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Background: To determine the interchangeability of Scansys (MediWorks, Shanghai, China) and entacam HR (Oculus, Wetzlar, Germany) in anterior segment measurements. Research designs and methods: 42Forty-two healthy individuals' right eye (mean age 31.5 ± 7.3 years) were assessed for keratometry (K), central corneal thickness (CCT), thinnest corneal thickness (TCT), pupil center pachymetry, corneal volume, anterior chamber volume (ACV), anterior chamber depth (ACD), terior chamber angle (ACA), intraocular pressure (IOP) sum, Q-value (asphericity), and horizontal white-to-white (WTW). Intraclass correlation coefficient (ICC), linear regression analysis, difference of mean, and Bland-Altman plots [bias line and 95% limits of agreement (LoA)] were analyzed. Results: Scansys repeated excellently the Pentacam HR for keratometry (except for anterior steep K), ACD, pupil center pachymetry, CCT, TCT, IOP sum, and corneal volume (all ICC > 0.9, r2 > 0.8, and narrow LoAs). There was strong correlations in measuring WTW and ACV (r2 = 0.631 and r2 = 0.623, respectively) and weak correlations in measuring ACA and Q values (all r2 < 0.5). Conclusion: The interchangeability of devices were confirmed in measuring ACD, pupil center achymetry, CCT and TCT, IOP sum, corneal volume, and keratometry except for the anterior steep K. However, in measuring WTW, ACV, asphericity, and ACA, Scansys should not be used instead of Pentacam HR. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the percent change in central corneal thickness (%ΔCCT) during air-puff-induced deformation as an indicator of corneal biomechanical response. Methods: Forty ex vivo human eyes from forty donors were imaged using the CorVis ST at experimentally controlled intraocular pressure (IOP) of 10, 20, 30, and 40 mmHg, followed by uniaxial strip testing to calculate tensile modulus. The CorVis ST research software tracked the anterior and posterior cornea edges and determined the dynamic corneal response (DCR) parameters. Eyes were excluded if image quality or posterior tracking issues were present. Custom algorithms were used to calculate CCT during deformation using a ray-tracing method to correct for Scheimpflug and optical distortion within each image. Correlation and stepwise regression analyses between the shape-related DCR parameters and %ΔCCT were conducted. A mixed model analysis was performed to test the effect of IOP and the strongest significant predictors of the stepwise regression on %ΔCCT. The significance threshold was set to p < 0.05. Results: Thirty eyes were ultimately analyzed and CCT increased significantly from the pre-deformation state to the highest concavity state at each IOP level (p < 0.001). IOP and multiple shape DCRs were found to be significantly related to %ΔCCT (p < 0.0001). The strongest predictor of %ΔCCT was integrated inverse radius (IIR) (p < 0.0001; partial R2 = 0.4772) with no other parameter having a partial R2 value greater than 0.04. The mixed model analysis showed that IIR was the sole predictor (p = 0.0098) and IOP was no longer significant as a single predictor. However, the interaction of IIR with IOP (p = 0.0023) had a significant effect on %ΔCCT. Conclusion: Percent change in CCT is influenced by corneal stiffness as indicated by the significant relationship with IIR. The %ΔCCT may be a potential biomarker for determining differences in corneal deformation response with corneal diseases. [ABSTRACT FROM AUTHOR]

To assess the effect of chronic cigarette smoking on corneal and lens densitometry measurements using Pentacam HR and to compare the results obtained with those in non-smokers. This cross-sectional comparative study included 40 chronic-smokers and 40 age-matched healthy non-smokers between 18–40 years. After general ophthalmic examination, the Pentacam HR imaging system was used to evaluate corneal and lens densitometry measurements of smokers and non-smokers. The mean corneal densitometry values were not statistically significantly different in all the concentric zones and layers in the eyes of the smokers and non-smokers (p > 0.05, for all). However, the mean values of zone 1, zone 2, zone 3 and average lens densitometry measurements of the smokers were statistically significantly higher compared to non-smokers (p < 0.05, for all). Additionally, significant positive correlations were detected between the number of pack-years smoked and lens densitometry measurements. Lens densitometry measurements of smokers were significantly increased while corneal densitometry measurements were not significantly altered compared to non-smokers. Smoking may contribute to cataractogenesis and smoking and age-related changes may act synergistically to cataract development among smokers. [ABSTRACT FROM AUTHOR]

