Ocular biometry in dense cataracts: Comparison of partial-coherence interferometry, swept-source optical coherence tomography and immersion ultrasound

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

Change in Axial Length in Highly Myopic Adults Using Partial Coherence Interferometry

PURPOSE: To investigate the change in axial length (AL) in highly myopic adults using partial coherence interferometry, and to identify the factors associated with the increase in AL. METHODS: Medical records of highly myopic adults (≥ −6 diopters [D] or AL ≥ 26.0 mm) were retrospectively reviewed. The AL of each patient was measured using partial coherence interferometry at least three times over 2 years, and the yearly change in AL was calculated. Associations between age, AL, choroidal thickness, and the rate of AL change were evaluated using multiple regression analysis. RESULTS: In total, 24 patients (4 males, 20 females) and 44 eyes were included in this study. The mean age was 54.9 ± 10.4 years, the initial AL was 29.335 ± 2.006 mm, the choroidal thickness was 72.7 ± 41.80 µm, the average spherical equivalent was −11.86 ± 3.85 D (−5.1~−22.0 D), and the mean follow-up period was 2.2 ± 0.5 years. A significant increase in AL of ≥0.05 mm was observed in 38 eyes (86.4%) at 2 years. The mean AL was significantly increased, to 29.409 ± 2.007 mm (p < 0.001), at 1 year and to 29.476 ± 2.028 mm (p < 0.001) at 2 years. The average rate of AL change was 0.071 ± 0.049 mm (−0.01~0.19 mm) per year. None of the included factors showed an association with the rate of AL change in multiple regression analysis. CONCLUSIONS: In this study, an increase in AL in highly myopic adults was more frequent than in previous reports using A-scan. Periodic measurements are therefore recommended for the early detection of complications.

Comparison of Intraocular Lens Calculation Formulas Measured by Immersion-Type A-Scan Ultrasound and Partial Coherence Interferometry

PURPOSE: To report the accuracy of intraocular lens (IOL) formulas according to axial length, anterior chamber depth, and mean corneal curvature when performing biometry with an immersion type A-scan with mannual keratomery and an IOL Master®. METHODS: Retrospective medical chart reviews were carried out for 82 eyes of 65 patients who underwent cataract surgery performed by a single surgeon. Biometry was performed using IOL Master®, mannual keratometry, and immersion type A-scan ultrasound in sequence. Prediction diopter was obtained using Sanders-Retzlaff-Kraff/Theoretical (SRK-T) and Holladay 1 formulas calculated with the biometric value measured by mannual keratomery and A-scan, and using SRK-T and, Holladay 2 formulas with IOL Master®. The final refractive outcome was determined as manifested refraction at least 7 weeks after the surgery, and it was compared with the preoperative prediction dipoter (D) of the IOL formulas. RESULTS: Mean axial length and mean keratomtric measurements as determined by A-scan with mannual keratomery showed significant statistical differences from those of IOL Master®. However, there was no difference in postoperative mean absolute error between biometric measurements, or among formulas according to axial length, anterior chamber depth, or mean corneal curvature. However, the percentage of actual refraction within ±0.50 D of the intended refraction was dirrerent among the four formalas according to axial length, anterior chamber dept, mean corneal curvature. CONCLUSIONS: Biometry measurement using the immersion-type A-scan with mannual keratomery is as accurate as that using IOL Master® for predicting the postoperative refractive state of cataract surgery. However, it is suggested that the best IOL formula be chosen according to axial length, anterior chamber depth, and mean corneal curvature.

