.The visual acuity, intraocular pressure, break up time of tear film (BUT),Schirmer Ⅰ test (S] t) and corneal fluorescein staining were examined in all the eyes,and then the patients were assigned to mild dry eye group (73 eyes), severe dry eye group (68 eyes) and non-dry eye control group (75 eyes).The axial length (AL) and anterior chamber depth (ACD) were measured using IOL Master for the calculation of IOL power and K value (corneal curvature).Phacoemulsification with IOL implantation was performed on all the eyes,and the refractive power was measured with KR 8100 automatic optometry 2 months after operation.The mean absolute refractive error (MARE) between actual refraction and predicted refraction was calculated, and percentage of eyes in different refractive error ranges was compared between the dry eye group and non-dry eye control group.The correlations of dry eye-related parameters with peroperative K value and refractive error were analyzed.This study was approved by the Ethics of Yanbian University,and written informed consent was obtained from each subject prior to entering the cohort.Results No significant differences were found in age, gender, AL,ACD and MARE among the mild dry eye group,severe dry eye group and non-dry eye control group (all at P＞0.05), and significant differences in BUT,S Ⅰ t and corneal fluorescein staining scores were found among these three groups (F=5.460,4.521,3.572, all at P＜0.05).The K values were (43.59± 1.39) , (44.66± 1.53) and (43.42± 1.32) D in the mild dry eye group,severe dry eye group and non-dry eye control group,and the K value in the severe dry eye group was significantly higher than that in the non-dry eye control group (P =0.012).The percentage of eyes with +0.50-+0.75 D deviation was significantly elevated(28.8％ versus 13.3％), and that with-0.50--0.75 D deviation was significantly declined (17.3％ versus 28.0％) in the dry eye group compared with non-dry eye control group (x2 =4.513 ,P=0.032;x2 =4.236,P=0.037).A negative correlation was found between BUT and K value (r=-0.204,P=0.011).Conclusions Dry eye affects the accuracy of the determination of IOL power.Compared with the preoperative refraction predictive value,the postoperative refraction shift toward hyperopia.
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PURPOSE: To compare the accuracy of different power-calculation formulas in predicting the postoperative refraction of three-piece and one-piece intraocular lenses (IOL). METHODS: We retrospectively reviewed the medical records of 74 eyes (62 patients) that had undergone cataract surgery involving implantation of one of two IOLs―the SENSAR® AAB00 1-Piece Acrylic IOL (44 eyes), or the Hoya® VA60BB 3-Piece Acrylic IOL (30 eyes)―between October 2014 and March 2015. Axial length was measured using an optical low-coherence refractometry (Lenstar®), and biometry was then calculated by the pre-installed Lenstar program, which used the SRK/II, Sanders-Retzlaff-Kraff/Theoretical (SRK/T), and Hoffer Q formulas. Mean absolute error (MAE) and mean numeric error (MNE) were measured 1 day, 1 week, 1 month, and 2 months after surgery. RESULTS: Using the SRK/T and Hoffer Q formulas, the one-piece IOL group differed significantly from the three-piece IOL group in terms of the MNE obtained 1 month and 2 months after surgery. Across all formulas and time points, there were no significant differences between the groups in terms of MAE. CONCLUSIONS: There was no significant difference between the different power-calculation formulas. Starting 1 month after surgery, the three-piece IOL group showed myopic postoperative refraction compared to the predictive spherical equivalent using the SRK/T and Hoffer Q formulas.
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Biometry , Cataract , Lenses, Intraocular , Medical Records , Refractometry , Retrospective StudiesABSTRACT
PURPOSE: To investigate the accuracy of intraocular lens power calculations using simulated keratometry (simK) of dual Scheimpflug analyzer and 5 types of formulas in cataract patients. METHODS: The keratometry (K), axial length (AXL) and anterior chamber depth (ACD) were measured using ultrasound biometry (USB) combined with auto-keratometry (Auto-K), parital coherence interferometry (PCI; IOL master®) and dual Scheimpflug analyzer (DSA; Galilei®) in 39 eyes of 39 patients. Predicted refraction was calculated using Auto-K, mean K of PCI, and simK and total corneal power (TCP) of DSA in the Sanders-Retzlaff-Kraff (SRK-T) formula. The SRK-II, SRK-T, Holladay II, Haigis, and Hoffer-Q formula were used to calculate predicted refraction with the simK of DSA and AXL of USB. Manifest refraction, mean numerical error (MNE) and mean absolute error were evaluated 1, 3 and 6 months after cataract surgery. RESULTS: TCP of DSA was lower compared with other keratometric values (p < 0.05). The MNE was not different among Auto-K, mean K and simK. The MNE using TCP was larger compared with Auto-K, mean K and simK at 1 month after surgery (p < 0.05). There was a difference in MNE between simK and TCP of DSA at 6 months after surgery (p < 0.05). The MNE of SRK-T formula was the smallest in the intraocular lens (IOL) power calculation using the simK of DSA. CONCLUSIONS: We suggest using IOL power calculations with simK of DSA and SRK-T formula rather than TCP of DSA in cataract patients with normal corneas.
