Accuracy of intraocular lens calculation formulas in cataract patients with steep corneal curvature

Accuracy of intraocular lens power formulas in patients with average keratometry greater than 46 diopters

OBJECTIVE

To compare the accuracy of Kane, Barrett Universal II, Haigis, and SRK-T formulas in eyes with average keratometry greater than 46 diopters (D).

METHODS

A retrospective analysis was conducted on 101 eyes of 101 patients with average keratometry greater than 46 D. The absolute prediction error (EA) was obtained for each patient one month after surgery. The mean absolute prediction error (MEA), median absolute prediction error (MedEA) and the percentage of patients with absolute refractive error less than 0.25 D, 0.50 D, and 1.00 D were calculated for each formula analyzed.

RESULTS

The Kane formula achieved the lowest MEA (0.53 ± 0.43) and the lowest MedEA (0.41), followed by Barrett Universal II (MEA: 0.56 ± 0.42, MedEA: 0.49), SRK-T (MEA: 0.59 ± 0.44, MedEA: 0.54), and Haigis (MEA: 0.77 ± 0.47, MedEA: 0.69), showing a significant difference in the results. It was also observed that the Kane formula was the most accurate, with the highest percentage of patients, with EA less than 0.25 D, 0.50 D, and 1.00 D (30.7%, 54.4%, and 86.1%, respectively), while the Haigis formula was the least accurate (12.9%, 33.7%, and 69.3%, respectively).

CONCLUSION

In eyes with corneas having average keratometry greater than 46 D, the Kane formula proves to be a useful tool in intraocular lens (IOL) power calculation and demonstrates higher precision compared to the Barrett Universal II, SRK-T, and Haigis formulas.

Comparison of Hill-RBF 3.0 with Barrett Universal II, SRK/T, Hoffer Q, Haigis, and Holladay 1 to predict the accuracy of post-cataract surgery refractive outcomes in Indian eyes

PURPOSE

To compare Hill-RBF 3.0 with Barrett Universal II (BU II), SRK/T, Hoffer Q, Haigis, and Holladay 1 in predicting the accuracy of post-cataract surgery refractive outcomes in Indian eyes.

METHODS

In this prospective, comparative, observational study, consecutive patients with uncomplicated age-related cataracts undergoing uneventful phacoemulsification with posterior chamber intraocular lens (IOL) implantation were included. The mean absolute errors (MAEs) and median absolute errors were used to determine the accuracy of predicted postoperative target refractions.

RESULTS

A total of 219 eyes of 173 patients were enrolled. Based on the axial lengths (AL), the patients were classified into: AL <22 mm (short), 22-24.5 mm (normal), and >24.5 mm (long). BU II exhibited the lowest MAE for normal ALs (0.2683 ± 0.2790 D) as well as for the entire population (0.2764 ± 0.2764 D). For the short ALs, Hill RBF 3.0 exhibited the lowest MAE (0.3268 ± 0.3268 D), while for the long ALs, SRK/T showed the lowest MAE (0.2823 ± 0.2642 D). BU II exhibited the highest percentage of eyes of 57.5%, 95.4%, and 98.6% within ±0.25, ±0.75, and ±1.0 D of postoperative target refractions respectively, whereas Hill RBF 3.0 had the highest percentages of eyes (88.1%) within ±0.5 D of postoperative target refraction.

CONCLUSION

Hill-RBF 3.0 exhibited the least MAE for patients with short ALs, while BU II showed the least MAE for normal ALs as well as for the entire population and SRK/T for long ALs. This study is likely to aid surgeons in selecting the most appropriate IOL power formula, which thereby improves the refractive outcomes with utmost accuracy.

Effect of capsule treatment on visual acuity and quality after phacoemulsification lens implantation in myopic patients with cataract

BACKGROUND

Cataracts pose a significant clinical burden due to their complex pathogenesis. In recent years, an increase in cataracts coexisting with myopia has heightened the incidence of retinopathy and posterior vitreous detachment. Additionally, symptoms of ocular axis elongation, lens nucleus hardening, and vitreous liquefaction have become more prevalent. While conventional extracapsular cataract extraction is commonly employed, it often yields suboptimal visual outcomes. Subsequent advancements in cataract phacoemulsification and lens implantation surgeries have gained widespread acceptance for their ability to improve refraction and significantly improve uncorrected visual acuity.

