Comparison of Anterior Chamber Parameters between Normal and Keratoconus Eyes using Scheimpflug Photography

ABSTRACT Aim To evaluate anterior chamber indices including anterior chamber depth (ACD) and anterior chamber volume (ACV) with the progression of keratoconus using a rotating Scheimpflug camera to determine the sensitivity and specificity of these parameters in discriminating keratoconus from normal eyes. Materials and methods After full ophthalmological examination in the Memorial Institute of Ophthalmic Research, the patients are divided into two groups: Group I consisting of 50 eyes of normal control. Group II consists of 50 eyes of moderate keratoconus. All the subjects were evaluated with a Pentacam Scheimpflug camera (Oculus, Wetzlar, Germany). Keratoconic eyes were evaluated by vertical asymmetry (VI), keratoconus index (KI), thinnest corneal thickness (TCT) with front elevation at thinnest location (F.Ele.Th) and back elevation at thinnest location (B.Ele.Th) and then divided into three groups according to mean keratometer (K) readings: Mild (K = less than 47.0 D), moderate (K = 47.0 to 52.0 D), and severe (K = 52.0 D or higher), and ACD and ACV were obtained after exclusion of mild and severe cases. Results With the progression of the disease, there was statistically significant differences in ACD and ACV measurements between the normal and moderate keratoconus eyes with progressive increase in the ACD and ACV with disease progression. Conclusion Anterior chamber parameters including depth and volume showed significant increase with moderate keratoconus than control. How to cite this article Ali NH, AbdElKhalek MO, El Ghonemy HM. Comparison of Anterior Chamber Parameters between Normal and Keratoconus Eyes using Scheimpflug Photography. Int J Kerat Ect Cor Dis 2016;5(3):105-108.

Corneal Deformation Response with Dynamic Ultra-high-speed Scheimpflug Imaging for Detecting Ectatic Corneas

ABSTRACT Purpose To test the ability of metrics derived from corneal response to noncontact tonometry (NCT) to distinguish between normal and ectatic cases. Materials and methods The prototype of CorVis ST (Oculus, Wetzlar, Germany) was used for assessing corneal biomechanical response using ultra-high-speed 8 mm horizontal Scheimpflug photography, taking 4,330 frames per second during NCT. Patients were stratified based on clinical data, including rotating Scheimpflug corneal tomography (Oculus Pentacam HR). Biomechanical data from one eye randomly selected of 177 patients with normal corneas (N) and from 79 patients with bilateral keratoconus (KC) were investigated. Group forme fruste keratoconus (FFKC) was composed of 20 eyes with normal topographic patterns from cases with ectasia detected in the fellow eye. Group keratoconus suspect (KCS) had 16 eyes from 16 patients with topographic patterns suspicious of KC but documented stability over 3 years and normal tomographic findings. A combination of deformation parameters using linear regression analysis (Prototype Factor 1, pF1) was created by the BrAIn (Brazilian Artificial Intelligence on Corneal Tomography and Biomechanics) study group in order to provide the best possible separation of KC and normals. Results Statistical significant differences were found for N × KC for several parameters, including first and second applanation times, deformation amplitude, and maximal concavity radius (Mann–Whitney, p < 0.001). However, the areas under the receiver operating characteristic curves (AUC) were lower than 0.90. The pF1 had AUC of 0.945 (IC 0.909–0.97; sensitivity = 87.3% and specificity = 89.3%). The pF1 had statistically significant differences between the ectatic (KC and FFKC) and nonectatic groups (N and KCS) (p < 0.05, Kruskall–Wallis Test with post hoc Dunn's test). Conclusion Corneal deformation response analysis by ultra- high-speed 8 mm horizontal Scheimpflug photography provides relevant data for distinguishing ectatic and nonectatic corneas but cannot be used independently to detect KC. This data may be integrated with corneal tomography data for enhancing sensitivity and specificity for screening ectasia. How to cite this article Salomão MQ, Correia FF, Ramos I, Luz A, Ambrósio R Jr. Corneal Deformation Response with Dynamic Ultra-high-speed Scheimpflug Imaging for Detecting Ectatic Corneas. Int J Kerat Ect Cor Dis 2016;5(1):1-5.

Evaluation of Pachymetric Measurements with Scheimpflug Photography-Based System and Optical Coherence Tomography Pachymetry at Different Stages of Keratoconus

The aim of this study was to compare the central and peripheral pachymetric measurements determined with Sirius system and Visante OCT and evaluate the agreement between them at different stages of keratoconus. Measurements were not significantly different in all patients and subgroups and showed high correlation for the corneal thicknesses of the entire cornea in different stages of keratoconus.