Comparison of Ocular Biometry and Postoperative Refraction in Cataract Patients between Galilei-G6(R) and IOL Master(R)

PURPOSE: To compare the axial lengths, anterior chamber depths, and keratometric measurements and to predict postoperative refractions of Dual Scheimpflug analyzer Galilei G6(R) and intra ocular lens (IOL) Master(R). METHODS: A total of 50 eyes in 50 patients who received cataract surgery were included in the present study. The axial length, anterior chamber depth, and keratometry were measured using 2 types of partial coherence interferometries (Galilei G6(R) and IOL Master(R)). The SRK/T formula was used to calculate IOL power and the predictive error which subtracts predictive refraction from postoperative refraction was compared between the ocular biometry devices. RESULTS: Axial lengths were 23.36 +/- 0.80 mm and 23.36 +/- 0.90 mm measured by Galilei G6(R) and IOL Master(R), respectively. Axial length measured by Galilei G6(R) was not statistically significant compared with IOL Master(R) (p = 0.321). The anterior chamber depth and keratometry were 3.22 +/- 0.35 mm and 44.29 +/- 1.40 D measured by Galilei G6(R) and 3.11 +/- 0.46 mm and 44.39 +/- 1.41 D measured by IOL Master(R), respectively. The differences of anterior chamber depth and keratometry between the 2 devices were statistically significant (p < 0.001 and p = 0.028, respectively). The mean absolute prediction errors were 0.45 +/- 0.37 D and 0.49 +/- 0.39 D in Galilei G6(R) and IOL Master(R), respectively and was not statistically significantly different (p = 0.423). CONCLUSIONS: The ocular biometric measurements and prediction of postoperative refraction using Galilei G6(R) were as accurate as with IOL Master(R).

Comparison of two optical biometers in intraocular lens power calculation.

Aims: To compare the consistency and accuracy in ocular biometric measurements and intraocular lens (IOL) power calculations using the new optical low‑coherence reflectometry and partial coherence interferometry. Subjects and Methods: The clinical data of 122 eyes of 72 cataract patients were analyzed retrospectively. All patients were measured with a new optical low‑coherence reflectometry system, using the LENSTAR LS 900 (Haag Streit AG)/ALLEGRO BioGraph biometer (Wavelight., AG), and partial coherence interferometry (IOLMaster V.5.4 [Carl Zeiss., Meditec, AG]) before phacoemulsification and IOL implantation. Repeated measurements, as recommended by the manufacturers, were performed by the same examiner with both devices. Using the parameters of axial length (AL), corneal refractive power (K1 and K2), and anterior chamber depth (ACD), power calculations for AcrySof SA60AT IOL were compared between the two devices using five formulas. The target was emmetropia. Statistical analysis was performed using Statistical Package for the Social Sciences software (SPSS 13.0) with t‑test as well as linear regression. A P value < 0.05 was considered to be statistically significant. Results: The mean age of 72 cataract patients was 64.6 years ± 13.4 [standard deviation]. Of the biometry parameters, K1, K2 and [K1 + K2]/2 values were significantly different between the two devices (mean difference, K1: −0.05 ± 0.21 D; K2: −0.12 ± 0.20 D; [K1 + K2]/2: −0.08 ± 0.14 D. P <0.05). There was no statistically significant difference in AL and ACD between the two devices. The correlations of AL, K1, K2, and ACD between the two devices were high. The mean differences in IOL power calculations using the five formulas were not statistically significant between the two devices. Conclusions: New optical low‑coherence reflectometry provides measurements that correlate well to those of partial coherence interferometry, thus it is a precise device that can be used for the pre‑operative examination of cataract patients.

Accuracy of Ocular Biometry and Postoperative Refraction in Cataract Patients with AL-Scan(R)

