Assessment of posture-induced cyclotorsion during cataract surgery using the Verion image-guided system.

BACKGROUND: The purpose of this prospective observational study is to analyse posture-induced cyclotorsion in eyes undergoing conventional phacoemulsification with toric intraocular lens (IOL) implantation and femtolaser-assisted cataract surgery (FLACS) using the Verion image-guided system. METHODS: Cyclotorsion was assessed in patients who underwent conventional phacoemulsification with toric IOL implantation and FLACS between June 2017 and November 2017 with registration of iris architecture, limbal and bulbar conjunctival blood vessels acquired preoperatively using the Verion Reference Unit (the patient in sitting position) and intraoperatively under the microscope using the digital marker of the Verion image-guided system with the patient in supine position. RESULTS: Forty-four eyes of 30 patients (21 men and 9 women) were included with the mean age of 56.5 ± 17.1 (range, 19-89; median, 62) years. The mean cyclotorsion induced by change in posture from sitting to supine position was 5.84 ± 3.25° (range, 1-17; median, 5). Overall, clockwise (CW) rotation (59.1%) was noted to be more common than counter clockwise (CCW) rotation (40.9%). Furthermore, CW rotation was more common in men than in women, and CCW rotation was significantly more common in women. Patients who underwent bilateral sequential cataract surgery show similar cyclorotation (CW or CCW) in both eyes more often than mixed rotation (85.7% vs 14.3%). CONCLUSION: Significant cyclotorsion can occur in supine position during cataract surgery. Accurate assessment of the amount and direction of cyclotorsion aids in appropriate alignment of the toric IOL for optimal visual outcomes.

Clinical Outcomes After Femtosecond Laser-Assisted Arcuate Corneal Incisions versus Manual Incisions.

PURPOSE: To compare the relative effectiveness of Verion-LenSx guided femtosecond arcuate incisions and manual incisions in reducing postoperative refractive astigmatism. PATIENTS AND METHODS: This was a contralateral eye, prospective study that included subjects with 0.50 D to 1.75 D of corneal astigmatism who wanted less refractive astigmatism post cataract surgery. The surgeon used anterior keratometry and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all laser arcuate incisions. Manual incisions were planned using the Donnenfeld nomogram and made with a fixed-depth diamond knife. The primary outcome measure was the residual refractive astigmatism at 3 months postoperative. Secondary outcome measures included the manifest refraction, uncorrected distance visual acuity and the change in corneal astigmatism from 1 to 3 months postoperative. RESULTS: Forty-one subjects were successfully enrolled in the study, with data from 38 subjects available at 3 months. There were no statistically significant differences in refractive astigmatism, corneal astigmatism, uncorrected distance visual acuity or manifest refraction between the Manual and Femto groups at either 1 month or 3 months. Significant changes in refractive and corneal astigmatism were noted between 1 months and 3 months. Ninety percent of eyes in both groups had ≤0.50 D of refractive astigmatism at 3 months. Two minor non-serious adverse events (full-thickness incisions of the cornea) occurred in two eyes of two different subjects in the Manual group; they were resolved without incident. CONCLUSION: Laser arcuate incisions appear to be an effective means of reducing postoperative refractive astigmatism at the time of cataract surgery. No significant clinical differences were observed between incisions made manually and those made with an image-guided femto-second laser system. The lower number of minor adverse events experienced with the femtosecond laser system is an apparent advantage.

Randomized trial comparing visual outcomes of toric intraocular lens implantation using manual and digital marker.