AIM

To investigate the effect of capsular treatment after phacoemulsification lens implantation in myopic patients with cataract.

METHODS

We selected 110 patients (with 134 eyes) with myopia and cataracts treated. These patients were categorized into two groups: an observation group (57 patients with 70 eyes) and a control group (53 patients with 64 eyes). The control group underwent cataract phacoemulsification and lens implantation, while the observation group received a refined capsular treatment based on the control group's procedure. We assessed the differences in visual acuity and quality between the two groups before and after surgery.

RESULTS

At six months post-operation, the observation group exhibited significantly improved far vision, intermediate vision, near vision, lower objective scattering index, higher Modulation transfer function cut-off frequency, and overall vision metrics at different contrast levels (100%, 20% and 9%) compared to the control group (P < 0.05). The total score of the National Eye Institute Visual Function Questionnaire in the observation group at 6 months after operation was significantly higher than that in the control group (P < 0.05). No significant difference in the incidence of adverse reactions was observed between the observation group and control group (P > 0.05).

CONCLUSION

Capsular treatment demonstrates efficacy in improving visual acuity and quality after phacoemulsification lens implantation in myopic patients with cataracts, warranting its clinical application.

Current concepts in the management of cataract with keratoconus

This review analyzed all pertinent articles on keratoconus (KCN) and cataract surgery. It covers preoperative planning, intraoperative considerations, and postoperative management, with the aim of providing a simplified overview of treating such patients. Preoperatively, the use of corneal cross-linking, intrastromal corneal ring segments, and topo-guided corneal treatments can help stabilize the cornea and improve the accuracy of biometric measurements. It is important to consider the advantages and disadvantages of traditional techniques such as penetrating keratoplasty and deep anterior lamellar keratoplasty, as well as newer stromal augmentation techniques, to choose the most appropriate surgical approach. Obtaining reliable measurements can be difficult, especially in the advanced stages of the disease. The choice between toric and monofocal intraocular lenses (IOLs) should be carefully evaluated. Monofocal IOLs are a better choice in patients with advanced disease, and toric lenses can be used in mild and stable KCN. Intraoperatively, the use of a rigid gas permeable (RGP) lens can overcome the challenge of image distortion and loss of visual perspective. Postoperatively, patients may need updated RGP or scleral lenses to correct the corneal irregular astigmatism. A thorough preoperative planning is crucial for good surgical outcomes, and patients need to be informed regarding potential postoperative surprises. In conclusion, managing cataracts in KCN patients presents a range of challenges, and a comprehensive approach is essential to achieve favorable surgical outcomes.

The effect of corneal power on the accuracy of 14 IOL power formulas

BACKGROUND

This study evaluates the impact of corneal power on the accuracy of 14 newer intraocular lens (IOL) calculation formulas in cataract surgery. The aim is to assess how these formulas perform across different corneal curvature ranges, thereby guiding more precise IOL selection.

METHODS

In this retrospective case series, 336 eyes from 336 patients who underwent cataract surgery were studied. The cohort was divided into three groups according to preoperative corneal power. Key metrics analyzed included mean prediction error (PE), standard deviation of PE (SD), mean absolute prediction error (MAE), median absolute error (MedAE), and the percentage of eyes with PE within ± 0.25 D, 0.50 D, ± 0.75 D, ± 1.00 D and ± 2.00 D.

RESULTS

In the flat K group (Km < 43 D), VRF-G, Emmetropia Verifying Optical Version 2.0 (EVO2.0), Kane, and Hoffer QST demonstrated lower SDs (± 0.373D, ± 0.379D, ± 0.380D, ± 0.418D, respectively) compared to the VRF formula (all P < 0.05). EVO2.0 and K6 showed significantly different SDs compared to Barrett Universal II (BUII) (all P < 0.02). In the medium K group (43 D ≤ Km < 46 D), VRF-G, BUII, Karmona, K6, EVO2.0, Kane, and Pearl-DGS recorded lower MAEs (0.307D to 0.320D) than Olsen (OLCR) and Castrop (all P < 0.03), with RBF3.0 having the second lowest MAE (0.309D), significantly lower than VRF and Olsen (OLCR) (all P < 0.05). In the steep K group (Km ≥ 46D), RBF3.0, K6, and Kane achieved significantly lower MAEs (0.279D, 0.290D, 0.291D, respectively) than Castrop (all P < 0.001).

