Differentiating Keratoconus and Corneal Warpage by Analyzing Focal Change Patterns in Corneal Topography, Pachymetry, and Epithelial. Cont Lens Anterior Eye. Sep;26(3) Hydrogel contact lens-induced corneal warpage. Schornack M(1). Author information: (1)Department of. Before the advent of corneal topography, corneal warpage was generally described as a condition that included distorted keratometer mires.
|Published (Last):||1 December 2010|
|PDF File Size:||7.46 Mb|
|ePub File Size:||7.93 Mb|
|Price:||Free* [*Free Regsitration Required]|
When this particular technique of rubbing is employed, the cornea rubbed by the thumb is usually more affected. Published online Aug 2. Overall, in RGP-wearing keratoconus eyes, there is a paradoxical negative shift of the Warpage Index due to cone-apex RGP touch, except in the unusual case where the RGP-corneal contact is not at the cone apex. The warpage map is the product of the PD maps of anterior topography and epithelial thickness.
In summary, this study confirms that OCT-based epithelial PSD can detect corneal distortions with high sensitivity and specificity. Methods Pachymetry and epithelial thickness maps of normal, keratoconus, and warpage, and forme fruste keratoconus FFK eyes were obtained from a Fourier-domain optical coherence tomography OCT.
In summary, this study confirms that OCT-based epithelial PSD can detect corneal distortions with high sensitivity and specificity. The Warpage Index is positive for warpage and negative for keratoconus, except in cases where keratoconus and warpage coexist.
The novel Anterior Ectasia Index and Warpage Indices can be used to distinguish between keratoconus and warpage.
This work is licensed under a Creative Commons Attribution 4. There were no keratoconus participants who used soft contact lens. They can be differentiated by the OCT epithelial map, which shows matching focal thickening in warpage and thinning in keratoconus. The resulting slit images were captured by a digital video camera and used to reconstruct the topography of corneal surface.
Nine of the contact lens-related warpage cases were correctly classified Correlation between epithelial thickness in normal corneas, untreated ectatic corneas, and ectatic corneas previously treated with CXL; is overall epithelial thickness cornesl very early ectasia prognostic factor? This is contrary to the positive Warpage Index we see in nonkeratoconic contact lens warpage.
The pachymetry map shows focal thinning in keratoconus, but not in warpage. It is calculated by the dot product of the PD maps of anterior topography and epithelial thickness Equation 1. On their own, these maps cannot differentiate keratoconus from other corneal pathologies with similar topographic patterns, such as contact lens-related warpage, dry eye disease, and epithelial basement membrane dystrophy. National Center for Biotechnology InformationU.
Those with negative Warpage Index values are diagnosed with keratoconus, while those with positive Warpage Index are diagnosed cormeal warpage. Normal subjects enrolled in this study were LASIK candidates who had no ocular diseases and have not been wearing contact lenses for at least 2 weeks prior to the exams.
Conclusions The epithelial PSD can distinguish normal from keratoconus or warpage, but does not distinguish between these two conditions.
Ectasia or permanent corneal warpage?
The initial corneal profile is depicted by an arc of a circle A. The warpage map is the product of the PD maps of anterior topography and epithelial thickness. Contact lens warpage was defined as contact lens wearers with topographic abnormality.
Intrinsic position uncertainty impairs overt search performance. Kanellopoulos AJ, Asimellis G. Keratoconus subjects included in this study were diagnosed clinically with the following inclusion criteria: However, topography is not sensitive to very early stages of keratoconus when the topographic steepening is masked by focal epithelial thinning. Schallhornand David Huang. The repeated trauma accounts for the corneal deformation seen. Epithelial pattern standard deviation PSD was waroage and combined with two novel indices, the Warpage Index and the Anterior Ectasia Index, to differentiate between normal, keratoconus, and warpage eyes.
Similarly, though Warpage index is positive in all warpage eyes and normal in most keratoconus eyes, warapge fails in cases where keratoconus and warpage coexist. The epithelial PSD was normal 0. You must be signed into an individual account to use this feature. The pattern deviation PD map was defined as the percent deviation from the normal reference map i. To differentiate between keratoconus and contact lens-related corneal warpage by combining focal change patterns in anterior corneal topography, pachymetry, and epithelial thickness maps.
Ectasia or permanent corneal warpage? | Defeat Keratoconus
Keratoconus subjects included in this study were diagnosed clinically with the following inclusion criteria: This system projects 40 optical slits, 20 from the right and 20 from the left, onto the cornea at a degree angle. LiOptovue, Inc. After years of vigorous rubbing, the corneal distortion can become very pronounced, leading to severe irregular astigmatism.
OCT corneal epithelial topographic asymmetry as a corenal diagnostic tool for early and advancing keratoconus. You can manage this and all other alerts in My Account.
Although a negative Warpage Index was consistent with keratoconus, corneao wanted to incorporate the pachymetry map information to further confirm the classification. One should not interpret this as an area of local protrusion. On the other hand, an abnormal i.
It occurs in Marfan syndrome, in which the cornea also thins and flattens read: SchallhornNone; D. Those with negative Warpage Index values are diagnosed with keratoconus, while those with positive Warpage Index are diagnosed with warpage. Open in a separate window. The Warpage Index was designed based on the insight that anterior focal steepening is accompanied by focal epithelial thickening in contact lens-related warpage, but associated with epithelial thinning in keratoconus Table 1.
Identifying progression of subclinical keratoconus by serial topography analysis. Though the Anterior Ectasia Index can separate the keratoconus and normal group perfectly, it does not differentiate between the warpage and normal group. The pachymetry map shows focal thinning in keratoconus, but not in warpage.
To date, all keratoconus diagnostic algorithms only attempt to distinguish keratoconus from normal eyes. Eyes with late keratoconic changes such as corneal scars or hydrops were excluded as they did not pose any diagnostic challenge.