Первый опыт клинического применения оптического биометра Argos. Сравнительная оценка биометрических показателей и расчетов интраокулярных линз на двух SS-OCT биометрах

To correlate intraoperative aphakic autorefraction to conventional emmetropic intraocular lens (IOL) calculations and derive an empiric predictive model for IOL estimation based on optical refractive biometry without axial length and keratometry measurements. Institutional Review Board of the University of Southern California, Los Angeles County General Hospital, Los Angeles, California, USA. A pilot group of 22 eyes of 22 patients scheduled for cataract surgery were enrolled in a prospective trial. All patients had a standard preoperative workup with subsequent cataract extraction and IOL implantation according to conventional biometric measurements and IOL calculations. Intraoperative autorefractive retinoscopy was used to obtain aphakic autorefraction and to measure the aphakic spherical equivalent before lens implantation. A linear regression analysis was used to correlate the aphakic spherical equivalent to the final adjusted emmetropic IOL power to empirically derive a refractive formula for IOL calculation (optical refractive biometry method). A second validation series of 16 eyes was used in a head-to-head comparison between the optical refractive biometry and the conventional IOL formulas. A subset of 6 eyes from the validation series were post-refractive cases having subsequent cataract surgery. Intraoperative retinoscopic autorefraction was successfully obtained in all 22 patients in the pilot group and all 16 patients in the validation group. The spherical equivalent of the aphakic autorefraction correlated linearly with the final adjusted emmetropic IOL power (P<.0001, with adjusted r(2)=.9985). The relationship was sustained over an axial length range of 21.43 to 25.25 mm and an IOL power range of 12.0 to 25.5 diopters (D). In a subsequent validation series of 10 standard and 6 post-laser in situ keratomileusis (LASIK) cataract cases, the optical refractive biometry method proved to be a better predictive model for IOL estimation than conventional formulas; 83% of the LASIK eyes and 100% of the normal eyes were within +/-1.0 D of the final IOL power when aphakic autorefraction was used, compared with 67% of LASIK eyes and 100% of the normal eyes, using the conventional methodology. A new model for IOL power calculation was derived based on an optical refractive methodology that breaks away from the conventional art introduced by Fyodorov in the 1960s. A purely refractive algorithm is used to predict the power of the IOL at the time of surgery without the need for axial length and keratometry measurements. This method bypasses some limitations of conventional biometry and shows promise in the post-refractive cataract cases.

To assess changes in ocular biometry of the phakic eye after pars-plana-vitrectomy (PPV) and silicone oil (SO) endotamponade in eyes with a retinal detachment. This retrospective, consecutive case series included 72 eyes of 72 patients who underwent PPV with 5000-centistokes SO endotamponade between July 2018 and June 2023. Pseudophakic eyes and eyes with a combined phacovitrectomy were excluded. Primary endpoints were keratometry values, anterior chamber depth (ACD), lens thickness (LT), horizontal corneal diameter (HCD), and axial length (AL) measured by swept-source optical coherence tomography-based biometry (IOLMaster 700) preoperatively and six weeks postoperatively. A recently described formula was used to adjust the AL (aAL) in eyes with SO endotamponade and a theoretical intraocular lens (IOL) calculation was performed. The mean age was 62.1 ± 8.3 years (range: 37-85). After PPV with SO fill, there was an increase in Kmean (0.19 ± 0.51D), while ACD (0.05 ± 0.13 mm), LT (0.03 ± 0.14 mm), and HCD (0.02 ± 0.24 mm) decreased. Preoperatively, the mean AL was 25.22 ± 1.78 mm, while postoperatively the AL was overestimated by 0.12 ± 0.42 mm on average (p = 0.04). By adjusting the AL, the mean difference could be reduced to -0.002 ± 0.41 mm. The aAL resulted in a difference in the refractive outcome in eyes with an AL > 25 mm of 0.34 ± 0.10D in the IOL calculation. While changes in biometry after PPV with SO endotamponade in the anterior segment are clinically less relevant, a considerable overestimation of AL with IOLMaster 700 was found. We recommend the use of a recently introduced formula for adjusting AL in eyes with SO, allowing overestimation to be minimised considerably.