To assess the repeatability and reproducibility of corneal measurements performed by the Galilei G6 and determine its agreement with the Pentacam® AXL. 105 eyes underwent examination by both devices, measuring nine parameters. Paired t-tests, Deming Regression, and Bland-Altman plots were used to determine agreement. Analysis of Variance was used to determine repeatability and reproducibility. Measurements showed no clinically significant differences between the two devices. On average, the Galilei G6 measured axial length longer than the Pentacam® AXL by 0.05 mm ± 0.03 mm (p < 0.001), just 0.2% of the mean value and therefore clinically insignificant. It measured central corneal thickness and anterior chamber depth 3.77 μm ± 7.71 μm longer (p < 0.001) and 0.04 mm ± 0.07 μm shorter (p < 0.001), respectively. They are also clinically insignificant, constituting just 0.7% and 1% of the mean values. The results showed evidence of repeatability and reproducibility. Only measurements of corneal cylinder showed some clinically significant variance. The Galilei G6 and Pentacam® AXL measurements show evidence of repeatability, reproducibility, and agreement for examined parameters. Certain caution needs to be applied in cases with moderate or severe corneal cylinder, due to discrepancies in repeatability and reproducibility of corneal cylinder measurements with the Galilei G6. [ABSTRACT FROM AUTHOR]

Background: The accurate evaluation of corneal thickness (CT) post small incision lenticule extraction (SMILE) is clinically relevant to reduce the risk of complications. We aimed to analyze repeatability and agreement of central corneal thickness (CCT), thinnest corneal thickness (TCT), and mid-peripheral corneal thickness (MPCT) measurements using Scheimpflug imaging, anterior segment swept-source optical coherence tomography (AS-SS-OCT, CASIA 1000, Tomey), and ultrasound pachymetry (USP, SP-3000, Tomey) in eyes with previous SMILE. Methods: Ninety-one eyes of 91 patients were included. Within-subject standard deviation (Sw), test-retest repeatability (TRT), intraclass correlation coefficient (ICC), and coefficient of variation (CoV) were used to evaluate repeatability. Agreement was assessed by repeat-measurement analysis of variance and Bland–Altman analysis. Results: The above three instruments revealed that Sw was <5.91 µm, CoV was <1.08%, TRT was <16.38 µm, and ICC was >0.94. The 95% limits of agreement were relatively narrow and Bland–Altman plots were more concentrated at the CCT, at the TCT, and at the CT2mm. However, it was shown to be wide at the CT5mm. Conclusions: The three devices provide good repeatability of CT measurements in patients who undergone SMILE. Agreement between measurements at the CCT, TCT, and CT2mm were high, but measurement agreements among CT5mm revealed poor agreement. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate corneal parameters in patients with polymyositis (PM) and dermatomyositis (DM) and compare them with those of healthy controls.Methods: A total of 43 PM and 32 DM patients and 93 controls were enrolled in this cross-sectional, observational, case-control study. Corneal parameters were evaluated by Pentacam. Objective clinical tests of dry eye disease (DED) were also performed.Results: All pachymetric measurements and corneal volumes (CVs) proved to be significantly lower both in PM and DM patients. The values of DM patients were closer to control values than those of the PM patients. For tear break-up time and Schirmer-I test values significant differences were observed between patients and controls, with values decreased both in PM and DM patients.Conclusions: PM patients rather than DM patients tend to develop thinner and low-volume corneas as compared to controls. Additionally, a high prevalence of DED among both PM and DM patients was also detected. [ABSTRACT FROM AUTHOR]

Background: Although ageing is the main reason for cataract progression, pseudoexfoliation syndrome (PES) represents an independent additional hazard for the development of nuclear sclerosis and cataract progression. PES can also affect corneal properties. From this perspective, this study aimed to perform a comparison of the corneal and lens densitometry measurements in eyes with PES and age-matched healthy eyes.Methods: This prospective cross-sectional study included 31 patients with unilateral PES and 40 control participants. The Pentacam HR imaging system was used to evaluate corneal densitometry (12 mm corneal diameter) and lens densitometry measurements of eyes with PES (Group 1), clinically unaffected fellow eyes (Group 2) and healthy eyes (Group 3).Results: Eyes in Group 1 and Group 2 had statistically significantly higher corneal densitometry values for all concentric zones and layers compared with eyes in Group 3 (p < 0.05 for all). However, the results were similar when Group 1 and Group 2 were compared (p > 0.05 for all). The lens densitometry values of zone 1, zone 2 and zone 3, as well as the average lens densitometry measurements, were statistically significantly higher in Groups 1 and 2, compared with Group 3 (p < 0.05 for all). On the other hand, these parameters were similar between Groups 1 and 2 (p > 0.05 for all). Additionally, there was no significant difference between the study and control groups with regard to the maximum lens densitometry measurements (p > 0.05).Conclusion: This study revealed that corneal and lens densitometry values of affected and fellow eyes of cases with clinically unilateral PES are significantly higher than those of healthy subjects. [ABSTRACT FROM AUTHOR]

