Keratoconus Clinical Trial
Official title:
Evaluation of the Sensitivity, Specificity, and Test Accuracy of Corneal Biomechanical Metrics, Anterior Segment Data and a Combination Model, in Differentiating Forme Fruste Keratoconus (FFK) From Healthy Corneas.
The present study attempts to evaluate the diagnostic capacity of a) anterior segment
parameters b) biomechanical metrics and c) a combination model, in differentiating Forme
Fruste Keratoconus (FFK) from healthy corneas.
The study adhered to the tenets of the Declaration of Helsinki and written informed consent
was given by all participants. The study was conducted at the Eye Institute of Thrace (ΕΙΤ),
in Alexandroupolis, Greece. EΙΤ is a Democritus University research institute focusing
primarily on the conditions of the anterior segment of the eye.
All participants underwent a complete clinical evaluation including review of medical
history, visual acuity measurements, uncorrected and best corrected visual acuity, placido
disc topography, Scheimpflug camera measurements, ORA measurements , slitlamp biomicroscopy
and fundoscopic examination.
All study participants were divided in two groups. The FFK group (FFKG) consisted of
patients with unilateral KC.
The control group (CG) was formed by refractive surgery candidates who visited EIT's
outpatients service for their preoperative examination.
CRF and CH parameters were obtained while the patient was sitting on a chair in front of the
Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Buffalo, NY, USA) device.
Upon successful fixation of the patient's eye on a red blinking target, the operator
activated the device. An air puff was released by a non-contact probe, which scanned the
central area of the eye and sent a signal to the ORA. In brief, the air puff causes the
cornea to move inward, past applanation, and into slight concavity. After milliseconds, the
air pumps shut off, the pressure decreases, and the cornea begins to return in its normal
state. The system monitors the entire process and measures two pressure values, which are
determined from the inward and outward applanation processes. The aforementioned measuring
procedure enables the determination of CH which is related to the viscoelastic structure of
the corneal tissue, and is calculated as the difference between the two pressure values at
the two applanation processes, and CRF which is indicative of the overall resistance of the
cornea and is calculated as a linear function of the two pressures associated with the two
applanation. In order to ensure accurate results, ORA was done four times for each eye, by
the same operator. Signals that differ significantly in appearance from the other signals
from the same eye were deleted.
Corneal Astigmatism (Cyl), Anterior Chamber Depth (ACD), Corneal Volume at 3mm (CV3), at 5mm
(CV5), and overall (CV), Central Corneal Thickness (CCT), Thinnest Corneal Thickness (TCT)
and TCT co-ordinates (TCTx, TCTy) were obtained using Pentacam. KISA index was calculated
using Pentacam derived topography. Pentacam is based on a rotating Scheimpflug camera and
monochromatic slit light source (a blue light emitted diode at 475 nm) which rotate
together. After proper alignment of the patient's head, a fixation target is shown which
guides the patients gaze. A real time image of the patient's eye is shown to the examiner on
the computer screen, and the image is manually focused and centered. Acceptable maps had at
least 10.0mm of corneal coverage. Moreover, images with extrapolated data in the central
9.0mm zone were excluded. Regarding the measuring procedure itself, patients were asked to
blink and then look at the fixation device. In case of low-quality image, the procedure was
repeated until the acceptable criteria were met.
The data from the FFKG were compared with those from the CG in separate series analyses.
Receiver operating characteristics (ROC) curves were applied to determine the overall
predictive accuracy of the test for each studied parameter, as described by the area under
the curve. We also used this approach to identify the cut-off points for studied parameters
to maximize sensitivity and specificity in discriminating FFK cases from normal corneas.
Logistic regression was used to support the cut-off point identified in the ROC curve
analysis. We determined a cutoff value that will gave us the best predictive fit for our
sample data. Furthermore, logistic regression analysis was performed to determine the
predictive capability of a model that combined both corneal biomechanical properties and
pentacam derived anterior segment parameters.
Differences between groups were evaluated using the Welch modified Student's two sample
t-test and Mann-Whitney U test, according to normality of distribution for each parameter. A
Kolmogorov-Smirnov test of normality was applied to all variables of each group. The level
of significance for each parameter was set at p<0.05. The Pearson and Spearman tests were
performed in order to assess correlations between anterior segment parameters and
biomechanical properties, depending on their parametric evaluation.
n/a
Observational Model: Case Control, Time Perspective: Prospective
Status | Clinical Trial | Phase | |
---|---|---|---|
Recruiting |
NCT04570020 -
Scleral Lens Fitting Using Wide-Field OCT
|
||
Recruiting |
NCT02921009 -
McNeel Eye Center Corneal Crosslinking Study
|
N/A | |
Terminated |
NCT02762253 -
Study of the Safety and Effectiveness of Photochemically Induced Collagen Cross-Linking in Eyes With Keratoconus.
|
Phase 2 | |
Completed |
NCT01691651 -
Botulinum Toxin A for the Treatment of Keratoconus
|
N/A | |
Completed |
NCT01527708 -
Accuracy of Curvature and Wavefront Aberrations of Posterior Corneal Surface, in Keratoconic and Post-CXL Corneas
|
N/A | |
Completed |
NCT01527721 -
Blurring Strength & Aberrometric Changes Following Corneal Cross-linking (CxL) and CxL Combined With Photorefractive Keratectomy (PRK) in Keratoconus
|
N/A | |
Recruiting |
NCT00841386 -
Treatment of Keratoconus Using Collagen Cross-Linking
|
Phase 2/Phase 3 | |
Completed |
NCT00347074 -
A Clinical Study of Keratoconus in Asian Patients and Assessment of Different Topographic Patterns of Keratoconus in Asian Patients
|
N/A | |
Completed |
NCT03187912 -
Accelerated Corneal Cross-linking With Different Riboflavin Solutions
|
Phase 3 | |
Completed |
NCT00584285 -
Corneal Topographer Fluorescein Patterns
|
||
Completed |
NCT03511495 -
Reliability of Topography Measurements in Keratoconus
|
||
Not yet recruiting |
NCT05395650 -
Cyanocobalamin as Photosensitizing Agent
|
||
Completed |
NCT04418999 -
Safety and Efficacy of Intracanalicular Dexamethasone Compared to Loteprednol Etabonate in Patients With Keratoconus
|
Early Phase 1 | |
Completed |
NCT03235856 -
Retrospective Digital Computer Analysis of Keratoconus Evolution - REDCAKE
|
||
Completed |
NCT05019768 -
Topo-pachimetric Accelerated Epi-On Cross-linking Compared to Dresden Protocol Using Riboflavin With Vitamin E TPGS
|
N/A | |
Withdrawn |
NCT01789333 -
Higher Irradiance in Keratoconus Ectasia
|
N/A | |
Completed |
NCT05114928 -
Correlation Between Q-value Changes and Progression of Pediatric Keratoconus.
|
||
Completed |
NCT03647046 -
Custom Anterior Surfacing of Scleral Lens for Vision Quality Improvement in Patients With Keratoconus
|
N/A | |
Recruiting |
NCT04439552 -
fMRI and IVCM Cornea Microscopy of CXL in Keratoconus
|
||
Recruiting |
NCT06100939 -
Epithelium-On Corneal Cross-linking in Subjects 8 to 45 Years of Age With Keratoconus
|
Phase 3 |