Bilateral congenital cataract is the most common cause of treatable childhood blindness. Nuclear cataract is usually present at birth and is non-progressive, while lamellar cataract usually develops later and is progressive. Prompt surgery has to be performed in cases with dense congenital cataract: if nystagmus has developed, the amblyopia is unfortunately irreversible. A treatment regime based on surgery within 2 months of life, combined with prompt optical correction of the aphakia and occlusion therapy with frequent follow-up, have been successful in both unilateral and bilateral cases. The surgery ought to include anterior and posterior capsulorexis in all children at the present time. Intraocular lens implantation has been safely performed below the age of 1 year and has also been successfully performed in bilateral cases. Anterior dry vitrectomy should be performed in preschool children to avoid visual axis opacification. Visual axis opacification is the most common complication found after cataract surgery in children. Secondary glaucoma is by far the most sight-threatening complication and is, unfortunately, common in the newborn so lifelong follow-up is essential in these cases.

Comparison of refractive outcomes obtained with two swept-source OCT-based optical biometers after cataract surgery: A study of 152 eyes

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.

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Aim: The aim of this study is to determine the agreement between applanation ultrasound biometry (AUB) and optical biometry using Lenstar 900 for precataract surgery axial length measurement and intraocular lens (IOL) power estimation and their effect on postoperative refractive outcomes. Methods: A case record-based retrospective study of 229 eyes which underwent phacoemulsification with foldable IOL, in a private hospital setting was done. All the eyes were evaluated using AUB and optical biometry for IOL power prediction. The IOL power was chosen based on the optical biometry and the final refraction was used to calculate the prediction error (PE) for both optical and ultrasound biometry. The concordance coefficient and Bland Altman's limits of agreement were determined to examine the disagreement between the two technologies. Results: The mean axial length ± standard deviation (SD) in the study eyes by ultrasound was 23.46 ± 1.01 mm and 23.57 ± 0.99 mm by optical biometry (P = 0.19). The axial length of 4.37% of eyes could not be measured by optical biometry. The mean IOL power prediction ± SD in the study eyes by ultrasound was 20.98 ± 2.68 D and 20.89 ± 2.85 D by optical biometry (P = 0.72). The mean ± SD absolute value of the refractive PE was − 0.32 ± 0.44 D (median − 0.25, interquartile range: −0.75–0). All eyes achieved a postoperative visual acuity of 6/18 or better including 204 (89.87%) that had a visual acuity of 6/6. One hundred and sixty-four eyes (71.62%) eyes had a postoperative spherical equivalent of 0 to ± 0.5D at 30 days. Two hundred and twenty eyes (96.07%) had a postoperative spherical equivalent of 0 to ± 1.0 D. Conclusions: The findings of the study prove that carefully done AUB is comparable to optical biometry and should not be a deterrent in providing the best possible refractive outcomes in a majority of our cataract patients. To ensure that these results are replicable on a wider scale will necessitate adequate training of personnel in the art and science of biometry.

Background: Precise biometry is one of the major key factors for obtaining desired refractive outcome after cataract surgery. Visual outcome strongly depends on accuracy of ocular parameters especially axial length (AL) and anterior chamber depth (ACD). It is very important to evaluate different biometry methods to have accurate measurements for IOL power calculation.&#x0D; Objective: The aim of the study is to compare and analyze the difference between the measurement of axial length (AL) and anterior chamber depth (ACD) using ultrasound applanation, immersion and optical biometry.&#x0D; Methodology: A prospective study conducted on 168 patients enrolled for cataract surgery from January 2018 to December 2018 in Dhaka Eye Care Hospital, Dhaka. 280 eyes have been tested by a single observer. Axial length (AL) and anterior chamber depth (ACD) was measured consecutively by optical, applanation and immersion biometry. The results have been statistically evaluated to establish efficacy and correlation among the three methods of biometry.&#x0D; Results: Statistical analysis showed the mean of axial length (AL) obtained from optical biometry is 23.36 ± 1.99 mm, which is 0.10mm (p=0.00) less by applanation biometry and 0.04 mm (p=0.00) less by immersion biometry. For anterior chamber depth (ACD), the mean value from optical biometry is 3.13 ± 0.47mm. This value is highest in compare to both applanation (0.002 mm less with p = 0.824) and immersion (0.04 mm less with p = 0.00) biometry. Further analysis reveals strong correlation of optical biometry with applanation biometry (r = 0.994 for AL and 0.945 for ACD) and immersion biometry (r = 0.995 for AL and 0.947 for ACD).&#x0D; Conclusion: The study reveals that among optical, applanation and immersion method the optical biometry method appeared to be the most precise way of measuring axial length (AL) and anterior chamber depth (ACD) of eye. The study also shows an excellent agreement and strong positive correlation of optical biometry with applanation and immersion biometry.&#x0D; J Shaheed Suhrawardy Med Coll, June 2019, Vol.11(1); 59-64