PURPOSE: To compare the axial lengths, anterior chamber depths, and keratometric measurements and to predict postoperative refractions of AL-Scan(R), IOL master(R), and ultrasound. METHODS: A total of 40 eyes in 30 patients who received cataract surgery were included in the present study. The axial length, anterior chamber depth, and keratometry were measured by 2 types of partial coherence interferometry (AL-Scan(R) and IOL master(R)) and ultrasound. The SRK/T formula was used to calculate IOL power, and the predictive error which subtracts predictive refraction from postoperative refraction was compared among the ocular biometry devices. RESULTS: Axial lengths were 23.08 +/- 0.62 mm, 23.09 +/- 0.62 mm, and 22.99 +/- 0.62 mm measured by AL scan(R), IOL master(R), and ultrasound, respectively. Axial length measured by ultrasound was statistically significantly shorter than AL scan(R) and IOL master(R) (p < 0.001, p < 0.001, respectively). The anterior chamber depth and keratometry were 3.11 +/- 0.06 mm and 44.82 +/- 1.34 D measured by AL scan(R), and 3.13 +/- 0.06 mm and 44.85 +/- 1.26 D measured by IOL master(R), respectively. The differences of anterior chamber depth and keratometry between the 2 devices were not statistically significant (p = 0.226, p = 0.331, respectively). The mean absolute prediction errors were 0.44 +/- 0.35 D, 0.40 +/- 0.34 D, and 0.39 +/- 0.30 D in AL-Scan(R), IOL master(R) and ultrasound, respectively, and were not statistically significantly different (p = 0.843, p = 0.847, p = 1.000, respectively). CONCLUSIONS: The ocular biometric measurements and prediction of postoperative refraction using AL-Scan(R) were as accurate as IOL master(R) and ultrasound.

Comparison of White-to-White Diameters Measured by IOLMaster, Lenstar, Orbscan, and a Manual Method

PURPOSE: To compare and evaluate device efficacy using white-to-white (WTW) diameter measurements by IOLMaster(R), Lenstar(R), Orbscan II(R), and a manual method with anterior segment photographs in normal eyes. METHODS: Three sets of WTW diameter measurements were obtained from 62 normal eyes of 31 patients, using the Orbscan II(R), Lenstar(R), IOLMaster(R), and a manual method with anterior segment photographs. Repeatability of each device was evaluated by coefficient of variation. ANOVA and Pearson's correlation were used to compare the differences among the devices. Bland Altman plot was performed to assess measurement agreement among the devices. RESULTS: The mean WTW distance was 11.79 +/- 0.46 mm with Orbscan II(R), 12.05 +/- 0.38 mm with Lenstar(R), 12.15 +/- 0.36 mm with IOLMaster(R), and 12.30 +/- 0.40 mm with a manual method. There were significant differences in the results among the methods (ANOVA, p 0.8, p < 0.05). The coefficient of variation of Orbscan II(R) was larger than those of Lenstar(R) and IOLMaster(R). CONCLUSIONS: The WTW measurement using Orbscan II(R) has low correlations with other devices and lower repeatability. Our findings suggest that partial coherence interferometry should be considered as a new standard.

Efectividad del cálculo del poder dióptrico de la lente intraocular con interferometría parcialmente coherente / Effectiveness of the intraocular lens power calculation using the partial coherent interferometry

OBJETIVO: Comparar la efectividad del cálculo del poder dióptrico de la lente intraocular con IOL Master y el método de biometría por aplanación convencional. MÉTODOS: Se seleccionó una muestra de 100 ojos (pacientes) mediante un muestreo simple aleatorio, en el Servicio de Catarata del Centro de Microcirugía Ocular, con diagnóstico de catarata unilateral o bilateral en la consulta preoperatorio, desde marzo hasta septiembre de 2006. Se clasificaron en dos grupos según el método utilizado para el cálculo de la lente intraocular. Se analizaron las variables: longitud axial media preoperatoria, promedio queratométrico preoperatorio, componente esférico esperado y obtenido, agudeza visual sin corrección y mejor agudeza visual corregida preoperatoria y posoperatoria. El análisis estadístico de los resultados se realizó mediante un análisis de varianza, la prueba t de Student de comparación de medias para datos pareados y chi cuadrado. Se utilizó un nivel de confiabilidad de 95 por ciento. RESULTADOS: Entre los principales resultados se encontró que la diferencia de las longitudes axiales entre los métodos IOL Master y biometría por aplanación A-Scan fue estadísticamente significativa. La agudeza visual sin corrección aumentó cuatro líneas y la mejor agudeza visual corregida seis líneas en el posoperatorio de los pacientes del grupo I. El 90 por ciento de los pacientes del grupo I, o sea, los calculados con IOL Master quedaron en la emetropía en cuanto al componente esférico. CONCLUSIONES: Se evidenció una diferencia significativa e inferior a la encontrada en estudios internacionales entre las longitudes axiales preoperatorias halladas mediante los métodos IOL Master y biometría por aplanación; resultaron superiores las calculadas por IOL Master. Se obtuvo ganancia en las líneas de la Cartilla de Snellen tanto de la agudeza visual sin corrección como la mejor agudeza visual corregida en ambos grupos (superior en el grupo II). Predomina ron los resultados refrac...

