ABSTRACT
Purpose: To assess the axial length (AL) measurement failure rate using partial?coherence interferometry (PCI) and swept?source optical coherence tomography (SS?OCT) in dense cataracts. As a secondary outcome, the SS?OCT biometry was compared to immersion ultrasound. Methods: This is a prospective cross?sectional and comparative study. Seventy eyes from 70 patients with dense cataracts were enrolled in this study. Dense cataract was defined according to the Lens Opacities Classification System III (LOCS III) scores equal to or more than NO4, NC4, C4, and P3. The failure rate of AL measurement was evaluated using PCI and SS?OCT. Anterior chamber depth (ACD), lens thickness (LT), and AL measurements obtained by SS?OCT were compared with IUS. Results: AL measurement failure rate with PCI was 68.57% and 21.43% with SS?OCT (P = 0.007). AL measurement was achieved in 69.23% of NO4, 66.6% of P3, and 15.3% of mixed cataracts using PCI, while SS?OCT was achieved in 100% of NO4, NO5, P3, and P5 and 76.9% of mixed cataracts. Cortical cataracts alone did not influence AL measurement. Biometric data of ACD, LT, and AL were statistically different comparing US and SS?OCT with a good correlation of AL. Conclusion: SS?OCT significantly improves the rate of successful AL measurements when compared to PCI in dense cataracts. The LOCS III clinical cut?off for the use of SS?OCT ocular biometry may well be up to P4 and NO5
ABSTRACT
Objective:To compare the accuracy of IOLMaster 700 and IOLMaster 500 in intraocular lens (IOL) power calculation.Methods:A cross-sectional study was conducted.Two hundred and sixty-two eyes of 262 patients who underwent phacoemulsification combined with IOL implantation at the Eye Hospital of Wenzhou Medical University from November 2018 to November 2019 were enrolled.Preoperative biometry for cataract surgery was performed using IOLMaster 700 and IOLMaster 500.IOL power was calculated through the built-in formulas, Haigis, Holladay Ⅰ, Hoffer Q and SRK/T of the two devices.The difference in IOL power calculation between the two devices was analyzed through the prediction error of IOL power calculation using different formulas across different axial length (AL) ranges.This study complied with the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of the Eye Hospital of Wenzhou Medical University (No.2020-038-K-33). Written informed consent was obtained from each patient before the surgery.Results:There was no significant difference in mean absolute error (MAE) between IOLMaster 700 and IOLMaster 500 using Haigis, Hoffer Q and SRK/T over the entire AL range (all at P >0.05). The MAE of IOLMaster 500 was 0.47 (0.24, 0.90) D, which was significantly lower than 0.50 (0.28, 0.99) D of IOLMaster 700 using Holladay Ⅰ formula ( Z=-3.120, P=0.002). When AL was <22.0 mm and ≥24.5 mm-<26.0 mm, there was no significant difference in MAE between the two devices using the four formulas (all at P >0.05). When AL was ≥22.0 mm-24.5 mm, there was no significant difference in the MAE between the two devices using Haigis, Hoffer Q and SRK/T (all at P >0.05), but 0.42 (0.18, 0.75) D from IOLMaster 500 was smaller than 0.45 (0.25, 0.79) D from IOLMaster 700 using Holladay Ⅰ, showing a statistically significant difference ( Z=-3.487, P <0.001). But the difference was negligible and therefore was of no clinical significance.When AL was ≥26.0 mm, there was no statistically significant difference in the MAE between the two devices using Haigis, Holladay Ⅰ and SRK/T, but 0.66 (0.38, 1.00) D from IOLMaster 500 was significantly smaller than 0.98 (0.62, 1.32) D from IOLMaster 700 using Hoffer Q ( Z=-3.046, P=0.002). Conclusions:The refractive prediction accuracy of IOLMaster 700 and IOLMaster 500 using Haigis, Hoffer Q and SRK/T is similar over the entire AL range.For patient with long AL, the IOL calculation from IOLMaster 700 using Hoffer Q is significantly larger than that from IOLMaster 500, which requires extra caution in clinical practice.The accuracy of IOLMaster 700 and IOLMaster 500 for IOL prediction is very similar.