To analyse the impact of ultrasound and optical intraocular lens (IOL) calculation methods on refractive outcomes of cataract phacoemulsification performed after penetrating keratoplasty (PK) in keratoconus. Phacoemulsification cataract surgery was performed on 42 eyes of 34 patients with keratoconus who had previously undergone PK. The IOL power was determined by using both standard and corneal topography-derived keratometry using the SRK/T formula. We used two independent methods-ultrasound biometry (UB) and interferometry [optical biometry (OB)] for IOL calculation. The analysed data from medical records included demographics, medical history, best corrected visual acuity (BCVA) on Snellen charts, technique of IOL calculation and calculation formula and its impact on final refractive result. BCVA ranged from 0.01 to 0.4 (mean 0.09±0.19) before surgery and ranged from 0.2 to 0.7 (mean 0.38±0.14) at 1mo and from 0.2 to 1.0 (mean 0.56±0.16) (P<0.05) at 3mo, postoperatively. The refractive aim differed significantly from the refractive outcome in both the UB and OB groups (P<0.05). There was no statistically significant difference in the accuracy of the two biometry methods. The refractive aim in keratoconus eyes post-PK is not achieved with either ultrasound or OB.

To assess the accuracy of axial length (AXL) measurements using two swept-source optical coherence biometers, IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany) and ARGOS (Alcon, Inc. Fort Worth, TX), for macula-off rhegmatogenous retinal detachment (RRD). This retrospective study included 100 eyes with phakic primary macula-off RRD. Preoperative AXL measurements were performed using different methods: applanation A-scan ultrasound (U/S) biometry, combined applanation vector A/B-scan biometry, and optical biometry measurements were obtained using IOLMaster 700 (Carl Zeiss, Meditec, Jena, Germany) and ARGOS (Alcon, Inc. Fort Worth, TX). All patients underwent pars plana phacovitrectomy. At 8-10weeks postoperatively, optical biometry was performed to record AXL. Mean preoperative AXL measured using vector-A/B-scan ultrasonography was higher than that of postoperative AXL measured using IOLMaster (p < 0.05). Mean AXL measured by the standard mode of the ARGOS optical biometer was lower than mean AXL measured by both enhanced retina visualization (ERV) mode and user-adjusted method (p < 0.05). Mean same-eye AXL measured using IOLMaster was lower than that measured using ARGOS (p < 0.05). The least difference was observed with combined vector-A/B-scan ultrasound (on the positive side), followed by fellow eye AXL measured using IOLMaster optical biometry (on the negative side). Optical biometry of fellow eye in macula-off RRD was noted to be highly correlating with postoperative optical biometry of same eye using IOL Master 700 in eyes without anisometropia. IOLMaster 700 showed less accuracy in the AXL measurements for same eye. The ARGOS optical biometer may have a good potential for measuring same eye AXL. Using ERV mode or a user-adjusted method for the ARGOS optical biometer may improve accuracy of AXL measurements. Most accurate method for measuring AXL in same eye was vector-A/B-scan ultrasound.

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. 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. 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%). 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.

Intraocular Lens Calculations

Purpose: To assess the refractive outcome of optical biometry (Nidek AL-scan) after elective phacoemulsification in a study of 30 eyes.&#x0D; Study Design: Descriptive case series.&#x0D; Place and Duration of Study: Elective cataract surgeries done at a private clinic from July 2015 to June 2016 were selected and their records were analyzed.&#x0D; Material Methods: The measurements of IOL calculation was done using optical biometry with partial coherence interferometry (Nidek AL-scan) that provides information about axial length, central keratometry, white to white diameter and anterior chamber anatomical depth. SRK-T formula was used to calculate IOL power. All patients underwent a complete ophthalmological examination. Phacoemulsification with clear corneal incision of 2.75 mm was done and IOL was implanted in the bag (Alcon Acrysof SN60WF IOL and MA60AC IOL). Post-operative refraction was taken with autorefractor (Huvitz HRK-7000) after 4 weeks and it was compared with pre-operative objective refraction. Comparison of K readings taken by AL-scan and autorefractor were done.&#x0D; Results: We studied 30 eyes of 23 patients who underwent elective cataract surgery with foldable IOL. Post-operative spherical equivalent was plano in 53% of cases with mean of -0.05 after 4 weeks postoperatively. The mean keratometric power using autorefractor was 44.4 D while with AL-scan it was 44.7 D. There were no intraoperative complications or postoperative subjective complaints (such as halo or glare) in our patients.&#x0D; Conclusion: Intraocular lens power calculations done by optical biometry are easy to use, reliable and result in excellent refractive outcomes. Ultrasound biometry may still be required in case of mature and dense posterior subcapsular cataract.

