scholarly journals Prevalence of variation in predicted refraction between different intraocular lens formulae

2018 ◽  
Vol 16 (2) ◽  
pp. 60-61
Author(s):  
Keith Ong ◽  
Linda Feng
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Iol Calculation ◽  
Iol Power ◽  
Refractive Surprise ◽  
Iol Calculation Formulae

Variations of 0.5 D in predicted refraction between the different intraocular lens (IOL) calculation formulae may occur in 19.4% cases. This has implications when reporting refractive surprise. It also shows that it is beneficial to consider more than one IOL formula when choosing IOL power for cataract surgery.  

scholarly journals Improved accuracy of intraocular lens power calculation by preoperative management of dry eye disease

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jinsoo Kim ◽  
Mee Kum Kim ◽  
Yuseung Ha ◽  
Hae Jung Paik ◽  
Dong Hyun Kim
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Dry Eye ◽  
Dry Eye Disease ◽  
Eye Disease ◽  
Power Calculation ◽  
Power Prediction ◽  
Loteprednol Etabonate ◽  
Iol Power ◽  
Refractive Surprise

Abstract Background To evaluate the effects of pretreatment for dry eye disease (DED) on the accuracy of intraocular lens (IOL) power calculation. Methods Patients who underwent uneventful cataract surgery were included in the study. IOL power was determined using the SRK/T and Barrett Universal II (Barrett) formulas. The patients were divided into non-pretreatment and pretreatment groups, and those in the pretreatment group were treated with topical 0.5% loteprednol etabonate and 0.05% cyclosporin A for 2 weeks prior to cataract surgery. Ocular biometry was performed in all groups within 2 days before surgery. The mean prediction error, mean absolute error (MAE), and proportions of refractive surprise were compared between the non-pretreatment and pretreatment groups at 1 month postoperatively. Refractive surprise was defined as MAE ≥ 0.75D. Results In a total of 105 patients, 52 (52 eyes) were in the non-pretreatment group and 53 (53 eyes) in the pretreatment group. The MAE was 0.42 ± 0.33, 0.38 ± 0.34 (SRK/T, Barrett) and 0.23 ± 0.19, 0.24 ± 0.19 in the non-pretreatment and pretreatment groups, respectively (p < 0.001/=0.008). The number of refractive surprises was also significantly lower in the pretreatment group. [non-pretreatment/pretreatment: 9/2 (SRK/T); 8/1 (Barrett); p = 0.024/0.016]. Pretreatment of DED was related to a reduction in postoperative refractive surprise. [SRK/T/Barrett: OR = 0.18/0.17 (95% CI: 0.05–0.71/0.05–0.60), p = 0.014/0.006]. Conclusions The accuracy of IOL power prediction can be increased by actively treating DED prior to cataract surgery.

scholarly journals Cataract Surgery following Sequential Myopic and Hyperopic LASIK

2018 ◽  
Vol 9 (2) ◽  
pp. 264-268
Author(s):  
Tao Ming Thomas Chia ◽  
Hoon C. Jung
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Calculation Method ◽  
Cataract Extraction ◽  
Power Calculation ◽  
Iol Implantation ◽  
Patient Dissatisfaction ◽  
Iol Power Calculation ◽  
Iol Power

We report a case of patient dissatisfaction after sequential myopic and hyperopic LASIK in the same eye. We discuss the course of management for this patient involving eventual cataract extraction and intraocular lens (IOL) implantation with attention to the IOL power calculation method used.

scholarly journals Improving Intraocular Lens Calculation in Fuchs Endothelial Dystrophy According To Preoperative Degree of Corneal Edema

2021 ◽  
Author(s):  
Beatriz Gargallo-Martinez ◽  
Amanda Ortiz-Gomariz ◽  
Ana Maria Gomez-Ramirez ◽  
Angel Ramon Gutiérrez-Ortega ◽  
Jose Javier Garcia-Medina
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Refractive Error ◽  
Target Selection ◽  
Corneal Transplantation ◽  
Corneal Edema ◽  
Power Calculation ◽  
Iol Power Calculation ◽  
Iol Power ◽  
Fuchs Endothelial Dystrophy