PURPOSE: The aim of this study was to compare the visual outcome of participants undergoing toric intraocular lens (IOL) implantation after cataract extraction using manual marking versus digital marking for intraoperative guidance. METHODS: Randomized controlled trial of participants with cataract and corneal astigmatism of 1.00 D-4.50 D. The eyes were grouped into manual marking (Group 1) and digital marking (Group 2). Preoperative Uncorrected distance visual acuity (UDVA), Corrected distance visual acuity (CDVA), and corneal astigmatism were determined. IOL power and axis of alignment were determined using Barrett toric calculator. Eyes were marked by bubble marker and Mendez ring in group 1 and by VERION (Alcon, Fort Worth, Texas) digital overlay in Group 2. Postoperatively, UDVA, CDVA, residual refractive cylinder and IOL misalignment were determined (iTrace system, Tracey technologies) at 1 week, 6 weeks, and 3 months. RESULTS: A total of 61 eyes of 50 participants, 31 in Group 1 and 30 in Group 2, were studied. The mean postoperative cylindrical error was 0.50 ± 0.39 D in Group 1 and 0.29 ± 0.34 D in Group 2 (P = 0.03). 67.74% (n = 21) and 93.55% (n = 29) eyes achieved a residual astigmatism of ≤0.50 D and ≤1.00 D, respectively, in Group 1, whereas 83.33% (n = 25) and 100% (n = 30) eyes achieved a residual astigmatism of ≤0.50 D and ≤1.00 D, respectively, in Group 2 at 3 months postoperatively. Toric IOL misalignment was 4.71 ± 3.12° in Group 1 and 4.03 ± 2.99° in Group 2 (P = 0.39). CONCLUSION: Accurate manual marking and digital marking are equally effective guides for toric IOL alignment, intraoperatively.

VERION® - A influência da tecnologia do sistema guiado por imagem expressa no controle pós-operatório de astigmatismo / VERION® - The influence of expressed image-guided system technology on postoperative astigmatism control

Resumo Objetivo: Avaliar o astigmatismo induzido pela cirurgia de catarata através da técnica de facoemulsificação (FACO) guiada pelo planejador cirúrgico VERION®, em um serviço oftalmológico do Paraná. Métodos: O estudo tem caráter observacional com avaliação individualizada de prontuários de forma retrospectiva, analisando 37 olhos de 20 pacientes operados de catarata pela técnica de FACO com a utilização do VERION® e implantação de lente não-tórica no Hospital de Olhos de Cascavel - PR no período de maio de 2016 a novembro de 2018. Resultados: Dentro de nossa amostra composta por 37 olhos abordados com assistência do VERION®, 43% dos participantes do estudo (n=16) apresentaram redução do astigmatismo inicial, inclusive com eliminação de graus mais graves de astigmatismo (≥2.5 D). Conclusão: O impacto do VERION® foi significativo uma vez que permitiu a correção do astigmatismo prévio de uma parte da amostragem. Em olhos que ocorreram astigmatismo induzido cirurgicamente essa complicação foi menos relevante clinicamente em comparação com incisões corneanas da técnica convencional.

Abstract Objective: To evaluate the astigmatism induced by cataract surgery through the phacoemulsification (PHACO) technique guided by the VERION® surgical planner, in an ophthalmological service of Paraná. Methods: This is an observational study with retrospective individualized evaluation of medical records, analyzing 37 eyes of 20 patients who underwent cataract surgery using the PHACO technique using VERION® and non-toric intraocular lens implantation at the Hospital de Olhos de Cascavel - PR in May 2016. Results: Within our sample of 37 eyes approached with VERION® assistance, 43% of study participants (n=16) had reduced initial astigmatism, including elimination of more severe degrees of astigmatism (≥2.5 D). Conclusion: The impact of VERION® was significant as it allowed the correction of previous astigmatism of a part of the sample. In eyes that had surgically induced astigmatism, this complication was less clinically relevant compared to conventional technique corneal incisions.

Verion digital marking versus smartphone-assisted manual marking and isolated manual marking in toric intraocular lens implantation.