ABSTRACT
Cataract with high myopia is a kind of complicated cataract with highly blinding disease. Surgery has always been the only treatment, but there is always a difference between actual postoperative refraction and target refraction. The cataract patients with high myopia have increasing demands for postoperative refractive status and visual quality now. The intraocular lens(IOL)calculation formulas have been updating for higher predictive accuracy. A variety of alternative IOL calculation formulas can be applied to clinical practice. However, there is no consensus on the selection of a more suitable formula for cataract patients with high myopia. Based on the principles and clinical application of different formulas, this paper reviews the development of IOL calculation formulas and research progress of IOL calculation formulas for cataract patients with high myopia, in order to provide reference for clinical application.
ABSTRACT
@#OBJECTIVE: To compare the different intraocular lens (IOL) calculation formulas available on the American Society of Cataract and Refractive Surgery (ASCRS) IOL power calculator website among Asian eyes with previous corneal refractive surgery. METHODS: A retrospective cohort study of 84 eyes in 68 Asian patients who had phacoemulsification with previous LASIK or photorefractive keratectomy (PRK) was done. Using the post-phacoemulsification manifest refraction spherical equivalent (MRSE) as target refraction, IOL prediction error (PE) for each formula was calculated as the implanted minus the predicted IOL power. Refractive PE was determined by calculating that 1 diopter (D) of IOL PE produces 0.7 D of refractive error at the spectacle plane. RESULTS: Comparing the Shammas, Haigis-L, Barrett True-K No History, ASCRS Average IOL Power No History, Barrett True-K, and ASCRS Average IOL Power with Change in Manifest Refraction (ΔMR), the mean IOL PEs ranged from -0.23 to -0.62 D, with the Barrett True-K having the lowest PE. The median refractive PEs for all formulas were similar at 0.35 D, except for the Haigis-L at 0.53 D. The ASCRS average with ΔMR had a statistically higher percentage of eyes within 0.5 D of target refraction versus other formulas (p<0.05). The Haigis-L IOL PE and refractive PE were significantly higher than the Barrett True-K (p<0.001), and the ASCRS average with ΔMR (p<0.001) respectively. The ASCRS average with ΔMR produced a significantly smaller variance of IOL PE (p<0.05). CONCLUSION: Accounting for PEs and variance, the ASCRS average IOL power with ΔMR is recommended, followed by the ASCRS average IOL power No History if without historical data.
Subject(s)
Keratomileusis, Laser In SituABSTRACT
@#AIM: To compare and study the differences of eyeball biometric measurements among Han, Hani and Yi nationality in Honghe Hani and Yi Autonomous Prefecture(Honghe Prefecture), and prediction accuracy of the intraocular lens(IOL)degree by SRK-T and Haigis formulas in the different eye axes, to provide further objective clinical evidence for the majority of basic-level hospitals and the blind prevention and treatment projects in minority areas.<p>METHODS: Selected 186 cases(200 eyes)cataract patients in our department, divided them into three groups according to different nations, get their eyeball biometric measurements(ocular axial length, anterior chamber depth and corneal curvature)by A-ultrasound combined with corneal curvature meter and corneal topography, and then compared the differences. According to the different eye axes, they were divided into three groups and then randomly divided into two groups. SRK-T and Haigis formulas were used to predict the IOL degree, and collected postoperative optometry results, calculated the absolute prediction error, then conducted statistical analysis. <p>RESULTS: There were no difference in the mean axial length, mean anterior chamber depth and mean corneal curvature(measured respectively by corneal topography and corneal keratometer)in the different ethnic groups(<i>P</i>>0.05), and the mean corneal curvature measured by the two methods had no difference(<i>P</i>>0.05). There were no difference of the mean corneal curvature measured by the two methods in the three axial eye groups(<i>P</i>>0.05)and in the same axial eye group(<i>P</i>>0.05). There were no difference in the absolute error of the two IOL measurement formulas in the three eye axis groups(<i>P</i>>0.05). The absolute error calculated by SRK-T formula for the short and the middle eye axis groups were smaller, while it calculated by Haigis formula for long eye axis group was smaller.<p>CONCLUSION: In our department, there are no statistical difference in the eye biometrics of Han, Yi and Hani nationality. Corneal curvature measured by corneal topography and corneal keratometer have no significant difference. SRK-T and Haigis formula both have high predictive value for IOL degree, SRK-T formula has smaller predictive error for patients which with short and middle eye axis, and Haigis formula has better predictive value for the long ones.
ABSTRACT
@#Current formulas tend to select intraocular lens with insufficient power for these patients, resulting in postoperative hyperopia. In addition to the traditional methods to address this problem such as reserving a myopic power in the power calculation, several more accurate and effective solutions have been suggested, including adjusting the axial lengths, using new formulas, and applying intraoperative refractive biometry. This paper will focus on the postoperative refractive error in highly myopic eyes after phacoemulsification and intraocular lens implantation and illustrate the progress of existing solutions.