Abstract Fuchs endothelial dystrophy (FED) is a bilateral, asymmetric, progressive corneal endothelium disorder that causes corneal edema. Resolution of corneal edema is only possible by corneal transplantation. Cataract surgery is a common surgery that replaces the natural lens of the eye by an artificial intraocular lens (IOL). The IOL-power calculation depends mainly on the anterior corneal keratometry and the axial length. In patients with FED, anterior keratometry may be affected by corneal edema and calculations may be less accurate. Therefore, the aim of this study is to establish the theorical postoperative refractive error due to corneal edema resolution after Descemet stripping endothelial keratoplasty combined with cataract surgery and IOL implantation. For this, anterior keratometry was measure preoperatively with edematous cornea and postoperatively after corneal edema resolution. Both keratometries were compared and used to calculate the respective theorical IOL-powers. The difference between target IOLs was used to establish the theorical refractive error due to corneal edema resolution. The results showed that corneal edema resolution induces a change in anterior keratometry, which affects IOL-power calculations and causes a hyperopic shift. The patients with moderate-to-severe preoperative corneal edema had higher theorical refractive error so their target selection should be adjusted for additional − 0.50D.

scholarly journals Improving the prediction of effective lens position for intraocular lens power calculations

2020 ◽  
Vol 17 (2) ◽  
pp. 233-242
Author(s):  
Juanita Noeline Chui ◽  
Keith Ong
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Sagittal Plane ◽  
Anterior Chamber Depth ◽  
Posterior Chamber ◽  
Power Calculation ◽  
Iol Power Calculation ◽  
Lens Position ◽  
Iol Power ◽  
Corneal Apex

Purpose: Achieving the desired post-operative refraction in cataract surgery requires accurate calculations for intraocular lens (IOL) power. Latest-generation formulae use anterior-chamber depth (ACD)—the distance from the corneal apex to the anterior surface of the lens—as one of the parameters to predict the post-operative IOL position within the eye, termed the effective lens position (ELP). Significant discrepancies between predicted and actual ELP result in refractive surprise. This study aims to improve the predictability of ELP. We hypothesise that predictions based on the distance from the corneal apex to the mid-sagittal plane of the cataractous lens would more accurately reflect the position of the principal plane of the non-angulated IOL within the capsular bag. Accordingly, we propose that predictions derived from ACD + ½LT (length thickness) would be superior to those from ACD alone. Design: Retrospective cohort study, comparing ELP predictions derived from ACD to aproposed prediction parameter. Method: This retrospective study includes data from 162 consecutive cataract surgery cases, with posterior-chamber IOL (AlconSN60WF) implantation. Pre- and postoperative biometric measurements were made using the IOLMaster700 (ZEISS, Jena, Germany). The accuracy and reliability of ELP predictions derived from ACD and ACD + ½LT were compared using software-aided analyses. Results: An overall reduction in average ELP prediction error (PEELP) was achieved using the proposed parameter (root-mean-square-error [RMSE] = 0.50 mm), compared to ACD (RMSE = 1.57 mm). The mean percentage PEELP, comparing between eyes of different axial lengths, was 9.88% ± 3.48% and −34.9% ± 4.79% for predictions derived from ACD + ½LT and ACD, respectively. A 44.10% ± 5.22% mean of differences was observed (p < 0.001). Conclusion: ACD + ½LT predicts ELP with greater accuracy and reliability than ACD alone; its use in IOL power calculation formulae may improve refractive outcomes.

scholarly journals Comparison of intraocular lens power calculation results before and after glaucoma surgery

2020 ◽  
Vol 13 (4) ◽  
pp. 15-20
Author(s):  
Dmitrii Fedorovich Belov ◽  
Vadim Petrovich Nikolaenko
Keyword(s):  
Intraocular Lens ◽  
Anterior Chamber Depth ◽  
Glaucoma Surgery ◽  
Power Calculation ◽  
Ahmed Glaucoma Valve ◽  
Iol Power Calculation ◽  
Iol Calculation ◽  
Before And After ◽  
Iol Power ◽  
Target Refraction

Aim to compare intraocular lens (IOL) power calculation before and after different types glaucoma procedures. Material and methods.Into the study, 115 patients were included, divided into 3 groups: group 1 patients, in whom sinustrabeculectomy was performed (n= 86); group 2 patients with implanted Ex-PRESS shunt (n= 19), group 3 patients after Ahmed glaucoma valve implantation (n= 10). For each patient before surgery optical biometry (IOL-Master 500) was performed and IOL power calculation using Barrett Universal II Formula (target refraction emmetropia). Baseline data were compared with corresponding examinations results obtained in 6 months after glaucoma procedure, to evaluate its effect on main biometric parameters of the eye and the IOL calculation accuracy. Results.Despite significant changes of optical and anatomic indices, mean values of target refraction before and after glaucoma surgery did not differ significantly: 0.00 0.03 versus 0.03 0.52 D (p= 0.628), 0.00 0.1 versus 0.19 0.61 D (p= 0.173), 0.04 0.08 versus 0.11 0.42 D (p= 0.269) for groups, respectively. However, there was a pronounced trend to the increase of target refraction data scattering. Conclusion.Glaucoma procedures cause changes of biometrical parameters of the eye, which leads to decrease in accuracy of IOL calculation. Consequently, when choosing intraocular lens, it is recommended to use measurement results obtained after glaucoma surgery. Keywords:intraocular lens; IOL power calculation; glaucoma; sinustrabeculectomy; Ex-PRESS shunt; Ahmed glaucoma valve; biometry; phacoemulsification; axial length; anterior chamber depth; keratometry.

