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Helaly HA, Elhady AM, Elnaggar OR. Accuracy of Traditional and Modern Formulas for Intraocular Lens Power Calculation After Radial Keratotomy Using Standard Keratometry. Clin Ophthalmol 2023; 17:2589-2597. [PMID: 37671334 PMCID: PMC10476658 DOI: 10.2147/opth.s417336] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 08/25/2023] [Indexed: 09/07/2023] Open
Abstract
Purpose To compare the accuracy of multiple traditional and modern intraocular lens (IOL) power calculation formulas in post-radial keratotomy (RK) patients undergoing cataract surgery. Methods This retrospective case series included 50 eyes with prior RK who underwent routine phacoemulsification surgery with single-piece acrylic IOL implantation (A constant = 118.8). Outcomes of multiple formulas were calculated. Included formulas were SRK/T, Holladay 1, Holladay 2, Haigis, Barrett True-K, Haigis and Barrett True-K (target refraction of 0.50 D), Barrett Universal II, Kane, PEARL-DGS, Shammas no history, DK SRK/T, DK SRK/T (target refraction of 0.50 D), Double K (DK) Holladay 1, and DK Holladay 1 (target refraction of 0.50 D). Averages of multiple combinations of best-performing single formulas were calculated. Primary outcome is mean absolute error (MAE). Results Haigis (with -0.50 D target refraction) and DK SRK/T showed the lowest mean and median absolute errors (MedAE) followed by Haigis, Barrett True-K, and Barrett True-K (with -0.50 D target refraction). Combinations of 3, 4, or 5 of best performing single formulas yielded good results with >60% of cases within +0.50 D of intended refraction and MAE around 0.50 D. The best performing formulas with flatter K readings were PEARL-DGS and Haigis (with additional -0.50 D target refraction) with MAE of 0.72 + 0.71 D and 0.70 + 0.70 D, respectively, followed by Barrett True-K (with intended -0.50 D target refraction) with MAE of 0.75 + 0.63 D. Conclusion Using an average of three or more Haigis (with -0.50 D target refraction), the Barrett True-K, DK Holladay 1, and DK SRK/T formulas showed better outcomes than using a single formula for IOLMaster 700 standard K readings. The PEARL-DGS formula showed better accuracy in eyes with flatter K readings (<38 D).
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Affiliation(s)
- Hany Ahmed Helaly
- Ophthalmology Department, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Amr Mohamed Elhady
- Ophthalmology Department, Faculty of Medicine, Alexandria University, Alexandria, Egypt
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Lin SR, Nutkiewicz M, Rasheed H, Nejad M, Hamilton DR. Method for IOL Power Calculation in the Second Eye of Patients With Previous Keratorefractive Surgery. J Refract Surg 2021; 36:826-831. [PMID: 33295995 DOI: 10.3928/1081597x-20200914-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/10/2020] [Indexed: 11/20/2022]
Abstract
PURPOSE To describe and evaluate a method for calculating intraocular lens (IOL) power in the second operative eye of patients with a history of keratorefractive surgery. METHODS All eyes had undergone cataract surgery by a single surgeon from 2015 to 2018. Postoperative outcomes on the first eye (eg, IOL power implanted and postoperative refractive error) were used to back calculate a "Real K" for the first eye. The difference (delta) between the second and first eye topographic simulated keratometry values was then added to the first eye Real K to calculate the second eye Real K. This Real K value was inputted into the Holladay IOL Consultant software as an "alternate K" to derive an accurate IOL power for the second eye. Mean absolute error, mean error, and percentage of eyes on target using the Delta K method were compared with results obtained with intraoperative abserrometry and the Haigis-L and Barrett True-K No History formulas. RESULTS The mean error for the Delta K method was significantly better than the Haigis-L (P = .00001) and Barrett True-K No History (P = .027) formulas, and on par with intra-operative aberrometry (P = .25). The mean absolute error of the Delta K method was significantly better than the Haigis-L formula (P = .03). The Delta K mean absolute error was on par with intraoperative aberrometry (P = .81) and the Barrett True-K No History formula (P = .56). CONCLUSIONS The Delta K mean absolute error is comparable to the Barrett True-K No History formula. The mean error is lower than that calculated with the Barrett True-K No History formula and comparable to intraoperative aberrometry. [J Refract Surg. 2020;36(12):826-831.].