Purpose: To compare the accuracy of isolated manual marking and smartphone-assisted manual marking with the Verion image-guided system for toric intraocular lens (IOL) implantation. Methods: In this prospective observational study, 42 eyes of 36 patients planned for phacoemulsification with toric IOL implantation with corneal astigmatism >1D as measured on Lenstar LS 900 optical biometer were included. Patients were preoperatively registered and photographed on the Verion image-guided system. In the operating room, the patient's eye was manually marked at the 6 o' clock limbus (Manual axis-90°) on slit-lamp in sitting position. Next, using the smartphone android app-iToric Patwardhan, the exact mark axis was confirmed (Smartphone axis). Following this, the patient was taken on the operation table where the mark axis was confirmed with Verion digital overlay on an external screen (Verion axis). The absolute angular deviation of manual axis from Verion was compared with the absolute angular deviation of the smartphone axis from Verion as the primary outcome measure. Results: The mean absolute angular deviation between the smartphone axis and the Verion axis was 2.62°, which was significantly lower (P < 0.05) than that between the manual axis and Verion axis (4.60°). Moreover, the intraclass correlation coefficient between the smartphone axis and Verion axis was 0.88 indicating a strong agreement between the two. Conclusion: Smartphone-assisted manual marking significantly improves the accuracy of manual marking alone when comparing with the Verion Digital Marker system for toric IOL implantation.

Agreement between Keratometric readings by VERION image guided System, Galilei G4 and Pentacam.

OBJECTIVE: To study Agreement between Keratometric readings by VERION image guided System, Galilei G4 and Pentacam. METHODS: The quasi experimental study was conducted at Armed Forces Institute of Ophthalmology, Rawalpindi, Pakistan from August 2016 to December 2016. Twenty five patients fulfilling the inclusion criteria participated in the study. All Patients were subjected to Keratometric assessment using Galilei G4 Dual Scheimpflug analyzer (Ziemer, Switzerland), Wavelight Oculyzer II (Pentacam, Germany) and Verion image guided system (Alcon). Steep and flat meridian and diopter of astigmatism by three systems were recorded and endorsed. All readings were taken by the same observer. Statistical Program for Social Sciences (SPSS) version 22.0 was used for statistical analysis. Results analyzed for significance by t-tests and Interclass correlation analysis. In t tests, P values of <0.05 was considered statistically significant while interclass coefficient of >0.7 was considered acceptable. RESULTS: Fifty eyes of twenty-five patients (22 male, 28 female) with mean age of 29.50 ± 3.46 years were studied. Flat K, steep K and dioptric power of astigmatism were measured with verion, pentacam and Galilei G4. Interclass correlation analysis showed agreement between individual variables measured by the three devices, while one sample t test showed no significant difference between dioptric power of astigmatism between Verion-Pentacam and Verion- Galilei group. (p 0.178 for former and 0.622 for later group). CONCLUSION: Verion image guided system is comparable to other instruments used currently for keratometry. Verion can be interchangeably used with Pentacam and Galilee G4 in assessing corneal astigmatism.

Assessment of Corneal Keratometric and Astigmatism Measurements Using Verion System and Other Instruments in Cataract Patient.

PURPOSE: To compare keratometry and corneal astigmatism measurements obtained by the Verion Image Guided System to those obtained by automated keratometry (IOLMaster), manual keratometry (YZ38, Suzhou 66 visual Polytron Technologies Inc., China), and Scheimpflug imaging (Pentacam HR) in eyes with cataract. METHODS: A total of 149 cataractous eyes of 149 patients were examined and categorized as low astigmatism (<1.0 D, N = 50), moderate astigmatism (1.0-2.0 D, N = 49), and high astigmatism (>2.0 D, N = 50). The flattest and the steepest keratometric values (Kf and Ks), the magnitude of astigmatism (Ast), the orientation of the steepest meridian (Axis), and power vectors J0 and J45 were compared. RESULTS: Keratometry readings (Kf, Ks, and Km) obtained by the Verion system showed statistically significant differences as compared to the other three devices. The magnitude of astigmatism (Ast) measured by the Verion (1.50 ± 0.85 D) was similar to that measured by the YZ38 (1.45 ± 0.82 D, P = 0.110) and slightly lower than that by the IOLMaster (1.56 ± 0.87 D, P = 0.014), but much higher than that by the Pentacam (1.36 ± 0.81 D, P = 0.000) significantly. However, no statistically significant differences were observed in the J0 and J45 vectors in the whole sample, besides moderate and high astigmatism subgroups. A difference in astigmatism magnitude of 0.50 D or more was detected between the Verion system and other three devices most commonly in moderate astigmatism eyes (16.3-24.5%). The difference in the location of the steep meridian was greater than 10 degrees most frequently in the low astigmatism eyes (26.0-52.0%). CONCLUSIONS: Keratometric and astigmatic results obtained with Verion were not completely interchangeable with those obtained with IOLMaster, manual keratometry, and Pentacam. The individual differences in power and orientation of the corneal cylinder should be considered while selecting the appropriate toric intraocular lens.