scholarly journals Congenital and developmental cataract surgery with undercorrected Intraocular lens (IOL) power implantation targeting emmetropia at 8 years of age and post-operative refractive status

2021 ◽  
Vol 12 (9) ◽  
pp. 126-129
Author(s):  
Kabindra Bajracharya ◽  
Anjita Hirachan ◽  
Kriti Joshi ◽  
Bimala Bajracharya
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Axial Length ◽  
Iol Implantation ◽  
Refractive Status ◽  
Developmental Cataract ◽  
Iol Power ◽  
The Mean ◽  
One Year

Background: In congenital and developmental cataract primary undercorrection of intraocular lens (IOL) power is a common practice. However, long-term refractive status of these children is largely unknown. Aims and Objective: To analyse refractive status after cataract surgery with undercorrected IOL power implantation in congenital and developmental cataract. Materials and Methods: This study was descriptive, retrospective conducted for three years from 1st January 2013 to 31st December 2015. The children (> 6 months to <=7 years of age) who underwent cataract surgery for congenital and developmental cataract with a primary IOL implantation and had reached the age of 8 years were studied. The data were collected in terms of demography, axial length, biometry, IOL implanted, hyperopic correction and postoperative refractive status at 8 years. Results: Total numbers of children operated were 181 with total eyes 288. Unilateral cases were 74 (40.88%) and bilateral 107 (59.12%). Male were 121 (66.85%) and female were 60 (33.15%) with male is to female ratio of 2:1. Right eye was involved in 152 (52.8%) and left eye 136 (47.2%). The mean axial length at the age of one year was 20.75 mm, and gradually increased as age increased which was 22.47 mm at 6 years. The mean biometry was 27.9 diopter (D) at the age of one year which gradually decreased as age increased. Of the total 288 congenital cataract operated, complete follow-up documents were available for 77 (26.74%) eyes up to 8 years which showed emmetropia achieved in 25.97%, myopia in 28.57% and hypermetropia in 45.45%. Conclusion: Primary IOL implantation with hyperopic correction is accepted practice in congenital and developmental cataract. Emmetropia can be achieved however some hyperopic or myopic refractive status at the age of 8 years is not a surprise. Myopic shift continues as the age increases. Parent awareness for early detection and surgery, optical correction and regular follow-up are essential for good outcome.

Intraocular Lens Calculation After Refractive Surgery

2012 ◽  
Vol 06 (01) ◽  
pp. 21 ◽  
Author(s):  
Wolfgang Haigis ◽  
Keyword(s):  
Clinical Practice ◽  
Measurement Error ◽  
Intraocular Lens ◽  
Refractive Surgery ◽  
Model Calculations ◽  
Iol Implantation ◽  
Iol Calculation ◽  
Iol Power ◽  
The Individual ◽  
Intraocular Lens Calculation

More and more patients who have had corneo-refractive surgery present for intraocular lens (IOL) implantation. IOL calculation in these patients is still a challenge. After refractive surgery, if eyes are treated as normal eyes, high hyperopic errors can occur in previously myopic eyes and moderate myopic errors in formerly hyperopic eyes. Three main sources for these errors can be identified: the radius measurement error, the keratometer index error and the IOL formula error. The literature presents a confusing variety of procedures and formulas to cope with this situation. An analysis of the available literature reveals the different methods used to address the individual error contributions, the magnitude of which is assessed by model calculations. The most relevant formulas for clinical practice are the no-history procedures, which require no previous patient data. Using these methods to calculate IOL power after refractive surgery makes it possible to obtain clinical outcomes of a similar quality to that for normal eyes.

scholarly journals Comparison of the influence of pupil dilation on predicted postoperative refraction and recommended intraocular lens power among Barrett Universal II, Haigis, and SRK/T calculation formulas: a retrospective study

2019 ◽  
Author(s):  
Takeshi Teshigawara ◽  
Akira Meguro ◽  
Nobuhisa Mizuki
Keyword(s):  
Retrospective Study ◽  
Intraocular Lens ◽  
Significant Positive Correlation ◽  
Anterior Chamber Depth ◽  
Pupil Dilation ◽  
Power Calculation ◽  
Positive Correlation ◽  
Iol Calculation ◽  
Before And After ◽  
Iol Power