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Chean CS, Aw Yong BK, Comely S, Maleedy D, Kaye S, Batterbury M, Romano V, Arbabi E, Hu V. Refractive outcomes following cataract surgery in patients who have had myopic laser vision correction. BMJ Open Ophthalmol 2019; 4:e000242. [PMID: 31179392 PMCID: PMC6528761 DOI: 10.1136/bmjophth-2018-000242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Objective Prediction errors are increased among patients presenting for cataract surgery post laser vision correction (LVC) as biometric relationships are altered. We investigated the prediction errors of five formulae among these patients. Methods and analysis The intended refractive error was calculated as a sphero-cylinder and as a spherical equivalent for analysis. For determining the difference between the intended and postoperative refractive error, data were transformed into components of Long's formalism, before changing into sphero-cylinder notation. These differences in refractive errors were compared between the five formulae and to that of a control group using a Kruskal-Wallis test. An F-test was used to compare the variances of the difference distributions. Results 22 eyes post LVC and 19 control eyes were included for analysis. Comparing both groups, there were significant differences in the postoperative refractive error (p=0.038). The differences between the intended and postoperative refractive error were greater in post LVC eyes than control eyes (p=0.012), irrespective of the calculation method for the intended refractive error (p<0.01). The mean difference between the intended and postoperative refractive error was relatively small, but its variance was significantly greater among post LVC eyes than control eyes (p<0.01). Among post LVC eyes, there were no significant differences between the mean intended target refraction and between the intended and postoperative refractive error using five biometry formulae (p=0.76). Conclusion Biometry calculations were less precise for patients who had LVC than patients without LVC. No particular biometry formula appears to be superior among patients post LVC.
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Affiliation(s)
- Chung Shen Chean
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Boon Kang Aw Yong
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Samuel Comely
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Deena Maleedy
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Stephen Kaye
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Mark Batterbury
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Vito Romano
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Esmaeil Arbabi
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | - Victor Hu
- International Centre for Eye Health, London School of Hygiene & Tropical Medicine, London, UK
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Hua Y, Pan C, Wang Q. Assessment of total corneal power after myopic corneal refractive surgery in Chinese eyes. Int Ophthalmol 2019; 39:2467-2475. [PMID: 30825050 DOI: 10.1007/s10792-019-01089-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 02/23/2019] [Indexed: 11/30/2022]
Abstract
PURPOSE To develop a new regression formula based on the Gaussian thick lens formula and to verify the accuracy of the regression formula. METHODS In this prospective study, 207 eyes of 207 myopic subjects and 133 eyes of 67 postoperative subjects were included. For the 133 postoperative eyes, 127 eyes underwent laser-assisted in situ keratomileusis, and 6 eyes underwent photorefractive keratectomy. Subjective refraction and Pentacam HR were performed preoperatively and postoperatively, and IOLMaster was performed in the postoperative group. SimK, keratometry based on the Gaussian optic formula (KGOF), KCHM obtained using the clinical history method, and the regression formulas KRF1 and KRF2 were calculated. RESULTS (1) A statistically significant difference (t = 155.164, P = 0.000) between SimK and KGOF of 1.24 ± 0.12 D was observed, and there was a good correlation between SimK and KGOF (r = 0.996, P = 0.000). The first regression formula (KRF1 = 0.351 + 1.021 × KGOF) was obtained using linear regression. (2) Statistically significant differences (t = 19.114, - 25.184, 4.702, and all P = 0.000) between SimK and KCHM, KGOF and KCHM and KRF1 and KCHM of 0.75 ± 0.45 D, 0.96 ± 0.44 D and 0.18 ± 0.43 D, respectively, were obtained. Good correlations between SimK and KCHM, KGOF and KCHM and KRF1 and KCHM (all r ≧ 0.977, all Ps = 0.000) were also observed. The regression formula (KRF2 = - 1.204 + 1.027 × KRF1) was obtained using linear regression. (3) Six methods were used for the prediction of IOL power in the postoperative group. The highest results were obtained from the Shammas formula (without preoperative data) combining Km (obtained by IOLMaster) followed by the KCHM and KRF2 combining Haigis formula. The third was obtained from the KCHM and KRF2 combining Hoffer Q formula; and the smallest was the Km combining Haigis formula. CONCLUSION The IOL power predicted by KRF2 in eyes after myopic CRS may be accurate.
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Affiliation(s)
- Yanjun Hua
- Department of Ophthalmology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, No. 600, Yishan Road, Xuhui District, Shanghai, 200233, China.
| | | | - Qinmei Wang
- School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, 325000, China.
