A Comparative Study of Eight Intraocular Lens Calculation Formulas

Ascaso, Francisco J.; Castillo, José Manuel Benítez del; Cristobal, Ja; Minguez, E; Palomar, Alejandro Palomar

doi:10.1159/000310241

Cited by 5 publications

(10 citation statements)

References 8 publications

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“…The difference between the predicted refractive error and the ultimate result lies within the accepted standard which is 5% >2 D and 25-30% >1 D [3,4]. The calculation of IOL power using the Colenbrander formula results in refractive errors, predominantly in eyes with shorter axial lengths.…”

Section: Discussionmentioning

confidence: 52%

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Astigmatism and visual recovery after phacoemulsification and conventional extracapsular cataract extraction

et al. 1995

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Abstract. In this study we wanted to investigate the post-operative astigmatism and visual acuity after phacoemulsification and conventional extracapsular cataract surgery. Patients operated between April and June 1993 (n=150) were retrospectively analyzed. The patients were examined prior to surgery and at day 1, at day 10, and in week 6 post-operatively. The difference between the post-operative log mean visual acuity in the Phaco group and in the CECCE group was significant after 1 and 10 days, however it was not significant (/)=0.191) after 6 weeks. The mean astigmatism was significantly less in the Phaco group than in the CECCE group during the whole post-operative check-up period. This study suggests that Phaco results in a lower post-operative astigmatism and an earlier visual rehabilitation compared to the CECCE technique.Abbreviations: Phaco-Phacoemulsification; CECCE-Conventional extracapsular cataract extraction. I n t r o d u c t i o nWith the introduction of small-incision cataract extraction with phacoemulsification, it was suggested that patients had a shorter post-operative recovery of the visual acuity and post-operative astigmatism using this technique [ 1, 2].In this study, the described advantage of the small incision cataract extraction with the phacoemulsification was assessed by comparing the visual rehabilitation and post-operative astigmatism in a group of cataract patients operated with the CECCE technique with a group of patients operated with Phaco.Secondly, with the use of echographic biometry of the operated eye, an emmetropizing intraocular lens can be planned [3,4]. Analysis of systematic errors in ultrasonic biometry results in a 25 to 30% post-operative refractive

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Section: Discussionmentioning

confidence: 52%

“…Secondly, with the use of echographic biometry of the operated eye, an emmetropizing intraocular lens can be planned [3,4]. Analysis of systematic errors in ultrasonic biometry results in a 25 to 30% post-operative refractive…”

Section: Introductionmentioning

confidence: 99%

Astigmatism and visual recovery after phacoemulsification and conventional extracapsular cataract extraction

et al. 1995

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“…Several studies have been published to compare the accuracy of the IOL power formulas available today [15,17,18,19]. In this study, we present the differences in the predictive value of six different IOL power formulas of five lens types implanted in a given time period.…”

Section: Discussionmentioning

confidence: 98%

A Retrospective Analysis of Five Intra-Ocular Lenses and the Predictive Value of Six Different Intra-Ocular Lens Power Calculation Formulas

Zuidervaart¹,

Luyten

2005

Ophthalmologica

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Purpose: To evaluate the refractive and visual outcome after implantation of five different lenses and to evaluate the accuracy of six different intra-ocular lens (IOL) power formulas. Setting: Department of Ophthalmology, University Medical Centre Rotterdam, The Netherlands. Methods: In total, 288 eyes had cataract surgery with implantation of a polymethylmethacrylate lens (Centra55B) or a foldable silicone lens (AMO SI40, Staar AA, Silens 5, Pliolens). The pre- and postoperative refraction and visual outcome were analysed for all lenses under study. Six different IOL power formulas have been used to compare the accuracy of the predictive refractive outcome. Results: The Staar Plate Haptic lens was found to have the best uncorrected visual acuity (UCVA) compared to the Centra55B, AMO SI40 and the Pliolens. Based on the A constant given by the company, the Pliolens revealed a significant overcorrection and the Staar Plate Haptic lens an undercorrection. The achieved postoperative refraction minus the intended postoperative refraction caused significant myopia with the Pliolens and hyperopia with the Staar Plate Haptic lens. The SRK-T and the Holladay formulas give the best predictive lens calculations in relation to the axial length. Conclusion: The A constant of all lenses has to be adjusted for our institute. Especially the AMO SI40, the Staar AA lens and the Silens 5 showed a remarkable difference compared to the A constant given by the company. All foldable lenses were comparable in their visual outcome. The significantly better UCVA of the Staar Plate Haptic lens can be explained by the emmetropic outcome of the postoperative refraction.

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“…Contrary to many earlier studies (Singh et al 1987;Hope-Ross & Mooney 1988;Ascaso et al 1991), only one type of IOL was used in the present study, thus eliminating different IOL design as a possible source of error in the comparison between the different IOL calculation formulas. Contrary to many earlier studies (Singh et al 1987;Hope-Ross & Mooney 1988;Ascaso et al 1991), only one type of IOL was used in the present study, thus eliminating different IOL design as a possible source of error in the comparison between the different IOL calculation formulas.…”

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confidence: 91%

The refractive error after implantation of a posterior chamber intraocular lens

Høvding

Natvik

Sletteberg

1994

Acta Ophthalmologica

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The study included 188 patients, in which a posterior chamber intraocular lens was implanted after extracapsular cataract extraction. After modifications of the intraocular lens constants (SRK formula and SRK II formula) and correction of the axial length measurements (Colenbrander-Hoffer formula) had been made, the mean differences between the actual postoperative spherical equivalent and that predicted by the three formulas were -0.23D, -0.22D and -0.46D, respectively. More than +/-1.0D deviation from the predicted postoperative refraction occurred in about one-third of the cases. Inter-observed discrepancy regarding the accuracy of the preoperative measurement of the ocular axis length is suggested to be the main cause of unpredicted postoperative refractive errors.

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A Comparative Study of Eight Intraocular Lens Calculation Formulas

Cited by 5 publications

References 8 publications

Astigmatism and visual recovery after phacoemulsification and conventional extracapsular cataract extraction

Astigmatism and visual recovery after phacoemulsification and conventional extracapsular cataract extraction

A Retrospective Analysis of Five Intra-Ocular Lenses and the Predictive Value of Six Different Intra-Ocular Lens Power Calculation Formulas

The refractive error after implantation of a posterior chamber intraocular lens

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