Orbscan ii, noncontact specular microscopy, and ultrasonic pachymetry in eyes after laser in situ keratomileusis. To validate the use of orbscan ii slitscanning topography for measuring posterior corneal curvature, by comparing corneal power calculations using. Three subjects dropped out of the study because they were apprehensive about the ubm examination. Displays multiple and complete mathematical surfaces. Pairwise comparisons of the orbscan ii vs ubm and orbscan ii vs artemis 2 vhfus.
Pdf repeatability and reproducibility of orbscan ii. The images used to construct the anterior corneal surface,posterior corneal surface,anterior iris and anterior lens surfaces. Measure surface slope directly using specular reflection, supplemented with triangulated elevation. Central corneal thickness was measured in 203 eyes after myopic lasik. The values of diff and anterior chamber depth acd were recorded. The current version of these documents and the interpretation guide are on.
The wide variety of maps can make orbscan bewildering. Accuracy of orbscan ii slitscanning elevation topography. The orbscan ii had wide limits of agreement when compared with both the galilei 11 to 47. Pdf comparison of the orbscan ii topographer and the. Orbscan ii is a 3dimensional slitscanning topography system for analysis of the corneal anterior and posterior surfaces as well as pachymetry. There was a statistically significant difference between mean acd measured with the orbscan ii, ubm and artemis2 vhfus, as determined by anova p0. Syn optophore and orbscan ii corneal topography were used to measure angle kappa. The mean horizontal corneal diameter measurements with the galilei, the eyesys and the orbscan ii were 12. The mean differences, sds, loa and pairwise comparisons using pvalues for acd measurements using the orbscan ii, ubm and artemis2 vhfus are summarized in table 2.
In this prospective study, one eye from each of 60 normal subjects was randomly selected. Central and peripheral corneal thickness measurement with. Pairwise comparisons of the orbscan ii vs ubm and orbscan ii vs artemis2 vhfus. The orbscan manufactured by orbtek and distributed by bausch and lomb received fda clearance in 1999. Holzman to evaluate the curvature and other dimensions of the cornea, which can tell him which procedure is. Comparison of corneal thickness measurement with orbscan ii and ultrasonic pachymetry article pdf available in journal of refractive surgery thorofare, n.
Refractions and orbscan ii mapping were obtained in a standard fashion preoperatively and at varying times postoperatively, when the eyes were deemed stable from lasik surgery. Both orbscan ii and iolmaster agreed with echoscan in measuring acd. Radius of the posterior sphere of reference the mean radius of. Keratoconus with congenital cataract, high myopia and high. Corneal topography, computer assisted photokeratoscopy.
Subjects having any type of ocular pathologic features or surgery or a family history of keratoconus were not included in this study. Sep 17, 2018 orbscan orbscan manual factor data at orbscan manual measurement zone are also recorded maunal table 3. Radius of the posterior sphere of reference the mean radius of the posterior bfs from the. The same patterns were obtained with the orbscan ii system for the same subject also displaying greater astigmatism of the posterior surface. Comparison and repeatability of keratometric and corneal. Agreement between clinical history method, orbscan iiz, and. The original version of orbscan slitscanning topography system was launched in 1995. Orbscan ii anterior system was used for early diagnosis of keratoconus. It uses calibrated video and a scanning slit beam to measure x, y, and z locations of several thousand points. The mean postoperative pachymetry measured by us, orbscan 0. Orbscan corneal topographer technology lasik flaum. Data were analyzed using the paired sample t test, blandaltman plots, and linear regression. Comparative evaluation of refractive surgery candidates with.
Central corneal thickness measurement with pentacam, orbscan. Orbscan corneal topographer technology lasik flaum eye. This value was measured three times per eye and per device, and the average was retained. Comparison of corneal thickness measurement with orbscan ii. Orbscan ii and itrace systems in 100 myopic patients.
The state of the art orbscan ii is one of the most technologically advanced corneal topography systems. High reproducibility was also found for all orbscan measurements r 2 0. Furthermore, the statistical model showed a marked significant difference in the orbscan ii assessment of keratectasia and change in acd p pentacam and orbscan ii before and after. For each device, the intraclass correlation coefficient for cct was. Measure surface elevation directly by triangulation of backscattered slitbeam. Orbscan orbscan manual factor data at orbscan manual measurement zone are also recorded maunal table 3. Andrew holzman to use when evaluating candidacy and planning refractive surgeries such as lasik. Furthermore, the statistical model showed a marked significant difference in the orbscan ii assessment of keratectasia and change in acd p orbscan ii device, the forward protrusion of the posterior corneal surface appears to coincide with a paradoxical reduction in depth of the anterior chamber.
One orbscan operator performed acd measurements in all eyes first. There was a statistically significant difference between mean acd measured with the orbscan ii, ubm and artemis2 vhfus, as determined by anova p 0. Central corneal thickness measurement with pentacam. Data regarding the corneal pachymetry and anterior chamber depth. Nov 20, 20 to measure angle kappa distance with orbscan ii and galilei g4, and to evaluate possible variations in this value for different accommodation degrees. Orbscan ii, ubm and artemis2 vhfus are summarized in table 2. Pdf repeatability and reproducibility of orbscan ii researchgate. The state of the art orbscan ii is one of the most technologically. This optical mapping or corneal topography system mapping system is a diagnostic tool that shows the overall architecture of the cornea including surface power, thickness, front and back shape. Bausch and lomb orbscan iiz corneal analysis system. Comparison of the orbscan ii topographer and the itrace aberrometer for the measurements of keratometry and corneal diameter in myopic patients.