OBJECTIVE: to compare the effectiveness of the intraocular lens dioptric power calculation using IOL Master and the conventional applanation biometry. METHODS: A sample of 100 eyes (patients), diagnosed with unilateral or bilateral cataract in the preoperative consultation service, was selected through simple random sampling in the Ocular Microsurgery Center in the period from March to September, 2006. They were divided into two groups based on the method for intraocular lens calculation. The variables were preoperative mean axial length, preoperative keratometric average, expected and obtained spheral component, visual acuity without correction and better corrected visual acuity preoperatively and postoperatively. The statistical analysis of the results was made by variance analysis, Student's t test for paired mean comparisons and Chi square. The confidence level of 95 percent was used. RESULTS: Among the main results, it was found that the axial length differences between IOL Master and A-Scan applanation biometry was statistically significant. Visual acuity without correction increased 4 lines and the best corrected visual acuity increased 6 lines in the postoperative period of the group I patients. Ninety percent of the group I patients, whose visual acuity was calculated with IOL Master, reached emetropia in terms of the spheral component. CONCLUSIONS: A significant difference but lower than that found in the international studies among the preoperative axial lengths calculated through ILO Master and applanation biometry were evinced. The differences were higher in the lenghts calculated by IOL Master. There was improvement in the number of lines of Snellen´s chart both in the visual acuity without correction and the better corrected visual acuity in the two groups; being better in group II. The refractive results tending to emetropy prevailed, taking into consideration the spheral component reached in both groups, which were also higher in group I

Refractive Predictability of Partial Coherence Interferometry and Factors that can Affect It

PURPOSE: To evaluate the refractive predictability of a partial coherence interferometry (PCI) biometry device (IOL Master(R)) for cataract surgery and to investigate factors that may affect it. METHODS: Retrospective review of 209 eyes from 151 patients that had undergone preoperative PCI biometry and an uneventful phacoemulsification cataract surgery with posterior chamber intraocular lens (IOL) implantation was conducted. Prediction error defined as the intended refraction minus the postoperative refraction in spherical equivalent (SE) and the absolute error were analyzed according to IOL calculation formulas, patient characteristics, preoperative visual acuity (VA) and refraction, posterior subcapsular cataract (PSC), signal-to-noise ratio (SNR), and axial length (AL). RESULTS: The overall refractive predictability of the PCI device was good. Generally, the SRK/T formula performed better than the SRK-II formula. Refractive predictability was slightly worse in eyes with > or =+2.0 diopters (D) of preoperative SE (with both SRK-II and SRK/T) and in eyes with an AL or =+2.0D was related to a significantly greater hyperopic shift in postoperative refraction. With proper verification of measured data and a suitable IOL calculation formula, good refractive predictability is expected from PCI biometry regardless of patient characteristics, preoperative VA, SNR, PSC, and AL.