Purpose: To assess agreement of a swept source-optical coherence tomography (SS-OCT) based Biometer with a standard IOLMaster device and Scheimpflug Imaging (SI) to acquire keratometric measurements in cataract patients. Methods: In this prospective comparative study, 101 eyes of 101 cataract surgery candidates, aged 24-81 years, were sequentially examined using three devices. Keratometry values at the flat (K1) and steep (K2) axis, mean corneal power (Km) and magnitude of corneal astigmatism as well as J0 and J45 vectoral components of astigmatism obtained with the SS-OCT based biometer (IOLMaster 700) were compared with those obtained with the IOLMaster 500 and SI. The agreement between measurements was evaluated by the Bland-Altman method, intraclass correlation coefficients (ICCs) and repeated-measures analysis of variance. Results: Mean K1 values from the three devices were similar (p = 0.09). Mean K2 and Km values of IOLMaster 700 were higher than SI and lower than IOLMaster 500 (p = 0.04 for K2 and p = 0.02 for Km). There was a strong correlation between K1, K2, Km and magnitude of astigmatism obtained with all devices (r ≥ 0.80 and p < 0.01). The 95% limits of agreement (LoA) width for each keratometric value were highest for the comparison between IOLMaster 500 and SI and lowest for the comparison between IOLMaster 700 and 500. The mean differences (width of 95% LoA) for J0 and J45 vectoral components were 0.005 (2.19) and 0.12 (2.92) for the measurements obtained by IOLMaster 700 vs IOLMaster 500 and 0.06 (1.79) and 0.02 (1.58) for the measurements obtained by IOLMaster 700 vs SI, respectively. Conclusions: With ICCs close to 1, the agreement between all devices was excellent for keratometric measurements. Mean K2, Km and astigmatism measurements from IOLMaster 700 were lower than IOLMaster 500 and higher than SI. However, the differences were quite small and are not expected to affect the final IOL power. [ABSTRACT FROM AUTHOR]

Purpose: To assess corneal parameters in constitutional thinness (CT) subjects and to compare them with those of healthy individuals.Methods: Twenty-four CT subjects (BMI < 18.5 kg/m2) and 24 healthy subjects (BMI: 18.5-25 kg/m2) were enrolled in this observational cross-sectional study. All participants were screened for age, gender, and medical history, then underwent a detailed ophthalmological examination. Corneal parameters were evaluated by Scheimpflug imaging. Height and weight of all subjects were measured and body mass index (BMI) was calculated.Results: The mean corneal thicknesses at the apex point, the center of pupil, the thinnest point, and the mean corneal volume were significantly lower in CT patients than those of controls. The mean intraocular pressure (IOP) was significantly lower in CTs than in controls. There was a significant correlation between BMI and IOP, and BMI was significantly correlated with all pachymetric measurements and corneal volume.Conclusion: Corneal thicknesses were significantly thinner in CT subjects compared to those in control subjects. The impact of constitutional thinness on corneal parameters should be further investigated. [ABSTRACT FROM AUTHOR]

Purpose: Our aim was to compare densitometry data between keratoconus and normal corneas and to assess the long-term changes in corneal backscattered light values after corneal collagen cross-linking (CXL) treatment. Material and methods: Retrospective analysis was performed on 26 eyes of normal patients (age: 32.71 ± 12.68 years) and 39 eyes of keratoconus patients (28.93 ± 7.59 years) using the Pentacam HR corneal densitometry module before CXL and during the postoperative period, which lasted a mean of 2.53 years (range: 1–4 years). Corneal backscattered light values in grey scale unit (GSU) were recorded for the anterior 120 µm, the center layer, and the posterior 60 µm of the cornea in four concentric, central rings. An additional calculation was performed with converting GSU values to GSU/cubic millimeters (mm3) with surface area calculations and using corneal thickness data. Results: Statistically significant differences were observed between normal and keratoconus group densitometry values (in GSU/mm3) in all annuli of the center layer; all, but anterior layer of the 10–12 annuli; all annuli of the total thickness and in all values of the total diameter. In all these cases, the normal cornea showed higher GSU/mm3values compared to keratoconus corneas (p < 0.05). One month after the CXL treatment, the GSU/mm3data increased significantly in the anterior, the center, and the posterior zone (p < 0.05), followed by its slow decrease. At the end of the follow-up period, the GSU/mm3values were significantly higher in all three zones compared to those before the CXL treatment (p < 0.01). Conclusion: Densitometry measurements can reflect the changes of optical quality of the cornea. These measurements may play a valuable role in assessing keratoconus and optical changes of the corneas after CXL treatment. [ABSTRACT FROM PUBLISHER]