CONCLUSIONS

The study highlights the varying accuracy of newer IOL formulas based on corneal power. VRF-G, EVO2.0, Kane, K6, and Hoffer QST are highly accurate for flat corneas, while VRF-G, RBF3.0, BUII, Karmona, K6, EVO2.0, Kane, and Pearl-DGS are recommended for medium K corneas. In steep corneas, RBF3.0, K6, and Kane show superior performance.

Comparison of optical biometry versus ultrasound biometry in different axial length groups

PURPOSE:

The accuracy of optical biometry is higher than ocular ultrasound, but it is expensive and has limitations in patients with dense cataracts. On the other hand, ocular ultrasound biometry is still a frequently used technique in most developing countries due to its lower cost. Therefore, it could be helpful for practitioners to know the interchangeability of optical biometry devices with ultrasound biometry devices. This study is conducted to compare the axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) measured by ocular optical and ultrasound biometers in different AL groups.

METHODS:

This prospective consecutive study was performed on 248 eyes of 248 patients. Ocular optical biometry was performed using IOLMaster 700 (swept-source optical coherence tomography-based optical biometry, Carl Zeiss, Germany), and the contact ultrasound biometry was carried out using the US-4000 Nidek Echoscan (Gamagori, Japan). Based on measured AL, patients were divided into three groups: the short eye (AL ≤22 mm), normal eye (22 < AL <24.5 mm), and long eye (AL ≥24.50 mm).

RESULTS:

The agreement of AL between these biometers in all, short, normal, and long eyes was 99.9%, 98.3%, 99.6%, and 99.9%, respectively. The ACD agreement between two devices in all, short, normal, and long eyes was 97.0%, 93.8%, 97.2%, and 96.1%, respectively. Furthermore, the agreement of LT between these biometers in all, short, normal, and long eyes was 74.4%, 89.2%, 66.9%, and 90.7%, respectively. There were a very strong positive correlation in AL (r = 0.999) and ACD (r = 0.947) and a good correlation in LT (r = 0.675) between these devices (all P < 0.001).

CONCLUSION:

AL and ACD measured by the IOLMaster 700 optical biometer can be used interchangeably with the US-4000 ultrasound biometer in different AL groups. However, LT measured by these biometers cannot be used interchangeably.

[Evaluation of the accuracy of modern intraocular lens calculation formulas when optical biometry is not possible]

PURPOSE

This study evaluates the accuracy of modern intraocular lens (IOL) calculation formulas using axial length (AL) data obtained by ultrasound biometry (UBM) compared to the third-generation SRK/T calculator.

MATERIAL AND METHODS

The study included 230 patients (267 eyes) with severe lens opacities that prevented optical biometry, who underwent phacoemulsification (PE) with IOL implantation. IOL power calculation according to the SRK/T formula was based on AL and anterior chamber depth obtained by UBM (Tomey Biometer Al-100) and keratometry on the Topcon KR 8800 autorefractometer. To adapt AL for new generation calculators - Barrett Universal II (BUII), Hill RBF ver. 3.0 (RBF), Kane and Ladas Super Formula (LSF) - the retinal thickness (0.20 mm) was added to the axial length determined by UBM, and then the optical power of the artificial lens was calculated. The mean error and its modulus value were used as criteria for the accuracy of IOL calculation.

RESULTS

A significant difference (p=0.008) in the mean IOL calculation error was found between the formulas. Pairwise analysis revealed differences between SRK/T (-0.32±0.58 D) and other formulas - BUII (-0.16±0.52 D; p=0.014), RBF (-0.17±0.51 D; p=0.024), Kane (-0.17±0.52 D; p=0.029), but not with the LSF calculator (-0.19±0.53 D; p=0.071). No significant differences between the formulas were found in terms of mean error modulus (p=0.238). New generation calculators showed a more frequent success in hitting target refraction (within ±1.00 D in more than 95% of cases) than the SRK/T formula (86%).

CONCLUSION

The proposed method of adding 0.20 mm to the AL determined by UBM allows using this parameter in modern IOL calculation formulas and improving the refractive results of PE, especially in eyes with non-standard anterior segment structure.

Efficacy of corneal curvature on the accuracy of 8 intraocular lens power calculation formulas in 302 highly myopic eyes

PURPOSE

To investigate the effect of corneal curvature (K) on the accuracy of 8 intraocular lens formulas in highly myopic eyes.