Oct 23, 2008 orbscan ii by orbtek bausch and lomb sets a new standard for precision measurement of the anterior segment of the eye. Agreement between orbscan ii, vumax ubm and artemis2 very. These results indicate the orbscan device achieves a high degree of agreement and correlation with pachymetry. Mar 31, 2016 the mean wtw distance measurements with the orbscan ii and itrace were 11. In another study of orbscans ability to measure corneal thickness, researchers in. Corneal changes after laser refractive surgery for myopia. Unify triangulated and reflective data to obtain accurate surfaces in elevation, slope, and curvature. P orbscan ii is a threedimensional slitscan topography system for analysis of the corneal surfaces and anterior chamber.
Comparison of the orbscan ii topographer and the itrace. The pentacam oculus is one of a number of rotating scheimpflug imaging systems produced in germany. Orbscan ii by orbtek bausch and lomb sets a new standard for precision measurement of the anterior segment of the eye. The difference of means between the orbscan ii and pentacam was 0. Comparison of corneal thickness measurements using orbscan. Acd measurement differences with the 3 studied devices proved to be statistically significant. Efficacy of orbscan ii and pentacam topographers by a. Measurement of angle kappa with synoptophore and orbscan ii in.
Knowing the shape and position of both corneal surfaces allows the computation of the thickness of the entire cornea. The aim was to compare the anterior chamber depth acd measurements taken with orbscan ii, ultrasound biomicroscopy ubm and the artemis2 vhf veryhighfrequency ultrasound scanner in normal subjects. Galilei, eyesys and orbscan ii measurements were compared with one another. A complete orthoptic and ophthalmologic examination was performed. Comparison of corneal thickness measurements using orbscan ii. Research article open access agreement between orbscan ii. Wed like to understand how you use our websites in order to improve them. Validation of orbscan ii posterior corneal curvature. Only a moderate level of agreement was found among these values. Bausch and lomb orbscan ii topographer vsi vision systems inc. The aim was to compare the anterior chamber depth acd measurements taken with orbscan. The mean wtw distance measurements with the orbscan ii and itrace were 11. The orbscan ii mean power maps were obtained at the following paracentral zones. There was a statistically significant difference between mean acd measured with the orbscan ii, ubm and artemis 2 vhfus, as determined by anova p0.
A topography unit is a machine that takes a specialized photo of the cornea, the front transparent window of the eye. Early diagnosis of keratoconus with orbscan ii anterior. Statistical evaluation was performed using the paired t test, pearson correlation, and blandaltman analysis for comparison of measurement techniques. Bausch and lomb orbscan 2 topographer model information. Doclive free unlimited document files search and download. In addition, the data from the right and left eyes were compared for each device. Feb 25, 2008 the reason for higher measurements by orbscan ii pachymetry as compared to ultrasound is the difference in the manner the instruments operate. Since the shape of corneal surface determines its refractive power, even a minor modification of its surface can lead to significant alteration of image formed on retina. The placido disk and 40 slits are sequentially projected on the cornea, then the anterior and posterior edges of the slits are captured and analyzed, and.
Measurement of angle kappa with orbscan ii and galilei g4. The orbscan ii also provides anterior segment data in the form of topographic surfaces. It uses a slitscanning system to measure 18 000 data points and uses a placidobased system to make necessary adjustments to produce topography data. The new platform, which features multiple enhancements driven by more than 20 years of field use and research, is designed to serve as an indispensable screening tool to the increasing number of ophthalmic. Central corneal thickness measurements using orbscan ii. To validate the use of orbscan ii slitscanning topography for measuring posterior corneal curvature, by comparing corneal power calculations using this value with the standard keratometric method. This study aimed to determine the repeatability and reproducibility of orbscan for anterior and posterior best fit. Comparison of anterior chamber depth in healthy myopic. Central corneal thickness measurement by ultrasound versus. Unlike current topography systems which scan the surface of the eye at standard points, the orbscan ii acquires over 9000 data points in 1. The second generation orbscan ii is a hybrid system that uses both projective slit scanning and reflective placido methods. To compare central corneal thickness measurements of three pachymetry devices in eyes after laser in situ keratomileusis lasik. Results indicated that values of diff and acd were increased in 4 eyes of 2 patients with keratoconus trend.
Evaluation of machine learning classifiers in keratoconus. Cornea is the most powerful refractive element of the eye contributing 43d70% of refractive power of eye. Pairwise comparisons of the orbscan ii vs ubm and orbscan ii. Evaluation of orbscan ii corneal topography in individuals. The mean keratometry values with the orbscan ii and itrace were 43. The orbscan ii topographer, combined slitscanning with a placido disk, has the capacity to directly acquire elevation and curvature data of both anterior and posterior corneal surfaces. Holzman to evaluate the curvature and other dimensions of the cornea, which can tell him which procedure is right for you, as well as the degree of correction. The middle dotted line corresponds to orgscan average bias. At that time, orbscan was the only commercially available machine that could measure surface elevation of the cornea. Utilizing a scanning slit measurement system, the instrument provides the clinician with important diagnostic information about the cornea, iris, and lens. In the later version, namely the orbscan ii, the placido disc technique was incorporated to enable direct measurement of corneal curvature. Pdf evaluation of machine learning classifiers in keratoconus. To establish the accuracy of orbscan ii orbtek inc.
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