Subject(s)
Humans , Anterior Chamber , Biometry , Cataract , Cornea , Interferometry , Lenses, Intraocular , UltrasonographyABSTRACT
PURPOSE: To investigate the feasibility of estimating effective lens position (ELP) and calculating intraocular lens power using corneal height (CH), as measured using anterior segment optical coherence tomography (AS-OCT), in patients who have undergone corneal refractive surgery. METHODS: This study included 23 patients (30 eyes) who have undergone myopic corneal refractive surgery and subsequent successful cataract surgery. The CH was measured with AS-OCT, and the measured ELP (ELP(m)) was calculated. Intraocular lens power, which could achieve actual emmetropia (P(real)), was determined with medical records. Estimated ELP (ELP(est)) was back-calculated using P(real), axial length, and keratometric value through the SRK/T formula. After searching the best-fit regression formula between ELP(m) and ELP(est), converted ELP and intraocular lens power (ELP(conv), P(conv)) were obtained and then compared to ELP(est) and P(real), respectively. The proportion of eyes within a defined error was investigated. RESULTS: Mean CH, ELP(est), and ELP(m) were 3.71 +/- 0.23, 7.74 +/- 1.09, 5.78 +/- 0.26 mm, respectively. The ELP(m) and ELP(est) were linearly correlated (ELP(est) = 1.841 x ELP(m) - 2.018, p = 0.023, R = 0.410) and ELP(conv) and P(conv) agreed well with ELP(est) and P(real), respectively. Eyes within +/-0.5, +/-1.0, +/-1.5, and +/-2.0 diopters of the calculated P(conv), were 23.3%, 66.6%, 83.3%, and 100.0%, respectively. CONCLUSIONS: Intraocular lens power calculation using CH measured with AS-OCT shows comparable accuracy to several conventional methods in eyes following corneal refractive surgery.
Subject(s)
Humans , Male , Middle Aged , Axial Length, Eye/pathology , Cornea/pathology , Lenses, Intraocular , Refractive Surgical Procedures , Retrospective Studies , Tomography, Optical , Tomography, Optical CoherenceABSTRACT
PURPOSE: To investigate the feasibility of estimating effective lens position (ELP) and calculating intraocular lens power using corneal height (CH), as measured using anterior segment optical coherence tomography (AS-OCT), in patients who have undergone corneal refractive surgery. METHODS: This study included 23 patients (30 eyes) who have undergone myopic corneal refractive surgery and subsequent successful cataract surgery. The CH was measured with AS-OCT, and the measured ELP (ELP(m)) was calculated. Intraocular lens power, which could achieve actual emmetropia (P(real)), was determined with medical records. Estimated ELP (ELP(est)) was back-calculated using P(real), axial length, and keratometric value through the SRK/T formula. After searching the best-fit regression formula between ELP(m) and ELP(est), converted ELP and intraocular lens power (ELP(conv), P(conv)) were obtained and then compared to ELP(est) and P(real), respectively. The proportion of eyes within a defined error was investigated. RESULTS: Mean CH, ELP(est), and ELP(m) were 3.71 +/- 0.23, 7.74 +/- 1.09, 5.78 +/- 0.26 mm, respectively. The ELP(m) and ELP(est) were linearly correlated (ELP(est) = 1.841 x ELP(m) - 2.018, p = 0.023, R = 0.410) and ELP(conv) and P(conv) agreed well with ELP(est) and P(real), respectively. Eyes within +/-0.5, +/-1.0, +/-1.5, and +/-2.0 diopters of the calculated P(conv), were 23.3%, 66.6%, 83.3%, and 100.0%, respectively. CONCLUSIONS: Intraocular lens power calculation using CH measured with AS-OCT shows comparable accuracy to several conventional methods in eyes following corneal refractive surgery.