SETTING

Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.

DESIGN

Retrospective consecutive case series.

METHODS

302 eyes (302 patients) were analyzed in subgroups based on the K value. The mean refractive error, mean absolute error (MAE), median absolute error (MedAE), root-mean-square absolute prediction error (RMSAE) and proportions of eyes within ±0.25 diopter (D), ±0.50 D, ±0.75 D, ±1.00 D were statistical analyzed.

RESULTS

Emmetropia Verifying Optical (EVO) 2.0, Kane, and Radial Basis Function (RBF) 3.0 had the lower MAE (≤0.28) and RMSAE (≤0.348) and highest percentage of eyes within ±0.50 D (≥83.58%) in the flat (K ≤ 43 D) and steep K (K > 45 D) groups. Hoffer QST had the lowest MedAE (0.19), RMSAE (0.351) and the highest percentage of eyes within ±0.50 D (82.98%) in the normal K group (43 < K ≤ 45 D). When axial length (AL) ≤28 mm, all formulas showed close RMSAE values (0.322 to 0.373) in flat K group. When AL >28 mm, RBF 3.0 achieved the lowest MAE (≤0.24), MedAE (≤0.17) and RMSAE (≤0.337) across all subgroups.

CONCLUSIONS

EVO 2.0, Kane, and RBF 3.0 were the most accurate in highly myopic eyes with a flat or steep K. Hoffer QST is recommended for long eyes with normal K values. RBF 3.0 showed the highest accuracy when AL >28 mm, independent of corneal curvature.

Accuracy of Different Lens Power Calculation Formulas in Patients With Mature Cataracts

Introduction To compare the prediction accuracy of lens power calculation formulas in patients undergoing mature cataract surgery. Methods A total of 90 operations involving the Alcon SA60AT IOL implant (Alcon, Geneva, Switzerland) were analyzed in terms of mean refractive prediction error (PE) and mean absolute prediction error (MAE) using backward calculation in a retrospective design. Results A negative PE was observed in SRK/T, Holladay 1, Holladay 2, Hoffer Q, Haigis, and Emmetropia Verifying Optical (EVO) formulas. In contrast, positive PEs were observed in Barrett Universal II (BAUII), Kane, and Radial Basis Function (RBF) formulas. Negative PE was observed with all formulas, except BAUII, in patients with a shallow anterior chamber depth (ACD). While the SRK/T, Holladay 1, BAU, Kane, and RBF formulas demonstrated positive PE, the Holladay 2, Hoffer Q, Haigis, and EVO formulas indicated negative PE. In patients with deep ACD, positive PE was observed in all formulas, barring Holladay 2 and EVO. No significant differences were identified between the formulas concerning MAE and percentages of 0.25 diopter (D), 0.50 D, 0.75 D, and 1.0 D across all study groups. Conclusion Although the new generation formulas provide very good results, achieving the best with a single formula is still impossible.

Evaluation of biometric formulas in the calculation of intraocular lens according to axial length and type of the lens

To compare the accuracy of the modern biometric formulas in cataract surgery according to axial length and lens type. It is a Cross-sectional design from 365 patients who underwent cataract surgery. The SRK/T, Hoffer Q, Haigis, and Holladay I formulas were extracted from the IOLMaster 500 biometer. Barret formulas and the Kane were obtained from the online calculator. Patients are classified according to axial length (AL) into three groups: AL ≤ 22 mm, 22 < AL < 25 mm, and AL ≥ 25 mm. In addition, implanted intraocular lenses are classified as Monofocal, extended focus, and Multifocal. There are no significant differences between the formulas. In short, the Kane formula was more accurate than the other biometric formulas. Kane and SRK/T were the most accurate in monofocal lenses, with the lowest residual refractive error. The Holladay I formula obtained the lowest mean absolute error with the highest number of eyes with minimum residual ± 0.5Dp in the multifocal lenses in the 22 < AL < 25 mm eyes. In the long AL eyes, SRK/T and Kane's obtained the lowest mean absolute error and the best percentage of eyes with ± 0.5Dp of residual refractive error. There are no significant differences between the formulas. However Kane's formula has shown high accuracy, especially in short and long eyes with monofocal lenses.