Validation of keratometric measurements obtained with an intraoperative image-guided system: intra-session repeatability and interchangeability with an optical biometer.

PURPOSE: To evaluate the intra-session repeatability of keratometric measurements obtained in healthy eyes with the Verion image-guided system (Alcon Laboratories Inc, Fort Worth, Texas, USA) as well as the interchangeability of such measurements with those obtained with an optical biometer (Aladdin, Topcon, Tokyo, Japan). METHODS: A total of 53 eyes of 53 patients (age 31-67 years) were enrolled in the study. All eyes received a comprehensive ophthalmologic examination including an analysis with the Verion image-guided and Aladdin systems. Three consecutive measurements of keratometry were obtained with the Verion system to assess the intra-session repeatability. Within-subject standard deviation (Sw ) and intraobserver precision (± 1.96 × Sw ) were calculated. Bland-Altman analysis was used for the interchangeability analysis. RESULTS: Mean Sw was 0.26, 0.24 and 0.10 D for the keratometric power in the flattest meridian (K1), keratometric power in the steepest meridian (K2) and astigmatism, respectively. Mean Sw was 4.29° for the axis of the flattest corneal meridian (AX1). Statistically significant but clinically acceptable differences were found in K1, K2 and keratometric astigmatism among systems (p < 0.01). In contrast, differences among systems in AX1 were not statistically significant (p = 0.385) but clinically relevant (mean difference: 15.74°; limits of agreement: -30.93 to 62.41°). CONCLUSIONS: The Verion system provides consistent measurements of keratometric parameters, with measurements of AX1 that are not interchangeable with that provided by the optical biometer Aladdin, especially in cases of low and oblique astigmatism.

Comparison of biometric measurements obtained by the Verion Image-Guided System versus the auto-refracto-keratometer.

PURPOSE: To compare the biometric measurements obtained from the Verion Image-Guided System to those obtained by auto-refracto-keratometer in normal eyes. METHODS: This is a prospective, observational, comparative study conducted at the Asociación para Evitar la Ceguera en México I.A.P., Mexico. Three sets of keratometry measurements were obtained using the image-guided system to assess the coefficient of variation, the within-subject standard deviation and intraclass correlation coefficient (ICC). A paired Student t test was used to assess statistical significance between the Verion and the auto-refracto-keratometer. A Pearson's correlation coefficient (r) was obtained for all measurements, and the level of agreement was verified using Bland-Altman plots. RESULTS: The right eyes of 73 patients were evaluated by each platform. The Verion coefficient of variation was 0.3% for the flat and steep keratometry, with the ICC being greater than 0.9 for all parameters measured. Paired t test showed statistically significant differences between groups (P = 0.0001). A good correlation was evidenced for keratometry values between platforms (r = 0.903, P = 0.0001 for K1, and r = 0.890, P = 0.0001). Bland-Altman plots showed a wide data spread for all variables. CONCLUSION: The image-guided system provided highly repeatable corneal power and keratometry measurements. However, significant differences were evidenced between the two platforms, and although values were highly correlated, they showed a wide data spread for all analysed variables; therefore, their interchangeable use for biometry assessment is not advisable.

