OBJECTIVE: 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.
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%).
CONCLUSIONS: 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.
UNASSIGNED: Оценка точности современных формул расчета интраокулярных линз (ИОЛ) с использованием данных о длине переднезадней оси (ПЗО), полученных при ультразвуковой биометрии (УЗБ), по сравнению с калькулятором третьего поколения SRK/T.
UNASSIGNED: В исследование включено 230 пациентов (267 глаз) с выраженными помутнениями хрусталика, препятствовавшими выполнению оптической биометрии, которым была проведена факоэмульсификация (ФЭ) с имплантацией ИОЛ. Калькуляция оптической силы ИОЛ по формуле SRK/T основывалась на длине ПЗО и глубине передней камеры, полученных с помощью контактной УЗБ (Tomey Biometer Al-100) и кератометрии на авторефрактокератометре Topcon KR 8800. В целях адаптации ПЗО для калькуляторов нового поколения — Barrett Universal II (BUII), Hill RBF ver. 3.0 (RBF), Kane и Ladas Super Formula (LSF) — к определяемой с помощью УЗБ аксиальной длине добавлялась толщина сетчатки (0,20 мм), а затем вычислялась оптическая сила искусственного хрусталика. В качестве критериев точности расчета ИОЛ использовались средняя ошибка и модуль ее значения.
UNASSIGNED: Обнаружена значимая разница (p=0,008) в средней ошибке расчета ИОЛ между формулами. Попарный анализ выявил различия между SRK/T (–0,32±0,58 дптр) и другими формулами — BUII (–0,16±0,52 дптр; p=0,014), RBF (–0,17±0,51 дптр; p=0,024), Kane (–0,17±0,52 дптр; p=0,029), но не с калькулятором LSF (–0,19±0,53 дптр; p=0,071). Значимых различий между формулами по параметру модуля средней ошибки найдено не было (p=0,238). Калькуляторы новых поколений показали более частое попадание в рефракцию цели (в пределах ±1,00 дптр более чем в 95% случаев), чем формула SRK/T (86%).
UNASSIGNED: Предложенный метод добавления 0,20 мм к определяемой с помощью УЗБ длине ПЗО позволяет использовать данный параметр в современных формулах расчета ИОЛ и улучшать рефракционные результаты ФЭ, особенно в глазах с нестандартным строением переднего отрезка.

One of the most recent advancements in the field of cataract surgery is optical biometry. With the advent of optical biometry ocular measurements are now simpler, quicker, and more precise. The devices have made intraocular lens (IOL) power calculations easier in difficult situations too, such as in cases with extremes of axial lengths, silicone filled eyes, cataract surgery in post-keratoplasty eyes, post Laser-Assisted in Situ Keratomileusis (LASIK) eyes, etc. The gold standard for IOL power calculation in the present day is by the use of optical biometry devices. The anatomical measurements by these devices are highly precise and because of these measurements and the incorporation of various IOL power calculation formulas the optical biometry devices give the accurate power and the post-operative visual outcome is highly satisfactory among the patients. The growing use of these devices has made cataract the most commonly performed refractive surgical procedure nowadays. In the current scenario, optical biometry has widespread acceptance in almost all countries and has many advantages over ultrasound or immersion biometry. Cataract surgeons can obtain easy and reliable measurements from these devices. Refractive surprises have also decreased considerably with their use. This article will comprehensively review the principles of the various optical biometry devices, the parameters used in each of the devices, the advantages and disadvantages, and add more like what all this article will add.