Accuracy of Intraocular Lens Power Calculation Based on Total Keratometry in Patients With Flat and Steep Corneas

PURPOSE

To analyze the accuracy of the current intraocular lens power calculation formulas using standard keratometry (K) and total keratometry (TK) data in patients with flat and steep corneas.

DESIGN

Retrospective consecutive cross-sectional study.

METHODS

An optical biometer with swept-source optical coherence tomography was used in this retrospective study. The standard deviation (SD), mean absolute error (MAE), median absolute error (MedAE), and the proportion of eyes with prediction error (PE) within ±0.25 diopter (D), ±0.5 D, ±0.75 D, and ±1.00 D were calculated to evaluate the refractive outcomes of each formula.

RESULTS

A total of 231 eyes from 231 patients were included. In the entire study cohort, the Emmetropia Verifying Optical (EVO) formula using TK data showed the lowest SD (0.383) and MAE (0.30) and the highest percentage of cases with a PE within ±0.5 D (81.4%). In the flat keratometry group, the EVO (P = .042), Haigis (P = .043), Hoffer Q (P = .038) and Holladay 1 (P = .013) formulas using TK data had significantly lower SD than using K data. The EVO formula using TK data showed the lowest SD (0.357) and MAE (0.28). In the steep keratometry group, the Hoffer Q (P = .036) and SRK/T (P = .029) formulas using TK data had significantly lower SD than using K data. The BUII TK formula showed the lowest SD (0.431), MedAE (0.26), and MAE (0.32).

CONCLUSION

The TK data set showed a better trend of refractive outcomes, especially in the flat and steep keratometry groups. EVO (TK) and BUII TK formulas were suggested for eyes with K values lower than 42 D and K values higher than 46 D, respectively.

[Reasonability of accounting for gender in intraocular lens power calculation]

PURPOSE

The study assesses the influence of gender on the accuracy of intraocular lens (IOL) power calculation by formulas SRK/T, Barrett Universal II (BUII), Ladas super formula (LSF), Hill RBF (RBF) and Kane.

MATERIAL AND METHODS

The study enrolled 214 patients (106 men and 108 women) who underwent cataract phacoemulsification (PE). Optical biometry was performed on IOL-Master 500. IOL power calculation was performed either adjusting for gender (formulas SRK/T, BUII, LSF) or without such adjustment (formulas RBF, Kane). Calculation error (CE) was assessed one month after PE by comparing the achieved (autorefractometer Topcon-8800) and target spherical equivalent of refraction.

RESULTS

Significant differences were found in mean IOL CE with gender-unspecific formulas (SRK/T, BUII, LSF) and no differences in gender-specific calculators (RBF, Kane). The Kane formula demonstrated the lowest CE between men and women (-0.01±0.43 versus -0.09±0.41 D; p=0.158), while the SRK/T formula had the highest CE (0.02±0.46 versus -0.21±0.44 D, respectively; p<0.001). Presence of a significant correlation between CE and gender was found for all formulas except Kane (R2=0.005, p=0.158).

CONCLUSION

Patient's gender has a significant impact on IOL calculation accuracy. Using gender-responsive formulas could help achieve better refractive results with PE. The present study showed Kane formula to have the least CE dependence from gender. However, the CE difference (less than 0.25 D) was lower than the value of division (0.5D) in modern IOL models.

Comparable postoperative myopic shift in eyes with retinal vascular diseases and vitreomacular interface diseases after phacovitrectomy

PURPOSE

To compare the predictive refractive error (PRE) of intraocular lens (IOL) power between retinal vascular and vitreomacular interface diseases after phacovitrectomy.

METHODS

We retrospectively reviewed patients who underwent phacovitrectomy for various retinal diseases. Patients with retinal vascular diseases and vitreomacular interface diseases were included in group A and group B, respectively. Age- and gender-matched senile cataract patients with phacoemulsification were set as controls. The mean PRE and absolute value of refractive error (ARE) among different groups were compared. The associated risk factors with ARE were also analyzed in the univariate and multivariate analyses.

