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Is there a link between corneal structure and the 'corneal cross'?
1Department of Electronic Engineering, La Trobe University, Bundoora, Victoria, Australia.
Eye (London, England)
|January 1, 1997
Summary
The corneal cross phenomenon, previously linked to corneal birefringence, may instead be caused by the cornea's curvature. This optical effect is observed in other curved surfaces, suggesting it's not unique to corneal structure.
Area of Science:
- Ophthalmology
- Optics
- Biophysics
Background:
- The 'corneal cross' is an optical phenomenon observed during polarized light examination of the cornea.
- It has been traditionally attributed to corneal birefringence caused by anisotropic structures or multiple reflections.
- This phenomenon is characterized by a cross-like pattern visible when polarized light reflected from the cornea is viewed through a crossed analyzer.
Purpose of the Study:
- To investigate the origin of the 'corneal cross' phenomenon.
- To determine if the corneal cross is exclusively related to corneal birefringence.
- To explore alternative explanations for the observed optical pattern.
Main Methods:
- Reflection of plane-polarized light from the cornea and isotropic curved surfaces.
- Observation through a crossed analyzer.
- Use of a gonioscopic lens to neutralize corneal curvature.
Main Results:
- Isogyres (cross patterns) were observed not only from the cornea but also from isotropic curved surfaces.
- The corneal cross pattern disappeared when the corneal curvature was neutralized using a gonioscopic lens.
- The presence of isogyres on isotropic surfaces suggests a geometrical optics explanation.
Conclusions:
- The 'corneal cross' is not a specific artifact of corneal birefringence.
- The observed pattern is likely an optical artifact related to the curvature of the reflecting surface.
- This finding challenges the traditional interpretation of the corneal cross as solely indicative of corneal anisotropic structure.