OBJECTIVE: To compare agreement of corneal epithelium thickness (ET) between AS-OCT system (RTVue, Optovue) and AS-OCT/Placido topographer (MS-39, CSO) in eyes with different stages of keratoconus (KC), and to assess the repeatability of RTVue AS-OCT.
METHODS: Prospective reliability analysis.
METHODS: KC eyes were classified into forme fruste KC (FFKC), mild, moderate, and severe KC. Agreement was evaluated with Bland-Altman plots and 95% limits of agreement (LoA). The repeatability of RTVue was assessed via within-subject standard deviation (Sw), test-retest variability (TRT), coefficient of variation (CoV), and intraclass correlation coefficient (ICC).
RESULTS: A total of 119 KC eyes were enrolled, with 21 being FFKC, 26 mild, 39 moderate, and 34 severe. The 95% LoA ranged between -5.9 and 4.8 µm for center epithelium thickness (CET), between -5.7 and 8.2 µm for thinnest epithelium thickness (TET). At 1-mm measuring points, the 95% LoA of superior, inferior, nasal, and temporal were -4.2 to 4.7 µm, -5.2 to 6.0 µm, -7.9 to 10.2 µm, and -11.2 to 6.0 µm. At 3-mm measuring points, the corresponding values were -2.8 to 9.3 µm, -2.0 to 13.0 µm, -4.6 to 9.6 µm, and -6.3 to 9.7 µm, indicating that the 2 instruments were not interchangeable without adjustment. Despite that the repeatability of RTVue measurements in KC patients were acceptable, repeatability decreased gradually with the peripheralization of the measurement points.
CONCLUSIONS: The 2 OCT-based devices, RTVue and MS-39, do not provide interchangeable measurements of epithelium thickness in KC patients. Repeatability decreases in cases of more severe KC, emphasizing the importance of grading before clinical examination to avoid diagnostic errors.

OBJECTIVE: To compare anterior chamber angle (ACA) parameters measured by Anterior Segment Optical Coherence Tomography (ASOCT) and biometric parameters measured by Swept-Source (SS) OCT-based biometry among patients with suspected occludable angles and open angles.
METHODS: An analytical, cross-sectional study was performed on subjects attending our ophthalmology outpatient department with suspected occludable angles (van Herick grades 0, 1, and 2) in group 1, and with open angles (van Herick grades 3 and 4) in group 2. Each subject underwent a complete ophthalmic examination to exclude any intraocular pathology like cataract. We recruited 128 eyes of 64 subjects, 34 in group 1 and 30 in group 2. Each eye was henceforth subjected to ASOCT (Spectralis, Heidelberg Engineering, Heidelberg) and SS-OCT-based optical biometry (IOL Master 700, Carl Zeiss Meditec AG). Anatomical parameters were recorded and compared between the two groups.
RESULTS: The main outcome measures of the study included nine ASOCT parameters (central corneal thickness [CCT], lens vault, AOD750, ACA, TISA750 [nasal and temporal], and ACW) and five optical biometric parameters (CCT, ACD, WTW, LT, and axial length). We found a significant difference (p < 0.05) among all the anatomical parameters between the two groups, except CCT which was not significantly different (p = 0.297).
CONCLUSIONS: ASOCT and SSOCT biometry overcome the challenges of gonioscopy and allow screening for angle closure disease in otherwise normal subjects. ASOCT may serve as an alternative to gonioscopy as it clearly separates occludable angles from open angles in a non-invasive and objective manner.

The VEMoS-AXL system is a new optical biometer based on spectral domain optical coherence tomography (SD-OCT) that has been tested in terms of intrasession repeatability and compared with a swept-source optical coherence tomography biometer (SS-OCT), which is recognized as the gold standard for the performance of an agreement analysis. A biometric analysis was performed three consecutive times in 120 healthy eyes of 120 patients aged between 18 and 40 years with the SD-OCT system, and afterwards, a single measurement was obtained with the SS-OCT system. Within-subject standard deviations were 0.004 mm, 4.394 µm, and 0.017 mm for axial length (AL), central corneal thickness (CCT), and anterior chamber depth (ACD) measures obtained with the SD-OCT biometer, respectively. The agreement between devices was good for AL (limits of agreement, LoA: -0.04 to 0.03 mm) and CCT (LoA: -4.36 to 14.38 µm), whereas differences between devices were clinically relevant for ACD (LoA: 0.03 to 0.21 mm). In conclusion, the VEMoS-AXL system provides consistent measures of anatomical parameters, being most of them interchangeable with those provided by the SS-OCT-based gold standard.