Comparison of Toric intraocular lens axis marking using VERION image guided system and slit lamp observation / 眼科新进展

Objective To evaluate the accuracy and validity of Toric intraocular lens (IOL) alignment by VERION image guided system.Methods In this retrospective study,75 eyes of 75 patients who underwent phacomulsification combined with Toric IOL implantation were enrolled from June 2016 to May 2017.Before operation,anterior segment images of all patients were collected using VERION image guided system,and target axis of IOL implantation was set.Horizontal axis was marked using 1 mL syringe needle under the slit lamp.During the procedures,the IOL was implanted referring to the target axis under VERION system or the slit lamp randomly,and there were 42 eyes with IOL implantation guided by VERION system (VERION group),and 33 eyes guided by slit lamp (slit lamp group).The best corrected visual acuity (BCVA) of each patient was recorded at day 1,1 week,1 month,and 3 months after operation.Anterior segment images were taken after mydriasis,and all the images were analyzed by Photoshop software.Finally,the BCVA at various time points after operation and the deviation value of actual axis and target axis was compared in both groups.Results The proportion of eyes with BCVA ≥ 0.8 at day 1,1 week,1 month,and 3 months after operation was 61.9％,78.6％,71.4％ and 76.2％ in VERION group,respectively,and 69.7％,78.8％,81.8％ and 75.8％ in slit lamp group,respectively,and there was no statistical significance between VERION group and slit lamp group (all P ＞ 0.05).The difference value of target axis marked by VERION system and by slit lamp was (3.04 ± 1.99) °.No significant differences were seen in the IOL actual axis and target axis between the two groups at various time points (all P ＞ 0.05).Conclusion It is accurate and stable of VERION image guided system for toric IOL axis marking.

Pseudophakic astigmatism reduction with femtosecond laser-assisted corneal arcuate incisions: a pilot study.

PURPOSE: The aim of this study was to assess the effectiveness of the Verion-LenSx guided arcuate incision technique to reduce refractive astigmatism in a pseudophakic population. PATIENTS AND METHODS: A prospective single-arm study was conducted in which one or both eyes of subjects required reduction of 1.0-2.0 D of refractive astigmatism after previous cataract surgery or refractive lens exchange. The surgeon used the refractive cylinder in the eye and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all arcuate incisions. The primary outcome measure was the uncorrected monocular distance visual acuity (UCVA). Secondary outcome measures included the change in corneal astigmatism, the change in refractive astigmatism, the best-corrected visual acuity and spectacle independence at distance from preoperative stage to 1 month and 2 months postoperatively. RESULTS: Twenty-eight eyes of 18 subjects were treated. The best-corrected visual acuity at the 2-month postoperative (PO) stage was not statistically significantly different from the preoperative visual acuity (0.02 logarithm of the minimum angle of resolution [logMAR] in both cases, P>0.05). Uncorrected visual acuity was statistically significantly better at the 2-month PO stage relative to the preoperative value (0.14 versus 0.34 logMAR, P<0.01). The mean change in refractive cylinder from the preoperative stage to the 2-month PO stage was 1.0 D. At the 2-month PO stage, two-thirds of the subjects (12/18) reported that they did not use glasses for distance vision and that their spectacle use for distance vision at 2 months was "lower" or "much lower" than the preoperative stage; in 71% of eyes (20/28), the residual refractive cylinder was ≤0.50 D. Vector changes in keratometric astigmatism were weakly associated with changes in refractive cylinder. CONCLUSION: Arcuate incisions made with a femtosecond laser to treat moderate levels of residual refractive astigmatism after previous cataract surgery may reduce dependence on spectacles for distance vision.

A comparison of three different corneal marking methods used to determine cyclotorsion in the horizontal meridian.

During toric intraocular lens (IOL) implantation, surgeons must take particular care to ensure that inaccurate preoperative measurement and intraoperative misalignment do not cause unexpected postoperative residual astigmatism. This retrospective, comparative case series study aimed to analyze the rotational deviation, or cyclotorsion, of three corneal marking methods: VERION digital marker (VDM; reference), horizontal slit beam marking (HSBM), and subjective direct visual marking (SDVM) on the table (using a bevel knife tip). Subjects included 81 eyes of 61 patients (mean age: 65.70±13.14 years; range: 32-91 years) undergoing scheduled cataract surgery. A preoperative reference image was taken of each eye. Subsequently, a slit lamp with the light beam turned to the horizontal meridian was used to align the seated patient's head, and two reference marks were placed at the 3- and 9-o'clock positions of the corneal limbus using a 27-gauge needle and marking pen (HSBM). Upon transfer to the surgical table, the VDM was used to display a real-time dial scale on the patient's eye, with the entrance of the temporal clear corneal incision (CCI) at 0° (horizontal meridian). Simultaneously, a bevel knife tip was used to create a marker based on the surgeon's visual determination of the temporal 0° point (SDVM). We used the VDM to quantitatively evaluate the accuracy of axis alignment via deviation from the horizontal reference meridian. Compared with the reference meridian, the SDVM (-3.46°±7.32°, range: -18° to 13°) exhibited greater average relative cyclotorsion versus the HSBM (0.41°±4.92°, range: -10° to 10°). Furthermore, the mean average misalignment was significantly less in the HSBM group versus the SDVM group (t=4.179, P<0.001). The VDM is likely a reliable marking method, similar to the HSBM. In contrast, the SDVM is not entirely reliable. The VDM usage may prevent inaccurate preoperative manual marking during toric IOL implantation.