RESULTS

In total, 106 patients (Group A), 108 patients (Group B), and 110 patients as controls were included. The PRE in Group A (- 0.35 ± 0.83D) and Group B (- 0.53 ± 0.74D) were more myopic compared to the control group (- 0.11 ± 0.58D) (p < 0.05). The ARE in Group A (0.70 ± 0.57D) and Group B (0.75 ± 0.51D) were significantly higher compared to the control group (0.47 ± 0.35D) (p < 0.05). There were no significant differences in the PRE and ARE values between the two study groups (p = 0.267 and 0.861, respectively). There were no significant differences of the PRE and ARE in the eyes with silicone oil tamponade (- 0.63 ± 0.75D, 0.81 ± 0.54D) and gas tamponade (- 0.42 ± 0.83D, 0.74 ± 0.56D) (p = 0.693 and 0.988, respectively). In the multivariate model, preoperative LogMAR visual acuity (β = 0.162, 95%CI = 0.113-0.211, p < 0.001), mean corneal curvature (β = 0.105, 95% CI = 0.074-0.135, p < 0.001), and age (β = 0.012, 95% CI = 0.005-0.019, p = 0.001) were all positively correlated with the ARE.

CONCLUSIONS

Postoperative myopic shift after phacovitrectomy may be comparable in retinal vascular diseases and vitreomacular interface diseases, no matter the gas or silicone oil tamponade. Older age, steeper corneal curvature, and worse preoperative visual acuity could produce more prediction errors.

Correlating Kane formula with existing intraocular lens formulae for corneal curvatures and axial lengths

BACKGROUND:

To evaluate the predictability of the Kane formula in estimating postoperative refractive outcome with various corneal curvatures and axial lengths (ALs) besides comparing with existing intraocular lens (IOL) formulae.

MATERIALS AND METHODS:

A prospective cross-sectional study was carried out among patients having uneventful cataract surgery at an eye hospital. A total of 50 eyes were considered for the study. The corresponding A-constant for the model of IOL implanted into the patient's eye was taken along with the actual power of IOL implanted and corresponding predicted power for the IOL power inserted were taken for all the chosen formulae and was termed as "Adjusted Predicted Refractive Power." This was compared with the actual refractive outcome and the absolute error (AE) was measured. The eyes were separated into groups in terms of corneal curvature as flat (<42D), medium (42D–46D), and steep (>46D) corneas. In terms of AL, it was grouped as short (≤22 mm), medium (>22.0–<24.0 mm), and long (>24.0 mm) eyes.

RESULTS:

The study included 50 eyes and the mean AE for all the selected formulae were calculated for each group. Over the entire corneal curvature range, none of the formulae showed any significance when compared with the Kane formula (P > 0.05). In short AL, SRK-T formula had a statistical significance over the Kane formula (P = 0.043), whereas no other group had any significance over the Kane formula in AL groups.

CONCLUSION:

The study shows, all formulae (SRK-T, Holladay1, Hoffer Q, Hill RBF, Barrett Universal II, Kane) are interchangeable to predict the IOL power for any of the corneal curvature and ALs.

Correlating Kane formula with existing intraocular lens formulae for corneal curvatures and axial lengths

BACKGROUND

To evaluate the predictability of the Kane formula in estimating postoperative refractive outcome with various corneal curvatures and axial lengths (ALs) besides comparing with existing intraocular lens (IOL) formulae.

MATERIALS AND METHODS

A prospective cross-sectional study was carried out among patients having uneventful cataract surgery at an eye hospital. A total of 50 eyes were considered for the study. The corresponding A-constant for the model of IOL implanted into the patient's eye was taken along with the actual power of IOL implanted and corresponding predicted power for the IOL power inserted were taken for all the chosen formulae and was termed as "Adjusted Predicted Refractive Power." This was compared with the actual refractive outcome and the absolute error (AE) was measured. The eyes were separated into groups in terms of corneal curvature as flat (<42D), medium (42D-46D), and steep (>46D) corneas. In terms of AL, it was grouped as short (≤22 mm), medium (>22.0-<24.0 mm), and long (>24.0 mm) eyes.

RESULTS

The study included 50 eyes and the mean AE for all the selected formulae were calculated for each group. Over the entire corneal curvature range, none of the formulae showed any significance when compared with the Kane formula (P > 0.05). In short AL, SRK-T formula had a statistical significance over the Kane formula (P = 0.043), whereas no other group had any significance over the Kane formula in AL groups.

CONCLUSION

The study shows, all formulae (SRK-T, Holladay1, Hoffer Q, Hill RBF, Barrett Universal II, Kane) are interchangeable to predict the IOL power for any of the corneal curvature and ALs.