UNASSIGNED: To assess the agreement between biometric parameters measured by a spectral-domain optical coherence tomography optical biometer device (Optopol Revo NX) with a validated swept-source biometer (IOLMaster 700) and a validated optical low-coherence reflectometry biometer (Lenstar LS 900), in cataract surgery candidates.
UNASSIGNED: In this prospective comparative study, 100 patients (100 eyes) who were eligible for cataract surgery were involved. Bland-Altman plots were used to assess agreement between devices for biometric parameters including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT).
UNASSIGNED: AL measurements were successful in 82 eyes (82.0%) with Revo NX, in 91 eyes (91.0%) with Lenstar LS 900, and in 97 eyes (97.0%) with IOLMaster 700. When Revo NX was compared to IOL Master 700 and Lenstar LS 900, the mean differences were as follows: -0.02 ± 0.02 mm and -0.02 ± 0.03 mm (P = 0.313, P = 0.525) for AL, 0.01 ± 0.03 mm and 0.10 ± 0.03 mm (P = 0.691, P = 0.002) for ACD, -0.15 ± 0.03 mm and 0.001 ± 0.04 mm (P < 0.001, P = 0.95) for LT, and -2.29 ± 0.92 μm, and 0.73 ± 1.43 μm (P = 0.015, P = 0.612) for CCT. Three devices were highly correlated for AL, ACD, LT, and CCT (interclass correlation coefficient > 0.75). Bland-Altman plots showed a narrower 95% limit of agreement (-0.35 to 0.31) between Revo NX and IOLMaster 700 in measuring AL.
UNASSIGNED: Despite the higher measurement failure rate in eyes with cataract, the Revo NX showed very good agreement with the IOLMaster 700 and Lenstar LS 900 optical biometers in measuring AL, ACD, LT, and CCT. However, ACD and LT measurements cannot be considered interchangeable between these devices.

Objective (Aim): To observe the ocular structural changes in active and inactive uveitis patients. Methods: This retrospective study involved 30 patients (32 eyes) with anterior and intermediate uveitis cases and 54 eyes of 54 cases in a control group, who were admitted to the Ophthalmology Department at Trakya University. In the study group, 14 patients were females, 16 patients were males and in the control group 26 volunteers were females, and 28 volunteers were male of the 54 volunteers. Anterior chamber depth, axial length, intraocular pressure, lens thickness, central corneal thickness, steep and flat values in keratometry, corrected visual acuity in both eyes, anterior chamber cells, and vitreous cells were measured and compared between three groups (two uveitis groups - active and inactive - and control group). Results: In the comparison of the median values of axial length, central corneal thickness, and steep and flat values of keratometry, the values of the patients with active uveitis were higher than the ones in the control group in each parameter, but no significant difference was observed. The anterior chamber depth parameter value was higher, the lens thickness value was lower in patients with active uveitis than the values in the control group and the differences were statistically significant (p<0,05). No significant structural differences in the values of the active and inactive group patients (p>0,05) were observed. Conclusions: Only lens thickness and anterior chamber depth parameters were statistically significant in patients with active uveitis, compared with the inactive uveitis group. Anterior chamber depth measurement values were higher and lens thickness measurement values were lower in patients with active uveitis when compared with the control group. Abbreviations: AAU = Acute anterior uveitis, CAU = Chronic Anterior Uveitis, AC = Anterior Chamber, IOP = Intraocular Pressure, IVCM = in vivo Confocal Microscopy, AS-OCT = Anterior Segment Optical Coherence Tomography, UBM = Ultrasound Biomicroscopy, LFP = Laser Flare Photometry, KP = Keratic Precipitates, OCT = Optical Coherence Tomography, AL = Axial Length, ACD = Anterior Chamber Depth, LT = Lens Thickness, CCT = Central Corneal Thickness, Ks = Steep Value of Keratometry, Kf = Flat Value of Keratometry, AUP = Active Uveitis Patients, IUP = Inactive Uveitis Patients, SUN = Standardization of Uveitis Nomenclature.

