Corneal Biomechanics as a Function of Intraocular Pressure and Pachymetry by Dynamic Infrared Signal and Scheimpflug Imaging Analysis in Normal Eyes

Huseynova, Tukezban; Waring, George O.; Roberts, Cynthia J.; Krueger, Ronald R.; Tomita, Minoru

doi:10.1016/j.ajo.2013.12.024

Cited by 152 publications

(99 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This finding demonstrated that deflection amplitude ratio, highest concavity radius, and inverse concave radius are good parameters to correctly evaluate in vivo corneal biomechanics due to their relative independence from IOP. Another important finding is the confirmation that many parameters used in earlier publications (eg, deformation amplitude) are strongly correlated with IOP 32,33 and that, if IOP is not matched or compensated statistically, comparison between groups would not be valid.…”

Section: Iop Groupsmentioning

confidence: 59%

“…[28][29][30][31] However, it has been demonstrated that IOP and pachymetry have important influences on most corneal biomechanical metrics provided by both the Corvis ST and ORA. [32][33][34] It is therefore relevant to investigate the distribution and normal limits for the in vivo corneal biomechanical data derived from dynamic corneal response parameters, and determine whether these metrics have correlations with IOP and corneal thickness.…”

Section: Resultsmentioning

confidence: 99%

“…These findings were confirmed by previous reports, which indicated that IOP and pachymetry have important influences on most corneal biomechanical metrics provided by the Corvis ST and ORA. [32][33][34] The conclusions of these earlier studies were that IOP and pachymetry are important in deformation response evaluation and must be taken into consideration. Additionally, the authors concluded that comparisons of research groups based on the ORA and Corvis ST with different IOPs and CCTs may lead to possible misinterpretations if either is not considered in the analysis.…”

Section: Pachymetry Groupsmentioning

confidence: 99%

See 2 more Smart Citations

Influence of Pachymetry and Intraocular Pressure on Dynamic Corneal Response Parameters in Healthy Patients

et al. 2016

View full text Add to dashboard Cite

n 1619, Scheiner provided the first precise description of the corneal shape using glass balls of known curvatures.1 From that first description, many other diagnostic tools have been developed to describe corneal shape, from keratometry to corneal topography (front surface curvature maps), 2 then into three-dimensional corneal tomography systems.3 More recently, it has been shown that corneal biomechanical behavior plays an important role in maintaining corneal shape, which is necessary for light refraction and clear vision, 4 and should therefore be considered in understanding the development of ectatic diseases 5,6 and the results of surgery. 4,7 Until recently, the evaluation of corneal biomechanical properties had been restricted to ex vivo laboratory studies 5,8 and mathematical corneal models. METHODS: Seven hundred five healthy patients were included in this multicenter retrospective study. The biomechanical response data were analyzed to obtain normative values with their dependence on corrected and clinically validated intraocular pressure estimates developed using the finite element method (bIOP), central corneal thickness (CCT), and age, and to evaluate the influence of bIOP, CCT, and age. RESULTS:The results showed that all DCRs were correlated with bIOP except deflection amplitude (DefA) ratio, highest concavity (HC) radius, and inverse concave radius. The analysis of the relationship of DCRs with CCT indicated that HC radius, inverse concave radius, deformation amplitude (DA) ratio, and DefA ratio were correlated with CCT (rho values of 0.343, -0.407, -0.444, and -0.406, respectively). The age group subanalysis revealed that primarily whole eye movement followed by DA ratio and inverse concave radius were the parameters that were most influenced by age. Finally, custom software was created to compare normative values to imported examinations.CONCLUSIONS: HC radius, inverse concave radius, DA ratio, and DefA ratio were shown to be suitable parameters to evaluate in vivo corneal biomechanics due to their independence from IOP and their correlation with pachymetry and age. The creation of normative values allows the interpretation of an abnormal examination without the need to match every case with another normal patient matched for CCT and IOP.[J Refract Surg. 2016;32(8):550-561.]

show abstract

Section: Iop Groupsmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Pachymetry Groupsmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Pachymetry and Intraocular Pressure on Dynamic Corneal Response Parameters in Healthy Patients

et al. 2016

View full text Add to dashboard Cite

show abstract

“…It is known that many DCR parameters are correlated with thickness. 14,27,28 Regarding the inclusion of A1 velocity, even though it has a poor single capability of separating healthy from keratoconic eyes, its presence increased the sensitivity by two percentage points (see step 3 of Table 1). We hypothesize that, given its correlation with IOP, 14 it compensates for the difference in IOP in the single cases.…”