Introduction: The evolution of modern technologies for cataract surgery has made it crucial for aiming emmetropia with highly defined vision. The key factor responsible for postoperative emmetropia is an accurate biometry, along with various other factors. Ultrasonic biometry is the gold standard method of Intraocular Lens (IOL) power calculation but the corneal indentation with the probe underestimate the axial length and result in a myopic shift which is overcome by the newer optical biometry devices, including swept source optical coherence biometry which uses infrared light to measure the ocular distances. Aim: To determine the precision and accuracy of IOL power calculation by ultrasound A-scan and optical IOL master and their refractive outcomes. Materials and Methods: This prospective, and observational study was conducted between September 2019 to February 2021 in 155 patients with cataract undergoing phacoemulsification in Kalinga Institute of Medical Sciences, KIIT University, Bhubaneswar, Odisha, India. All subjects underwent comprehensive ocular examination and biometry with two formulae {Sanders-RetzlaffKraff (SRK) and Holladay-I}. Biometry included corneal curvature (keratometry), axial length, anterior chamber depth, IOL power calculation, predicted refractive error. There were two broad groups. One group underwent biometry by ultrasound A-scan and the other group underwent optical biometry by IOL Master 700. The IOL power was calculated with the two formulae in both the groups. Comparisons between variables measured using the IOL master and A-scan were done using paired t-test. The p-values &lt;0.05 were considered statistically significant. Results: In a 18 month period, 155 eyes were consecutively enrolled in the study. The mean age of all enrolled patients was 62.1±8.65 years (range 34-80 years) with male:female ratio of approximately 1.25:1. The mean axial length measured by IOL master was higher (23.15 ± 0.85) than that by A-scan (22.96±0.81 diopters) with a mean difference of 0.197±0.35 mm (p-value &lt;0.001, paired t-test). The mean predicted IOL power was 20.81±1.84 diopters by IOL master and 21.13±1.62 by A-scan by SRK-II formula (p-value &lt;0.001). While mean predicted IOL power with Holladay-I by IOL Master 700 was 20.61±1.92 and 21.44±1.98 diopters by A-scan with a mean difference (-0.82±0.76 diopters) with a significant p-value &lt;0.001. Bland-Altman analysis plots showed almost perfect agreement between both methods regarding predicted IOL power. Conclusion: The swept source Optical Coherence Tomography (OCT) based IOL master 700 proved to be a faster non contact device to use with a shorter learning curve, higher accuracy in average axial length eye and less refractive surprises.

To evaluate differences in preoperative measurements and refractive outcomes between ultrasound and optical biometry when using the Barrett Universal II intraocular lens (IOL) power formula. In this consecutive case series, cataract extraction and IOL implantation cases from two surgical centers in Toronto, Canada, were recruited between January 2015 and July 2017. Differences between ultrasound (applanation or immersion A-scan) and optical biometry (IOLMaster 500) were compared for axial length (AL), anterior chamber depth and refractive outcomes. The primary outcome was the percentage of cases in each cohort within ± 0.50D of refractive error. In total, 527 cataract cases underwent IOLMaster testing. Of these, 329 eyes (62.4%) were also measured by applanation A-scan, and the other 198 eyes (37.6%) received immersion A-scan testing. Applanation ultrasound led to 5.8%, 16.0% and 46.4% of eyes within ± 0.25D, ± 0.50D and ± 1.00D of refractive error, respectively, whereas the IOLMaster 500 led to 48.5%, 77.1% and 94.9%, respectively (n = 293, ± 0.50D: p < 0.001). Immersion ultrasound led to 31.2%, 57.6% and 91.2% of eyes within ± 0.25D, ± 0.50D and ± 1.00D of refractive error, respectively, whereas the IOLMaster 500 led to 42.4%, 72.0% and 92.0%, respectively (n = 125, ± 0.50D: p = 0.001). Applanation (n = 329, A-scan AL: 23.64 ± 1.67mm, IOLMaster AL: 24.20 ± 1.70mm, p < 0.001) and immersion ultrasound (n = 198, A-scan AL: 25.01 ± 2.06mm, IOLMaster AL: 25.08 ± 2.13mm, p = 0.002) yielded significantly lower AL values compared to optical biometry measurements. Optical biometry yielded a significantly larger percentage of cases within ± 0.50D of refractive error compared to ultrasound biometry when using the Barrett Universal II IOL power formula.