BACKGROUND: To evaluate the axial length acquisition success rates and agreement between various biometric parameters obtained with different biometers in dense cataracts.
METHODS: Fifty-one eyes were measured using Anterion®, Argos® and IOLMaster® 700 swept-source optical coherence tomography (SS-OCT) biometers, a Pentacam® AXL partial coherence interferometry (PCI) biometer, and an OcuScan® RxP ultrasound biometer. We measured keratometry (K1, flattest keratometry and K2, steepest keratometry), white-to-white (WTW), anterior chamber depth (ACD), lens thickness (LT) and axial length. Cataracts were classified according to the Lens Opacities Classification System III grading system, the dysfunctional lens index (DLI) and Pentacam® nucleus staging (PNS) metrics. Percentage of acquisition success rate and a Bland-Altman analysis for the agreement between biometers were calculated.
RESULTS: The mean LOCS III score was 3.63 ± 0.92, the mean DLI was 2.95 ± 1.30 and the mean PNS was 2.36 ± 1.20. The acquisition success rates for the Anterion®, Argos®, IOLMaster® 700, Pentacam® AXL and OcuScan® RxP biometers were 94.12%, 100%, 98.04%, 60.78% and 100%, respectively. There were significant differences in the success rates between biometers (P = 0.014). There were statistically significant differences between biometers for all parameters evaluated (P < 0.05). The range of the limit of agreement (LoA) for all comparisons of K1 and K2 were > 1.00 D. The LoA for WTW ranged from 0.095 to 1.050 mm. The LoA for ACD and LT ranged from 0.307 to 0.114 mm and from 0.378 to 0.108 mm, respectively. The LoA for axial length ranged from 0.129 to 2.378 mm.
CONCLUSIONS: Among optical biometers, those based on SS-OCT technology are more successful at measuring axial length in eyes with dense cataracts.
BACKGROUND: The study was registered with the National Institutes of Health (clinical trial identifier NCT05239715, http://www.
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UNASSIGNED: This study aimed to investigate the effects of severe COVID-19 infection on the corneal endothelium via in vivo specular microscopy.
UNASSIGNED: This was an observational, prospective, and controlled study including 56 eyes of 56 severe COVID-19 patients, compared to after-recovery and 56 eyes of 56 age- and gender-matched healthy controls.
UNASSIGNED: Endothelial cell density was lower in the active disease period compared to healthy controls (p = .001) and decreased even more after recovery (p < .0001). After recovery, the average cell area and coefficient of variation were higher compared to the active disease period (p < .0001 and p = .008, respectively) and the healthy controls (for both, p < .0001), whereas hexagonality was lower (p < .0001). Central corneal thickness increased in the active disease period compared to after recovery (p < .0001) and healthy controls (p = .002).
UNASSIGNED: These results may be due to direct host-virus interaction or linked to immune dysregulation, subclinical corneal endotheliitis, or still yet a viral-mediated inflammation.

BACKGROUND: To evaluate the repeatability of a fully automated swept-source optical coherence tomography (SS-OCT) and its agreement with an optical low coherence reflectometry (OLCR) for several biometric parameters.
METHODS: In this study, 74 eyes of 74 patients were measured using the Eyestar 900 SS-OCT and Lenstar LS 900 OLCR. Flat keratometry (K1) and steep keratometry (K2), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were measured three times with each device. The repeatability was analyzed with the intrasubject standard deviation, coefficient of variability (CoV), and coefficient of repeatability (CoR) for each instrument. The agreement between the instruments was evaluated with Bland-Altman analysis.
RESULTS: K1, K2 and CCT CoV values were < 0.2%, < 0.4% and < 0.55%, respectively. Higher CoV values were found for ACD and LT ranging from 0.56% to 1.74%. The lowest CoV values were found for the AL measurements (0.03% and 0.06% for the Eyestar 900 and the Lenstar LS 900, respectively). AL measurements provided the highest repeatability, measured with both CoV and CoR values, and the CCT was the parameter with the lowest repeatability. The CCT and LT measurements were statistically significant between the two biometers (P < 0.001). The interval of the limits of agreement was < 0.6 D for K1 and K2, 15.78 µm for CCT, 0.21 mm for ACD, 0.34 mm for LT, and 0.08 mm for AL.
CONCLUSIONS: Both biometers provide repeatable measurements for the different parameters analyzed and can be used interchangeably.