ABSTRACT
PURPOSE: To evaluate the accuracy of intraocular lens (IOL) power calculations between Hoffer Q and other formulas according to corneal curvature by comparing the results of cataract surgery and calculation of chosen formulas in short axial lengths. METHODS: We performed a retrospective analysis of patients who underwent cataract surgery from January 1st, 2012 to June 12th, 2012. The patients were selected if their axial length was below 23.00 mm and 77 patients (90 eyes) were included in the present study. The patients were divided into 2 groups according to mean corneal curvature below 44.0 D and over 45.0 D. IOL power was calculated using the Hoffer Q and SRK II, SRK-T and Holladay I formulas and the error between the calculations and refractive outcome of cataract surgery were measured. The accuracy of each formula was evaluated by comparing the error between the 2 groups. RESULTS: Hoffer Q formula showed a higher predictive accuracy than other formulas regardless of corneal curvature in eyes with short axial lengths (p < 0.001, p = 0.023). Particularly, SRK II, SRK-T and Holladay I showed a lower predictive accuracy in eyes with flat corneal curvature than Hoffer Q (p < 0.001, p = 0.215). CONCLUSIONS: In eyes with short axial lengths, preoperative predicted IOL power calculations showed better accuracy with Hoffer Q formula than SRK II, SRK-T and Holladay I formulas. SRK II, SRK-T and Holladay I formulas showed a lower predictive accuracy in flat corneal curvature eyes than steep corneal curvature eyes with short axial lengths. We hypothesize that SRK II, SRK-T and Holladay I tend to underestimate effective lens position in eyes with short axial lengths indicating Hoffer Q formula is more accurate.
Subject(s)
Humans , Cataract , Lenses, Intraocular , Retrospective StudiesABSTRACT
PURPOSE: To investigate the accuracy of biometry and intraocular lens (IOL) power calculation using partial coherence interferometry (IOL Master(R)) in highly myopic patients with axial lengths of 26 mm or greater. METHODS: Patients with axial lengths equal to or greater than 26 mm who had undergone cataract surgery were enrolled. IOL power was calculated using IOL Master and/or applanation ultrasonography with the SRK/T formula. Twenty-seven eyes using both IOL Master and applanation ultrasonography were included in a paired group, and forty-eight eyes using the IOL Master only and twenty-five eyes using applanation ultrasonography only were included in unpaired groups. The differences between the predicted refraction and the actual refraction were compared and analyzed. RESULTS: In the paired study, the axial lengths in patients using IOL Master (29.14+/-2.32 mm) were significantly longer than those of patients using applanation ultrasonography (28.57+/-2.23 mm) (p0.05). In the unpaired study, the MAEs of the IOL Master and applanation ultrasonography groups were 0.61+/-0.61D and 0.65+/-0.63D, respectively. CONCLUSIONS: In eyes with axial lengths of 26.0 mm or greater, the accuracy of IOL power calculation with IOL Master using the SRK/T formula was comparable to that with applanation ultrasonography.
Subject(s)
Humans , Biometry , Cataract , Eye , Interferometry , Lenses, Intraocular , MyopiaABSTRACT
PURPOSE: To report a new method for measuring corneal refractive power after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) using the Orbscan(R) and autorefractokeratometer. METHODS: This study involved 12 cases that had undergone cataract surgery after corneal refractive surgery. Five cases had PRK and seven had LASIK. Keratometric values were evaluated with three different methods. The first, defined as RK, used an autorefractokeratometer (AK) (n=1.3375). The second, defined as K1, added the posterior surface diopter using AK and anterior surface diopter using an Orbscan. The last, defined as K2, added the posterior surface diopter and the anterior surface diopter using an Orbscan. Low K was a lower value between K1 and K2. RK, K1, K2 and Low K were compared with the back-calculated K value (Real K) 2 months after cataract surgery. RESULTS: The mean differences between RK, K1, K2, Low K and Real K were 3.08 +/- 0.98D, 0.41 +/- 0.66D, 0.27 +/- 0.77D, and -0.02 +/- 0.53D, respectively. In 9 of the 12 patients the difference was within 1D (75%) when either K1 or K2 was selected and in all patients, the difference between Low K and Real K was within 1D. CONCLUSIONS: The method of IOL calculation using Low K showed more accurate and predictable results in patients who had had cataract surgery after corneal refractive surgery.