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Jabbarvand M, Askarizadeh F, Sedaghat MR, Ghadimi H, Khosravi B, Amiri MA, Narooie-Noori F. Comparison between Pentacam HR and Orbscan II after Hyperopic Photorefractive Keratectomy. J Ophthalmic Vis Res 2017; 12:374-379. [PMID: 29090045 PMCID: PMC5644402 DOI: 10.4103/jovr.jovr_47_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Purpose: The aim of this study was to determine the agreement between Pentacam HR (Scheimpflug imaging, Oculus) and Orbscan II (scanning slit topography, Bausch and Lomb) in measuring corneal parameters after photorefractive keratectomy (PRK) for hyperopia. Methods: In this prospective cross-sectional study, 38 hyperopic eyes undergoing PRK were examined before refractive surgery and 8 to 10 months postoperatively using Pentacam HR and Orbscan II. Ultrasound (US) pachymetry was also used to measure central corneal thickness (CCT). The radius of anterior (A-) and posterior (P-) best-fit sphere size (BFS), central elevation (CE), and anterior maximum tangential power in 3 mm (TG3) and 3-5 mm (TG5) zones, anterior chamber depth (ACD), and central corneal thickness (CCT) were collected and used in the analyses. To study the agreement between the measurements made by the two devices, the method described by Bland and Altman was used and the 95% limits of agreement were calculated. Results: The 95% limits of agreement show reasonable agreement between the measurements by Pentacam HR and Orbscan II for A-BFS, P-BFS, A-TG3, and CCT, but not for A-CE, P-CE, A-TG5, or ACD. CCT values obtained by both Pentacam HR and Orbscan II correlated well with the values determined by US pachymetry. Conclusion: Pentacam HR and Orbscan II after PRK for hyperopia show reasonable agreement for determining A-BFS, P-BFS, A-TG3, and CCT, but not for A-CE, P-CE, A-TG5, or ACD. CCT measurements with Pentacam HR have reasonable agreement with US pachymetry.
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Affiliation(s)
- Mahmoud Jabbarvand
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Farshad Askarizadeh
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohamad Reza Sedaghat
- Cornea Research Center, Khatam-Al-Anbia Hospital, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hadi Ghadimi
- Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Bahram Khosravi
- Department of Optometry, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Foroozan Narooie-Noori
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
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Wu Y, Liu S, Liao R. Prediction accuracy of intraocular lens power calculation methods after laser refractive surgery. BMC Ophthalmol 2017; 17:44. [PMID: 28390411 PMCID: PMC5385019 DOI: 10.1186/s12886-017-0439-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/05/2017] [Indexed: 11/14/2022] Open
Abstract
Background This study aimed to evaluate the prediction accuracy of postoperative refractions using partial coherence interferometry (IOL-Master) and applanation ultrasound (AL-3000) assisted with corneal topography (TMS-4) in eyes that had undergone myopic laser-assisted in situ keratomileusis (LASIK). Methods Haigis-L formula, Koch–Maloney method using Haigis formula, Shammas clinically derived K-value (simulated keratometric value) correction (Shammas c.d.) using Haigis formula, and Shammas post-LASIK (Shammas-PL) formula were used in eyes with myopic LASIK. Constants were derived from the optimized constants in 133 virgin eyes. Refractive outcomes were determined by streak retinoscopy and subjective manifest refraction. Methods and formulas were evaluated by mean error (ME), standard deviation (SD), range of error, mean absolute error (MAE), median absolute error, 95% confidence interval of MAE, and percentage of eyes within ±0.5 diopter (D), ±1.0 D, and ±1.5 D of prediction. Results SDs of the Haigis-L, Koch-Maloney method using the Haigis formula, Shammas c.d. using the Haigis formula, and the Shammas-PL formula using IOL-Master were 0.721, 0.695, 0.695, and 0.698; and those using AL-3000 assisted with TMS-4 were 0.782, 0.741, 0.743, and 0.778, respectively. Conclusions No-history methods that corrected corneal power with measurements using IOL-Master were promising in myopic post-LASIK eyes, but still a gap in prediction accuracy exists between virgin eyes and post-LASIK eyes. Electronic supplementary material The online version of this article (doi:10.1186/s12886-017-0439-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yubo Wu
- Department of Ophthalmology, The First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, Anhui, 230022, China
| | - Songyu Liu
- Department of Ultrasound, The First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, Anhui, 230022, China
| | - Rongfeng Liao
- Department of Ophthalmology, The First Affiliated Hospital of Anhui Medical University, No. 218 Jixi Road, Hefei, Anhui, 230022, China.
