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.

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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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.

UNASSIGNED: To assess the agreement in automated corneal diameter (CD) and anterior chamber depth (ACD, measured from corneal epithelium to lens) distances measurements between the IOLMaster 500 and 700 optical biometers in myopic eyes.
UNASSIGNED: One hundred and sixteen eyes of 116 myopic patients aged between 21 to 60 years were included in this study. Measurements of CD and ACD distances were taken with each biometer for all patients in the same session. A t-test and a p-value less than 0.05 was considered statistically significant when the measurements were compared. The agreement between biometers was studied by applying a Bland-Altman analysis.
UNASSIGNED: The mean CD values obtained using the IOLMaster 500 and 700 biometers were 12.26±0.35 mm and 12.13±0.34 mm, respectively. The mean ACD distance values were 3.61±0.29 mm and 3.62±0.31, for the IOLMaster 500 and 700 biometers, respectively. There were statistically significant differences between the two devices only for CD measurements (p<0.001), but not for ACD measurements (p=0.26). The limits of agreement obtained were wide in both types of measurements, being 0.422 mm for the CD distance and 0.389 mm for the ACD distance.
UNASSIGNED: There were statistically significant differences between the IOLMaster 500 and 700 biometers regarding CD but not in ACD measurements in healthy myopic eyes. These differences could be clinically significant in some cases. According to these results, medical judgement should be used to assess whether the two devices could be used interchangeably for CD and ACD measurements during the clinical practice.

UNASSIGNED: To evaluate changes in higher order aberrations (HOAs) induced by implantable collamer lens (ICL) implantation in correction of high myopia and to compare the anterior segment parameters before and after surgery. Also, to correlate these parameters with HOAs, the best corrected visual acuity (BCVA) and intraocular pressure (IOP).
UNASSIGNED: This prospective interventional cohort case series study included 40 eyes with high myopia that underwent ICL V4c implantation. They were evaluated pre-operatively and post-operatively at 1st and 3rd month HOAs using Scheimpflug Sirius Camera. The anterior segment parameters were evaluated by optical biometry. Correlations between HOAs, BCVA and anterior segment parameters were evaluated.
UNASSIGNED: The mean pre-operative BCVA was 0.67 ± 0.17, while post-operative BCVA was 0.74 ± 0.16 (p-value < 0.001). The spherical equivalent was -13.66 ± 2.23 pre-operatively, while post-operatively it was -0.77 ± 0.65 (p-value < 0.001). The mean pre-operative root mean square (RMS) of HOAs was 0.62 ± 0.11 µm, while mean post-operative RMS in the 1st month was 0.82 ± 0.29 µm (p-value < 0.001). At 3rd month, it was 0.63 ± 0.17 µm (p-value = 0.685). The mean pre-operative anterior chamber depth (ACD) was 3.66 ± 0.26 mm. It decreased in the post-operative 1st month to 3.46 ± 0.30 mm, while in 3rd month 3.45 ± 0.24 mm (p-value < 0.001, < 0.001) respectively. The mean pre-operative anterior chamber angle (ACA) 45.98 ± 8.39 o while, the mean ACA was 31.65 ± 4.14, 31.03 ± 3.74 post-operatively (p-value < 0.001, < 0.001) respectively. There was significant increase in IOP (p-value < 0.001).
UNASSIGNED: ICL implantation is safe and effective in correction of high myopia, as HOAs increase at first month post-operatively then, return to the pre-operative level by 3rd month. However, anterior segment parameters show significant changes which may need longer follow up.

UNASSIGNED: In eyes with severe corneal pathology, biometric measurements of the corneal curvature (K) can be challenging. The aims of this study were to test whether K mean values from the fellow eye can be used as substitute in lens power calculations and to determine if similarity in axial length (AL) in a patient\'s two eyes implies similarity also in the corneal curvature.
UNASSIGNED: A retrospective study of optical biometry measurements in 500 adults (1000 phakic eyes) that was scheduled for cataract surgery. Inclusion criteria were complete recordings of all parameters in both eyes and a signal-to-noise ratio of at least 10. Similar AL was defined as less than 0.3 mm difference between the patient\'s two eyes.
UNASSIGNED: The IOL power calculated with K mean from the fellow eye was 0.39 D (standard deviation (SD) 0.57) different from the calculation with both AL and K mean from the correct eye. The difference was larger than 1.0 D in 26 (5%) eyes. In patients with similar AL in their two eyes (n = 372), the interocular difference in K mean was 0.43 D (SD 0.67 D), compared to 0.45 D (SD 0.49 D) for the patients with an AL difference of 0.3 mm or more (n = 128) (p = 0.81).
UNASSIGNED: Lens calculations with keratometry values from the fellow eye as substitute yielded quite similar results as calculations with the correct values. Hence, this seems to be an acceptable approach in patients with incomplete keratometry recordings. Similarity in AL between a person\'s two eyes did not imply more similar corneal curvatures.

UNASSIGNED: To investigate the accuracy of 6 intraocular lens (IOL) power calculation formulas in predicting refractive outcomes in extremely long eyes.
UNASSIGNED: Department of Ophthalmology, Far Eastern Memorial Hospital, Taiwan.
UNASSIGNED: Retrospective comparative study.
UNASSIGNED: In this retrospective single-center study, we reviewed 70 eyes of 70 patients with axial length (AL) ≥ 28 mm who had received an uneventful 2.2 mm corneal wound phacoemulsification and in-the-bag IOL placement. The actual postoperative refractive results were compared to the predicted refraction calculated with 6 formulas (Haigis, Hoffer Q, Holladay 1, SRK/T, T2, Barrett Universal II formulas) using IOLMaster 500 as optical biometry in the User Group for Laser Interference Biometry (ULIB) constants.
UNASSIGNED: Overall, the Haigis and Barrett formulas achieved the lowest level of mean prediction error (PE) and median absolute error (MedAE). Hoffer Q, Holladay 1, SRK/T, and T2 had hyperopic prediction errors (p < 0.05). The Hoffer Q and Holladay 1 had significantly more MedAE between the 6 formulas. After the mean PE was zeroed out, the MedAE had no significant difference between each group. The absolute error tends to be larger in patients with longer AL. The absolute errors were 30.0-37.1% and 60.0-64.3% within 1.0 D of all patients compared to predicted refraction calculated using various formulas.
UNASSIGNED: The Haigis and Barrett Universal II formulas had a better success rate in predicting IOL power in high myopic eyes with AL longer than 28 mm using the ULIB constant in this study. The postoperative refractive results were inferior to the benchmark standards, which indicated that the precision of IOL power calculation in patients with high myopia still required improvement.