The Reproducibility and Accuracy of Biometry Parameter Measurement from IOL Master(R)

PURPOSE: To evaluate the reproducibility and accuracy of axial length and anterior chamber depth measurements from IOL Master(R). METHODS: The axial length and anterior chamber depth measurements in 30 eyes with normal crystalline lens, 30 eyes with cataract and 30 pseudophakic eyes were measured by two practitioners using IOL Master(R) followed by A-scan and Orbscan II. The reproducibility of IOL Master(R) was analyzed by comparing the results from the first and second practitioners. To evaluate the accuracy of IOL Master(R), the axial length was compared to A-scan and the anterior chamber depth was compared to A-scan and Orbscan II. RESULTS: The difference between the axial length and anterior chamber depth measurements from the two practitioners using IOL Master(R) were not statistically significant (p>0.05). The axial length of measurement from IOL Master(R) was 0.16 mm, 0.18 mm, and 0.96 mm longer than that from A-scan, in the normal, cataract and pseudophakic groups, respectively. In addition, the anterior chamber depth measurement from IOL Master(R) was significantly deeper than that from A-scan and Orbscan II (p<0.05). CONCLUSIONS: There was good reproducibility and accuracy of axial length and anterior chamber depth measurements from IOL Master(R). However, some patients who had media opacity were not measured using IOL Master(R). It is a noncontact method, which provides an alternative to A-scan.

The Accuracy of Axial Length Measurement Using Partial Coherence Interferometrys

PURPOSE: IOLMaster(R), a non-contact device using partial coherence interferometry, serves as a new optical method for axial length determination. The accuracy of this device was analyzed by comparing the measurements from IOLMaster(R) and A-scan. METHODS: We measured the axial lengths in 150 eyes of 80 patients with IOLMaster(R) and A-scan. Then, we examined the difference of measurements between the IOLMaster(R) and A-scan according to the patients' age, refractive error, type of cataract, and existence of cataract. RESULTS: Axial length could not be measured with IOLMaster(R) in 12 eyes, which all had severe cataract. The measurements from IOLMaster(R) in both, the cataract group and the normal group, resulted 0.02mm longer than those from A-scan, but did not differ significantly (p>0.1). Also, there was no statistical difference of measurements between IOLMaster(R) and A-scan according to the patients' age, refractive error, and types of cataract (p>0.05). CONCLUSIONS: Axial length measurement with IOLMaster(R) shows no significant difference from A-scan measurement. Therefore, IOLMaster(R) can be a new clinical method of axial length measurement except for cases of a severe cataract.

Comparison of IOL Master, A-scan and Orbscan II for Measurement of Axial Length and Anterior Chamber Depth

PURPOSE: The purpose of the study was to compare IOL Master, A-scan and Orbscan about axial length(AL) and anterior chamber depth(ACD) measurement for IOL power calculation. METHODS: We evaluated AL and ACD using the IOL Master, A-scan and Orbscan. The subjects included were cataractous 66 eyes, pseudophakic 31 eyes, refractive surgery 24 eyes, keratoconus and keratoplasty 9 eyes. The AL length was measured with the non-contact optical biometry(IOL Master) and contact biometry (A-scan). The dirrerences in anterior chamber depth were compared among the aforementioned two methods and optical Orbscan. RESULTS: The average AL of 64 eyes of cataract patients was 23.85+/-1.88 mm in IOL Master and 23.76+/-1.78 mm in A-scan. There was no statistically significant difference(p>0.05). The mean ACD was 3.04+/-0.51 mm with IOL Master, 2.87+/-0.76 mm with A-scan and 3.09+/-0.54 mm with Orbscan. The differences among the methods weren't statistically significant(p>0.05) but ACD of A-scan were measured shorter than ones in IOL Master and Orbscan. Two eyes were unable to be examined by IOL Master due to the dense cataract. The ACD between IOL Master and A-scan was significantly different in pseudophakic eyes(p0.05). CONCLUSIONS: The AL and ACD using IOL Master with non-contact and easy method in comparison A-scan, Orbscan weren't significantly different in cataract, refractive surgery, keratoconus and kelatoplasty. And the ACD of pseudophakic eye measured with IOL Master was better than A-scan. But the AL of some patients who had mature cataract weren't measured using IOL Master.