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Evaluation of Equivalent Keratometry Readings Obtained by Pentacam HR (High Resolution). PLoS One 2016; 11:e0150121. [PMID: 26950834 PMCID: PMC4780706 DOI: 10.1371/journal.pone.0150121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/09/2016] [Indexed: 11/20/2022] Open
Abstract
Purpose To assess the repeatability of Equivalent Keratometry Readings (EKRs) obtained by the Pentacam HR (high resolution) in untreated and post-LASIK eyes, and to compare them with the keratometry (K) values obtained by other algorithms. Methods In this prospective study, 100 untreated eyes and 71 post-LASIK eyes were included. In the untreated group, each eye received 3 consecutive scans using the Pentacam HR, and EKR values in all central corneal zone, the true net power (Knet) and the simulated K (SimK) were obtained for each scan. In the post-LASIK group, each eye received subjective refraction and 3 consecutive scans with the Pentacam HR preoperatively. During the 3-month post-surgery exam, the same examinations and the use of an IOLMaster were conducted for each eye. The EKRs in all zone, the Knet, the mean K (Km) by IOLMaster and the K values by clinical history method (KCHM) were obtained. The repeatability of the EKRs was assessed by the within-subject standard deviation (Sw), 2.77Sw, coefficient of variation (CVw) and intraclass correlation coefficient (ICC). The bonferroni corrected multiple comparisons were performed to analyze the differences among the EKRs and K values calculated by other algorithms within the 2 groups. The 95% limits of agreement (LoA) were calculated. Results The EKR values in all central corneal zone were repeatable in both the untreated group (Sw≦0.19 D, 2.77Sw≦0.52 D, CVw≦1%, ICC≧0.978) and the post-LASIK group (Sw≦0.22 D, 2.77Sw≦0.62 D, CVw≦1%, ICC≧0.980). In the untreated group, the EKR in 4mm zone was close to SimK (P = 1.000), and the 95% LoA was (-0.13 to 0.15 D). The difference between Knet and SimK was -1.30±0.13 D (95% LoA -1.55 to -1.55 D, P<0.001). In the post-LASIK group, all the EKRs were significantly higher than KCHM (all P<0.001). The differences between the EKR in 4mm zone and KCHM, the EKR in 7mm zone and KCHM, Knet and KCHM, Km and KCHM, SimK and Knet were 0.64±0.50 D (95% LoA, -0.33 to 1.62 D), 1.77±0.88 D (95% LoA, 0.04 to 3.51 D), -0.98±0.48 D (95% LoA, -1.92 to -0.04 D), 0.64±0.53 D (95% LoA, -0.40 to 1.68 D), and 1.73±0.20 D (95% LoA, 1.33 to 2.13 D), respectively. Conclusions The EKRs obtained by the Pentacam HR were repeatable in both untreated eyes and post-LASIK eyes. Compared to the total corneal power obtained by the clinical history method, the EKR values generally overestimated the total corneal power in post-LASIK eyes. So, further calibrations for the EKR values should be conducted, before they were used for the total corneal power assessment in post-LASIK eyes.
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Lekhanont K, Nonpassopon M, Wannarosapark K, Chuckpaiwong V. Agreement between clinical history method, Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery. PLoS One 2015; 10:e0123729. [PMID: 25853655 PMCID: PMC4390196 DOI: 10.1371/journal.pone.0123729] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 03/06/2015] [Indexed: 11/19/2022] Open
Abstract
The purpose of this study was to investigate the agreement between the clinical history method (CHM), Orbscan IIz, and Pentacam in estimating corneal power after myopic excimer laser surgery. Fifty five patients who had myopic LASIK/PRK were recruited into this study. One eye of each patient was randomly selected by a computer-generated process. At 6 months after surgery, postoperative corneal power was calculated from the CHM, Orbscan IIz total optical power at the 3.0 and 4.0 mm zones, and Pentacam equivalent keratometric readings (EKRs) at 3.0, 4.0, and 4.5 mm. Statistical analyses included multilevel models, Pearson’s correlation test, and Bland-Altman plots. The Orbscan IIz 3.0-mm and 4.0 mm total optical power, and Pentacam 3.0-mm, 4.0-mm, and 4.5-mm EKR values had strong linear positive correlations with the CHM values (r = 0.90–0.94, P = <0.001, for all comparisons, Pearson’s correlation). However, only Pentacam 3.0-mm EKR was not statistically different from CHM (P = 0.17, multilevel models). The mean 3.0- and 4.0-mm total optical powers of the Orbscan IIz were significantly flatter than the values derived from CHM, while the average EKRs of the Pentacam at 4.0 and 4.5 mm were significantly steeper. The mean Orbscan IIz 3.0-mm total optical power was the lowest keratometric reading compared to the other 5 values. Large 95% LoA was observed between each of these values, particularly EKRs, and those obtained with the CHM. The width of the 95% LoA was narrowest for Orbscan IIz 3.0-mm total optical power. In conclusion, the keratometric values extracted from these 3 methods were disparate, either because of a statistically significant difference in the mean values or moderate agreement between them. Therefore, they are not considered equivalent and cannot be used interchangeably.
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Affiliation(s)
- Kaevalin Lekhanont
- Department of Ophthalmology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
- * E-mail:
| | - Manachai Nonpassopon
- Department of Ophthalmology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | | | - Varintorn Chuckpaiwong
- Department of Ophthalmology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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