Evaluation of new Corvis ST parameters in normal, Post-LASIK, Post-LASIK keratectasia and keratoconus eyes

Abstract

The aim of this study was to evaluate the distribution of new Corneal Visualisation Scheimpflug technology (corvis St) parameters in normal, post-laser in situ keratomileusis (LASiK), post-LASiK keratectasia (Ke) and keratoconus (Kc) eyes, and explore the diagnostic ability of these parameters in distinguishing KE from LASIK eyes. Twenty-three normal eyes, 23 LASIK eyes, 23 KE eyes and 23 KC eyes were recruited in this study. the following new corvis St parameters were measured: Max inverse Radius, deformation amplitude (DA) Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Ambrosio's relational thickness horizontal (ARTh), Integrated Radius, stiffness parameter at first applanation (SP-A1) and Corvis biomechanical index (CBI). The general linear model, linear regression model, relation analysis and receiver operating characteristic (Roc) curve were performed. the Max inverse Radius, DA Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius and CBI in LASIK eyes, KE eyes and KC eyes were higher than in normal eyes, while the ARTh and SP-A1 parameters were lower than in normal eyes. The KE eyes had higher Max Inverse Radius, DA Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius, and lower SP-A1 value than LASIK eyes (all P < 0.05). The central corneal thickness was related to the pachy Slope (r = −0.485), ARTh (r = −0.766), SP-A1 (r = 0.618) in Ke eyes (all P < 0.05). The area under the ROC curve of Integrated Radius, Max Inverse Radius, DA Ratio Max [2 mm] and SP-A1 were above 0.800 in identifying KE from LASIK eyes. Thus, the new Corvis ST parameters were different between LASIK and KE eyes, suggesting that they might be helpful in distinguishing Ke eyes from LASiK eyes. However, a further multi-center and large sample study is necessary to confirm these findings.

Accuracy of new Corvis ST parameters for detecting subclinical and clinical keratoconus eyes in a Chinese population

“…This prospective study was conducted between September 2018 and January 2020. Clinical KC in current study was diagnosed according to the following criterion: (1) corneal topography revealing an asymmetrical bowtie pattern with or without skewed axes; (2) KC sign on slit-lamp examination, such as localized stromal thinning, conical protrusion, Vogt’s striae, Fleischer’s ring, or anterior stromal scar; (3) Belin Ambrosio enhanced ectasia total deviation index (BAD-D) value > 2.6 1 , 13 . The SKC eye in the current study was defined by (1) no clear evidence of KC in one eye; (2) the contralateral eye diagnosed with clinical KC eye 17 .…”

“…With the software updated (number: 1.5r1902), new parameters were gradually used in the clinic 12 . Our previous studies found that new Corvis ST parameters were different between KC and normal control eyes 12 , 13 . Several studies have also reported that new Corvis ST parameters of SKC eyes are different from normal and KC eyes 14 , 15 .…”

A hospital-based study on clinical data, demographic data and visual function of keratoconus patients in Central China

“…The inclusion criteria of clinical KC were as follows 7 , 19 : asymmetric bowtie pattern with or without skewed axes revealed by corneal topography and at least one KC clinical sign detected by slit-lamp examination (localized stromal thinning, Vogt’s striae, Fleischer’s ring, conical protrusion, or anterior stromal scar). Unilateral KC was considered if a patient had KC in one eye but did not meet the diagnostic criteria in the contralateral eye.…”

Evaluation of Intraocular Pressure and Other Biomechanical Parameters to Distinguish between Subclinical Keratoconus and Healthy Corneas

“…The Corvis ® ST device (Oculus Optikgeräte GmbH; Wetzlar, Germany) is a non-contact tonometer system with an ultra-high-speed Scheimpflug camera that provides corneal biomechanical parameters and IOP information [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. It also affords a high degree of repeatability [ 13 , 25 , 26 , 27 ] and gives a correlation between age, corneal thickness, IOP, and some Corvis ® ST biomechanical parameters [ 17 , 24 , 28 ].…”

“…Some studies show differences in biomechanical Corvis ® ST parameters between keratoconic and healthy corneas [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. More recently, other studies have evaluated SCKC with this device [ 12 , 18 , 19 , 29 , 30 ].…”