Abstract Background We investigated the effect of pupil dilation on predicted postoperative refraction (PPR) and recommended intraocular lens (IOL) power calculated using three different generations of IOL power calculation formulas: Barrett Universal II (Barrett) (new generation), Haigis (4th generation), and SRK/T (3rd generation).Methods This retrospective study included 150 eyes. The following variables were measured and calculated using an optical biometer before and after dilation: anterior chamber depth (ACD), lens thickness (LT), white-to-white (WTW), mean absolute change (MAC) in PPR, and recommended IOL power. PPR and recommended IOL power were calculated by Barrett, Haigis, and SRK/T IOL calculation formulas. Correlations between all changes were analyzed. The influence of pupil dilation on recommended IOL power calculated by each formula was also analyzed.Results MAC in PPR before and after dilation was highest in Barrett, followed by Haigis and SRK/T. Significant differences were found among each MAC. Significant changes were observed before and after dilation in ACD and LT but not in WTW. In Barrett and Haigis, there was a significant positive correlation between change in PPR and change in ACD and a negative correlation between change in PPR and change in LT. Correlations were strongest in Barret followed by Haigis, especially in LT. Change in PPR in Barrett also demonstrated a significant positive correlation with change in WTW. The recommended IOL power using Barrett and Haigis changed before and after dilation in 23.3% and 19.3% cases; SRK/T showed no change.Conclusions In PPR and recommended IOL power, pupil dilation influenced Barrett most strongly, followed by Haigis and SRK/T. Given the stronger correlation between the change in PPR in Barrett and the change in ACD, LT, and WTW, the change of ACD, LT, and WTW is more important to the influence of dilation on Barrett. The influence of dilation on each formula and variables, including ACD, LT, and WTW is key to improving IOL calculation.

scholarly journals A comparison of axial length measurement by using applanation A- Scan and IOL master for accuracy of predicting postoperative refraction

2021 ◽  
Vol 7 (3) ◽  
pp. 477-481
Author(s):  
Harish R Trivedi ◽  
Bhavik C Zala ◽  
Nitesh S Pancholi
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Axial Length ◽  
Length Measurement ◽  
Power Calculation ◽  
Spherical Equivalent ◽  
Significant Difference ◽  
Group A ◽  
Iol Power ◽  
Group B

The higher cost of IOL master is an issue in developing countries and hence it cannot be widely used for calculation of IOL power in such countries. Thus, the aim of the current study is to evaluate a cheaper alternative for the calculation of IOL power by comparing the axial length measurement obtained using applanation A-scan with that of IOL Master for accuracy of predicting postoperative refraction.A prospective, randomized, comparative study was done with 100 patients who were posted for cataract surgery. The patients were randomly divided into two groups of 50 patients each using computerized random number method. In Group A (n=50) axial length was measured with applanation A-scan and in Group B (n=50) axial length was measured with IOL Master. Before cataract surgery keratometry reading was taken with auto keratometer and intraocular lens (IOL) power calculation was done using SRK 2 formula in all patients. All patients were operated for cataract surgery by phacoemulsification and foldable intraocular lens were implanted in the bag. Postoperatively, best accepted refraction at 8th week was taken and mean spherical equivalent was calculated. 100 patients of cataract were subjected for cataract surgery by phacoemulsification.Corrected spherical equivalent on 8th postoperative week showed: 88% patients in Group A and 96% patients of Group B were within ± 1.00 D.56% patients of Group A and 76% patients of Group B were within ± 0.50 D.There was no statistically significant difference (p &#62; 0.05) in axial length and corrected spherical equivalent between the two groups. There is no extra advantage of IOL Master over applanation A-scan for measuring Axial Length between 21 and 24.50 and predicting post-operative refractive outcome.

How to get Accuracy in Intraocular Lens Calculation in Normal and Extreme Cases

2017 ◽  
Vol 11 (01) ◽  
pp. 25
Author(s):  
Noel Alpins ◽  
Keyword(s):  
Intraocular Lens ◽  
Toric Intraocular Lens ◽  
Toric Iol ◽  
Corneal Power ◽  
Iol Calculation ◽  
Refractive Surprise ◽  
Intraocular Lens Calculation

With so many toric intraocular lens (IOL) calculators available online it is important for the doctor to know what is included to improve the accuracy of the toric IOL recommended. Does it allow for long eyes, short eyes, personalised IOL constants, posterior corneal power, and what are the options available after a refractive surprise? There is more to toric IOL calculation than just the question, ‘which is the best formula?’ The calculator features also need to be taken into account.

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