Comparison of keratometric measurements obtained by the Verion Image Guided System with optical biometry and auto-keratorefractometer.

The aim of this study was to compare the keratometric measurements of Verion Image Guided System with an optical biometer (Zeiss IOLMaster 500, Carl Zeiss Meditec, Jena, Germany) and an automated keratorefractometer (AKR) (Topcon KR-8900, Topcon, Japan). In this prospective clinical trial, the right eyes of 52 patients with cataract were examined (mean age 62.25 ± 12.16 years). The measurements were taken by the three systems in a random order. Keratometric data, magnitude of astigmatism, and astigmatic axis measurements from all three instruments were compared. The results were evaluated using, intraclass correlation coefficients (ICC), Bland-Altman plots, and paired samples t tests. The mean flat/steep K of Verion, IOLMaster, and AKR were 43.22 ± 1.38D/44.23 ± 1.46D, 43.07 ± 1.26D/44.05 ± 1.34D, and 43.07 ± 1.31D/43.89 ± 1.42D, respectively. Flat K readings of Verion were higher than IOLMaster and AKR (p < 0.05 for both). Steep K readings were different for all three (p < 0.05). The magnitude of astigmatism by Verion and IOLMaster were 0.98 ± 0.65D and 0.98 ± 0.59D (p = 0.88). The mean astigmatism measured by the AKR was 0.82 ± 0.62D, less than the other two instruments (p < 0.001). Astigmatic axis measurements of Verion and AKR differed <10° in 38, between 10° and 20° in 5, and >20° in 9 eyes; the same difference was 30, 11, and 11 eyes, respectively, between Verion and IOLMaster. Although, keratometric and astigmatic results obtained from Verion were not completely interchangeable with IOLMaster and AKR, especially the agreement between Verion and IOLMaster was excellent with ICCs close to one. However, there were pronounced astigmatic axis measurement differences between three instruments.

Reproducibility of VERION Digital Guidance System and its comparability with iTrace, Lenstar LS900 and manual keratometer in measuring keratometry and astigmatism / 眼科新进展

Objective To analyze the reproducibility of keratometry and astigmatism measured by the VERION Digital Guidance System and the comparability of VERION with iTrace,Lenstar LS900 and manual keratometer.Methods The keratometry of 62 cataract patients were measured using four different devices.The steep keratometry (Ks),flat keratometry (Kf),astigmatic magnitude,astigmatic axis,cylinder at 0-degree meridian (vector component,J0) and cylinder at 45-degree meridian (vector component,J45) from each machine were recorded and analyzed.The three repeated measurements and the results of VERION system with other three devices were compared to analyze the reproducibility and comparability of VERION system.Results Reproducibility:Intraclass correlation coefficients and Cronbach's alpha values were higher than 0.9 for Ks,Kf,astigmatic magnitude,astigmatic axis,J0 and J45 measured by the VERION system (all P ＜ 0.001).Comparability:The results of Ks and magnitude of astigmatism of VERION were larger than the iTrace (all P ＜ 0.05) in the paired-samples t test.There was no statistical difference for the rest of parameters (all P ＞ 0.05).The Bland-Altman graphs revealed the 95％ limits of agreement (LOA) of J0,J45 and the astigmatic axis between VERION and iTrace were (-0.31-0.35) D,(-0.25-0.31) D and-13.5 °-12.3 °,respectively;There was no statistical differences for all parameters except for J45 in the paired-samples t test between the VERION and Lenstar LS900 (all P ＞ 0.05).The Bland-Altman graphs revealed the 95％ LOA of J0,J45 and the astigmatic axis were (-0.25-0.31)D,(-0.27-0.36) D and-13.5°-11.0°,respectively;There were statistical differences for the results of Kf and magnitude of astigmatism between the VERION and manual keratometer (all P ＜ 0.05).The Bland-Altman graphs revealed the 95％ LOA of J0,J45 and the astigmatic axis between VERION and manual keratometer were (-0.38-0.35) D,(-0.41-0.42) D,-12.6°-16.4°,respectively.Conclusion The VERION system is a reliable system for the measurement of keratometry and astigmatism.The keratometry and astigmatic magnitude of the VERION system have a good agreement with the iTrace,Lenstar LS900 and manual keratometer.However,the astigmatic axis measurements are significantly different among the four devices.