Purpose: To evaluate corneal parameters of scleroderma (SC) patients by Pentacam-HR.Methods: Twenty-two eyes of 22 SC patients and 33 eyes of 33 control subjects were enrolled. All participants underwent Pentacam (Pentacam-HR, Oculus, Germany) evaluation. Both SC and control groups were divided into two subgroups as dry eye (DE) (Schirmer test with topical anesthesia (STA) ˂5 mm) and without DE (STA ˃5 mm).Results: Pachymetric measurements and mean corneal volume (CV) were significantly lower in the SC group than in the control group (p<0.001). Pachymetric measurements and CV of SC patients with DE were significantly lower than all the other subgroups. Control subgroups with or without DE were similar in pachymetric measurements and CV.Conclusions: The results suggest that SC patients have thinner corneas compared with control subjects. Additionally, coexistence of DE seems to have an additional impact in the thinning of cornea in SC patients. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the predictive association between the horizontal anterior chamber diameter (HACD) and other measurements using Scheimpflug imaging, and to assess whether a method superior to using fixed constants can be proposed. Methods: This hospital-based study was performed in the Cornea and Refractive Surgery Services, New Medical Center (NMC) specialty hospital, Abu Dhabi. Initially, 100 candidates were included serially in the model building group (group1). All candidates underwent detailed evaluation and Scheimpflug imaging (CSO, Sirus, Italy). Subsequently, another 100 candidates were included serially in the validation group (group 2). Candidates in both groups underwent the same tests. Results: In group 1, the mean HACD was 12.25 ± 0.48 mm. This measurement correlated significantly with the horizontal visible iris diameter (HVID), anterior chamber depth, angle (ACA), and volume (ACV) (r = 0.2–0.7). The overall regression equation was HACD = 5.62 + 0.01 × ACV + 0.45 × HVID − 0.013 × ACA (adjusted R2= 0.66, p < 0.001). Situation-based equations derived from the outcomes of group 1 were tested in group 2. Equation A included all factors found significant during model-building, Equation B included only non-volumetric significant factors, and situation C only included the HVID. Equations D through F used direct substitution by HVIDplusa constant to predict HACD (the constant was 0.0, 0.5, and 1.0 for Equations D, E, and F, respectively). The predicted HACD (pHACD) was within ±0.5 mm of the actual HACD (aHACD) in 93%, 88%, 87%, 83%, 69%, and 16% case for Equations A, B, C, D, E, and F, respectively. The mean prediction error was −0.14 ± 0.27 mm (p= 0.08), −0.15 ± 0.28 mm (p= 0.03), −0.18 ± 0.30 mm (p= 0.001), −0.18 ± 0.32 mm (p< 0.001), 0.33 ± 0.35 mm (p< 0.001), and 0.83 ± 0.35 mm (p< 0.001) for Equations A, B, C, D, E, and F, respectively. Conclusion: Regression equations using Scheimpflug-derived anterior chamber parameters may predict HACD to varying degrees, depending on the input parameters. Adding 0.5 or 1.0 mm to the corneal diameter (CD) to estimate the HACD is not recommended. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the differences in the biometric parameters of the anterior segment in Fuchs' uveitis syndrome (FUS).Methods: 30 eyes of 15 consecutive patients with unilateral FUS were examined. Anterior segment parameters were measured by rotating Scheimpflug imaging camera. Central endothelial cell count was measured by noncontact specular microscopy.Results: The central cornea was thinner (p < 0.001), the iridocorneal angle was significantly larger (p < 0.010), anterior chamber depth was deeper in the eyes with FUS (p < 0.006). The iris bowing was different between the affected eye and the healthy eye. The mean endothelial cell density of eyes with FUS was significantly lower than control eyes (p < 0.001).Conclusions: Scheimpflug imaging method is a useful tool to analyze the anterior segment parameters in FUS. Endothelial cell loss, as well as decreased percentage of endothelial hexagonal cells, is obtained by noncontact specular microscopy in patients with FUS. [ABSTRACT FROM AUTHOR]