Section: Discussionmentioning

confidence: 99%

Detection of Keratoconus With a New Biomechanical Index

Vinciguerra¹,

Ambrósio²,

Elsheikh³

et al. 2016

J Refract Surg

390

346

View full text Add to dashboard Cite

he early diagnosis of corneal ectasia is of foremost importance in both screening for refractive surgery and the early treatment of keratoconus. Topography or tomography analysis using either videokeratography or optical coherence tomography instruments can help detect alteration in the shape of the cornea such as thinning and increased curvature. However, these instruments cannot measure the mechanical stability, which is thought to be the initiating event of the disease, even before notable changes in corneal morphology take place.1,2 For this reason, there has been increasing interest in developing instruments to measure the in vivo biomechanical properties of the cornea to aid the diagnosis of an ectasia in a "biomechanical" stage, when topography and tomography are nor-T ABSTRACT PURPOSE: To evaluate the ability of a new combined biomechanical index called the Corvis Biomechanical Index (CBI) based on corneal thickness profile and deformation parameters to separate normal from keratoconic patients.METHODS: Six hundred fifty-eight patients (329 eyes in each database) were included in this multicenter retrospective study. Patients from two clinics located on different continents were selected to test the capability of the CBI to separate healthy and keratoconic eyes in more than one ethnic group using the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). Logistic regression was employed to determine, based on Database 1 as the development dataset, the optimal combination of parameters to accurately separate normal from keratoconic eyes. The CBI was subsequently independently validated on Database 2. RESULTS:The CBI included several dynamic corneal response parameters: deformation amplitude ratio at 1 and 2 mm, applanation 1 velocity, standard deviation of deformation amplitude at highest concavity, Ambrósio's Relational Thickness to the horizontal profile, and a novel stiffness parameter. The receiver operating characteristic curve analysis of the training database showed an area under the curve of 0.983. With a cut-off value of 0.5, 98.2% of the cases were correctly classified with 100% specificity and 94.1% sensitivity. In the validation dataset, the same cut-off point correctly classified 98.8% of the cases with 98.4% specificity and 100% sensitivity. CONCLUSIONS:The CBI was shown to be highly sensitive and specific to separate healthy from keratoconic eyes. The presence of an external validation dataset confirms this finding and suggests the possible use of the CBI in everyday clinical practice to aid in the diagnosis of keratoconus.[J Refract Surg. 2016;32(12):803-810.]

show abstract

“…7,8 Despite its potential, the former has demonstrated limited ability for screening of ectatic disease. 9,10 The latter features advanced parameters that can help detect early ectasia and fruste keratoconus with higher accuracy.…”

Section: Introductionmentioning

confidence: 99%

First Clinical Impressions on the Integrated Corneal Tomography and Corneal Deformation with Scheimpflug Imaging

Haddad¹,

Barnwell²,

Rocha³

et al. 2017

International Journal of Keratoconus and Ectatic Corneal Diseases

View full text Add to dashboard Cite

The purpose of this study is to report the preliminary findings and the retrospective clinical impressions of the integrated corneal tomography and corneal deformation parameters with a dynamic ultra-high-speed Scheimpflug camera equipped with a noncontact tonometer. Twelve eyes of six patients were evaluated by the Scheimpflug imaging system of the Pentacam HR and Corvis ST (OCULUS Optikgeräte GmbH, Wetzlar, Germany) devices. The parameters used were the Belin/Ambrósio deviation (BAD-D) and Corvis biomechanical index (CBI), as well as the recently published tomographic and biomechanical index (TBI), combined with a detailed clinical data and evaluation of normal eyes and patients with different stages of corneal ectasia.

show abstract

Corneal Biomechanics as a Function of Intraocular Pressure and Pachymetry by Dynamic Infrared Signal and Scheimpflug Imaging Analysis in Normal Eyes

Cited by 152 publications

References 18 publications

Influence of Pachymetry and Intraocular Pressure on Dynamic Corneal Response Parameters in Healthy Patients

Influence of Pachymetry and Intraocular Pressure on Dynamic Corneal Response Parameters in Healthy Patients

Detection of Keratoconus With a New Biomechanical Index

First Clinical Impressions on the Integrated Corneal Tomography and Corneal Deformation with Scheimpflug Imaging

Contact Info

Product

Resources

About