Comparison of Refractive Power and Astigmatism between Digital Keratometer and Autorefractor

PURPOSE: To compare the corneal refraction, astigmatism, and corneal marking for toric intraocular lens measured with a VERION® Image Guided System and an autorefractor in order to precisely determine the toric intraocular lens target. METHODS: The medical records of 29 eyes of 29 patients were retrospectively reviewed to compare the corneal refraction, axis, and amount of astigmatism measured with a VERION® Image Guided System and an autorefractor. We compared the difference in marked axis for toric intraocular lenses as measured by a VERION Digital Marker and a manual marker. RESULTS: The average corneal refraction and amount of astigmatism were greater with the VERION® Image Guided System than with the autorefractor. The average difference in axis of astigmatism was 9.62°. The difference in axis of astigmatism in patients with more than 1.0 D of astigmatism (18 eyes) was 2.82 ± 2.27°, while that in patients with less than 1.0 D of astigmatism (11 eyes) was 20.27 ± 28.14°. The average difference in marked axis for toric intraocular lens measured by the VERION® Digital Marker and manual marker was 2.50° (0°-9.27°). CONCLUSIONS: The corneal refraction and amount of astigmatism were significantly higher with the VERION® Image Guided System, so careful concern and comparison of surgical outcomes between the two devices is needed in biometry.

Assessment of corneal curvature using verion optical imaging system: a comparative study.

BACKGROUND: Keratometry is a critical determinant of the postoperative refractive outcome. This study evaluates the comparability of keratometry measurements obtained using the Verion Optical Imaging System with devices used in current clinical practice. Further, it determines the interobserver reliability of the Verion Optical Imaging System. DESIGN: Retrospective analysis of patient data PARTICIPANTS: Keratometric data was obtained from 100 patients presenting for pre-operative evaluation. Furthermore, repeatability and reproducibility were assessed using 15 healthy volunteers. METHODS: Corneal curvature values acquired by the Verion Optical Imaging System were compared with existing keratometry devices including autokeratometry, partial coherence interferometry (IOLMaster) and Scheimpflug corneal topography (Pentacam). MAIN OUTCOME MEASURES: Direct comparison of corneal power, cylinder, axis of astigmatism and vector analysis were performed using correlation and Bland-Altman analyses. Reproducibility and reliability of the device were assessed using within-subject standard deviation and intraclass correlation coefficients for experienced and inexperienced technicians. RESULTS: There was no statistically significant difference between Verion values and those obtained by other methods in relation to mean keratometry, corneal astigmatism, steep meridian and vector analyses (P > 0.05). Bland-Altman plots showed narrow limits of agreement for keratometry and astigmatism and wider agreement for steep meridian. Intraoperator reliability for both experienced and inexperienced operators and interoperator reproducibility showed no statistically significant differences between values. CONCLUSION: Measurements show no significant difference from those obtained by the other devices. This suggests the Verion system is en par with instruments used in current clinical practice. The Verion Optical Imaging System produces repeatable data with no difference related to operator experience.