For the modern day refractive surgeon, tomography has become an invaluable tool for selection of patients for refractive surgery; in addition it is essential for the diagnosis and treatment planning of ectatic disorders of the cornea. This review article attempts to compare the Scheimpflug with the Placido disc systems, stresses the value of elevation-based topography and the importance of posterior float. Finally, this article provides a comprehensive literature review of the most widely used tomographers, the Orbscan IIz, anterior segment optical coherence tomography, Pentacam, and Galilei Scheimpflug systems. Comparisons of the above tomographers provided in the available literature with respect to corneal elevation, corneal curvature (power) and pachymetry and calculation of intraocular lens power post-refractive surgery have also been discussed. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the nature of ocular residual astigmatism (ORA) in myopic patients and to identify indicators to predict a patient's ORA from corneal and ocular refractive data. Methods: In total, 356 myopic eyes from 178 patients (M:F = 41:137) were examined using a Scheimpflug keratometer (Pentacam) and a wavefront analyzer (Wave Scan). Vertex distance-adjusted total ocular astigmatism and corneal astigmatism [anterior corneal power (ACP) and true net power (TNP)] were used to calculate ORA, respectively. A power vector system (J0 and J45) was adopted for the astigmatism analysis. Results: The mean age of the study eyes was 27.6 ± 5.0 years, and mean refractive spherical equivalent, sphere and cylinder was -4.94 ± 1.90 diopter, --4.42 ± 1.87 diopter, and --1.05 ± 0.82, respectively. Corneal astigmatism measured by TNP was more representative of total ocular astigmatism than ACP (p < 0.001). Both the J0 and J45 components of ORA showed significant negative correlation with corneal astigmatism measured by ACP and TNP (p< 0.001). ORA (J0 and J45) was negatively correlated with total ocular spherical equivalent and positively correlated with total ocular astigmatism. Conclusions: We verified the general compensatory effect of corneal astigmatism by internal optics in myopic patients. TNP was closer to refractive astigmatism than ACP was. Total ocular spherical equivalent and total ocular astigmatism showed significant correlation with ORA. Therefore these can be possible indicators to predict ORA. [ABSTRACT FROM AUTHOR]

Since the Scheimpflug principle was first described more than a century ago, there has been great interest among ophthalmologists in the use of Scheimpflug cameras in anterior-segment imaging. Scheimpflug cameras have advanced significantly and modern-day instruments provide comprehensive imaging and topographic data of the anterior segment. The clinical applications and limitations of Scheimpflug imaging in corneal, cataract and refractive surgery patients are discussed. This article also covers an assessment of anterior chamber biometry for precataract surgery calculations and glaucoma screening, corneal topography of the anterior and posterior corneal surfaces using elevation data for early detection of keratoconus and post-laser in situ keratomileusis ectasia, lens changes with accommodation, lens transparency for cataract grading, and integrity and density of the posterior capsule for posterior-capsule opacification grading using the currently commercially available Scheimpflug cameras. [ABSTRACT FROM AUTHOR]

Background: Both Shack-Hartmann aberrometry (IRX3, Imagine Eyes, Orsay, France) and Scheimpflug photography (Oculus Pentacam, Oculus Inc Wetzlar, Germany) are known to provide repeatable measurements. The variability in measurements of corneal and ocular aberrations obtained with these instruments over one week had not been assessed. The aim was to study the variability in corneal and ocular aberrations in the human eye over one week and to determine the impact of age on corneal and crystalline lens aberrations and on the variability of these measurements. Methods: Monochromatic ocular aberrations were measured with the IRX3 and monochromatic corneal aberrations were measured using Scheimpflug photography on one eye of 23 normal subjects at periods of a few seconds, one hour and one week after the initial measurement. Results: No significant differences were found between the initial aberrations and aberrations measured at 59 ± 24 seconds, 1.10 ± 0.24 hours and 7.11± 0.31 days later. Analysis with Bland and Altman plots showed that measurements with both instruments were highly repeatable over the times studied. There was no relationship between age and the variance of corneal and ocular aberrations (higher order, spherical and coma aberrations). Corneal spherical aberration did not show a significant correlation with age, whereas the lens aberrations changed from being negative in the younger age groups to positive in the older age group, however, these differences failed to reach statistical significance (p > 0.05). Conclusion: The variability found in all the measurements was small and not clinically significant and could be attributable to instrument noise, changes in the tear film and to small fixational eye movements. [ABSTRACT FROM AUTHOR]